TBE UNIVERSITY OF TEXAS PUBLICATION NO. 5716 August 15, 1957 Occurrence of Oil and Gas in West Texas Edited by Frank A. Herald BUREAU OF ECONOMIC GEOLOGY THE UNIVERSITY OF TEXAS, AUSTIN John T. Lonsdale, Director Publications of The University of Texas COMMITTEE ON PUBLICATIONS L . u. HANKE H. Y.McCowN c. L. CLINE A . MOFFIT J.R.D.EDDY c. P. OLIVER J. T. LONSDALE B.E.SHORT s. A. MACCORKLE J. R . STOCKTON C. T. McCORMICK F. H. WARDLAW ADMINISTRATIVE PUBLICATIONS AND GENERAL RULES H. Y. McCowN c. H.EADS J. G. ASHBURNE F. H. GINASCOL M. v. BARTON B. GONZALES c. E. LANKFORD The University publishes bulletins twice a month, so numbered that the first two digits of the number show the year of issue and the last two the position in the yearly series. (For example, No. 5701 is the first publication of the year 1957.) These bulletins comprise the official publications of the University, publications on humanistic and scientific subjects, and bulletins issued from time to time by various divisions of the University. The follow­ing bureaus and divisions distribute publications issued by them; communi· cations concerning publications in these fields should be addressed to The University of Texas, Austin, Texas, care of the bureau or division issuing the publication: Bureau of Business Research, Bureau of Economic Geology, Bureau of Engineering Research, Bureau of Industrial Chemistry, Bureau of Public School Service, and Division of Extension. Communications con· cerning all other publications of the University should be addressed to University Publications, The University of Texas, Austin. Additional copies of this publication may be procured from the Bureau of Economic Geology, The University of Texas, Austin 12, Texas PUBLISHED BY THE UNIVERSITY TWICE A MONTH . ENTERED AS SECONO­ CLASS MATTER ON MARCH 12, 1913, AT THE POST OFFICE AT AUSTIN , TEXAS, UNDER THE ACT OF AUGUST 24, 1912 TBE UNIVERSITY OF TEXAS PUBLICATION NO. 5716 August 15, 1957 Occurrence of Oil and Gas in West Texas Edited by Frank A. Herald BUREAU OF ECONOMIC GEOLOGY THE UNIVERSITY OF TEXAS, AUSTIN John T. Lonsdale, Director The benefits of education and of useful knowledge, generally diffused through a community,· are essential to the preservation of a free govern­ment. ·Sam Houston Cultivated mind is the guardian genius of Democracy, and while guided and controlled by virtue, the noblest attribute of man. It is the only dictator that freemen acknowledge, and the only security which freemen desire. Mirabeau B. Lamar OCCURRENCE OF OIL AND GAS IN WEST TEXAS Compiled by BUREAU OF ECONOMIC GEOLOGY, THE UNIVERSITY OF TEXAS in cooperation with WEST TEXAS GEOLOGICAL SOCIETY WEST TEXAS GEOLOGICAL SOCIETY BUREAU OF ECONOMIC GEOLOGY Presidents Project Supervisor & Editor John M. Hills 1950 Frank A. Herald W. Dave Henderson 1951 L. E. Patterson, Jr. 1952 W. Henry Conkling 1953 George R. Gibson 1954 Research Assistants Addison Young 1955 John E. Woodward C.H. Atchison 1956 John W. Dietrich Nugent T. Brasher 1957 Typists & Compositors Project Committee Chairmen Marilyn Defrates (Mrs. Clyde, Jr.) Charles F. Henderson Marilyn J. Schulle (Mrs. Wallis E.) George R. Gibson Lois I. Watson (Mrs. Wm. E., Jr.) F. L. Stead Lila Williams (Miss) Paul H. Kolm Eloise Hill (Mrs. Geo. W.) Charles D. Vertrees Draftsmen Editors Rhoda S. Clark (Miss) (R) E. Russell Lloyd Norman E. Croslin (N) Addison Young Jerome C. Hejl (C) R. V. Hollingsworth Arlette C. Hill (Mrs. H. L.) (H) Charles D. Vertrees Patricia Mathews (Mrs. John) (M) Johnny L. Mock (J) Melvin W. Parse (P) Dan F. Scranton (D) Most of the authors are Betsy D. Shatley (Mrs. D.R.) (G) members of the West Texas Donald H. Speck (S) Geological Society. Barbara Warren (Mrs. C. D.) (B) CONTRIBUTING AUTHORS Bailey, Marshall W. Russell Beaver, Paul J. Flat Rock Bentz, Felix P. Martin Bodjo, J. A. Hoover Simpson Boney, B. H. Petersburg Brown, Jackson B. Elkhorn Buthman, B. David Crossett Byerley, L. G., Jr. Parker Caffey, William M. Tucker Carlsen, Marvin T. Canning Cravens Carter, William H. Lee Harrison Carver, Hershel S., Jr. Tucker Caussey, Donald E. Homann Cockburn, Archie B. Brahaney Henard Cole, Thomas H. Water Valley-Clark Cooper, C. G. Bedford Monahans Nelson Ownby TXL Waples -Platter Cotton, James Russell Parks Cox, J.B. Cox Creager, Barbara M. McKee Custer, M.A., Jr. Polar Daugherty, D. E. Hoover Simpson Donoghue, David Yates Douglas, E. R. Seminole Elam, Jack G. Abell Elkin, James L., Jr. East Polar Ellis, William B. Von Roeder Ellison, Samuel P., Jr. Apco Page Ferris, B. J. Bedford Monahans Nelson Ownby TXL Waples -Platter Forward, Fred Harper Fuszek, John Northwest Block 31 Galloway, W. D. Smith -Spraberry Glaze, Frank L. Adair Graham, D. W. Susan Peak Grice, Charles R. Lancaster Hill Gupton, W. L., Jr. Yates Harbison, Robert R. Pegasus Sweetie Peck -Warsan Wilshire Hardwick, J. V. Block 31 Hargrave, Rolla E. Huddle Harris, Roy Gib Hartman, F. H. Mc Elroy Henderson, W. Dave Fuhrman -Mascho Hills, John M. Fuhrman -Mascho Hodges, Jake W. Lehn-Apco Holloway, C. K. Lion Holme, J. D. Olson Shannon Horkey, Joe R. Dixieland Hughes E. S. Hurdle McCamey Webb Ray Hyde, B. Cooper Arick Jordan, J.B. Mccutchen Kennedy, Edward R. , Jr. Pruitt Quito Verhalen Wil-John CONTRIBUTING AUTHORS Kiene, J. R~ Arledge San Benito Keener, M. H. L . Dollarhide Knox, Gordon S. Mason Le Blond, R. E. Wheeler Ley, Ross H. Pecos Valley Lindeblad, E. E. Block 47 Friend Lisman, Richard A. Brushy Top Tennyson Luckett, Joseph W., Jr. Chancellor Mason, Marshall L. , Jr. South Brownfield McCool, H.J. Hoover Simpson McDearmon, Booker Monroe McGee, Edward F. Baugh Mclnnis, A. B. Mc Elroy Muery, Warren World Murphy, James P. White & Baker -Walker Lehn -Apco Neel, Charles S., Jr. Doss Nichols, Joe M. Miers Ogden, Bill C. North Gail Osborne, W. C. Keystone South Keystone Patterson, L. E. , Jr. Clara Couch Pederson, Clyde M. West Seminole Preston, C. S. West Anton Raney, Donald R. Oates Rascoe, Clyde M. Russell Redline, R. Leland Reinecke Reid, William T. Tunstill Reiter, F. H. Wheat Risley, E. C. O'Donnell Scherer, John E. North Polar Schiemenz, A. M. C-Bar Schneider, W. T . Wasson Schreiner, Carl S., Jr. Good Sides, Jerry F. Carter Skrabacz, C . F. Marvin Smith, M. V. West Anton Spencer, Maria World Stafford, Philip T. Scurry Stephenson, Marion R. Dunn Stine, E. V. Clairemont Sweet, John M. Midway Lane Taylor, Robert H . Taylor -Link Tharp, R. L. Marvin Monroe Thornton, Jack D. Breedlove Van den Bark, Edwin Embar North Goldsmith Vaughn, J.C. Addis -Johnson -Foster ­South Cowden Waldrep, J. L. , Clairemont Watson, R. N. Martin Whealdon, E. P. Dockrey Williams, J. L. Emma Williford, J. L. Harris Winkler, C.R., Jr. Wendland Yager, Perry L. Jones Ranch Young, Addison Addis -Johnson -Foster ­South Cowden Zimmerman, James B. Shafter Lake -Deep Rock OCCURRENCE OF OIL AND GAS IN TEXAS ., . . r--., KERR i , ,,, HAYs , / • AusT1N , c;:.. ~--, I PRESIDIO :•• l. • •B•R•E•WS•T•E•R• • • • • .''-. VAL VERDE , EDWARDS , • 'KENDALL)" ·-....., ' '\.. , FAYETTE/\, • "'~ HA~~IS • j • ( REALl-----___[ , GOMAL v"!'ALDWELCX / -. \-· , , A BERS, \ • BA NDERA /,.__< ./ "\. · ' , \. ' -........ • ', '"t ~----,\__ _J__T ___....-r ~UADALUP;;' r--~ ~· \ i I i "'· , ' r-.. , \~AVERICK, ZAVALLA j FRIO , ATASCOSA ).KARNES)'' ..... ' L . I ' <-"'-<: GOLIAD I , -----\----1·--y ' ' ) \ I DI MMIT I i i \\ BE(-yREF UGIO \ I _ _ ___ j LA SALLE __ tCMULLENi u vE OAK\_}. -..!-- · • ' SAN I ' '\ L--·-;---_J·r·--1,,,, PATRICI O \ i i J1M('---)/) SCALE "' WEBB ' DUVAL IWEL~NUECES f' , I .. '-·- j I ! KLEBERG ___ , .r-·;__ ..J....,.. ..... L ir.-----~--­ ! EL PASO --i----­.'-"... ! i \ I ' . I '-~ Huos ~, PETH / CULBERSON ' I : ""' '1 , , ' I / "'-' • / ',0,/ JEFF DAVIS '\---­ ~ ­ ) • . 1--~----,--,-r-:=J 1 DALLA M iSHERMAN~NSFORD~CHILTREEiLIPSC~M01 ~----j---f---j____ _;_ __ ]' I HARTLEY ! MOORE iHU~Ct~N-!ROBERTSiHEMPHILL ~----L--~---l---L--J L_o~~':___to::):'.:J_::'J:"J : I 1'ARM-'1 '1coLLINGs-' I D(Af SMITH 'RANDALL' STRONG • DONLEY • WORT~;,-1 1 ---,-J_r--.l,---l,---l-, __J : PAR MER • CASTRO ISWISHER ! BRISCOE ! HALL iCRHtk~-~ _J ' ' :'Jv' ----..L-----,J----~AROE~AN, \ : • • • • • • • • • • ·:;;,:,~ • • ::M~ • '• ~;,; • i ~:d,; "!:o•T:~;i~;;T;•E i ''---!WILBAR:r:~:i~-\,"\.., (i',,J( ~~~ : . : : . : . : • : : • : • : · ///////////////////////////. ~· --l--T! --+---1--f-:l i -'~~'--~---+---~ CLAY i, r-"'l,n '-YP : LAMAR i "f,,,,.,,m I . ' . n ' i 'MONTAGUE! COOKE I GRAYSON ~FANNIN I ' RIV R I aowl[ -~ 'COCHRAN. HOCKLEYiLUBBOCK! CROSBY IDICKENS! Kl~G ! KNOX iBAYLOR! ARCHER' ___ ! ---L,---lw/~----1''~:~~:-:J y·-·1!?. .___ __J __+--t---+ --t--:H----t--~----r l . ~~ 1'I". l~lmus1:g. I I ' ' ' ' • ' I KI '1 JACK I WISE I DENTON OLUN ' HUNT 'HOPK INS ':· '·~I CASS YOAKUM' TERRY I LYNN !GARZA I KENT I SJ~~~ I HASKELL! ~i~~i;. YOUNG' ' ' __Ji__ -1 ,.L.,_ _--1"'-0A~':S'j____ ~ _J L L ' ' 1l ~-_J__,. L ---y//; "RW' "RAINS' \__MARION\ il ,___ --r -, -,_L_-,_J__. --,--, --, I ' I!' c.J---,-' -1 WOOD l uPSHUR ' ---" I ' • • ISHACKEL-' ' PALO I PARKER I TARRANT ~DALLAS~ ' VAN " ' ..1J ~ GAINES I DAWSON [BORDEN ISCURRY I FISHER_ JONES ' FORO [STEPHENS! PINTO ' I ~--~AUfMAN\ ZANOT ~-----..L -.,-~'HARRISON ------i---1---+----i----: ' ----+----+-----11 ----t~,;;-,l-I---w ;._.J---~'\ SMITH ~--"-';·~-~ ' • I ' • ' ' ' • __.JOHNSON 0 ELLIS /' • I I PANOLAl : ANoREws 1MARTIN !HOWARD IMITCHELL! NOLAN~ I TAYLOR !cALLAHAN ! EAsTLAN_o-( ERATH ',.... sv,~d,,,,p.. _,,,.,,,.-~,HENDERsoN_..i----1 RusK • __ _ __}-' ' "' [ I ,/ ' V -ft,_"" \-( NAVARRO ~ ---' ' '\ --.----r---,i--,1--, .L.-; L., --.... --( \ "\ -,..-''\ \ CHERO·'<----~ SHELBY~ l'l:HILL --' . . GLA i ' I ' i '~MANCHE'."""<' ~ ,/" ) __ ......-'-4N OERSON'\,KEE • NAC OG-\ ~ 'BOS02E ·1. LovrNG I WINKLER I ECTOR IMIDLAND I co~:· 'STERLI~ COKE •RUNNELS lcoLEMAN ' BROWN. ,/' \ /h, \ -· \rREESTONE~1r ~ \ DOCHES \ -v€$0 """ • ' . · 1 I----~ . , I \.-yHtiMtLTON ... -\ ~r , LIME· \ ,,......~---...... , A._ •SAN/ ?.: ""l-L--+--f----+---•I= J __ 1 ..f \ ,,·,... M-~ --, ~uws;SAB·~ CLENNAN > sroNE \./ ~ wARD • I ·.=-....., • r ' .1 /. MILLS • ~ • ' ..r 'HOUSTON 0. , · nNE\ , \...""" ! cRANE ! PT • RE AGAN' ~ TOM~ '1 '1L "I.... ·1 '"'-..1.. . "'-0:./ \ /~ dr/////~ ~ANGELINA~-d~ ..~ ...>"\ coRYELL LE~N REE --->---.; -I u ON I I IRION I GREEN, CONCHO ' ')/ \ , ~~ rALLS ,/ ' /,[ , ""t~:{I/~ ' 1 1 VES /. '\...,'! ' I ' ' • MCCULLO~ SAN 'LAMPASAS• ,/ ~-~ROBERT-\ ') (TRlNIT;/ '~ ·, JAS-\NEW-, / ~----J__ _J_-, __J ___ • 4--~ • SABA '\____ )' BELL v· .~.SON,$ W.DISON :y' \ • \ •PER TON ' -------, ' . '-r---L-,----' ',___ / "" ff'---(-~'< POLK 'lVLER\ ' ! ' /. PECOS l I SCHLEICHER ! MENARD ' .., / ---• MILAlil --,, ,--' I i L j_ --s 4-\ --\,/\BURLESON\ > \ --." <' \ HARDON ( _j_ ( , -,_ ' ~ I SUTTON : I KIMSLE -:-· -~AN?o• .,, ./ ><: LH·'\. _,.......,.. ................, ,MONlGOMERY, \ -r-· -~ ·, ,_J • • -----1 GILLESPI[ I /\,TRAV IS I '· ; WASHING;..'-·~ AUBERlY• • ./ ~ANGE, , r '------J...-1 --JI 1 , , , ,_..... TON, .zt-..i--~-/" 1 '-/ ''-i TERRELL j -, : i '----,--\_ / '>(BASTROP\/ \----'\f'\, '-' '; _j_;£FFERSDN: I : ' l . (.. ZAPATA [ JI M HOGG~BROOKS [\ j , •KENEDY , i----...Lr--1 '\,J STARR J \---­ / . ~.,WILLACY -,"-..,/._ HIOALGO "\.,_ __ .,J_C:~ERDN '\._,_:' EXP LANATION Boundary of ar ea covered by mop on opposite page . All fields treated in this volume ore located within this boundary Boundary of area defined os WEST TEXA S for the purposes of this project Boundary of area defined os NORTHEAST TEXA S for the purposes of PubHGotion 5116, OCCURRENCE OF OIL AND GAS IN NORTHEAST TEXAS OCCURRENCE OF OIL AND GAS IN WEST TEXAS ··························· ··················· ······················ ........................... ································· ··············· ······ ························ ··· ········ ··········: __1__1 I I MOTLEY COTTLE BAILEY LAMB HALE FLOYD I , I I· ROOSEVELT Pt1t rsburq., L_l I ~-----+---~.. ---~--~--------f---_· I Wut Anion I C1o vens · · I .•" I I ~~=------J· C~RAN j L~~CROSBY W«, HOCKLE~ ~ ~.'~'a.;:.• i DICKENS CHAVES I • -• •I . ' II . ." •.;. ,. ,, I ~ . .; ~-~· --. -~-~-+--------~-----+-----~ --. 1.J • > i. YOAKUM , • I ·1~·,. . ·, ' , J, •·"~"'~' .I I·'"'°\.. ·-~ .'"' ~ ..~1KENT J 4 ,. . .. . •ohoney • o.rn,. TERRY LYNN ~ .i 4' .,, • ' . f . opluJ ,. Soulh 1 1 'GARZA \ 1 Clairtmonl . I • ' · Plotlt) 4' Brownl1eld l ' ••• Nor lhPol.o: t •·· · j LEA ' J, . • O'Donnell ~ 1• 1 "Ill • , ' 6'Eost Polo• ~ Wasson I I • ' ' ' Polor 'I I •1 ,-: ·,• . J~::,,. -..-1-----~--r--,.-l-,~---~ _J_____ r,·_.J_,_ ---,-- .. _*-. =: Sproberry . 1 Nor lh ,,.. •......~ ·1' ·4 ,• • ""'•-.'!' • ·.,. 1 " Go 1I \. . Scurry l .1 . ·~ : • . .. . ... r -. ·~ 7 •;:~.~:;',, ' ~,.,.: : 1·•.. ., ""1 BOROEN • 1'· , .SCURR.·Y '1, F/SHER. : : _: 0 '• t Sem1~0~ GAINES ~~!;;.,SON #': ' ( ' I Conn1n9 • •' D I ~-I I i : /". . . •.. :. "' ~ ' . . ... ·:~~ .·.:::4·.:. . ' ,, ' 1 \ .'~!t-z.:=----·-· r, • ·1 ~·-~·-r.-'.:._,~ ANDREWS I MARTIN I ... ' ~.,.MITCHELL 1' ~.. , : -:;ary ... ~ HOWARD . ' ~krey NOLAN . : ~~'1_ ..,.. i ":... ~I . 1/. ·~. I :l c.., • . -' ..---'... . . ' ~l --· -rt........;,-.-LI _' __--'-T·l_._--1·· _1_ _' -~---,Arled9e --·-· • · 1 ,.,..,-_ . -• .. ~moth ECTOR i ' : '1 . ..son eemto °. ' Keystone Ad dis-Johnson-Fosler-" • • 1 Correr ~ ' '. , ~ 'l '"'d":l "w • ' • 1·· Co~••\ \ • . ; . I • ( ""':,;,. I so~• · .,. '•• ~ ' · -GLASSCOCK • . ' ' ~ ··~·'" .,.$ ,,,,, MIDLAND ~ 5_TERLING I COKE .: '"'""' \ ~l '\.\ !' H~--~. 5:,... J.,.;:aA'''"" " ! """" • j_ l•ooy~1: "'"'''"' ~~~-,-~f"._.?· ----~ ,.~:te;VoUey-~o;;-_----.-. -, ~ ·. (~·i· ' . -' ~~-~~__:_-,--i . : c-e,., ;, \'t4 " r.\ ... ' · ~ ·;.....,.: I .·1 · : • .-; e1ock31 ' • • , 00, "''" ·'tt.. UPTON , . TOM GREEN a REEVES •• -?'.~-·,CRA~;~, \ : ~ I. /RION I . ' j ,~A;j;-'-t_ · ' • ' t • 1 SusonPeok f ;~ 't • ~' . ~ • McCamey Flot Rock\)I •· .• I , ,· •· • I ~ • '.~ / ~ •.._ Lehn-Apco ) • •, •• · • t ;• ;1 4 J· r ,,. , 1 • Hurdle 1 • •• 1 / I • ' ''"' " '' .•,.,..... . • . . I . • ,..,..... l__ . . ,, L I : Ve1ho len / ··· ~~~~~----_l_-~.-.--'··~t . ·----r______,_--.-.. :~-·:I . ., ~ "'--~-"\..-· , '9': :' Block 47 1 C • ; .. ·: »."' .,... . . I : "'"' . Bok..- Chonce llo1 . • ~~'"" . ' -,. . ; """"' .;:'.:~· ' SCHLE!Cf!ER . ..,.,, :I '"" -"" / "-' ''''"-lmk'-~ Yotes , °'"" ~"''"";" ' -,, ' •.~ f' , ' • ; PECOS • \ ~-• 1' C 6 { .,, '9S1mpson '• · · Poqe • JEFF ""' -~-/ • CtoroCou~~;.~ ' Hoover "' '~ t Brush y ~~ DAVIS Oates" \_ .co. CROCKETT . ---T-:j-·--. -­ ~ ___l__ ·Loncosler f .,... ,>-,-~------1. ,,,, I . .• . /, ""'­, / ""-""-/ i :1rTON TERRELL I ·--( I ,-_J ., ." I r.' ' f-----.-_____ ___l _____, .----­ EXPLANATION BREWSTER ' c ' •· I I I " · • Fields treated 1n this volume VAL VERDE EOWAROS I I I • Other produc ti ve oreos as of Moy I, 1957 I •••••••••••• •• ••••••••••• • ••• •• •••• •• ••• • •••• • •••••• •• •• •• •• • • •• •• • •••••••• • •••••• • •• • ••• . •••••••• . •• . •• . ••• • •• . ••• • •• • ••••••••••••••••••••••• • •••••••••• , •••••••••• • ••••••••••••••~o-~p·ll·e~. ~Y. ~.~ ~-•••••• •••• ••• N PREFACE This volume is the second in a series which was planned for presentation of data perta ining to the occurrence of oil and gas in Texas. The prior volume, OCCURRENCE OF OIL AND GAS IN NORTHEAST TEXAS (Publication5116) includes treatment of every commercial occurrence of oil and/or gas discovered in the designated area prior to January 25, 1950. When the project for West Texas was undertaken, it was hoped to present corresponding data for all fields in West Texas which had been discovered prior to a definite date (later set a s Jan. 1, 1951). Although we were not able to accomplish that goal, the papers presented in this volume serve remarkably well to convey an understanding of the occurrence of oil and gas in West Texas. The fields treated provide examples of nearly all significant conditions of nature which would have been exemplified if coverage were complete. This volume contains 112 papers by 104 authors. The distribution of fields treated is indicated on the map on the next preceding page. That map also indicates the geo­graphic relationships with other productive areas. The approximate distribution of productive areas is shown as of May 1, 1957. Field names for only the fields treated in this volume are entered on that map. Names of many nearby fields are shown on the maps in the following papers and also are entered in the FIELD NAME INDEX at the back of this volume. During the time the project has been in prog­ress, there has been extensive development in West Texas. Many new fields have been discovered and new reservoirs have been discovered in known fields . The manuscripts on which this publication is based were received in this office throughout the period since shortly after the project was launched until shortly before the completed volume goes to the printer for printing by the offset process. The first paper was received on June 11, 1951, and processing for publication was immediately initiated. As soon as practically possible after its receipt, each paper was setup and submitted to its author for check­ing and then it was put in final form (except for page numbers and for certain changes of type in headings) for printing by the offset process. Many papers have been revised to recog­nize all developments subsequent to the dates entered on the original manuscripts ; the dates of such papers have been changed accordingly. Each paper presents data available as of a particular date, which date is clearly indicated in the heading. In this project, the primary units of presentation are field papers. The fact that the reservoir is the basic unit in nature is recognized in the design of the field papers. To accomplish maximum utility, to assist in getting com­parable data for the many fields and to facilitate state-wide summarizations, an effort is made to s tandardize the con­tents of the field papers to the greatest extent feasible without forfeiting meager data where only meager data are a vailable and without any limitations on presentation of significant facts in addition to those indicated on the check-list. In order to accomplish clear presentation of data for each reservoir separately, the method of presentation ' in this project relies largely on graphic representation on TYPICAL SECTION OF ROCKS PENETRATED. Since only few West Texas reservoirs are named, the designations that are herein used, generally, are the names of the smallest stratigraphic units which wholly contain the re­spective reservoir rocks ; however, designations that are established as reservoir names a re us ed in a few of the papers. Generally, the designations in the text are inclusive stratigraphic names which serve as references to TYPICAL SECTION OF ROCKS PENETRATED, where the stratigraphic position and vertical extent of each reservoir rock are shown by symbol (vertical bars in the extreme right column). In the preparation of their papers for this volume, the authors were guided by Publication 5116, OCCURRENCE OF OIL AND GAS IN NORTHEAST TEXAS. The original check-list and the original suggestions to authors continued effective and are presented in ·the appendix at the back of this volume. These items were supplemented by circular letters, one of which contains a definition which is appropri­ately presented here. That definition is as follows : DEFINITION OF RESERVOIR ROCK: As to each reservoir, the reservoir rock is that portion of the stratigraphic section which yields, or has yielded, com­mercial oil and/or gas within the area of the field. Such stratigraphic unit constitutes the reservoir rock and is the unit for treatment regardless of its fluid contents at the margins of the field. This definition means that the downward extent of the reservoir rock is commonly determined by the chance position of the stratigraphically lowest commercial oil or gas; the chance position of water-level may determine the downward extent of the stratigraphic unit. The lithologic characteristics may be equally favorable throughout considerable additional section, but the mere fact that only water is yielded eliminates such additional lithologically favorable rock. The significance of the last two sentences of the above definition (applicable anywhere by deletion of "strati­graphic• in three places) may be illustrated by reference to the cross section in the accompanying paper on the Wheeler field where the thickness of the Ellenburger reservoir rock is represented by the distance from the top of Ellenburger at Well #7 to the oil-water contact below that well (page 405). The following listed annual publications, or their predecessors (names of certain organizations and certain titles of publications have been changed slightly), have presented regularly several items of information relative to the occurrence of oil and gas in West Texas : Statistics of Oil and Gas Development and Production, American Institute of Mining, Metallurgical and Petroleum Engineers (AIME). 1933 et seq. ; irregular and general, 1921 to 1933. Oil and Gas Field Development in United States, National Oil Scouts & Landmen's Association. 1931 et seq. Developments in West Texas and Southeastern New Mexico, Bulletin, American Association of Petro­leum Geologists, August issue in 1937; June issue thereafter. Annual Reports of the Oil and Ga s Division of the Rail­road Commission of Texas. 1939 et seq. Since most of the above indicated publications contain data relative to every field in West Texas producing at time of respective issues, specific references are omit­ted from SELECTED REFERENCES in the following papers; their complete listing in ea ch paper would require much space. However, for every field, these sources should be exa mined in any exhaustive research study. They have been used extensively in the compilation of this volume. Operators' engineering committees functioning in connection with cooperative operations in several fields keep good records and issue occasional reports to the respec­tive operators. These reports are valuable sources of information relative to certain fields and would be helpful in any exhaustive research studi es of the particular fields . Since these reports ha ve not been published, they are not sufficiently readily available to justify entries under SELECTED REFERENCES in the following papers. Frank A. Herald July 11, 1957 Project Supervisor CONTENTS Page vi Contributing Authors Key map of Texas viii Index map showing locations of oil and gas fields ix Preface Frank A. Herald x ABELL FIELD Pecos and Crane Counties, Texas . • • . . . . . . • . . • . Jack G. Elam 1 ADAIR FIELD Gaines and Terry Counties, Texas ....... . Frank L. Glaze 12 ADDIS-JOHNSON-FOSTER-SOUTH COWDEN FIELD Addison Young Ector County, Texas •......•.•..•.. and J. C. Vaughn 17 APCO FIELD Pecos County, Texas . . . . . • . . . . . . . . . Samuel P. Ellison, Jr. 23 ARICK FIELD Hale and Floyd Counties, Texas ....•...•..... B. Cooper Hyde 31 ARLEDGE FIELD Coke County, Texas J. R. Kiene 33 BAUGH FIELD Schleicher County, Texas •.......•....... Edward F. McGee 35 BEDFORD FIELD C. G. Cooper Andrews County, Texas ..•.•............. and B. J. Ferris 36 BLOCK 31 FIELD Crane County, Texas .•......••.........• J. V. Hardwick 40 BLOCK 47 FIELD Crockett County, Texas . . . . . . . . • • . . . . . . . . E. E. Lindeblad 4 7 BRAHANEY FIELD Yoakum County, Texas . . • . . . . . . . . . . . . . Archie B. Cockburn 50 BREEDLOVE FIELD Martin County, Texas Jack D. Thornton 53 BRUSHY TOP FIELD Sutton County, Texas • • . . • . . . . . . . . . . . . . Richard A. Lisman 56 CANNING FIELD Borden County, Texas • . • . . • . . . . . . . . . . . Marvin T. Carlsen 58 CARTER FIELD Glasscock County, Texas .................. Jerry F. Sides 60 C-BAR FIELD Crane County, Texas . . . . . . . . . . . . . . . • . . . A. M. Schiemenz 62 CHANCELLOR FIELD Pecos County, Texas. . • . . . . . . . . . . • . . Joseph W. Luckett, Jr. 65 CONTENTS Page CLAIREMONT FIELD Kent County, Texas E. V. Stine and J. L. Waldrep 67 CLARA COUCH FIELD Crockett County, Texas L. E. Patterson, Jr. 69 COX FIELD Crockett County, Texas • • • . . • . . . . . • . • • • . • • • . J.B. Cox 75 CRAYENS FIELD Lubbock County, Texas •......•••••.•... Marvin T. Carlsen 76 CROSSETT FIELD Crane and Upton Counties, Texas ••.......••. B. David Buthman 79 DIXIELAND FIELD Reeves County, Texas . • • • . . • • . • . . . . . • . . . . . . Joe R. Horkey 82 DOCKREY FIELD Mitchell County, Texas • . . • . . . E. P. Whealdon 85 DOLLARHIDE FIELD, Andrews County, and Lea County, New Mexico .•.. Texas, M. H. L. Keener 87 DOSS FIELD Gaines County, Texas . . • . • . . . . • . • . • • . Charles S. Neel, Jr. 97 DUNN FIELD Mitchell County, Texas • • . • . • . • . . . . . . . Marion R. Stephenson 102 EAST POLAR FIELD Kent County, Texas ..•.....•.••.•.•.. James L. Elkin, Jr. 104 ELKHORN FIELD Crockett County, Texas .......••..•....• Jackson B. Brown 107 EMBAR FIELD Andrews County, Texas ••.....•.•...... Edwin Van den Bark 110 EMMA FIELD Andrews County, Texas ....•••.••••.•..••• J. L. Williams 116 FLAT ROCK FIELD Upton County, Texas ... · . . • . . • . . . . • • . . . • Paul J. Beaver 120 FRIEND FIELD Reagan County, Texas •. E. E. Lindeblad 123 FUHRMAN-MASCHO Andrews County, FIELD Texas • W. Dave Henderson • and John M. Hills 126 GIB FIELD Crane County, Texas . . . . . . . • • • . . . • . • . . . . . . Roy Harris 132 GOOD FIELD Borden County, Texas • • • . . . • . . • . • . . . Carl S. Schreiner, Jr. 134 HARPER FIELD Ector County, Texas . . . . . . . . . . • . . • . • • • • . Fred Forward 137 CONTENTS Page HARRIS FIELD Gaines and Andrews Counties, Texas • • • • • • • • • • . J. L. Williford 141 HENARD FIELD Yoakum County, Texas . . • • . • . • . • • • • • • • Archie B. Cockburn 144 HOMANN FIELD Gaines County, Texas . • • • . • . . • • • • . • . • • Donald E. Caussey 145 HOOVER FIELD D. E. Daugherty, Crockett County, Texas • • • • • . • . . . H.J. McCool and J. A. Bodjo 148 HUDDLE FIELD Dawson County, Texas • • • • • • . . . • . • . • • • . Rolla E. Hargrave 150 HURDLE FIELD Upton County, Texas E. S. Hughes 152 JONES RANCH FIELD Gaines and Yoakum Counties, Texas . . • • . . . . . . . Perry L. Yager 153 KEYSTONE FIELD Winltler County, Texas . W. C. Osborne 156 LANCASTER HILL FIELD Crockett County, Texas Charles R. Grice 172 LEE HARRISON FIELD Lubbock County, Texas William H. Carter 174 LEHN-APCO FIELD James P. Murphy Pecos County, Texas and Jake W. Hodges 176 LION FIELD Ward County, Texas . • • • . • . • • . • • • . • . • . • C. K. Holloway 181 MARTIN FIELD R. N. Watson and Andrews County, Texas · • · · • •••••••.••.. • Felix P. Bentz 183 MARVIN FIELD R. L. Tharp and Sterling County, Texas .•••.••.•••••••••.• C. F. Skrabacz 190 MASON FIELD Loving County, Texas • • • . • . • . • • • . • • • • . • • Gordon S. Knox 192 McCAMEY FIELD Upton and Crane Counties, Texas •.•.•.•.••.•.•• E. S. Hughes 194 McCUTCHEN FIELD Coke County, Texas • . . . • • . . . . . • • . • • • . • J.B. Jordan 201 McELROY FIELD A. B. Mc!nnis and Crane and Upton Counties, Texas . • . • . • . • . • • . F. H. Hartman 203 McKEE FIELD Crane County, Texas •.•.•......•••••• Barbara M. Creager 207 MIDWAY LANE FIELD Crockett County, Texas •.•...•.••••..•.•.• John M. Sweet 210 CONTENTS Page MIERS FIELD Sutton County, Texas Joe M. Nichols 214 MONAHANS FIELD C. G. Cooper Ward and Winkler Counties, Texas ..•.••.•..•. and B. J. Ferris 218 MONROE FIELD R. L. Tharp and Ward County, Texas . . • • • . . . . . . . . . . • • . Booker McDearmon 222 NELSON FIELD C. G. Cooper Andrews County, Texas . . . . .. . .. . . . . . . . . .and B. J. Ferris 225 NORTH GAIL FIELD Borden County, Texas • . • . . . • • • • . • • • . • . . Bill C. Ogden 228 NORTH GOLDSMITH FIELD Ector County, Texas Edwin Van den Bark 230 NORTH POLAR FIELD Kent and Garza Counties, Texas . . • . . • • . • . . • • John E. Scherer 234 NORTHWEST BLOCK 31 FIELD Crane County, Texas . • • • • John Fuszek 236 OATES FIELD Pecos County, Texas . • • • . • . . • . • . . . • . . . . Donald R. Raney 237 O'DONNELL FIELD Lynn County, Texas . • • • . . • • . . . • • • • • • • • • . . E. C. Risley 239 OLSON FIELD Crockett County, Texas . • • . . . . . • . . • • • • • • • • • J. D. Holme 242 OWNBY FIELD C. G. Cooper Yoakwn County, Texas . • . . . . . . • • . . • . . • . • and B. J. Ferris 245 PAGE FIELD Schleicher County, Texas . . • • • . . . • • • . . Samuel P. Ellison, Jr. 247 PARKER FIELD Andrews County, Texas . • • . . . . . . • • . • • . • L. G. Byerley, Jr. 252 PARKS FIELD Midland County, Texas James Russell Cotton 259 PECOS VALLEY FIELD Pecos and Ward Counties, Texas . • . • . . . . . • . . . • Ross H. Ley 262 PEGASUS FIELD Midland and Upton Counties, Texas .•.••.•••. Robert R. Harbison 271 PETERSBURG FIELD Hale County, Texas ...................... B.H. Boney 277 POLAR FIELD Kent County, Texas . • . • . . . . . . . . . . . • . . • M.A. Custer, Jr. 280 PRUITT FIELD Ward County, Texas . . . . . . . . . . • . . . . Edward R. Kennedy, Jr. 283 CONTENTS Page QUITO FIELD Ward County, Texas Edward R. Kennedy, Jr. 285 REINECKE FIELD Borden County, Texas • . • • • • • • . . • • • • . . • R. Leland Redline 287 RUSSELL FIELD Marshall W. Bailey Gaines County, Texas and Clyde M. Rascoe 290 SAN BENITO FIELD Coke County, Texas J. R. Kiene 294 SCURRY FIELD Scurry, Kent and Borden Counties, Texas • . . . • • . Philip T. Stafford 295 SEMINOLE FIELD Gaines County, Texas • . • . E. R. Douglas 303 SHAFTER LAKE -DEEP ROCK FIELD Andrews County, Texas . . • • • • . James B. Zimmerman 307 SHANNON FIELD Crockett County, Texas • • • • . • • • • • • • . • • • . • J. D. Holme 319 SIMPSON FIELD D. E. Daugherty, Crockett County, Texas .••....•••• H.J. McCool and J. A. Bodjo 322 SMITH-SPRABERRY FIELD Dawson County, Texas •• • • • • • . • . • • • • • . • • W. D. Galloway 324 SOUTH BROWNFIELD FIELD Terry County, Texas • . • . • . • • . • • • . . • Marshall L. Mason, Jr. 327 SOUTH KEYSTONE FIELD Winkler County, Texas W. C. Osborne 331 SUSAN PEAK FIELD Tom Green County, Texas . . . D. W. Graham 333 SWEETIE PECK -WARSAN FIELD Midland and Upton Counties, Texas . . • • . . • . • . Robert R. Harbison 338 TAYLOR-LINK FIELD Pecos County, Texas • . • . . . . . • . . • . • • TENNYSON FIELD Coke County, Texas TUCKER FIELD Crane County, Texas ............... TUNSTILL FIELD Loving and Reeves Counties, Texas • • • • • . . TXL FIELD • • • Robert H. Taylor 343 Richard A. Lisman William M. Caffey and Hershel S. Carver, Jr. 348 350 • • . . William T. Reid C. G. Cooper 355 Ector County, Texas ................... and B. J. Ferris 358 VERHALEN FIELD Reeves County, Texas · · · · . . . • . • . • . . Edward R. Kennedy, Jr. 369 CONTENTS Page VON ROEDER FIELD Borden County, Texas William B. Ellis 372 WAPLES-PLATTER FIELD C. G. Cooper Yoakum County, Texas . and B. J. Ferris 375 WASSON FIELD Yoakum and Gaines Counties, Texas W. T. Schneider 377 WATER VALLEY -CLARK FIELD Tom Green and Sterling Counties, Texas .•....... Thomas H. Cole 385 WEBB RAY FIELD Upton County, Texas • . • • • . • . • . . . • . • . • . • . . E. S. Hughes 388 WENDLAND FIELD Coke County, Texas C.R. Winkler, Jr. 389 WEST ANTON FIELD C. S. Preston Hockley County, Texas and M. V. Smith 391 WEST SEMINOLE FIELD Gaines County, Texas . Clyde M. Pederson 394 WHEAT FIELD Loving County, Texas . • . . . • • • • . . . • • . • . . . . F. H. Reiter 397 WHEELER FIELD Ector and Winkler Counties, Texas . • . . . • • • • • . . . R. E. LeBlond 401 WHITE AND BAKER -WALKER FIELD Pecos County, Texas James P. Murphy 410 WIL-JOHN FIELD Ward County, Texas . • . • • . . . • . . . . • • Edward R. Kennedy, Jr. 415 WILSHIRE FIELD Upton County, Texas Robert R. Harbison 418 WORLD FIELD Maria Spencer and Crockett County, Texas . • . . . . . . • • • • . • . . Warren Muery 422 YATES FIELD David Donoghue and Pecos and Crockett Counties, Texas . • . . . . . • • W. L. Gupton, Jr. 426 APPENDIX Suggestions to Authors of Field Papers 434 Check-list for Field Papers • . . . . . • 436 FIELD NAME INDEX . . • • . . . . . . . . . • . . . . . . . . . . • . • . . . . 437 ABELL FIELD Pecos and Crane Counties. Texas JACK G. ELAM Consulting Geologist, Midland, Texas June 20, 1953 LOCATION and INTRODUCTION The Abell field is mainly in north-central Pecos County with minor extensions across the county boundary into southwest Crane County. The Abell field includes 16 fields as designated by the Railroad Commission of Texas. Two of the Commission units, the Abell 2200-foot Permian and the Abell 3800-foot Permian, were designated as Abell Permian until July 1, 1949, when they were designated as separate fields by the Commission. The Com­mission designations are entered alphabetically as column headings in the following tabulation; the strati­graphic positions of the reservoirs producing in such units are indicated by entry of letters. These letters serve to identify, on the accompanying maps, the wells which produce from the respective stratigraphic positions as well as from the respective Commission units. ST RATIGR APHIC POSITION zZ o O ...... ...... (/) E-<(/) < ...... z 2 CJ2 ......0 (/) l) ~ q ...... ...... ..0 < >. ...... I-< >. ~ ...... ...... ..0 < ..>:: H 0 ..... H rd ...... 0 ...... ...... ..0 < ...... ...... "O "O rd ;s: ...., (/) C'd ~ ...... ...... ..0 < (/) I-< "O ~ < ~ rd (/) ..c:...., I-< 0 z ...... ...... ..0 < ...., (/) ~ ..c:...., I-< 0 z ...... ...... ..0 < ~ rd ..... 8 I-< 0.. ...... ...... ..0 < rd >. 0...., ~ 0 2 I ~ C'd ..... I-< ::l ...... ..... (/) ...... ...... ..0 < ..>:: I-< 0 ..... I-< rd ...... l) ...., (/) rd ..c:...., ::l 0 (/) ~ ..0 < ~ u 2 ...., (/) C'd ..c:...., ::l 0 (/) ...... ...... ..0 < I-< OD I-< ::l ..0 ~ ...... ...... ~ ..c:...., ::l 0 (/) ...... ...... ..0 < (/) I-< "O ~ ~ rd (/) ..c:...., ::l 0 (/) ...... ...... ..0 < ~ C'd ..... 8 H 0.. ...., 0 0 ..... I 0 0 co ""' ...... ...... ..0 < ~ rd ..... 8 H 0.. ...., 0 0 ..... I 0 0 N N ...... ...... ..0 < ~ u 2 I-< 0. 0. ::i ...... ...... ..0 < ~ C'd ..... 8 H 0.. H 0. 0. ::i ...... ...... ..0 < San And r es Ab Aa Ac Aa Glorieta Ba Ba Bb Upper Clear F ork c Lower Clear F ork Db Da Db Wichita E Fusselman -Montoya F Upper McKee G G L ow e r McKee Ha Hb He Wa ddell l a Tc l b J oins J Ellenbu rg e r Ka Kb SURFACE FORMATION and ELEVATION OF SURFACE Surface elevation ranges from 2 ,350 feet to 2 ,400 feet . Quaternary alluvium deposited by the Pecos River occurs over most of the area of the field. North of the river, in the Pecos River cutbank , Cretaceous Edwards limestone overlies red , green and maroon shales of the Triassic Dockum group. ABELL FIELD I Pecos and Crane Counties, Texas METHODS OF EXPLORATION LEADING TO DISCOVERY Study of subsurface data led to the discovery of this field. In 1936, George T . Abell acquired leases on 13,000 acres of land including most of the present area of the field . On the basis of data provided by three San Andres tests and by numerous core holes to the Yates formation, Abell caused the drilling of Tex-Mex Petroleum Co. #1 J. F. McKee in Sec . 24, Block 9, H. & G. N. R:R . survey, which flowed sulphur water and gas from its total depth of 2 ,720 feet and was shut down with a string of cable tools in the hole . Abell then assigned leases on 7 ,000 acres to Magnolia Petroleum Company in consideration of its deepening the test to 6 ,000 feet. It was impossible to deepen the original hole. A second hole was started and was junked at 1,210 feet. The rig was skidded southeastward and Magnolia Petroleum Co. #1-A J. F. Mc Kee was drilled at the location where total depth 6,267 is indicated on accompanying maps . After finding showing_s of oil and gas in the Lower McKee, gas in the Waddell and water in the Ellenburger, this test was finally abandoned on September 14, 1938 . In the fall of 1940, about a mile south of the Magnolia test, Taubert, McKee and Simeoneit #1 Mrs . V . W. Crockett was com­pleted in the Lower McKee reservoir as the discovery well of the field. It flowed 933 barrels of 43 gravity oil in 11 i hours through i-inch choke on 2-inch tubing with a gas-oil ratio of 783:1; T. D. 5,357 feet . OLDEST HORIZON PENETRATED The oldest horizon penetrated is in pre-Cambrian granite. Stanolind Oil & Gas Co . #1 Conry-Davis-Graham Unit (No . 14 on the accompanying cross section) penetrated 915 feet of Ellenburger, 20 feet of coarse quartzitic sand­stone of Cambrian age and bottomed in pre-Cambrian granite. The Ellenburger , which is higher at this location than anywhere else in the field, yielded only salt water. As indicated on. the accompanying cross section, the upper portion of the Ellenburger has been removed by truncation at this location. WATER PRODUCTION San Andres: Certain zones of the San Andres yield considerable amounts of water, while others yield none . Even offset wells completed in the same zone vary greatly in the amount of water produced; water varies from 0 to 80%. Several wells have been plugged and abandoned because of excessive water production. Glorieta, Upper Clear Fork and Lower Clear Fork: Several wells have been abandoned because of excessive water production. Wichita: The one well has not yielded an appreciable amount of water . Fusselman -Montoya: No water encroachment is apparent. Lower McKee: Many of the edge wells have had less than average decline in rate of oil production, indicating that there is no substantial water drive. However, in the northwest · Lower McKee reservoir (Hb), one well has been plugged and abandoned because of water encroachment. Waddell: Water encroachment has forced abandonment of 4 structurally low wells. Joins: Water constitutes 25'ro of gross production. ETI"eii"burger: One well has been abandoned because of excessive water production. DISCOVERIES San Andres: Abell 2200-foot Permian (Aa): December 1, 1941; Magnolia Petroleum Co . and George T. Abell #1-B State-Myrick Abell North San Andres (Ab): March 15, 1950; George T. Abell #1-A R.G.Peiper Abell South San Andres (Ac): November 12, 1950; C.H. Murphv & Co. #2 Ben Dansby Glorieta: Abell 3800-foot Permian (Ba): August 16, 1941 ; Stanolind Oil & Gas Co . #1 Thrapp-Walker Unit Abell Upper Permian (Bb): April 7, 1947; Magnolia Petroleum Co . #2 State-Grove Upper Clear Fork: Abell Clearfork (C) : February 9, 1950; Magnolia Petroleum Co . #4 State-Myrick Lower Clear Fork: Abell Southeast Clearfork (Da): June 1, 1951; Wood River Oil & Ref. Co. #2-A J. Williams Abell 3800-foot Permian (Db): July 2, 1941 ; Stanolind Oil & Gas Co. #1 Conry-Davis-Graham Unit Wichita: Abell Byerley (E): March 3, 1950! George T . Abell #1 L.G . Byerley, Jr . Fusselman -Montoya: Abell Silurian -Montoya (F): August 25, 1948; Magnolia Petroleum Co . #2 J. W. Lutz Upper McKee: Abell Upper McKee (G) : September 26, 1949; Magnolia Petroleum Co. #1 J. F. McKee (No. 1 on line of cross section) George T . Abell et al #1 E. J.Rixse (No. 6 on line of cross section), completed on May 13, 1941, was the first well to produce from this zone, but it was classified as in the Railroad Commission Abell field . Lower McKee: Abell (Ha) and Field: October 17, 1940; Taubert, McKee and Simeoneit #1 Mrs . V. W. Crockett (Now, Stanolind Oil & Gas Co. #1 Mrs. V . W. Crockett) Abell Northwest (Hb} : August 21, 1948; E.A.Hall #1 E . A.Hall (Now, George T. Abell #1 E. A. Hall) Abell Southeast McKee (He}: September 9, 1951; C.H. Murphy & Co. #1 Maud E. Ford Waddell: Abell (Ia): March 13, 1941; Magnolia Petroleum Co. #1 State-Sharp Abell East Waddell (lb) : May 23, 1950; Magnolia Petroleum Co . #2 State-Vollmar Abell Humble -Tucker (le): January l, 1946; Humble Oil & Ref. Co. #1 N . M. Tucker et al Joins : ~ell(J): July 6, 1941; Magnolia Petroleum Co . #3 Mrs. V . W. Crockett Ellenburger: Abell (Ka): June 18, 1941; Magnolia Petroleum Co. # 1 J. F. McKee Abell South Ellenburger (Kb) : September 9, 1951; C.H. Murphy & Co. #1 R . D. Blaydes ABELL FIELD, Pecos and Crane Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED w a: "' :z: w >­ i' 3: w ._ DEPTH 1752 1800 ELECTRIC CURVES AND LITHOLOGY 2398 2350 1900 2000 ~2250 . ~-----..::l'.=1 2150 2050 1950 1850 3 t-+--+---,,>-------t::r::.'X> ,~----~~-------1. <[ 0 <[ ::> 2500 "' 1650 A 2600 ~1550 2700 1'450 :'.: a: 0 z <[ z <[ "' z <[ a: "' w ._ • c 0 0 0 0 0 0 0 0 " ~ ~ <[ z a: 0 <[ w w _, _, '-' D Pre-Wichi ta-post-Fusselman detritus zone NOTE : The above is based on a composite of the logs of four wells . It was compiled to show the stratigraphic relationships o( the productive reser voirs . This manner of U//i\;j sondstone ~Umestone ~Dolomite LJShole presentation results, of course, in indicating depths and elevations of pre-Permian strata generally in excess of actual depths and elevations. Because of pre-Permian erosion, the amount of section between Permian and Ellenburger is quite different in different mlAnhydrite :!~1~1f~ Detritus ~Chert parts of the field . At some locations, Permian rests on rocks as young as Fusselman , • Oil production o Show of oil ~ Gos production .:tf.. Show of gos while at other locations, truncated Ellenburger is immediately overlain by P ermian. ABELL FIELD, Pecos and Crane Counties, Texas NATURE OF TRAPS San Andres: There are three areas on the g en­eral regional structural hig h where San Andres is productive. These productive areas occur where a condition of favorable porosity and permeability is present, and only in area Aa is this related to a local San Andres high. Even here , production is restricted to the south flank. Uncommercial shows in this zone have been noted in numerous other wells in the field . Glorieta: The accumulation at each of the two productive areas {one with two wells and one with one well) is on the axis of the main Abell anticline , but production results from favorable porosity conditions at these areas. Upper Clear Fork: A single well has encoun­tered sufficient porosity to yield oil in this zone, although shows have been logged in numerous other wells . It is presumed to be a porosity trap in high structural position . Lower Clear Fork: There are two areas where Lower Clear Fork is currently producing and one area where the one producing well has now been abandoned. The reservoir in each of these areas is presumed to be separate and distinct. The trap in each case is stratigraphic, and the accumulation results from a variation in degree of porosity. Wichita: The sole Wichita producer is located in close proximity to the fault bounding the east side of the Fusselman-Montoya graben, and it appears that the accumulation is in a fracture zone associated with that faulting. Fusselman -Montoya: The accumulation in this reservoir is primarily due to updip termination of reservoir rock by truncation and to overlap by impervious beds. Lateral closure is effected by faulting . Upper McKee: Only two wells are producing from the Upper McKee reservoir, which is located near the axis of the Abell anticline . It appears that faulting and truncation with overlapping impervious beds are the controlling trap-forming factors . Lower McKee : There are four reservoirs in the Lower McKee sandstone . The accumulation in each occurs on the flanks and/or in the downfaulted blocks on the Abell anticline. In the highest structural locations, this zone has been removed by erosion, and the cap is provided by impervious beds of Leonard age . Within the local lower fault blocks, gas is encountered at the crest of the anticline, and markedly different elevations of gas-oil and oil­water contacts in the field attest to the presence of fault barriers. The Lower McKee sand has been tested by only a single well (near center of Sec. 27) on the north flank of the Abell anticline, and here it is tight and silty. Waddell : There is commercial production from the Waddell sandstone at nine places in the Abell field; the number of separate, distinct reservoirs is not known. The productive areas, each with one to four wells , are scattered over the field in various structural positions. It appears likely that variation in degree of porosity in sloping reservoir rock is NATURE OF TRAPS (Continued) the principal trap-forming factor, with faulting playing a minor role . Howr!ver, it is recognized that the degree of poros ity and permeability required for commercial production is greater than that required for migration of reservoir fluids in geologic time and that the nine productive areas may be all in a single area of accumulation; in which case, convex folding would appear to be the domi­nating factor. Joins : The trap at the location of the single well appears to be due to fracturing along a fault. Ellenburger: There are two productive reser­voirs in the Ellenburger dolomite. Each is at the apex of a convex fold . Faulting is not a trap-forming factor in either case. However, on the contrary, fracturing associated with faulting has provided avenues of escape from nearby Ellenburg er closures formed partly by faulting. LITHOLOGY OF RESERVOIR ROCKS San Andres : Gray, dense, slightly fractured dolomite and dark brown, soft, finely crystalline dolomite ; good vuggy type porosity in reservoir Aa. Glorieta: Finely crystalline dolomite, with intergranular porosity, interbedded with detrital sands and limestone. Upper Clear Fork: Finely crystalline gray dolomite with scattered vuggy type porosity. Lower Clear Fork: Finely crystalline to litho­graphic dolomite; in scattered areas, porosity is of large vuggy to cavernous type . The porosity is extremely erratic as evidenced by patchy productive areas and by yielding of sulphur water both laterally and updip from oil productive areas . Wichita: Slightly porous, fractured, gray-brown dolomite. Fusselman -Montoya: Fusselman: White to light gray, crystalline dolomite with secondary vugs, caverns and frac­ tures. Montoya : Brown, dense and cherty dolomite and limestone; characterized by fractures, vugs and caverns that contain many secondary calcite crystals. Upper McKee: At the locality in Sec. 25, Block 9, where two wells are producing from Upper McKee, the reservoir rock is sandstone, fine-grained, green, with abundant rounded, frosted sand grains with some silt intermingled. Lower McKee: Coarse green sandstone with very abundant rounded, frosted sand grains. A shale parting occurs at several places. Waddell : Varies from a coarse-grained, cal­careous sandstone to a fine-to coarse-grained, loosely cemented white sandstone. Joins: Gray-green marly limestone. E1Tenburg er: Massive, gray and brown, finely crystalline dolomite, with solution cavities and narrow irregular fractures lined with calcite and dolomite crystals . ABELL FIELD I Pecos and Crane Counties, Texas PRODUCTIVE AREAS , ELEVATION AND RELIEF OF PRODUCTIVE ZONES and CHARACTER OF OIL PRODUCTIVE ELEVATION AND RELIEF CHARACTER AREAS (feet) OF OIL Top Bottom Gravity San Andres : (acres) of oil of oil Relief (A.P .I. @ 60° F.) Abell 2200-foot P ermian {Aa ) 320 144 35 109 35 Abell North San Andres {Ab) 150 -46 47 37 .2 Abell South San Andres {Ac) 80 -31 -55 24 32 G lorie ta: Abell 3800-foot P ermian (Ba) 100 -799 -8 34 35 26 Abell Upper P ermian {Bb) (one well) 40 -767 -791 24 34 Upper Clear Fork: Abell Clearfork {C): {one well) 40 -967 -977 10 34.7 L ower Clear F ork: Abell Southeast Clearfork (Da) (one well) 80 -1,460 -1,509 49 38 Abell 3800-foot Permian {Db, s outheast) 250 -1 ,445 -1,610 165 34 Abell 3800-foot Permian (Db, northwest) 250 -1,463 -1,580 11 7 37 Wic hita: (E): {one well) 40 -2 ,544 -2,569 25 41 Fusselman -Montoya: (F): l ,200 -2 ,426 -2 ,698+ 272+ 41 Upper McKee: (G): (two wells) 40 -2 ,551 -2 ,618 67 38.6 Lower McKee: Abell {Ha) 2 ,150 -2,575 -3 ,044 * 41-43 Abell Northwest (Hb) 720 -3,012 -3 ,198 186 41.6 Abell Southeast McKee {He) 200 -2,682 -2 ,770 88 43 Waddell: Abell (Ia) {7 ar eas) 450 -3,064 -3 ,553 ** 43 Abell East Wa ddell (l b) 160 -3 ,519 -3,662 143 44.2 Joins: {J): {one well) 40 -3,322 -3,345 **'' 42 Ellenburg er : Abell {Ka) 540 -3 ,410 -3 ,547 137 42 Abell South Ellenburger {Kb) (one well) 40 -3,417 -3 ,554 137 42 PRODUCTIVE AREAS: The above estimates total 6 ,890 acres. Allowing for overlapping of areas , the total area of the Abell field is estimated to be 6,200 acres . It is probable that future development will warrant increasing the above estimates for Fusselman -Montoya and Waddell . ELEVATION AND RELIEF OF PRODUCTIVE ZONES : *In Lower McKee Abell (Ha), fluid elevations are different in the s everal fault blocks . Gas has been produced from -2 ,518 in Magnolia # 1 Grove to -2 ,969 in Stanolind #1 Thrapp-Walker; oil, from -2 ,575 in Magnolia #2 Francisco to -3,044 in Magnolia #1 Mcintosh; water , from -2,957 in Magnolia #1 J . W . Lutz to -3 ,066 in Sinclair # 3 Heirman. **In the seven Waddell Abell (la) areas, there is considerable range in elevations of fluid contacts . Gas has be en produced from -3,019 in Magnolia #2 Grove to -3,327 in Magnolia #2 State-Baldwin; oil, from -3,064 in Stanolind #1 Wright to -3 ,553 in Magnolia #5 Silverman; water , from -3,049 in Stanolind .#1 Grove to -3 ,446 in Stanolind #1 Thrapp-Walker. ***The only Joins well produces from -3,322 to ­ 3,345. Water cons titutes 2 5% of the gross production. CHARACTER OF OIL : For oil analyses see : U. S . Bureau of Mines Lab. ref. No . 41 398 46113 46094 46096 46095 50050 Analyses of Crude Oils from Some Fields of Texas R.I. 3699 (1943) Item Analyses of Crude Oils from Some West Texas Fields R .I. 4959 (1953) Item 2 3 4 5 ABELL FIELD, Pecos and Crane Counties, Texas ABELL FIELD, Pecos and Crane Counties, Texas CONTINUITY OF RESERVOIR ROCKS San Andres: The stratigraphic unit in which there are productive wells at three localities appears to be continuous throughout the area of the field, but it is only locally sufficiently porous to yield oil into bore holes . Porosity is erratic and is independent of structural position. In the productive area at the southeast end of the field, the best porosity is at the crest and on the south flank of the Abell anticline. The other productive areas are 'considerably lower structurally. At the locations of several wells at the crest of the anticline, porosity is too low for commercial production. Glorieta: The continuity of the reservoir rock is not known. Porosity adequate for commercial production is a local condition. Upper Clear Fork and Lower Clear Fork: The stratigraphic units appear to be continuous through­ out the area of the field but they are only locally sufficiently porous to yield oil into bore holes. Porosity is erratic and is independent of structural position. Wichita: The continuity of the reservoir rock in the Wichita is unknown and appears to be of little importance. It appears that the accumulation of oil is a result of trapping after escape along a fault from the Fusselman -Montoya reservoir. Fusselman -Montoya: The Fusselman and Montoya groups are eroded from the crest of the Abell anticline. They are productive only on the northeast flank where their truncated sub-crops are overlain by impervious Permian beds, mainly where they have been preserved in a down-dropped block. No.rmally, the Montoya is dense and impervious. Porosity in the productive area has resulted from pre-Permian weathering . Less vigorously weathered Montoya in downdip wells fails to yield commercial oil, but here overlying Fusselman is productive. McKee : The McKee member was deposited as a blanket stratigraphic unit over the entire area of the field, but subsequent erosion has removed it from the structural crests . The porosity of the sandstones in the McKee member is quite variable within the area of the field. The upper sandstone is sufficiently porous to yield oil in only a very limited area. While the lower sandstone has adequate porosity for com­mercial production over a much greater area, even in this sandstone, such porosity is not continuous throughout the area of the field. Waddell: The Waddell sandstone is a blanket deposit which is locally silty and highly cemented. It has exhibitedan erraticpatternof production; but this is, in part, the result of non-uniform exploitation. Joins : The Joins has produced in only one well. In ~thefact that this well cut seve.ral faults, it is suggested that this zone is productive only because Ellenburger oil has migrated up the shear zone. Ellenburger: The productive portion of the Ellenburger was deposited throughout the area of the field but has been removed by erosion from the apex of a structural high at the southeast end of the field. Its continuity is interrupted in a minor way by a series of northeast-southwest normal faults. THICKNESSES OF RESERVOIR ROCKS Net productive, feet Min. Max. Avg. San Andres 5 43 18 Glorieta 24 40 32 Upper Clear Fork ........ ...... 10 10 10 Lower Clear Fork 11 100 50 Wichita 35 35 35 Fusselman -Montoya 41 ....... 220 ........ 100 Upper McKee 10 10 10 Lower McKee 0 60 30 Waddell . ...... ... ....... ....... .. ... 3 ......... 30 ... . ..... 15 Joins 23 23 23 Ellenburger 18 152 75 COMPLETION TREATMENTS San Andres, Glorieta, Upper Clear Fork, Lower Clear Fork and Wichita: Most of the wellscom: pleted in the Permian reservoirs were treated with 500 to 1, 000 gallons of acid at time of completion; as much as 3,000 gallons was used in a few wells. However, some of the better wells were completed without either acid or fracture treatment. Fusselman -Montoya: Most of the wells were completed without either acid or fracture treatment, but, downdip where porosity of Montoya is low, one well was shot with 610 quarts of nitroglycerin and was treated with 3,000 gallons of acid. Lower McKee: Most early wells were completed "natural". In some of the more recently completed wells inAbell Northwest (Hb) the reservoir rock was hydraulically fractured with 1, 500 gallons of fluid. Waddell: Most Waddell wells were completed "natural", but in Abell East Waddell (lb) most wells were given hydraulic fracture treatments with 1,500 gallons of fluid. Joins: The well was treated with 2, 000 gal. of acid. ~burger: Mostof the Ellenburger wells were acidized with 2,000 to 3,000 gallons of acid. SELECTED REFERENCES Cole, T., Cordry, C . D., and Hemphill, H. A. (1942) McKee and Waddell sands, Simpson group, West Texas: Arner.Assoc.Petr . Geel., Bull., vol. 26, pp. 279-282 . Cole, T . ,Dickey,R . !.,and Kraus,E. (1941) Develop­ments in West Texas and Southeastern New Mexico during 1940: Amer . Assoc. Petr. Geo!., Bull., vol. 25, pp. 1056-1057. Powers, Elliot H. (1940) Sand Hills area, Crane County, Texas : Arner . Assoc . Petr. Geel., Bull., vol. 24, pp. 119-133. Stratigraphic Problems Committee of West Texas Geological Society (1951) North-South cross section through Permian Basin of West Texas; West Texas Geel. Soc . ABELL · Texas Counties, Pecos and Crane ----­ FIELD, AREAS MAP EXPLANATION . -Permian reservorr • ing from pre . Oil well produc e Permian reservoir ducing from pr -. Gos well pro from Permian reservoir Oil well producing rvoir * from Permian rese Gos wel I producing p Dry hole + Abandoned well PRODUCTIVE AREAS Fusselman _Montoya { F) Upper McKee ( G) Lower McKee (Ho• Hb and He) Waddell (lo' lb and le) D Ellenburger ( t o:i 1949 1950 1951 1952 83 103 113 Ill 43 34 46 56 IZ 9 I 0 843 ,300 1,801,603 Z,046 ,646 I ,546,894 7,447,733 9,249,336 l l ,295 ,982 !2 ,842 ,876 1,331 1,972 I ,4 56 Z ,025 4 ,241 6,213 7 .669 9.694 793 ,21 7 373,704 457 ,098 490 ,811 1,720,021 2,093.725 2,550,823 3 ,041 ,634 1951 1952 26 31 976 ,807 702 ,554 I .952 ,953 2 ,655 .507 tT1 L' L' Upper McKee: 'Tj San Andres : Abell Upper McKee (G): Earlier production (one well) not segregated; included in Abell. ...... Abell 2200-foot Permian (Aa) : j949 I 0 I 969 969 1,191 1.191 339.358 339,358 tT1 Prior 1949 Not segregated; included below in Abell Permian. 0 1 1 18,005+ 18,005+ 1950 1951 I 949 769 1,918 2,687 I.660 921 2,851 3 ,772 240,383 208 ,790 579 ,741 788,531 L' t1 1950 l Z 38 ,Z6Z 56 ,267+ 1952 675 3 .362 1.481 5 ,253 230 ,170 I ,018 ,70 I 1951 IZ 34,525 90.792+ 1952 IZ 31 ,495 IZZ,287+ ~ Lower McKee : Abell (Ha): Oil not segregated; gas and condensate not segrega ted prior to 1947; included in Abell. Abell North San Andres (Ab): 1947 ? ? 5 ? ? 0 ? 54,046 --5-4 .046+ g 1950 4 I 61 ,070 61.070 1948 ? ? 7 ? ? 1,474 1.474+ 302,158 356 ,204+ 1951 0 8 50,476 11 1,546 Q 1952 37 ,049 148.595 1949 0 1,474+ 346 ,412 702 .616+ ::s 1950 13 l ,487+ 72 ,606 775,222+ 0... Abell South San Andres (Ac): 1951 II I ,498+ 7 3 ,677 848,899+ () 19 50 I 0 I ,531 I ,531 1952 14 I ,512+ 169 ,092 1,017.991+ 1951 0 ZZ .143 2 3 ,67 4 a 195Z 12 ,214 35.888 Abell Northwest (Hb): ~ 1949 5 I 08 ,664 108,664 G lori eta : 1950 7 170,604 279 ,268 ~3800-foot Permian (Ba): (2 oil wells): Not segr egated; included be low in Abell 3800-foot Permian. 1951 16 209 ,543 488 ,8 1 J 1952 18 132,016 620 ,827 ~ ...... Abell Upper Permian (Bb): The one well has produced from this reservoir as an oil well and also, at times, as a gas well. Abell Southeast (He}: m· 1947 943 943 1951 5 92 ,648 92 ,648 1948 l ,527 Z,470 9,589 9 .589 1952 78,605 17 I ,2 53 1949 967 3 ,437 15 ,238 24 ,827 -3 1950 I ,128 4,565 24,827 Waddell: s 1951 678 5,243 408 408 67 ,781 92 ,608 ~(la,7 areas) and (le): Oil not seg r egated; gas and conds . not segregated prior to 1947; in Abell below . tll 1952 Ill 5 ,354 241 649 19,965 112 ,573 1947 ? ? 2 ? ? 473 473+ 79,194 --79,194+ 1948 ? ? 3 ? ? 322 795+ 120,762 199,956+ Upper Clear Fork : 1949 140 935+ 92 ,209 292,165+ Abell Clearfork (C): 1950 299 l ,234+ 60 ,7 15 352,880+ 1950 I 2 ,307 2 .307 195 1 0 1.152 3 ,459 1951 116 1,350+ 7 3 .677 426,557+ 1952 0 2,774 6.233 1952 187 1,537+ 71,584 498,141+ Lower Clear Fork : Abell East Waddell (lb}: Abell Southeast Clearfork (Da): 1950 I 0 11,393 11 ,393 1951 0 I 1.199 I ,199 1951 3 28 ,5 42 39 ,935 1952 281 I .480 1952 14,800 54,735 Abell 3800-foot Permian {Db): Not segregated; included below in Abell 3800-foot Permian . Abell Humble-Tucker (le): (one gas well}; Not segregated; included above with (la). WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Oil Gas Y ear Flow . Pump . Cumulative ~ Joins: (J): (one well) : Not segregated; included below in Abe ll. Ellenburg er; Abell (Ka): Not seg regated; included below in~- Abell South Ellenburger (Kb): 1951 6' 116 6.116 1952 6 ,579 12 .69 5 PRODUCTION CONDENSATE PRODUCTION (barrels) GAS PRODUCTION (Mcf@ 14 .6Sff & 60"F.) yea-rtY -curnur-ailVe Yearly Cumulative NOT SEGREGATED IN ACCORDANCE WITH STRATIGRAPHIC POSITION : Abell Permian (includes Aa, Ba and Db prior 1941 8 0 14 ,384 1942 16 5 78' 14 3 1943 13 9 93 .090 1944 12 I 0 141 .335 1945 9 12 127 .908 1946 7 13 112 ,285 1947 5 13 I 04. 165 1948 5 16 98 ,177 1949 6 15 36 ,440 to July J, 1949 .) 14 ,384 92 .527 185 ,617 326 ,952 454 .860 567,1 4 > 67 I ,310 769 ,487 805 .9l7 NOT SEGREGATED IN ACCORDANCE WITH STRATIGRAPHIC POSITION : (Continued) HISTORY (Continued) Year WELLS PRODUC at end of year Oil Flow. Pump . ING Gas OIL PRODUCTION {barrels) Yearly Cumulative CONDENSATE PRODUCTION (barrels) GAS PRODUCTION (Mcf@ 14 .6Sff & 60"F.) Yearly Cumulative Yearly Cumulative Abell 3800-foot Permian (includes Ba and Db after July l, 1949; prior thereto their production was reported in Abell Permian .) 1949 I 8 ,00 I I8 ,00 I 1950 36 ,402 54 ,403 I951 37' 148 91 ,55 1 1952 31 ,389 122 ,940 Abell (includes Ha, Ia, le, J and Ka except as to production reported above.) 1940 I 0 0 5 ,650 5 .650 1941 1942 45 75 2 5 3 6 190 ,633 735,619 196 ,283 931 .902 1943 1944 78 77 6 8 5 4 955 ,792 1.143,568 I ,887 ,694 3 ,031 ,262 1945 1946 77 74 I 0 5 4 3 779 .788 695 .795 3 ,8 I I ,050 4 ,506 ,845 641 641 1947 1948 67 63 8 10 0 0 611,647 707, 124 5. 11 8,492 5 .825 ,616 1949 19 50 61 56 12 15 0 0 502 ,077 654 ,382 6,327,693 6 ,982,075 195 l 1952 54 47 13 25 0 581.510 494 ,02 5 7 ,563 .585 8,057,610 >­tp rr:I 50 ,365 95 ,360 50,365 145,7l5 r-' r-' 36 ,328 44 ,878 182,053 226 .931 '""Tj ....... 46 ,302 87 ,822 273,233 36 1,055 rr:I r-' t:.l ~ () 0 Ul 0 [ 0 a ::::s CD 0 g ::::s - a» Ul >-:3 CD ~ Ul ..._. ..._. ADAIR FIELD Gaines and Terry Counties, Texaa FRANKL. GLAZE Exploitation Geologist, Tide Water Associated Oil Co., Midland, Texas November 14, 1953 LOCATION and OTHER NAME The Adair field is in northeast Gaines County and south-central Terry County about 15 miles east of the town of Seagraves . During its early develop­ment, it was known as the East Seagraves field . METHODS OF EXPLORATION LEADING TO DISCOVERY Seismograph surveying and interpretation of s\fbsurface data. DISCOVERIES San Andres : May 1, 1947 ; Amerada Petroleum Corp. #1 Sam Adair. Pumped at rate of 608 barrels of oil per day during initial potential test. Wolfcamp reef: September 25, 1950; Amerada Pe­troleum Corp. #2 N. W . Willard . This well was the discovery well according to the rules of the Railroad Commission, since it was the first well to be completed. However, commercial production had been proven previously by Amerada #1 Willard. After flowing 144 barrels of oil in 4 hours on a drill stem test of this zone, the #1 Willard was drilled to a total depth of 12,465 feet . In the meantime , the #2 Willard was drilled and completed in the reef for a daily flow of 912 barrels of oil through a t-inch choke on 2-inch tubing in St-inch casing set at 8,573 feet and perforated at 8,500 to 8 ,560 feet. ELEVATION OF SURFACE The average surface elevation is 3 , 190 feet above sea level. The surface is nearly flat . All ele­vations are within a very few feet of this average . SURFACE FORMATION Quaternary sand. OLDEST STRATIGRAPHIC HORIZON . PENETRATED The oldest horizon penetrated is 95 feet below the base of the Woodford shale. The sample recov­ered from the bottom of the hole is believed by geologists of Midland Residue Research Laboratory, headed by Eugene W . Vanderpool, to be of the Montoya formation; other leading geologists consider the sample to be of the Devonian system. This penetration was in Amerada Petroleum Corp. # 1 N. W. Willard, one of the two wells credited for discovery of commercial production in Wolfcamp reef, at its total depth of 12,465 feet (-9,230 feet) . NATURE OF TRAPS San Andres : Anticlinal folding is dominant, but variation in porosity has also influenced accumula­tion . Wolfcamp reef: Accumulation is limited to the higher portions of a reef mass which is surrounded by shale. THICKNESSES OF RESERVOIR ROCKS San Andres Wolfcamp Average net productive, feet 60 80 LITHOLOGY OF RESERVOIR ROCKS San Andres: Dolomite; anhydritic, buff to gray, finely crystalline to crystalline; scattered inter­crystalline, pinpoint and fracture porosity. Wolfcamp reef: Reef limestone; dolomitic, buff to light greenish-gray, dense, finely crystalline to chalky, fossiliferous; vuggy, intercrystalline, frac­ture and solution types of porosity; occasional shale partings . CONTINUITY OF RESERVOIR ROCKS San Andres: The stratigraphic unit which is productive is continuous throughout the area of the field . Effective porosity is continuous throughout the field, with the top of the porous zone strati­graphically lower southward. Wolfcamp reef: The productive zone is at the apex of a reef. It is continuous within the presently productive area but probably not far beyond. There are other reefs of about the same age in the general region, but conditions favorable for migration of fluids are not continuous between the several reefs. WATER PRODUCTION San Andres: No recent water report is available. On May l, 1952, 98 of the 114 producing wells were making 2 % or more water and each of the others was making about 1% water . Wolfcamp reef: Data are not available . ACID TREATMENT San Andres: It is customary to tr eat each well before completion; usually with 5,000 to 12,000 gallons of acid . Wolfcamp reef: It is customary to treat each well before completion; usually with about 500 gallons of mud acid. AD A IR F I ELD , Gaines and Terry Counties, Texas 5B I 39 SCAL E THOUSANO FEET 38 19 20 ---1275 -­ -1 n1 T. 0~5 l 0.~'4J 37 o. a-w. R. R. co. BLOCK H Ory 2322 21 14 15 II 10 N 19 20 16 15 9 10 PUBLIC SCHOOL L AND BLOCK C-31 4 Conto\Jr on top of Son Andres formation Elevation of top of Son Andres forma tion Total depth Oil well , eompleted in Son Andres Oil well, completed in Wolfcomp reef ho le • \=::o Discovery AD A IR FIELD, Gaines and Terry Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED ELECTRIC a RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY ond S. P. RESISTIVITY DEPTH ELEVATION ELECTRIC a RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY RESISTIVITY ..J ond S. P. ELEVATION (5 DEPTH z <( • "' 5 Q. AD A IR FIELD, Gaines and Terry Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED z ELECTRIC S; RADIOACTIVITY CURVES 0 :E LITHOLOGY \i ... ... ..."' ii: :E GAMMA RAY RESISTIVITY and S. P. "'>-... :!i ..._ DEPTH ELEVATION "' "' 0 9900 1 '26665 0 "' 0 10100 -6865 z 0 >­z ­"' z z... 0. z ~ cc ... "' 10800 10900 11000 11100 11200 11300 -8065 11400 -8 165 JI 500 -8265 0 z... "' 11600 -8365 I 1700 -8465 11800 -8565 11900 -8665 z ANO ~ ~ g -' LITHOLOGY >-w 0: Vl If) !.!> DEPTH • ELEVATION Q • " z z 3 >­ z "' ~ 0.. z " z §? w 0 z "iii. 3 u; z 0 z 0.. " "' ~ Vi 0 0 0: 0 0: w 0: :::> "' ID z w -' -' w NOTE : The above TYPICAL SECTION is based on the log of Stanolind fl Kayser , theCisco discovery well , to its total depth of 13,620 feet and, below that, with depths and elevations adjusted, on the log of Stanolind ll-D Cowden, where the oldest horizon was penetrated. EXPLANATION ~Limestone mgAnhydritt [}}/.~%! Sorwjsfooe Seit ~Dolomitic ~sandstone ~Chert ~Shole ~ Colcoreous chert ~ Colcoreous r===::=l Rock indicottd, ~ shole ~ sholy ~Dolomit e D Rock indicated, re d • Oil production 20 ADDIS-JOHNSON-FOSTER-SOUTH COWDEN FIELD, Ector County, Texas ---1100-Contour on top of Groyburg Formation Oil well , completed in Queen -Groyburo 'i Oil well, completed in Son Andres 19 Oil wel I, completed in Wolf comp et Oil well , completed in Cisco .!. Oil well , completed in Strawn Abandoned oil well Jf o Location or drilling well SCA LE ADDIS-JOHNSON-FOSTER-SOUTH COWDEN FIELD, Ector County, Texas 21 WEST EAST ELEVATION A' FEET THICKNESSES OF RESERVOIR ROCKS ELEVATION AND RELIEF OF PRODUCTIVE ZONES Feet Elevation of oil, feet Known Min. Max. ~ Bottom relief ~ Queen-Grayburs;: From top to bottom 10 260 95 Queen-Grayburg* -900 -1,170 to 1,850± Net productive 10 200 70 San Andres (Z wells) -1.199 -1 ,264 65 San Andres: (Z wells) Wolfcamp (1 well) -5,167 -5,277 110 From top to bottom 65 65 65 Cisco (l well) -5,517 -5 ,567 50 Net productive 40 40 40 Strawn (Z wells) -6,190 -6 ,216 26 Wolfeamp: ( 1 well) ~topto bottom 110 110 110 *Oueen-Grayburg: Elevation of t op of gas, -794 ft.; Net productive 40 40 40 elevation of bottom of gas, -900 ft.; relief of gas col ­Cisco: (1 well) umn, 106 ft. The wate r table is not horizontal. Water ~romtop to bottom 50 50 50 has been found at various elevations up to as high as Net productive 20 20 20 -1 ,170 feet and oil has been found as low as about -1 ,850 Strawn: (Z wells) feet, but it is unlikely that there is a continuous oil­~omtop to bottom 20 20 20 water contact through such range of elevation. The Net productive 20 20 20 base of the oil corresponds roughly to structure. CHARACTER OF OIL Queen-Gr ayburg* San Andres Cisco Str awn Gravity, A.P.I.@ 60• F. 33"-36.4" 32.8" 34.4" 33• 39. -41. •Queen-Grayburg: Color, greenish black; sulphur, 1.07 -l.38'r.; viscosity, Saybolt universal @ 100° F., 41 -46 sec.; base, intermediate. For analyses see: Railroad Commission of Texas Foster Johnson South Cowden Analyses of Texas Crude Oils (1940), pp. 32 and 63 33 and 64 U.S. Bureau of Mines Lab. ref. No. 40009 41240 34004 Tabulated Analyses of Texas Crude Oils T. P. 607 (1939) Item l , Gr oup Z Analyses of Crude Oils from Some Fields o! Texas. R. I. 3699 (1943) Item 34 35 Analyses of Crude Oils from Some West Texas Fields. R. I. 3744 (1944) Page 10 II Analyses of Crude Oils from Z83 Important Oil Fields of the United States R. I. 4289 (1948) Item 204 198 22 ADDIS-JO.HNSON-FOSTER-SOUTH COWDEN FIELD, Ector County, Texas METEOR CRATER WATER PRODUCTION The meteor crater known as the Odessa crater is at the southwest tip of the field at the location indicated on the accompanying map. NATURE OF TRAPS Queen-Grayburg : The trap is due to westward diminu­ tion and disappearance of porosity throughout a broad area on the east flank of the Central Basin platform. On the east side of the field, porosity is continuous from top to bottom of the productive zone; but westward this zone grades into a sequence of porous members separated by impervious members. Traced farther westward these porous members become progressively thinner and ultimately grade into impervious dolomite. San Andres: Oil.is trapped in a small dome of low relief. Wolfcamp: Meager data indicate that the trap is an anticline. Cisco: The trap is due to updip loss of porosity in a thin limestone reservoir on a structural nose. Strawn: Meager data indicate that oil is trapped on the northeast plunge of an anticline and that updip loss of porosity may be an important factor. LITHOLOGY OF RESERVOIR ROCKS Queen-Grayburg: This reservoir rock is mainly a brown dolomite, in part finely crystalline, in part aphanitic . Oolites are common. Particularly in the northwestern part of the field, a few thin beds of fine-grained sandstone and fine sandy dolomite are interbedded in the main dolomite mass. Porosity in the dolomite occurs as an interconnected system of fine pores with average diameter of less than a millimeter. In general, the sandy beds are non-porous but in places a basal Queen sandstone yields some oil. San Andres: The reservoir rock is a light gray, very finely crystalline dolomite. Porosity, which is interstitial and of fine size, occurs in thin zones alternating with imper­ vious layers. Wolfcamp: The upper member of this reservoir rock is a thin fragmental limestone. The lower member is a slightly sandy dolomite, very finely crystalline, with fine, interstitial porosity. The producing strata are interbedded with non­ porous limestones and green shales. Cisco: The reservoir rock is a light gray to light brown limestone, very finely crystalline to aphanitic, interbedded with gray-green shale beds. Porosity is furnished by pores of fine size. Strawn: The reservoir rock is a light brown limestone, aphanitic to finely fragmental. Porosity occurs as fine-size pores, generally less than 0.5 millimeter in diameter. COMPLETION TREATMENTS Queen-Grayburg: Most of the wells were completed with the aid of nitroglycerin. The normal quantity was 400 to 500 quarts. A few wells were completed "natural". Before 1950, only a very few wells were acidized. Most of the later wells in the southwest extension were acidized with a n average quantity of about 10,000 gallons. Within the past year, some of the old wells have been helped by hydraulic fracture treatments. San Andres: The two wells were completed "natural". Wolfcamp: The lone well was acidized with 2,500 gallons. Cisco: The single producer was acidized with a total of 15,000 gallons . Strawn: Each of the two wells was acidized with 500 to l, 500 gallons. Queen-Grayburg: Some water is produced by each of about 30o/. of the wells . Total water amounts to a quantity nearly equal to 30% of the total amount of oil. Most of the water production is along the east flank. San Andres, Wolfcamp, Cisco and Strawn: No water is produced. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year F lowing P umping Yearly Cum ulative Qu een-Grayburg 19 33 6 0 109.987 109 .987 1934 10 2 190,034 300 ,021 1935 13 4 238 ,503 538 ,524 1936 8 15 249,134 787 ,658 1937 28 62 958,38 1 1.746,039 1938 106 114 I .9 35 ,897 3,681,936 1939 220 174 3,017,298 6 ,699 ,234 1940 351 294 4,048,97 1 10,748,205 1941 478 311 5,843,949 16,592,154 1942 464 348 3 ,552 ,348 20,144,502 1943 422 408 4 ,366 ,365 24,510 ,867 1944 368 468 9,044,325 33,555 ,192 1945 301 550 8,824,737 42 ,379 ,929 1946 250 629 8 ,509 ,051 50 ,888 ,980 1947 175 729 9,055 ,691 59.944,671 1948 134 856 I 0 ,302 ,268 70 ,246 .939 1949 165 909 9 ,093,291 79 ,340 ,230 1950 76 I ,02 1 8,858.989 88,199.219 1951 76 1,033 8,932,115 97,131,334 1952 63 l ,060 8, 122,786 105,254,120 1953 53 I ,073 7 ,438 ,592 112 ,692 ,712 San Andres 1953 0 2 27 ,427 27 ,427 Wolfcamp 1953 0 12,204 12 ,204 Cisco 1947 0 6 .902 6,902 1948 0 4,656 11 ,558 1949 0 3,746 15 ,304 1950 0 3,294 18 ,598 1951 0 2 ,905 21,503 1952 0 2 ,569 24,072 1953 0 2 ,400 26 ,472 Strawn 1948 0 11,078 11 ,078 1949 2 0 34,841 45 ,919 1950 0 2 42 ,879 88,798 1951 0 2 49 ,1 96 137 .994 1952 0 2 35 .9 39 173,933 1953 0 2 30,727 204,660 APCO. FIELD Pecos County, Texas SAMUEL P. ELLISON, Jr. Professor of Geology, The University of Texas, Austin, Texas September 9, 1955 LOCATION and INTRODUCTION The Apco field is in north-central Pecos County about 25 miles northeast of Fort Stockton, county seat. It is on the Central Basin platform near its so"uthwestern edge. The Apco field includes 6 fields as designated by the Railroad Commission of Texas; those designa­tions are entered alphabetically as column headings in 'the following tabulation. There are 10 reservoirs in 6 named stratigraphic units, which units are list­ed below in stratigraphic order. The approximate stratigraphic positions of the productive reservoirs in the respective Commission units are indicated by entry of letters which serve also to designate the reservoirs in following entries in this paper. The stratigraphic positions of the several reservoirs are indicated more definitely on the accompanying TYPICAL SECTION. Oil is now being produced from 8 distinct reservoirs; production from two others, San Andres (De) and Clear Fork (Ed) has been abandoned. zZ !-< o~ : !-< ~z ro :E :E ­ ;:: o"' I o"" 0 0 (1j ro (/) (/) u 0 ::::> w ~ 0 I I 0 "\:x: 1:': UJ 0 " ::> Cf . EXPLANATION ~ Rock indicated, Limestone Shale Sandstone sandy ~ ~ lli28 LZJ Limestone ~Dolomitic Sandstone Rock indicated, and shale shale and shale sholy ~ ~ ~ ~ Solt and Rock indicated,Dolomite Anhydrite anhydrite onhydritic ~ mm ~ D Anhydritic ~Dolomitic .. -0 Insoluble residue Chert dolomite ~ anhydrite marker CJ • 0 .. Igneous and metamorphic complex (granite, Estimated percent of diorite, gobbro, gneiss, schist) .. insouble res idue in Ellenburger samples " • Oi l production *Gas production ... NOTE: The above is based on a composite log. It was compiled to show the complete section and is not applicable in its entirety to any one location. > "'O 0 0 '"r:I ,_. t'Tj t'""" t1 f ~ ~ r APCO FIELD, Pecos County, Texas OLDEST HORIZON PENETRATED The oldest horizon penetrated is in the pre­Cambrian complex. Sixteen wells have been drilled into the pre-Cambrian complex, which consists of granite, gabbro, schist and gneiss. NATURE OF TRAPS All reservoirs in Seven Rivers, Queen and Grayburg formations: Convex folding. San Andres (De} and Clear Fork (Ed}: Updip de­crease of porosity in a sloping reservoir rock. Ellenburger (Fa}: Updip termination of reservoir rock by truncation and with sealing by relatively impervious rock. PRODUCTIVE AREAS Acres Fromme (Ab) and (Bb} 250 Masterson (Ac) and (Be) 120 Shearer (Ae}, (Be) and (De) 270 G,rayburg (Cf) 30 Clear Fork (Ed) (depleted} 40 Ellenburger (Fa) 1,960 Apco field 2,455 THICKNESSES OF RESERVOIR ROCKS From top to bottom, average, approx. Feet Seven Rivers: Fromme (Ab) 24 Masterson (Ac) 21 Shearer (Ae) 10 Queen: Fromme (Bb) 8 Masterson (Be) 4 Shearer (Be) 6 Grayburg: Shearer (1700') (Cf) 12 San Andres: Shearer (De) 35 Clear Fork: Masterson (3500') (Ed} 29 Ellenburger: Apco-Warner (Fa) 775 The oil-producing rock throughout the Apco-Warner productive area is generally only a small portion of the total reservoir rock. In the eastern part of the productive area, the upper portion of the reservoir rock is absent due to truncation, and, in the western part, the lower portion is below the oil-water contact. LITHOLOGY OF RESERVOIR ROCKS All reservoirs in Seven Rivers, Queen, Grayburg and San Andres formations: Silty sandstone and dolomite. Clear Fork (Ed}: Dolomite with relatively high porosity. Ellenburger (Fa): Dolomite; weathered, cherty, relatively high porosity. From a study of insoluble residues, the writer has been able to distinguish five stratigraphic positions which are usable for correlating from well to well within the field. These are indicated on the accompany­ing TYPICAL SECTION. CONTINUITY OF RESERVOIR ROCKS All reservoirs in Seven Rivers, Queen, Grayburg and San Andres formations : Each of the reservoir rocks is in a zone which is of the same general character throughout the area of the field. However, the productive zones in the four named stratigraphic units are not subject to definite correlation from one geographic sub-division to another. They mayor may not provide continuity for migration of reservoir fluids beyond their respective geographic areas. Clear Fork (Ed}: The dolomite member which was locally and temporarily productive may or may not be continuous throughout the area of the field. Tli.e favorably porous condition which occasioned commercial production is definitely local and is not continuous beyond the immediate vicinity of the single productive well. Ellenburger (Fa} : The continuity of the Ellenburger reservoir indicated sections. interrupted by accompanying maps is on truncation and cr as oss WATER PRODUCTION Water production is negligible except that water constitutes about 30% of the gross production of the three wells producing from the Grayburg (Cf) reservoir . ACID TREATMENT The reservoir rock in each of the Ellenburger wells has been treated with 500 to 9 ,500 gallons of acid. Data relative to acid treatment of other reservoir rocks are not available. CROSS SECTIONS l:'V 0) " p6~ DEVELOPMENT MAP A-A' B-81 :;i::o. 'U () 0 "Tj ....... tr1 r-' t1 'U CD 8 en () § i:< --3 ~ EXPLANATION FOR ALL CROSS SECTIONS Oet rltu1 ftt~&~i~~I ~#~ IQ~a:1~~:~;~lc Oil well, productive from Permian Oil well, obondoned in Permian • Oit well, productive from Ellenbun~er + Oil well, abandoned in Eltenbur9er INSOLUBLE RESIDUE MARKER HORIZONS IN ELLENBURGER GROUP * Productive from Permian; first as on oil wetl , then as o gos well and toter os on oil well (I well) 1f Gos well, productive from Perm ion (I well) ~ Gos well, productive from Ellen burger .P Ory hate, total depth in Permian fl Dry hole, total depth in pre -Permian &. Injecting water into Permian ( 8 wells) .:n Total depth • \:11 Discovery FLUIDS IN ELLENBURGER GROUP PRODUCTIVE AREA BOUNDARIES EI]Gas D • 011 Water ...,... ...,... -.-...,... ~ Apco-Worner Masterson ----Shearer ++++++++ Fromme ···················· ········· Masterson (35001) Shearer (1700') HORIZONTAL SCALE SCALE 0 • 10 Mod ified from llQurH 9 and tO, Apca Field, Pecos Caul"ltr, Texo1: Amer. A11oc. Petrol. Geol., Bull. , val. 24, pp. 414 ond 416 THOUSAND FEET a8.'; SAN ANDRES MAP > 'U 0 0 '"Tj ...... M L"' 0 'U CD () g ~ ~ --3 ~ EXPLANATION --+1350---Conlour on lop of Yotes formolion ---+550---Conlour on lop of Son Andres formotion Oil well, productive from Permion Oil well, abandoned in Permian Oil well, productive from Permia n Oil wetl, abandoned in Permion Oil well, productive from Ellenburc;ier + Oil well, abandoned in Ellenbur9er• Oi l well, productive from Ellenbur9er Oil well, abandoned in Ellenbur9er * Productive from Permian; first as an oil well, then os a 90s well and later as an oil well (I well) * Produclive from Permion; first as on oil well, !hen as o 90s well and taler as on oil well (1 well) from Permian ( 1 well) * Gos well, productive from Per mian 11 well) '* Gos well, productive from Ellenburoer llf Gos well, produclive * Gos well, productive Ellenbur9er from p Ory hole, total depth in Perm ion fl Ory hole, total depth in pfe-Permion JI Ory hole, lotal depth in Permian p Ory hole, total depth in pre-Permian fl::. lnjeclin9 water into Permian I 8 wells) 1,u Total depl h • \:] Discovery&. tnjec1in9 water into Permian (8 wells) "~3 Tota l depth • ""C] Discovery SCALE SCALE 10 15 10 15 THOUSAND FEETTHOUSAND FEET N Modified from ll9ur1 4, Apco Fleld, Pecos County, Tuos: Amer. Anoe. Pllrol. Geol., Bull., vol. 24, p9. 406 Modlfi•d from tlQur• 5, Apco Field, Pecos Counly, Tnos: Amer. Anoe. Pelrol. Geo1., Bull., vol. 24, pQ. 4 07 -.....:i ;i ·~ ELLENBURGER MAP ~ 864 >. "':' ~ G' ., 6'< Q tn APCO FIELD, Pecos County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES Elevation of oil, feet Relief, Top Bottom feet Seven Rivers: Fromme (Ab) 1,269 1,029 240 Masterson (Ac) 1,024 977 47 Shearer (Ae) 1,069 981 88 Queen: ~omme(Bb) 995 815 180 Masterson (Be) 986 936 50 Shearer (Be) 932 841 91 Grayburg: Shearer (1700 ') (Cf) 704 692 12 San Andres: Shearer (De) (depleted) 535 510 25 Clear Fork: Masterson (3500') (Ed) -1,123 -1,152 29 Ellenburger: Apco-Warner (Fa) -2,033 -2, 300 267 The Ellenburger (Fa) reservoir is the' only reservoir containing free gas. Elevation of top of the gas, -1,767 feet; elevation of bottom of gas, -2,033 feet; relief, 266 feet. CHARACTER OF OIL Gravity A.P.l. @ 60"F. Fromme, (Ab) and (Bb) 27°-31° Masterson, (Ac) and (Be) 21°-25° Shearer, (Ae), (Be) and (De) 25° -36° Grayburg: Shearer (1700') (Cf) 30° Clearfork: Masterson (3500') (Ed) 21.9 ° Ellenburger: Apco-Warner (Fa) 36 ° -43 ° For analyses see: Railroad Commission of Texas Analyses of Texas Crude Oils (1940), pp. 32, 33, 34, 63, 64 and 65. U.S. Bureau of Mines Lab. ref.# 38154 40015 46115 Tabulated Analyses of Texas Crude Oils. T. P . 607 (1939) Group 2 Item 63 Analyses of Crude Oils from Some Fields of Texas. R . I. 3699 (1943) Item 6 Analyses of Crude Oils from Some West Texas Fields. R . I. 3744 (1944) Page 3 Analyses of Crude Oils from Some West Texas Fields . R. I. 4959 (1953) Item 9 SELECTED REFERENCES Cole, Taylor (1940) Ordovician development, Apco structure, Pecos County, Texas: Amer. Assoc. Petrol. Geol., Bull., vol. 24, pp. 478-481. Cole, Taylor (1942) Subsurface study of Ellenburger for­mation in West Texas: Amer. Assoc. Petrol. Geol., Bull., vol 26, pp. 1398-1409. Ellison, Samuel P., Jr. (1948) Apco field, Pecos County, Texas: Amer. Assoc. Petrol. Geol., Structure of Typical American Oil Fields, vol. 3, pp. 399-418. SECONDARY RECOVERY Water injection into Masterson (Ac) and (Be) reservoirs was started on November 1, 1954, The project was initiated by injection through the 8 wells indicated on an accompanying map. PRODUCTION IUSTORY WELLS PRODUCING OIL PRODUCTION OIL at end of year (barrels) Year Flowing Pumping Yearly Cumulative Field totals 1930 ? ? 7,964 7,964 19 31 ? ? 1,883 9,847 1932 ? ? 620 10,467 19 33 ? ? 2,838 13, 305 19 34 0 3 10,916 24,221 1935 0 5 7,040 31,261 1936 3 11 194,156 225, 417 1937 5 15 290,420 515,837 1938 13 23 264,333 780,170 1939 42 25 585, 755 1,365,925 1940 45 36 429,047 l, 794,972 1941 45 47 386,943 2, 181,915 1942 34 61 362, 712 2,544,627 1943 46 65 561,367 3,105,994 1944 52 70 852, 138 3,958,132 1945 50 76 888,891 4,847, 023 1946 46 76 845,402 5,692,425 1947 38 84 808, 716 6,501, 141 1948 34 88 806,857 7,307,998 1949 29 92 558,175 7,866,173 1950 23 88 537,582 8,403, 755 1951 21 98 587,367 8,991,122 1952 18 98 538,148 9,529,270 1953 19 101 520, 108 10,049,378 1954 19 101 437,814 10,487, 192 APCO FIELD , Pecos County, Texas PR 0 DU C TI 0 N HIS T 0 RY (Continued) WELLS PRODUCING OIL PRODUCTION WELLS PRODUCING OIL PRODUCTION OIL at end of year (barrels) OIL at end of year (barrels) Year Flowing Pumping Yearly Cumulative Year Flowing Pumping Yearly Cumulative Fromme (Ab) and (Bb) Shearer {Ae), {Be) and {De) 1939 4 0 9 ,093 9 ,093 19 38 13 0 72,163 72,163 1940 8 2 28 ,508 37 ,601 1939 35 3 463 ,570 535,733 1941 8 2 34 ,391 71 ,992 1940 30 12 288 ,653 824,386 1942 4 3 22 ,580 94 ,572 1941 27 20 204 ,218 1,028 ,604 1943 5 2 16 ,744 111,316 1942 10 33 182 ,868 1,211,472 1944 5 2 10 ,035 121,351 1943 5 38 157,097 l ,368 ,569 1945 5 4 12 ,4 12 133,763 1946 4 5 11,274 145 ,037 1944 5 41 116 ,447 1,485,016 1945 0 46 84,603 1,569 ,619 1947 4 5 10,155 155,192 1946 0 43 62 ,050 1,631,669 1948 3 5 8,745 163 ,937 1949 3 7 8 ,833 172,770 1947 0 43 58,299 l ,689 ,968 1950 2 12 12,194 184,964 1948 0 43 52 ,263 1,742,231 1949 0 41 46 ,554 1,788 ,785 1951 0 12 16,269 20 1,23 3 1952 0 12 12,512 21 3,745 1950 0 41 41,340 1,830,125 1953 14 21,117 2 34,862 1951 0 38 35 ,300 l ,865 ,425 1954 14 17 ,656 252,5 18 1952 0 38 33,475 l,898,900 1953 0 38 33,628 l ,932,528 Masterson (Ac) and (Be) 1954 0 38 31,527 l ,964 ,055 1930 ? ? 7 ,964 7 ,964 1931 ? ? 1,883 9 ,847 1932 ? ? 620 10 ,467 Shearer (1700' ) (Cf) 1933 ? ? 2 ,838 13,305 1949 0 2 6 ,788 6,788 1950 0 2 12 ,034 18,822 1934 0 3 10 ,916 '24 ,221 1951 0 3 5,948 24,770 1935 0 5 7 ,040 31,261 19 36 3 11 194,156 225,417 1952 0 3 6,724 31,494 1937 5 15 290,420 ~15,837 1953 0 3 5 ,57 3 37,067 1954 0 3 4,705 41,772 19 38 0 23 192 ,170 7 08 ,007 1939 0 22 90,208 798,215 1940 0 22 65 ,501 863,716 Apco-Warner (Fa) 1941 0 24 59 ,006 922 ,722 1939 3 0 22 ,88 4 22 ,884 1940 7 0 46 ,385 69 ,269 1942 0 24 46 ,860 969 ,582 1941 10 89 ,328 158 ,597 1943 0 24 46,482 1,016 ,064 1944 0 24 39 ,464 1,055 ,528 1942 20 110,404 269 ,00 l 1945 0 23 35,501 1,091,029 1943 35 l 319,564 588 ,565 1944 41 3 657 ,350 1,245,915 1946 0 23 33'135 l,124,164 1947 0 22 31 ,308 1,155,472 1945 44 3 739,962 l ,985 ,877 1948 0 24 30 ,356 l ,185 ,828 1946 41 5 7 36 ,243 2,722,120 1949 0 22 30 ,834 1,216,662 1947 33 14 707,728 3 ,429 ,848 1950 0 20 38 ,699 1,255 ,361 1948 30 16 715,081 4,144,929 1951 0 20 37 ,655 1,293,016 1949 26 20 464,967 4,609,896 1952 0 20 34,701 1,327,717 1950 21 13 433,315 5,043,211 1953 0 17 3 1 ,542 1,359 ,259 1954 0 18 31 ,243 1,390,502 1951 21 25 492,195 5 ,535 ,406 1952 18 25 450,736 5,986,142 1953 18 29 428 ,248 6,414,390 Masterson (3500') (Ed) 1954 18 28 352 ,683 6,767 ,07 3 1943 1 0 21,480 21 ,480 1944 0 28 ,842 50,322 1945 0 16 ,413 66 ,7 35 GAS PRODUCTION: The only available records of gas 1946 0 2 ,700 69,435 production indicate that 2 wells in Fromme (Ab) and (Bb) produced 40,382 Mcf during 1942; 46,346 Mcf during 1943; 1947 0 1,226 70,661 46,519 Mcf during 1944; 67,160 Mcf during 1945; 12,312 Mcf 1948 0 412 7 l ,07 3 during 1946 and none thereafter. Two wells were completed 1949 0 0 199 71,272 in Apco-Warner (Fa) as gas wells; we find no record of 1950-1954 0 0 0 71,272 their having produced any gas . ARICK FIELD Hale and Floyd CoUDti-. Texas B. COOPER HYDE District Geologist, Houston Oil Co. of Texas, Midland, Texas March 23, 1955 LOCAtlON The Arick field is on the Hale-Floyd county line about 3 miles north of the south end of this common boundary. It is about 2 miles northeast of the town of Petersburg in southeast Hale County. From the standpoint of regional structure.the field is near the apex of the Matador arch. METHODS OF EXPLORATION LEADING TO DISCOVERY The discovery was the result of analysis of data afforded by gravity meter, magnetometer and seis­mograph surveys and by previous drilling operations. The discovery resulted directly from work-over operations on a hole which had been drilled into pre-Cambrian igneous rock and abandoned as dry. DISCOVERIES Wichita: December 2, 1948; General American Oil Co. #2 E.M.Carmichael. Wolfcamp and Field: April 20, 1948; General American Oil Co. #1 A.F .Byrd (work­ over of hole drilled in 1941 as Humble Oil & Refg. Co. #1 A.F.Byrd). ELEVATION OF SURFACE At well locations: Highest, 3,239 ft.; lowest,3,226 ft. SURF ACE FORMATION Wind blown sand and caliche of Quaternary age. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest stratigraphic horizon penetrated is at the base of detrital sediments overlying grano­diorite. Within the productive area, the oldest stratigraphic horizon known to have been penetrated is in the Mississippian system about 110 feet below its top. This penetration was in the Wolfcamp dis ­covery well. The accompanying TYPICAL SECTION is based on the log of that well. At its total depth of 6, 760 feet, that well had been drilled 15 feet into pre-Cambrian granodiorite. NATURE OF TRAPS Wichita and Wolfcamp: The trap in each of the two reservoirs is due primarily to convex folding. It appears likely that termination of reservoir rock against a fault has functioned in a minor way in forming each of the two traps. PRODUCTIVE AREAS Acres Wichita ---:w- Wolfcamp 300+ Arick field 300+ THICKNESSES OF RESERVOm ROCKS Wichita Wolfcamp Average net productive, feet 28 49 LITHOLOGY OF RESERVOm ROCKS Wichita: Dolomite; brown and tan, dense to finely crystalline, slightly oolitic, with intergranular and vuggy porosity. Wolfcamp : Limestone; tan to white, dense, slightly oolitic, sparingly fossiliferous, with porosity which is largely vuggy with some indications of fracturing. CONTINUITY OF RESERVOm ROCKS Wichita and Wolfcamp : The stratigraphic equiv­alent of each of the reservoir rocks is identifiable throughout the area of the field. However, as to each, only locally is the degree of porosity and permeability adequate for commercial production. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Wichita: Elevation of highest known oil Elevation of oil-water contact Known relief Wolfcamp: Elevation of highest known oil Elevation of oil-water contact Known relief CHARACTER OF OIL Wichita Gravity, A.P.I.@ 60° F. 42.0° ACID TREATMENT Feet -1.505 -1,540 35 -2,554 -2,660 106 Wolfcamp 42.2 ° Wichita and Wolfcamp: The reservoir rock in each well has been acidized. The quantity of acid has ranged from 1,500 gallons to 7 ,500 gallons. SELECTED REFERENCE Shepherd, G.Frederick (1949) A Structural Interpre­tation -Arick Field: The Petroleum Engineer, Nov. 1949, pp. Bl l -Bl6. ARLEDGE FIELD Cob County, T.xaa J. R. KIENE Geologist, Sinclair Oil & Gas Co., Midland, Texas July9, 1954 LOCAnON The Arledge field is in north central Coke County i mile south of the northern boundary and is in Sec. 261, Blk. 1-A, H. & T . C. survey. METHOD OF EXPLORAnON LEADING TO DISCOVERY The location !)f the discovery well was determined on the basis of a surface geological survey supplemented by sub­surface data and by seismograph survey. DISCOVERY Strawn: January 19, 1948; ---S-un Oil Company #1 J. W.Arledge. ELEVAnON OF SURFACE At well locations: Highest, 2,261 ft.; lowest, 2,239 ft. SURFACE FORMAnONS Undifferentiated formations of the Fredericksburg and Trinity groups are exposed on the hills and undifferentiated Tertiary beds occur in the valleys. OLDEST HORIZON PENETRATED The oldest horizon penetrated is 10 feet below the top of pre-Cambrian metamorphic rock. This penetration was in Sun Oil Co. #2 J. W.Arledge, the abandoned well located about 1,750 feet northeast of the discovery well. The accom­panying TYPICAL SECTION is based on the log of the lower 1,775 feet of penetration by that well. NATURE OF TRAP Strawn: The trap appears to be due to decrease of porosity updip on a structural nose. PRODUCTIVE AREA Strawn: Gas, 40 acres; oil, 80 acres. TIUCKNESS OF RESERVOIR ROCK Strawn: Net productive, approximate, 35 feet. UTHOLOGY OF RESERVOIR ROCK Strawn: Limestone; dark brown, finely crystalline to dense, both intercrystalline and vug type porosity. CONTINUITY OF RESERVOIR ROCK Strawn: The reservoir rock appears to be continuous throughout the area of the accompanying map. It was readily identified in each of the wells shown on the map. ELEVAnON AND RELIEF OF PRODUCTIVE ZONE Strawn: Feet ----iTighest known elevation of gas -4,311 Lowest known elevation of gas -4,346 Known relief 35 Highest elevation of oil, estimated -4,350 Lowest known elevation of oil -4,364 Relief, estimated 14 CHARACTER OF OD. Strawn: --cravity, A.P.1.@ 60° F., 47° Sulphur, 0.2% WATER PRODUCTION Strawn: Water production is negligible; less than 70 barrels per well per year. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year {barrels) Year Flowing Yearly Cumulative 1948 2 15 ,266 15,266 1949 2 5,947 21 ,213 1950 2 4,657 25,870 1951 2 4 ,007 29 ,877 1952 2 3,640 3 3 ,51 7 195 3 2 3 ,363 36 ,880 The second of the two oil wells was deepened to test the Cambrian sandstone and was plugged and abandoned on May 18, 1954 after having been drilled to the total depth of 7 ,825 feet. GAS PRODUCTION: One of the three wells in the field was completed as a gas well on May 31, 1948. It had a rated capacity of 960 Mcf of gas per day. This well has been shut in since the time of its completion. TYPICAL SECTION OF ROCKS PENETRATED w ~ :i:=­:::0 r-' M t:l 0 M 'Tj ....... M r-' t:l ~ CD ~ ~ r ~Limestone r~~~?///h\i Sondstone ~Metamorphic ~Dolomite G~:tJ Sandy shale ~ rock Oil production -00 6400 6500 6600 6700 6800 6900 7'00 ..z z 7200 ~ >­ ~ z 7'00 0.. "' 7400 BARNE TT ? 7500 -2936 -3036 -313 -3236 _,, -3436 -3536 _,, -l836 -39 36 -4036 -•U3 -4236 -4636 -4736 -4836 -4936 GROSS SECTION A -A' A U!YAJION 4 rnr PERMIAN PENNSYLVAN IAN BARNE TT ? WOODFORD DEVON IAN ! z .. OIL -W.t.T£11 --­ ::::t===------­ --«iiil~==-===-=t::==-•F'iiuS,ssiEEULM~A;.=====r / / ~= T--..\-.::: •ON~To~v•'_____ _ -&•oo / / ,,----­ -7000 ~/~====== -noo /~ // --..:-cONN[LC ----~ ~==== ElLENBURGER ~ / -:?;:::::= -­ ~_,,.L---__,,.,__ -­ -----~ HORIZONTAL SCALE PllC-C.Ut!lllt&N. -9072 TO -909Z TOTA L OU•T•<. u,. .. , nt-90921 EllEN&Vll GCll T0 -90 72 EXPLANATION ~Dolomite t:\/{{//] Sandstone ~Limestone Ll Shole • Oil production ~Chert BLOCK 31 FIELD, Crane County, Texas LITHOLOGY OF RESERVOIB ROCKS Clear Fork: Dolomite; alternating dense argillaceous dolomite and brown finely crystalline dolomite, quite anhy­dritic with numerous shale partings and stylolites. The porosity is irregular, generally very low and is of both intercrystalline and vuggy types. Devonian: Chert, limestone and siliceous limestone, In this field, sediments of the Devonian system consist of three generally distinguishable zones: (a) The upper zone is 100 to 150 feet thick and con­sists predominantly of grayish brown opaque chert with varying amounts of gray crystalline limestone with erratic porosity. This zone produces oil only locally where poros­ity is favorable. (b) Below the upper cherty zone is 650 to 700 feet of predominantly limestone rocks, fairly pure in the upper portion and quite siliceous in the lower portion, where gray, finely crystalline, siliceous limestone constitutes the prin­cipal Devonian producing zone. The porosity is very fine, uniform, intercrystalline and contrasts with the usual frac­tured, vuggy porosity characteristic of the Devonian on the Central Basin platform. (c) The lower 200 feet of the Devonian system is dark colored chert in the upper part; it grades into shaly lime­stone and brown shale near the base. There are thin porous zones of siliceous limestone in this lower cherty zone. These porous zones are quite prolific oil producers wher­ever above the elevation of the oil-water contact (-6, 410 ft.) . As shown on an accompanying map, the boundary of the Devonianproductive area does not conform to the structural contours. This is a result of the varying porosity in the upper part of the Devonian rocks. Variations in the distance from the top of the Devonian (contour datum) to the first effective porosity determine the relationship of contours to the boundary of the productive area. The elevation of the Devonian oil-water contact is apparentlyfairly constantover the field. The upper Devonian reservoir is apparently separated from the principal Devonian producing zone by a series of impermeable beds. The symbol on the accompanying TYPICAL SECTION in­dicating reservoir rock from -5,830 to -6, 336 is not intended to imply that the rock is productive throughout the whole of that thickness; there are barren streaks within that zone, McKee: Sandstone. The McKee reservoir rock is a zone of friable, poorly cemented and poorly sorted, rounded to subangular sand grains about 40 feet below the top of the McKee member, which member has a gross thickness aver­aging about 120 feet and consists predominantly of sand, much of which is shaly and contains numerous streaks of waxy green shale. The reservoir rock is a thin, permeable sandstone of only limited areal extent and which is shaly and asphaltic at locations high up on the flanks of the structure. Connell: Sandstone; 7 to 12 feet of poorly cemented, friable sandstone consisting of grains of variable size and angularity; shaly at downdip locations. This productive zone is ·at the top of the Connell member, which has an overall thickness of approximately 25 feet. Ellenburger: Dolomite; hard, various colors, crystalline with varying degrees of crystallinity. The extreme upper­most part is light tan, finely crystalline. Within the Ellen­burger there are distinguishable zones of coarsely crystalline white to tan dolomite, which zones cannot be correlated from well to well, suggesting that they are products of localized secondary crystallization. Porosity is evident in both the finely crystalline and coarsely crystalline dolomite. Oil productivity is independent of the character of crystallization. Production is from fractured zones and openings associated with the fractures. OLDEST STRAnGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in pre-Cambrian rocks about 20 feet below the Ellenburger -pre-Cambrian contact. This penetration was at the total depth of 11,645 feet in the Connell discovery well, which is identified as No. 3 on the accompanying cross section. THICKNESSES OF RESERVOIB ROCKS Net productive, feet Min. Max. Avg. Clear Fork 65 65 65 Devonian 50 370 250 McKee 6 10 7 Connell 7 12 9 Ellenburger 30 120 60 CONTINUITY OF RESERVOIB ROCKS Clear Fork: This zone, as far as is known now, shows possibilities for production from only a very restricted area in the northeast portion of the field, where porosity is locally favorable on the northeastern flank of the Block 31 uplift. The Clear Fork group is continuous over a very large area, but the porous zones within the Clear Fork are of only local extent. Occurrences of oil and gas in the upper portion of the Clear Fork are very widespread but there appears to be no connection between the individual produc­tive reservoirs. Devonian: The Devonian occurs throughout most of the Permian basin of West Texas and outcrops in the mountains to the west and south. While to the northward it is dj.fferent in character, grading into dolomite north of Ector County, eastward it has characteristics about the same as in the Block 31 field. McKee: The McKee reservoir rock extends over only a very small portion of the Block 31 uplift. The McKee member, however, is recognizable over most of the Central Basin platform, but productive reservoirs within it are merely local. Connell: This reservoir rock is apparently less widely distributed than is the McKee, but is apparently of more uniform lithologic character, particularly in Crane County. The Connell member is hardly recognizable as a lithologic unit in the TXL field in northwestern Ector County, but either produces or has indicated capacity for production in each of five fields in Crane County and in one in northern Pecos County. Ellenburger: The Ellenburger group is continuous over an enormous area. Its lithologic characteristics are essen­tially the same over very large areas -predominantly dolo­mite with some limestone beds which are more prominent toward the Eastern Shelf area of West Texas. It is one of the more important producing zones in West Texas, and produces over a greater area than any other single strati­graphic unit. Its stratigraphic equivalent, the Arbuckle, is a prolific producer in many fields in Oklahoma and Kansas. BLOCK 31 FIELD, Crane County, Texas PRODUCTIVE AREAS Acres Clear Fork 120 Devonian 5,200 McKee 320 Connell 1,280 Ellenburger l, 720 Block 31 field 5,200 Clear Fork: The estimate of the productive area of this reservoir is no more than a rough guess. The reservoir evidently contains only a very small amount of commercially recoverable oil. Only one well has been completed in it to date. Devonian and Ellenburger: The estimates for these reservoirs are believed to be quite accurate. Development of each is essentially complete. McKee and Connell: Coring and drill-stem testing have provided data for reasonably accurate estimates of the productive areas of these reservoirs. Although no well is now producing from either of these reservoirs, neither is regarded as depleted. CHARACTER OF GAS No gas analyses are available. The combined field gas is known to be sour. Incidental to pressure maintenance operations, about 16,000 gallons of liquid products are extracted daily from the pressured gas. The only gas in the reservoirs at respective discovery dates was in solution in the oil. ACID TREATMENT Clear Fork: The one well in this reservoir was shot with nitroglycerin and acidized with 4,000 gallons of acid. Results were not good although acid should be beneficial in this reservoir rock even though it is anhydritic throughout most of its thickness. Devonian: Most wells were completed without acid treatment. During subsequent workovers of several flank wells, treatments with 10,000 gallons of regular 15% acid have resulted in sustained increases in production. Some treatments included .the squeezing of l,000 gallons of mud acid into the reservoir behind the regular acid, but no diff­erence·in results was observed. McKee: Not treated with acid. Connell: Not treated with acid. Ellenburger: Some of the wells have been completed without acid treatment while others have been treated with va'rying amounts of regular 15% acid. The Ellenburger dolomite responds very favorably to acid treatment. RESERVOIR ENERGY Clear Fork: The energy operating to expel the oil from the reservoir appears to be that occasioned by gas corning out of solution due to decrease in pressure. The oil was undersaturated at the original reservoir pressure. There are no indications of an effective water drive. Devonian: Solution gas energy appears to be augmented to a minor extent by water drive. There was no free gas at time of discovery. A program for artificial injection of gas has been initiated and is currently injecting 27,280 Mcf of gas daily atan average pressure of approximately 4,000 psi. Of the total gas injected, 17,500 Mcf per day is produced locally and the remainder is purchased. Gas was being in­jected into this reservoir through one well at the end of 1949, through two wells at the endofl950, through four wells at the end of 1951, and through twelve wells at the end of 1952. The injection operation is described in the paper by Carlson cited under SELECTED REFERENCES. McKee and Connell: Solution gas energy appears to be the only effective reservoir energy in each of these reser­voirs. There is no water drive and no gas cap. The oil was considerably undersaturated at the original reservoir pressures. Ellenburger: There is an effective water drive aug­mented by energy supplied by gas coming out of solution. The reservoir pressure has declined only slightly. CHARACTER OF RESERVOIR WATERS Clear Fork: No data available. Devonian: Average chloride content: 120,000 parts per million. McKee: No data available. Connell: No data available. Ellenburger: Average chloride content: 50,000 parts per million. SELECTED REFERENCES Carlson, Roy F. (1951) Block 31 pressure-maintenance plant believed to be world's highest-pressure gas­injection program: Oil and Gas Journal, April 19, 1951, pp. 154, 157, 220. Park, Lee B., and McKay, Alexander E. (1948) Geophysical history, Block 31 field, Crane County, Texas: Soc. Explor. Geophysicists, Geophysical Case Histories, vol. l -1948, pp. 389-399. Griffith, B. L., and Hollrah, V. M. (1952) High pressure gas injected in Block 31: World Oil, July l, 1952, pp. 163-168. ~ ~ tJ:1 t""" 0 0 :;-::: w ......... 'Tj ........ rr:i L' CJ 0 a ::1 (!) ~ c ::1 ...... '.:< w C/I BLOCK 31 FIELD, Crane County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES No free gas in any reservoir Clear Fork § Devonian § § McKee Connell Ellenburger Highest known elevation of oil , feet* -1,687 -5 ,800 -7 ,066 -7 ,610 -7 '7 10 Elevation of oil-water contact, feet Unknown -6 ,410 Unknown Unknown -7 ,980 Known oil column, feet ? 610 ? ? 270 * Each figure on this line represents the highest elevation at which the top of the reservoir has been penetrated in wells . § The Clear Fork has been found capable of commercial production in only one well. § § The entries in this column apply to only that part of the Devonian below the top of the blanket porous zone which occurs quite uniformly throughout the field. The erratic porous zone near the top of the Devonian is neglected in this tabulation . RESERVOIR TEMPERATURE AND PRESSURE and CHARACTER OF OU. Clear Fork Devonian McKee Connell Ellenburger Pressure, psi. 1,600 4 ,105 4,100 Est. 4,300 4 ,178 Temperature, "F. Not avail. 138 150 160 160 Gravity of oil, A.P.I. @ 60 ° F . 40 44-48 44 44 42-47 Ga s-oil ratio, cu. ft./bbl. 458 1,300 300 576 820 The above da ta represent conditions at respective discovery dates. For analyses of oil see : Analyses of Crude Oils from Some West Texas Fields, U.S . Bureau of Mines, R. I. 4959 {1953), Item Nos. 18 and 19. WATER PRODUCTION Devonian Ellenburger No . of wells Barrels No . of wells Barrels Year producing water Yearly Cumulative producing water Yearly Cumulative 1945 ? 12 12 ? 12 12 1946 4 4,279 4,291 3 4,387 4,399 1947 6 5 ,940 10 ,231 3 53 ,476 57 ,875 1948 6 9 ,418 19 ,649 3 21,084 78,959 1949 7 8 ,227 27 ,876 4 23 ,841 102,800 1950 8 12,690 40,566 5 24,755 127,575 1951 4 13,601 54, 167 6 39 ' 151 166 ,726 1952 2 13,795 67 ,962 8 221,622 388 ,348 Clear Fork , McKee a nd Connell have produced only negligible amounts of water . BLOCK 31 FIELD, Crane County, Texas PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION at end of year* {ba rrels) (Mcf) Year Flowing Pumping Total Yearly Cumula tive Yearly Cumula tive Field totals 1945 2 0 2 24,186 24,186 16,655 16,655 1946 26 3 29 893,547 917,733 1,013,472 1,030,127 1947........... 30 ............ 8 ............ 38 ............ 1,560,210 ........ 2,477,943....... 1,560,610 .•. .... 2,590,737 1948 42 7 49 1,748,005 4,225,948 2,102.911 4,693,648 1949 59 8 67 1,873 ,859 6 ,099 ,807 2,310 ,799 7,004,447 1950 .......... 69............ 8 .. .......... 77 ............ 2 ,524,930 ........ 8,624,737....... 3,096 ,276 ......10,100 ,723 1951 71 9 80 3,579.989 12,204,726 4,263,934 14,364,657 1952 63 10 73 3,512,347 15,717,073 4,360,149 18,724,806 Clear Fork 1950 0 2'158 2 ,158 0 0 1951 0 l ,584 3 ,742 0 0 1952 0 l ,265 5 ,007 0 0 Devonian 1945 1( 1) 0 11.984 11.984 8,772 8,772 1946 17( 9) 3 20 578,939 590 .923 706 ,808 715 ,580 1947........... 19 ( 11) ....... 8 ............ 2 7 ............ 1,043 •.050 ......... 1,633 .97 3....... 1' 192 '7 54 ....... 1.908 ,334 1948 34(13) 5 39 1,302 ,182 2 ,936 ,155 1,732,582 3,640,916 1949 47(15) 7 54 1,374,829 4,310,984 1,894,189 5,535,105 1950........... 54(16) ....... 6 ............ 60 ............ 2 ,045 ,448 ......... 6 ,346 ,432 ....... 2 ,762 ,717 ....... 8 ,297 ,822 1951 57(16) 6 63 2 ,982 ,159 9 ,328 ,591 3 ,888,697 12,186,519 1952 49(16) 7 56 3 ,020,493 12,359,084 4,035 ,448 16,221,967 McKee§ 1948 2( 2) 0 2 2 ,049 2 ,049 2,463 2,463 1949 1( 1) 0 1 53 ,610 55 ,659 41,042 43 ,505 1950............ o·............ o ............. 0 ...... .............. 923............. 56,582 ............ 1,155 ........... 44,660 1951 0 0 0 0 56,582 0 44,660 1952 0 0 0 0 56,582 0 44,660 Connell § § 1948 1( 1) 0 9.903 9,903 0 0 1949 1 ( 1) 0 1 84 ,686 94 ,589 0 0 1950..•.......•. . o ............ o ............. 0 .. .. ............. 2 ,039 ... .......... 96 ,628 .................. 0 .................. 0 1951 0 0 0 0 96.628 0 0 1952 0 0 0 0 96 ,628 0 0 Ellenburger 1945 1( 1) 0 12,202 12,202 7 ,883 7,883 1946 9( 9) 0 9 314,608 326 ,810 306 ,664 314,547 1947........... 11(11) ....... 0 ............ 11 ............... 517,160 ........... 843,970 ......... 367,856 ......... 682,403 1948 8( 8) 2(2) 10 433,871 1,277 ,841 367 ,866 1,050,269 1949 12(12) 1(1) 13 360,734 1,638,575 375 ,568 1,425 ,837 1950........... 15(15) ...•... l(l) ........ 16 ............... 474,362 ......... 2,112,937 ......... 332,404 ....... 1,758,241 1951 14(14) 2(2) 16 596,246 2,709 .183 375,237 2 ,133,478 1952 14(14) 2(2) 16 490,589 3,199,772 324 ,701 2,458,179 *Un.der Field totals, a well producing from two reservoirs is counted as two wells. Under the respective reservoir headings, figures in parentheses indicate number of wells producing also from another reservoir. §The two wells which produced from the McKee were producing also from the Devonian. They could not be operated satisfactorily in this manner. They were recompleted so as to produce dually from Devonian and Ellenburger . §§Three wells have produced from the Connell. Each was completed so as to produce also from the Devonian. They could not be operated satis­factorily in this manner . They were recompleted so as to produce dually from Devonian and Ellenburger. BLOCK 47 FIELD Crockett County, TexaB E . E . LINDEBLAD Geologist , Continental Oil Co . , Midland, Texas January 1, 1953 LOCATION The Block 47 field is in northeastern Crockett County, 12 miles northeast of the World field and 5 miles south of the Barnhart field . It comprises portions of sections 8, 9, 13 and 14, Block47, University Land survey. METHODS OF EXPLORATION LEADING TO DISCOVERY It appears that the discovery of this field was the result of having purchased leases at random in a general region indicated as favorable by the results of previous drilling operations . Expiration dates of leases prompted commencement of the test which resulted in discovery. A previous near­by deep test had found showings of oil in the Guada­lupe series . DISCOVERIES Grayburg: October 24, 1947; Continental Oil Co . #l-A-12 University. Pumped 17 barrels of 32° gravity oil per day with no water ; 2-inch tubing. The top of pay was found at the top of the Grayburg formation at depth of 2,110 feet and the well was drilled to total depth of 2 , 17 5 feet. The section from top of pay to total depth was shot with 130 quarts of nitroglycerin. On October 10, 1948, the well was plugged and abandoned. Fusselman: March 28, 1948; Continental Oil Co. #l-A-13 University. Pumped 104 barrels o( 45° gravity oil per day; T. D . 10 ,232 feet; plugged back to 9 ,408 feet; top of pay at 9 ,210 feet, l 0 feet below top of Fusselman formation; treated with 47 ,000 gallons of acid. This is the only well which has produced from the Fusselman, and it was plugged and abandoned on October 25, 1948. The Fusselman was tested in the north offset and found non-produc­tive at that location. ELEVATION OF SURFACE At well locations : Highest,2,711 ft.; lowest,2,643 ft. 10 + TO 2267 640 +T D 22001 + 604 ;+o~~To ro"i"110 T 02 3 52 Jf T0 2.f66 J~6l7 + 560 --p ,~02274 ro2s2s / e.+604 • . •f.ro2 300 +557~, • + 601 /"f ~ t3I)(+691 llTD9390 t------1-;---T D234 7 _rD2 3 04 I r;:,Y + 60• / /Y.+m \)<(: f:f I TD2170 i'l ~~ + 6 30 \:J~/ TO 9 770 + 704 TD 10, 232 Fuss +:05 ·~ p' l 1 T0 25 90 T~t'."38 19 20 +610 TD2 SI O 22 0 x 0 )( 6" )( .s 6" 0 .s 00 0 I 47 BLOCK 23 46 4 BLOCK 5 EXPLANATION -+600-Contour on top of Groybur9 formation +6~8 Elevation of top of GroyburQ formation • Oil well o Drilling well ff Ory h ole • -c:Jl Discovery well + Abandoned oil well' SCALE 10 THOUSAND FEE T .. 22 4 SURF ACE FORMATION Undifferentiated rocks of the Comanche series of the Cretaceous system. BLOCK 4 7 FIELD, Crockett County, Texas TYPICAL SECTION OF ROCKS PENETRATED -' Q V> 0. .., ::> 0: 0 .., 0: Ul Cl ELECTRIC CU RVES AND LITHOLOGY DEPTH ELE VATION "' u u. .., -' 0. 0 ): z " ! z > "' -'" >­ V> z z .., 0. z " 0: ::> -7501 -7533 NOTE: This TYPICAL SECTION is based on the log of Continental Oil Co.Nl-A-13 University, the Fusselman discovery well. The Grayburg reservoir was non-productive at this location . E X PLANATION ffi[J ~~~coted sediment, ITT Argi\loceous dolomitt [][] Indicated sediment, rr:=i Dolomite gray ~ sediment, ~ Dlll lndicoted green l:::!:::::c:Y Limutont §shale [)\:J .Sandstone mAnhydrite ~Gypsiferou1 1ondstont • Oil production 1:.d;.dl Chert BL 0 CK 4 7 FIELD, Crockett County, Texas OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 838 feet below its top. This pene­tration was in the Fusselman discovery well, which is the well on which the accompanying TYPICAL SECTION is based. NATURE OF TRAPS Grayburg: Variation in degree of porosity. Fusselman: To date there is insufficient infor­ mation to determine definitely the nature of the trap-forming factors. Only three wells have been drilled to ~he Fusselman and only one of those was productive. PRODUCTIVE AREAS Acres Grayburg 280± Fusselman (depleted} 40 Block 47 field 280± THICKNESSES OF RESERVOIR ROCKS Grayburg Fusselman From top to bottom, feet 195 140 Net productive, feet 15 35 LITHOLOGY OF RESERVOIR ROCKS Grayburg: Gray, fine to medium grained , crys­talline dolomite with some anhydrite inclusions. Fusselman: Medium to coarse grained, crys­talline, fossiliferous, flesh colored dolomite. CONTINUITY OF RESERVOIR ROCKS Grayburg : Continuous throughout area of field; degree of porosity is variable. Fusselman: The reservoir rock was recognized at each of the three locations where wells were drilled to its depth within the area covered by the accompanying map. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Grayburg : Feet Elevation of top of oil 529 Elevation of bottom of oil 489 Relief 40 Fusselman: Elevation o(top of oil -6 ,511 Elevation of bottom of oil -6,581 Relief CHARACTER OF OIL Grayburg : Range Avg. Gravity, A.P.I.@ 60° F. 35.8° -32.0° 33.0° Fusselman: Gravity, A.P.I.@ 60° F. 45.0° WATER PRODUCTION Little or no water has ever been produced by any well in the field. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrel s ) Year All pumping Yearly Cumulati ve G rayburg: 1947 3 334 334 1948 6 10,147 19 ,481 1949 7 6,886 17 ,367 1950 6 5 ,645 23,012 1951 6 6,957 29 ,969 1952 6 5,680 35 ,649 The above indicated quantiti es ar e less than corresponding quantities reported by the Rail­road Commission for the Block 47 field because the Commission figures include the production from the well in Block 49 in the Friend field. Fusselman: 1948 0 2,302 2,302 Only one well has ever produced from the reservoir in the Fusselman formation. That well was completed on March 28, 1948 and plugged and abandoned on October 2.5, 1948. BRAHANEY FIELD Yoakum County, Texas ARCHIE B. COCKBURN Geologist, Cabot Carbon Company, Midland, Texas May 26, 1953 LOCATION The Brahaney field is in west-central Yoakum County, 3 miles west of the town of Plains, county seat. It is in Secs. 423, 424, 445 and 446 of Block D, 1ohn H. Gibson survey. METHOD OF EXPLORATION LEADING TO DISCOVERY Study of subsurface geological data. DISCOVERY San Andres: June 26, 1945; Dunigan Bros. & Brahaney Ill W . S.Hodges. The well was originally drilled to its total depth of 7 ,717 feet by Skelly Oil Company. It was sold to Dunigan Bros. & Brahaney, who plugged it back to 5,312 feet and completed it, after treating with 14,500 gallons of acid, as a pumper from San Andres with initial potential of 76 barrels of oil per day. ELEVATION OF SURFACE Derrick floor: Highest, 3,711 feet; lowest, 3,693 feet. SURFACE FORMATION Ogallala formation of Tertiary system. OLDEST STRATIGRAPIDC HORIZON PENETRATED The oldest horizon penetrated is 23 feet below the top of the Devonian limestone. This penetration was in Signal Oil & Gas Co. III J. D. Webb, a dry hole at the location·in Sec . 423 where total depth of 11,510 feet is indicated on the accompanying maps. The discovery well is the only other well which penetrated below the San Andres formation; at its total depth of 7,717 feet it was near the base of the Clear Fork group. NATURE OF TRAP San Andres: Accumulation is in a porosity trap on a southward plunging anticlinal nose. PRODUCTIVE AREA San Andres and Field: 360 acres. THICKNESS OF RESERVOIR ROCK San Andres: The gross thickness of the produc­tive portion of the San Andres dolomite is 225 feet. The stratigraphic position of the top of the zone sufficiently porous to yield oil varies considerably within the area of the field. The maximum thickness of the gross pay zone in any well is 180 feet. It is estimated that total thickness of net effective pay averages 30 feet. LITHOLOGY OF RESERVOIR ROCK San Andres: Dolomite; light gray to brown, finely· crystal.line, with scattered chert nodules and thin streaks of dark gray bentonitic shale. CONTINUITY OF RESERVOIR ROCK San Andres: The stratigraphic equivalent of the reservoir rock which is productive in this field is probably widespread. However, the high degree of porosity andpermeability which occasions commer­cial production is a local condition. ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Andres: Feet No free gas cap Elevation of top of oil -1,471 Elevation of bottom of oil, approximate -1,650 Relief, approximate CHARACTER OF OIL San Andres: Gravity, A.P.I.@ 60° F., average: 30° Sulphur: High percentage Odor: Sour Color: Brown to black BRA HANEY FIELD, Yoakum County, Texas TYPICAL SECTION OF ROCKS PENETRATED RADIOACTIVITY CURVES LITHOLOGY NOTE : Thi s TYPICAL SECTION is based on the log of F . T. Brahaney HI S.Henard to the de pth of 4,565 feet and below that on the log of Signal Oil and Gas Co. HI J . D . Webb, the deepest well in the field . EXPLANATION Sandy limestone and ~ Sands lone ~ chert cont;1lomerote ~ Dolomitic sandstone !Im Anhydr ite ~ Shale Solt ~ ~ Stock shale Cheri t~ ~ Dol omi te Granite wash Anhydnlic Rock indicated , ~ dolomite sandy ~ Limestone • 0 Oil production sno~ of Oii ELECTRIC CURVES AND LITHOLOGY -' EL£VATIOtl Q 0 BRAHANEY FIELD, Yoakum County, Texas WATER PRODUCTION PRODUCTION HISTORY San Andres : Water constitutes an average of 20% of gross liquid produced by most wells initially, but this ratio usually decreases to 10 to 15% within a few weeks. No bottom hole water encroachment is evident at the pr es ent time. ACID TREATMENT San Andres: Each of the wells was treated with 3 ,000 to 21,000 gallons of acid. In most cases the treatment resulted in little or no increase in paten.:. tial. The poor results from acid treatment are believed to be due to effects of the bentonitic shale in the reservoir rock. WELLS PRODUCING OIL PRODUCTION at end of year {barrels) Year Flowing Pumping Yearly Cumulative 1945 0 3 ,385 3 ,385 1946 0 6,027 9 ,412 1947 0 4,876 14,288 1948 0 5,577 19 ,865 1949 0 2 6,448 26,313 1950 0 2 6,970 33 ,283 1951 0 2 6,250 39 ,533 1952 6 19,765 59 ,298 EXPLANATION -­-875 -­ Contour on top of San Andres formation -~a Elevation of top of Son Andres formation e Oil Well p Dry Hole BREEDLOVE FIELD Martin County, Texas JACK D. THORNTON Geologist, British-American Oil Producing Co., Midland, Texas July 25, 1953 LOCATION The Breedlove field is in the east quarter of League 258, Briscoe County School Land survey, in northwest Martin County about 13 miles northwest of the town of Tarzan and about 35 miles north of Midland. It is in the central portion of the Midland b?-sin. METHODS OF EXPLORATION LEADING TO DISCOVERY The location of the discovery well was based on seismograph work which had been conducted as a result of a study of subsurface geological data. DISCOVERY Devonian: July 19, 1951; Pan American Produc­tion Co. et al #1 F. D. Breedlove. This well was commenced on December 2, 1950, drilled to total depth of 13,053 feet in barren Ellenburger and plugged back to 12, 120 feet and completed in Devonian dolomite. During initial potential test, it flowed at rate of 2,341 barrels of 41.3° gravity oil per day. ELEVATION OF SURFACE At well locations: Highest, 2,901 ft.; lowest, 2,895 ft. SURFACE FORMATION Undifferentiated rocks of the Cenozoic era. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 340 feet below the top of the Ellenburger group. This penetration was in the discovery well. The accompanying TYPI­CAL SECTION is based on the log of that well. NATURE OF TRAP Devonian: The accumulation is at the apex of a convex fold. Low porosity appears to delimit the productive area at the south end of the field . PRODUCTIVE AREA Devonian and Field: Estimated, 420 acres. Further development may provide data which would warrant changing this estimate. THICKNESS OF RESERVOffi ROCK Devonian: Min. Max. Avg. Net productive, feet 17"" 88 ~ LITHOLOGY OF RESERVOffi ROCK Devonian: Dolomite; light gray to colorless, vuggy and crystalized. Many vugs are partially filled with dolomite crystals that appear to be loosely cemented but are tightly held by dolomitic cement; good intercrystalline porosity is left since the small rhombohedral crystals are not surrounded by the cement. CONTINUITY OF RESERVOffi ROCK Devonian: The reservoir rock is continuous throughout the area covered by the accompanying map. There is dolomite at the same stratigraphic position throughout most of the Permian basin, but whether the particular bed which is productive in this field is continuous over a large area cannot be determined. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Devonian: Feet, approx. No free gas cap Elevation of top of oil -9 ,167 Elevation of bottom of oil -9,272 Relief 105 CHARACTER OF OIL Devonian: Gravity, A.P.I.@ 60° F .: 40.8° Base: Paraffin Sulphur: .18% (No hydrogen sulphide) Viscosity: 60 sec.@ 50° F.; 47 sec.@ 75° F.; 41 sec.@ 100° F . WATER PRODUCTION · Devonian: No water has been produced to date. ACID TREATMENT Usually the wells are treated with 500 gallons of acid in the process of completion. However, one well was treated with 11,000 gallons of acid. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUC TION at end of year (barrels) Year Flowing Yearly Cumulative 19 51 57 ,211 57 ,211 1952 3 301,030 358,241 195 3 to 5/ 1 5 2 5 ,215 383 ,456 BREEDLOVE FIELD, Martin County, Texas TYPICAL SECTION OF ROCKS PENETRATED ,. w "­ w "' ::> >­ ii' 0 w >­ "' l3 "' "' z 0 ELECTRIC 6r RADIOACTIVITY CURVES er w LITHOLOGY ~ ,. CD ,. er GAMMA RAY RESISTIVITY w,. :? ELE VATION BREEDLOVE FIELD, Martin County, Texas TYPICAL SECTION OF ROCKS PEN E TRA TED ~ I­"' >­"' ~ "' w"' CL ::> 0"' "' z ~ :> "' ii' ELECTRIC Br RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY DEPTH and S.P. 760a 1100 7800 790a 800a 81 aa 820a 8300 84aO 8500 86ao 8 700 88ao 8900 9000 9 100 ~ ~ 93aa 94ao 95ao 9600 RESISTIVITY ELEVATION 50 too 1 -~555 1 -~605 l -~905I . I . , ­~Oa5 I . 1-5105 I I 1-:205 I . I : 1-~305 I 1 -~805 I . I 1 -5905 I . I i -~Oa5 i -~6a5 I I ; 1-?705 -6805 _J 0 0 0 0 0 0 0 0 0 z '.:! " 5 Q_ 0 "' " z 8 _J " "' ~ "' " w _J 0 >­"' 5 ID " "' Q_ "' z " w 0 EXPLANAT ION !~/):\~W~~J Sandstone r=.=8 Argillaceaus ~sandstone ~Chert D Rock indicated, groy DJ Rock indicated, block D Rock indicated, brown • Oil production O Oil show BRUSHY TOP FIELD Sutton County. Texas RICHARD A. LISMAN Geologist, Vincent & Welch, Inc., Midland, Texas June 27, LOCATION The Brushy Top field is in north central Sutton County, less than a mile from the northern boundary of the county, and at miles north of Sonora, county s eat. It is in sections 66 and 67, Block A, H.E. & W. T. R.R. Co. survey. METHOD OF EXPLORATION LEADING TO DISCOVERY Mapping of subsurface geological data led to the drilling of the discovery well. DISCOVERY San Angelo: December 28, 1950; C.L.Norsworthy, Jr. , and Lone Star Producing Co. #1 R.M. Thomson. ELEVATION OF SURFACE At well locations (derrick floor) : Highest, 2, 340 feet; lowest, 2, 284 feet. SURFACE FORMATION Edwards formation of the Fredericksburg group. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 537 feet below its top. This penetra­tion was in the discovery well. The accompanying TYPICAL SECTION is based on the log of that well. NATURE OF TRAP San Angelo: Lensing out updipward on a s mall t e rrace on a monocline. 1955 PRODUCTIVE AREA San Angelo and Fi eld: 160 acres. THICKNESS OF RESERVOm ROCK San Angelo: Top to bottom, 86 feet, average Net productive, Not yet determined LITHOLOGY OF RESERVOm ROCK San Angelo: Sandstone; gray, white and tan; fine­to medium-grained. ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Angelo: Feet Elevation of top of oil 1,411 Elevation of bottom of oil 1,325 Relief 86 CHARACTER OF OIL San Angelo: Gravity, A. P . I. @ 60°F. 36.4° ACID TREATMENT San Angelo: The reservoir rock in the discovery well was treated with 500 gallons of acid; in one well, with 1,000 gallons and in another well, with 3,000 gallons. PRODUCTION HISTORY WE LLS P RODUCING OIL P R ODUCTION at end of year (barrels) Year All pumping Yearly Cumulative 1950 490 490 195 1 4 8,990 9,480 1952 3 5, 610 15,090 19 53 3 5,527 20,617 1954 2 4,369 24;986 BRUSHY TOP FIELD, Sutton County, Texas TYPICAL SECTION OF ROCKS PENETRATED 100 2240 "'a: => "' 200 "' <..> " 8 ~ w (C 300 G~ <..> z w "-a: .... "'"' ::; 0 400 w:3 <..> ELECTRIC CURVES AND LITHOLOGY _, DEPTH ELEVATION 0 soo --­ ,.. .... ~ a::: 600 .... 700 z SAN ANDRES(?) w .... "' Cl. z ::> :> 800,._.. ..J 0 ct ~ ~ 0 w w "' ..J"' ::> cc z 900 "' => 4 0 0 z <( (/) 1000 1100 1200 1300 1400 1500 z "' ::; 1600 a: w Cl. 1700 a: " a: ~ 1800 z a: <( 0 4 w w ..J ..J 1900 <..> 2000 2100 2200 2300 2400 2500 2600 2630-­ ~..,...,____~_,.__~ EXPLANATION ~Limestone [ }-}/] Sondslone ~Dolomit e ~Shale, E-=-=-j shale, • Shale, ~Shale, ~brown -_-_-gray green ~red 000 .o..o o.o Cheri 000 ~Unconformity ~~-~~-w w Probable unconformity • Oil production DEPTH 2700 2600 2900 3000 3100 3200 3300 3400 3500 3600 3700 z Cl. "' 0 ~ 7200 0 ..J a: w 0 7300 7400 7442. -5102 CANNING FIELD Borden County, Texas MARVIN T . CARLSEN Geologist, Standard Oil Co. of Texas, Lubbock , Texas April 28, 1954 LOCATION The Canning field (one well) is in southeastern Borden County about 3 miles north of the Von Roeder field. METHOD OF EXPLORATION LEADING TO DISCOVERY Seismographic surveying . DISCOVERY Wolfcamp : August 2, 1950; Vickers Petroleum Co. & Norwood Drilling Co. #1-A J.R. Canning. ELEVATION OF SURFACE At discovery well: 2 ,320 feet. SURFACE FORMATION Undifferentiated Dockum group, Triassic system. OLDEST STRATIGRAPlllC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is 120 feet below the top of the Ellenburger group. This penetration was in the dry hole 1,320 feet north of the producing well. The accompanying TYPICAL SECTION is based on the log of that dry hole. NATURE OF TRAP Wolfcamp: The accumulation is at the apex of a local convex fold. It appears likely that the extent of the commercially productive area is determined in part by degree of porosity and permeability. It is possible that southward (updip) decrease of porosity and permeability has functioned as a trap-forming factor. PRODUCTIVE AREA Wolfcamp: 40 acres. THICKNESS OF RESERVOIR ROCK Wolfcamp: Feet, estimated From top to bottom, maximum 90 Net productive, maximum 40 to 60 LITHOLOGY OF RESERVOIR ROCK Wolfcamp: Tan to dark brown, crystalline, moderately to slightly porous, fossiliferous lime­stone with brown, fossiliferous chert in variable amounts up to about 15% and with traces of pyrite. CONTINUITY OF RESERVOIR ROCK Wolfcamp: The stratigraphic equivalent of the reservoir rock is present throughout most of the northern part of the Midland basin. Its thickness, porosity, permeability and degree of purity vary considerably from county to county. So far as the writer knows , the only other place where this stratigraphic unit produces oil is in eastern Andrews County. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Wolfcamp: In discovery well No free gas cap Elevation of top of oil, feet -3,593 Elevation of total depth, feet -3 ,611 Known relief of oil , feet 18 The elevation of the oil-water contact has not been determined. Showings of oil in near-by dry holes indicate that the oil column may extend con­siderably lower than the lowest elevation observed in the productive well. The erratic nature of the porosity leaves doubt that the oil column extends downward to the elevation of the lowest showing in near-by dry holes. CHARACTER OF OIL Wolfcamp: Gravity, A.P .I.@ 60° F. 41° WATER PRODUCTION None ACID TREATMENT None PRODUCTION HISTORY Wolfcamp: The one well produced 20,102 barrels of oil in 1950; 42,221 barrels in 1951; 22 ,8 30barrels in 1952; 19,586 barrels in 1953; total to end of 1953, 104,739 barrels of oil. CANNING FIELD, Borden County, Texas TYPICAL SECTION OF ROCKS PENETRATED z ELECTRIC CURVES 0 ;:: ­ ­ 0 ­ 0: 0: " I al 0:" 3 "' " 0 3 ELECTRIC CURVES 6200 0. z "' - " 6300 " "' 0: .... " ..J 0 3 6400 6500 6600 7600 z 3 7700 " I­ 8 s p NOTE: The above section is based on the log of Vickers Petroleum Co. & Norwood Drilling Co. Hl -B J.R. Canning, the dry hole 1320 feet north o( the producing well. EXPLANATION ~Limestone [:}:rUt;{J sandstone ~Dolomi tic b±I±J 1imestone ~Dolomite t======~ Shale ~Anhydritic ~Dolomitic ~dolomite ~shale ~Colcoreous ~Chert ~dolomite ~ • Oil production o Show of oil ~Show of oos w Sulphl.r water CARTER FIELD Glasscock County. Texas JERRY F. SIDES Geologist, The Superior Oil Company, Midland, Texas April 7, 1954 LOCATION The Carter field is in north-central Glasscock County 7 miles north of Garden City, county seat, and 6~ miles south of the western portion of the Howard-Glasscock field. METHOD OF EXPLORATION LEADING TO DISCOVERY Random drilling. DISCOVERY San Andres: October 4, 1936; Floyd C. Dodson & B. A. Duffy #1 Carter Heirs. During potential test, this well produced at rate of 128 barrels of oil per day; actual pumping capacity was estimated as 50 barrels of oil per day. The accompanying TYPICAL SECTION is based on the log of this well. ELEVATION OF SURFACE The elevation of the surface is 2 ,610 feet above sea level at the producing well and is 2 ,623 feet above sea level at the abandoned well. SURFACE FORMATION Undifferentiated formation in the Trinity group. OLDEST STRATIGRAPIUC HORIZON PENETRATED Each of the two productive wells was drilled only a few feet below the productive zone. The oldest horizon penetrated in the vicinity of the field is about 52 feet below the top of the Ellenburger group. This penetration was in Ralph Lowe fl 1 Neal-Ballinger, a dry hole in SE cor. Sec. 16, about Z miles east of the field, at its total depth of 10,336 feet. NATURE OF TRAP San Andres: The trap is formed by updip lensing of porous zone on a structural nose. PRODUCTIVE AREA San Andres and Field: 40 acres. THICKNESS OF RESERVOIR ROCK San Andres: Feet From top to bottom -rr Net productive 10 LITHOLOGY OF RESERVOIR ROCK San Andres: Dolomite; cream to tan, fine to medium crystalline, scattered pin-point porosity, gray-green shale stringers. CONTINUITY OF RESERVOIR ROCK San Andres: The reservoir rock is continuous throughout the area covered by the accompanying map and also throughout a much larger surrounding area. However, the degree of porosity which occasions commercial production is not continuous beyond the immediate vicinity of the two productive wells (one, abandoned). ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Andres: Feet No free gas cap Elevation of top of oil -19 Elevation of bottom of oil -54 Relief 35 CHARACTER OF OIL Gravity: 28.5 ° to 33 • Color: Dark green Sulphur: 0.673 Base: Intermediate For analysis see: U.S. Bureau of Mines Lab. ref. No. 38152 Tabulated Analyses of Texas Crude Oils. T. P. 607 (1939) Item 36, Grp. Z WATER PRODUCTION San Andres: Water currently constitutes about 903 of the gross production. ACID TREATMENT San Andres: The discovery well was treated with 3 ,000 gallons of acid. PRODUCTION HISTORY TYPICAL SECTION OF ROCKS PENETRATED CARTER FIELD I Glasscock County, Texas 61 ..J 0 WELLS PRODUCING OIL PRODUCTION z Q at end of year (barrels) ~ ~ Year P umping Yearly Cumulative -w a: 0 >­ w 1939 2 10 ,021 19 ,07 4 u !::: z .... 1940 7 ,098 26 ,1 72 <( Qi w .... a: u 100 1941 5 ,212 31 ,384 1942 0 1,937 33,321 1943 0 0 33 ,321 1944 0 0 33 ,321 zoo 1945 0 0 33 ,321 1946 0 0 33 ,321 1947 2;643 35 .964 1948 2,672 38 ,636 1949 2 ,829 41 ,465 1950 2 ,701 44 ' 166 195 1 2,997 47 ,163 1952 2,474 49 ,637 1953 2,136 51,773 The second well was completed in July 1937 and abandoned in October 1940. The discovery well was not operated du ring the period from July 1942 to April 1947 . w ~ .... ­ Oii 911 2811 2711 2611 2511 24 11 231t 2211 2111 20<1 1911 18 11 1711 L61t 1511 14 11 1361 -' 5 ELECTRIC CURVES ANO LITHOLOGY -' ELEYATl()N Q 1361 1950 13 11 2000 12 11 2100 2200 2JOO 1011 911 2400 "" 2600 7" 611 2800 5'1 411 3000 311 3IOO 211 3200 3300 3400 -89 3500 -189 3600 . -289 .., d 3700 -389 In <( " 3800 -4 3900 -589 SCALE -J 40 Sandstone -u.o Bevotion of total depth • Oil well + Abandoned oil we ll fl Dry hde • ~Discovery CLAIREMONT FIELD Kent County. Texas E. V. STINE and J. L. WALDREP Geologists, Sunray Oil Corporation, Midland, Texas January 1, 1954 LOCATION As indicated on the accompanying map, the Clairemont field is located near the town of Clairemont, county seat of Kent County, Texas. METHOD OF EXPLORATION LEADING TO DISCOVERY The discovery of this field was due primarily to the operator having acquired, in consideration of test drilling, a large block of leases in a general region indicated as favorable by the results of previous drilling operations. The first deep test on the block was located about 5 miles northwest of Clairemont on the basis of core drill data and was completed as a dry hole. The operator was obligated to drill another deep test and located that test adjacent to large holdings of another operator who was prompted by core drill data to contribute dry hole money. The core drill data determined the specific location of that test, which became the discovery well. DISCOVERY Strawn: April 3, 1950; ---ceneral Crude Oil Co. #1-A Percy Jones ELEVATION OF SURFACE At well locations: Highest, 2,209 feet; lowest, 2,090 feet. SURFACE FORMATION Anhydrite and sands of Whitehorse group. OLDEST STRATIGRAPHIC HORJZON PENETRATED The oldest horizon penetrated is about 94 feet below the top of the Ellenburger group. This penetration was in Sun Oil Co. #F-1 Bilby Wallace, completed in November 1953 at the location in Sec. 24, Block 98, where the sub-sea elevation of total depth is indicated as -5, 287 feet on the accompanying map. NATURE OF TRAP Strawn: The accumulation of oil appears to be due to a simple convex trap resulting from reef topography. The strata above and below the reef appear to dip quite regularly westward. PRODUCTIVE AREA Strawn: Approximately 720 acres. THICKNESS OF RESERVOIR ROCK Strawn: Feet From top to bottom 4 to 19 Net productive, average 13 LITHOLOGY OF RESERVOIR ROCK Strawn: Tan, crystalline, granular in part, coralliferous oolitic limestone with vuggy porosity. CONTINUITY OF RESERVOIR ROCK Strawn: The reservoir rock is continuous throughout the area of the field, as is evidenced by the uniformity of reservoir pressures. It is a local reef and probably does not extend far beyond where it has been t'ound in the pre­sently productive wells. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Strawn : Feet Elevation of top of oil -4,562 Elevation of bottom of oil -4,609 Oil column 47 In the well in the southwest corner of Sec. 10, the oil­water contact is at -4,641 feet . The reservoir which is producing in that well appears to be separate from the reservoir which is producing in all other wells in the field . CHARACTER OF OD. Strawn: Gravity, A.P.l.@ 60° F . 36 .1. Sulphur 0.49% Salt 0 .004% Paraffin 2.16% Viscosity @ 60 ° F. 59 sec . S. U. Viscosity @ 100 • F. 43 sec. S. U. The above data are from an analysis of a sample from Sun Oil Co. #1 D.G.Sampson. For analyses see: U.S. Bureau of Mines Lab . ref. No . 50068 Analyses of Crude Oils from Some West Texas Fields. R. I . 4959 (1953) Item 48 WATER PRODUCTION Strawn: Five of the wells are definitely known to be producing water and there is a possibility that two others are producing some water. Water constitutes about 8'?o of the total gross fluid produced in the field. The average chloride content of the water is about l 00 ,000 to 110 ,000 parts per million. ACID TREATMENT Strawn : Six of the 13 productive wells have been acid­ized. The quantity of acid used has varied from 500 gallons to 4,000 gallons. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Yearly Cumulative 1950 3 0 60,535 60 ,535 1951 7 l 151.459 211,994 1952 9 4 311 .644 523,638 1953 7 7 314,075 837,713 CLAIREMONT FIELD, Kent County, Texas TYPICAL SECTION OF ROCKS PENETRATED ELECTRIC CURVES AND LITHOLOGY DEPTH ELEVATION NOTE, This TYPICAL SECTION is based on the log of the discovery well (TD 6752) to the depth of 6740 feet, and, below that depth, with adjusted depths and elevations , on the log of the dry hole in Sec. 9,where actual total depth is 7384 feet (elevation of total depth, 52.11) . EXPLANATION ~Dolomite ~Chert ~Anhydritic ~dolomite b:\\(:·1Sandstone ~Anhydrite i==-=l Rock indicated, ~orgilloceous ~Dolomitic ~anhydrite D Rock indicated, red ~Oolor:nite6 Rock indicated, tz:t:::ztj IImestone block or 9roy [[] ~Sholeond e Oil production ~dolomite ELECTRIC CURVES ELECTRIC CURVES ,. "' a (/) 0.. AND t;; w w AND er t;; ~ 5 LITHOLOGYLITHOLOGY > w > w a: ELEVATION (f) (/) DEPTH ELEVATION V> (I) DEPTH Q. z ,. "' ,. ~ a:_, ~ w 0 Q."' z 0 > z u "' "' z z ~ "'> z z w Q. 0 u "' "' z z "' ~ > z "' z w Q. z 0 > z u "' ORDOVICIAN ELLENBURGER N ~~~-4-2+-~ 43 ff -5028 44 45 W. a N. W. R.R. CO. BLOCK ff 1-~~~,~0~7-t-~~~~~~~,~0~0+-~~~~~~~~,~ o+-"'-~2::+~~~~~~~--= ---'~~~~~~2375+-~~ II"""'"'" ff -5111 80 23 49 34 H. a T. C. R.R. CO. BLOCK 98 77 24 33 EXPLANATION --4600-Contour on top of -4611 Elevation of top of • -521 1 Elevation of total 50 • Oil well Jf ff SCALE -5276 reservoir rock reservoir rock depth Ory hole . i;;;;;;;;;;i THOUSAND FEET -' CLARA COUCH FIELD Crockett County. T exaa L. E. PATTERSON, Jr. District Geologist, Cities Service Oil Co . , Midland, Texas June l, 1953 LOCATION The Clara Couch field is in west -central Crockett County about 30 miles west of Ozona, county seat. It is near the western margin of the southern portion of the Midland basin. METHOD OF EXPLORATION LEADING TO DISCOVERY The location of the test which resulted in the discovery of the field was made on the basis of an interpretation of subsurface geological data which indicated a structural axis through this locality in the shallow Permian beds. The operator intended to locate the test in section 37 on land on which he held an oil and gas lease and which was owned in fee by Clara Couch. When production was discovered, the well was thought to be on Clara Couch land and the field was designated as the Clara Couch field. How­ever, a survey revealed that the well was 167 feet north of the north line of section 37 and was in section 14 on land owned in fee by A. C. Hoover and under lease to Cities Service Oil Co ., which company theri took over the well on a negotiated basis and has operated it since that time . Although the field was named for Mrs. Clara Couch, there was no produc­tion on her land until about 8 months after the com­pletion of the discovery well. ELEVATION OF SURFACE At well locations: Highest, 2 ,771 feet; lowest, 2 ,294. feet. Tributaries along the east side of the Pecos River which have cut canyons into the Edwards Plateau have produced considerable topographic relief within the area of the field. VARIATIONS IN TIUCKNESSES The younger Permian beds are characterized by marked lateral variations in thickness and lithology. They probably were deposited.in a very shallow sea. There is great variation in the amount of lime­ stone deposited during Pennsylvanian time. It seems likely that during that time this area was a platform area bounded by marginal reefs and across which both reef and lagoonal limestone deposition occurred continuously. Apparently the platform area retreated to the northwest during Pennsyl­ vanian time, and even further to the northwest during early Permian time. To the southeast of this area, the limestone build-up appears to have ended in Strawn or earlier Pennsylvanian time; to the northwest of this area, the build-up probably extended well into Leonard time. SURFACE FORMATIONS Undifferentiated Comanche series; mainly of the Washita group but probably with rocks of the Fredericksburg group exposed low in some canyons. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest bed penetrated is in the Ellenourger group 1,504 feet below its top . This penetration was in the Cisco East discovery well at its total depth of 8 ,264 feet. DISCOVERIES Yates: March 29 , 1942; Humble Oil &t Refining Co . #B-1 J. W. Owens; now E. J . Mccurdy #1-B J . W.Owens. While gas shows have been reported in many of the cable tool holes, only one additional well has been completed in this reservoir. The two wells were completed as small gas producers. There was no commercial outlet; the only gas produced has been utilized for lease and other local purposes . Since very little information is available and since there appears to be no com­mercial production discovered to date, there will be no further entries concerning this reservoir. Upper Queen: May 28, 1944; E. J. McCurdy #1 W.L.Hobbs Middle Queen: August 20, 1944; McCurdy &t McElroy #2 W. L. Hobbs San Andres and Field: August 17, 1941; R. H. Henderson #1 Clara Couch (on A .C .Hoover land); now Cities Service Oil Co. #1 A.C.Hoover. See explanation in column at left under METHOD OF EXPLORATION. Wolfcamp: April 19, 1949; Humble Oil &t Refining Co . #1-G J. W . Owens Cisco East*: May 28, 1947; Cities Service Oil Co. #1-B J . W. Owens Cisco West*: October 22, 1949; Cities Service Oil Co. #1-C J. W. Owens Canyon*: April 12, 1951; Cities Service Oil Co . #1-E J . W. Owens *Paleontological data available at time of discovery of oil in the eastern of the two Cisco reservoirs suggested that the reservoir rock there is of Wolfcamp age and the reservoir was officially designated by the Railroad Commission of Texas as the ''Clara Couch Wolfcamp field.'' Although Cisco age is now definitely established , this designation continues to be applied by the Railroad Commission, and, as now used, includes not only this reservoir but all reservoirs older than San Andres. CLARA COUCH FIELD, Crockett County, Texas NATURE OF TRAPS Upper Queen: Updip termination of reservoir due to decrease of porosity and permeability because of change in character of sediments. Sand­stone grades into shaly sandstone, sandy shale and shale. Middle Queen: Updip and lateral termination of reservoir due to lensing of sandstone. San Andres: Anticlinal folding appears to be the dominating factor in causing the accumulation of oil in this reservoir. Variation in degree of porosity and permeability appears to have contributed to forming the trap. Porosity and permeability are relatively low over the axis of the anticline and updip northward and updip southward from the pro­ductive area. Wolfcamp, Cisco East, Cisco West and Canyon: The traps which occasioned the accumulation in these four reservoirs are due primarily to reef conditions. Both convexity and simple lateral termination of reservoir have contributed to forming the traps. It appears that the traps are due mainly to burial of eroded reef features. It is believed that local structure, as so far revealed, is of less signi­ficance to the accumulations in these reservoirs than is the regional stratigraphy of these beds; accordingly, contours on top of the reef-bearing limestone mass, as shown on an accompanying map, are more informative than would be those along a time horizon in the Pennsylvanian sequence. Assuming a platform of limestone deposi tion with marginal reefs, the portions of the reefs not destroyed by subsequent weathering would be preserved as permeable and porous reservoirs when finally buried, and the general alignment of those reservoirs would approximate the perimeter of the platform to whi ch the reefs were adjacent. As so far developed, the Pennsylvanian reservoirs of this field appear to fit such a concept. Along the length of the ancient marginal reefs, the present reservoirs are probably interrupted where the old tidal channels prevented reef development and where differential erosion, prior to final burial, completely destroyed portions of the reefs and preserved variable thicknesses of other portions. PRODUCTIVE AREAS Acres Upper Queen 40 Middle Queen 140 San Andres 920 Wolfcamp 40 Cisco East 160 Cisco West 960 Canyon 320 Clara Couch field 2,540 It appears likely that future development will UTHOLOGY OF RESERVOm ROCKS Upper Queen and Middle Queen: Sandstone; generally medium-to fine-grained with occasional larger grains. Generally, the grains are subangular, but some are rounded and frosted. Normally the grains are well cemented with siliceous material. The degree of cementation markedly affects the porosity and permeability within short distances. The reservoir rock is interbedded with anhydrite and silty, reddish sandstone and red shales. San Andres: Dolomite; medium-grained to granular, crystalline dolomite which grades locally into lenses of both coarse-grained and fine-grained material. Generally, the dolomite is sandy, with medium to large sand grains well distributed and locally sufficiently concentrated to form dolomitic sandstone. Oolites occur rarely. The color is generally cream to buff, grading to white and light brown locally. Porosity is generally good, ranging from interstitial to the void spaces of medium-sized vugs . Ingeneral in the producing areas, the porosity decreases updip. Wolfcamp, Cisco East, Cisco West and Canyon: Limestone; ranges in color from white to tan and light brown and in texture from fine-grained to medium-grained. Generally there is an abundance of fossils, primarily foraminifera and crinoids. Porosity consists primarily of vugs. The voids were undoubtedly produced by agents of weathering which attacked the reef prior to final burial. Some vugs associated with individual fossils are evident. THICKNESSES OF RESERVOm ROCKS Feet Min . Max . Avg. Upper Queen From top to bottom 22 35 26 Net effective 15 25 20 Middle Queen F r om top to bottom 14 26 18 Net effectiv e, app r oximate 10 20 15 San Andr es F rom top to bottom 2 115 29 Net effective 2 70 15 Wolfcamp ( 1 well) From top to bottom 40 Net effective 25 Cisco Eas t From top to bottom 25 57 33 Net effective 19 50 30 Cis co West From top to bottom 24 185 105 Net effective 24 110 67 Canyon ( 1 well) From top to bottom 107 warrant increasing some of the above estimates. Net effective CLARA COUCH FIELD, Crockett County, Texas CONTINUITY OF RESERVOm ROCKS Upper Queen and Middle Queen: These reser­voirs are · local members of a formation which characteristically contains more sandstone than either the overlying Seven Rivers formation or the underlying Grayburg formation. Local productive reservoirs in the Queen formation have been developed in many fields in West Texas and Southeast New Mexico. Some of these reservoirs are at or near the stratigraphic positions of the two local Queen reservoirs in this field and some are at other positions within the formation. It is charac­teristic of the formation throughout its extent that the proportions of sandstone, anhydrite, dolomite and shale vary markedly within short dis~ances. Most producing sandstone reservoirs in this formation probably occur as lenses . There is no reason to believe that either of the two Queen reservoirs in this field extends much beyond its presently producing area. San Andres: A dolomite bed with the general litholog'ic character of the reservoir rock is recog­nized and appears to be continuous over a broad area in central-western Crockett County, but its characteristics disappear northward, where the granular-type dolomite grades into finer-grained materials and where the distinctive characteristics of the overlying green bentonic shale gradually disappear. Wolfcamp, Cisco East , Cisco West and Canyon: The continuity of each of these reservoir rocks is limited generally by the boundary of the area of high degree of porosity in preserved portions of buried reefs. CHARACTER OF GAS Analyses are not available for gas produced from Yates, Upper Queen , San Andres or Wolfcamp. Following are analyses showing percentage of components of samples from Cisco and Canyon reservoirs. Components Cisco East Cisco West Canyon Hydr ogen s ul phide P resent* Present * 0.00 Ca rbon dioxide 2.80 0.75 0 .90 Nitrogen 2 .96 3 .92 2 .25 Methane 79 .9 3 76 .35 85.58 Etha n e 7 .76 9 .46 6 .80 Propan e 3 .92 4.72 2.74 !so-but ane 0.37 0 .58 0.47 Nor mal buta n e 1.23 1.47 0 .62 lso-pentane 0.22 0 .35 0 . 17 Normal pentan e 0. 34 0 .38 0 .20 Hexanes 0 .30 0.48 0 .12 Heptane & h eavier 0 .17 1. 53 0 .15 Specific gravity .732 .717 .6617 *The quantity of hydr ogen sulphide was not determined because of r ea ction with material of container in which g a s was shipped t o laborator y . ELEVATION AND RELIEF OF PRODUCTIVE ZONES F eet Upper Queen: {2 wells) Elevation of top of gas 1 ' 150 Elevati on of bottom of gas 1 ' 104 R elief 46 Probably no oil in this reservoir Middl e Queen: No free gas cap Elevation of top of oil 1,017 Elevation of bottom of oil 942 R elief 75 San Andres : No free gas cap Elevation of top of oil 645 Elevation of bottom of oil 465 Relief 180 The lowest el evation to which oil is known to extend is 465 feet above sea level. Non­productive tests in the vicinity of the productive ar ea have encountered water at el evations ranging from 363 feet to 547 feet. Wolfcamp: (1 well) Elevation of top of gas -3 ,124 Elevation of bottom of gas -3,164 R elief 40 P robably no oil in this reservoir Cisco E ast: Elevation of top of oil -3,215 Elevation of bottom of oil -3 ,289 Relief 74 Cisco West: Elevati on of top of gas -3 ,094 Elevation of bottom of gas -3 ,279 Relief 185 P robably n o: oil in this reser voir Canyon: (1 well) Elevation of top of gas -3 ,4 19 Elevation of bottom of gas -3 ,526 Relief 107 CHARACTER OF OIL Middle Queen San Andres Cisco East Gravity, A.P .I.@ 60° F . 31° 2s· 39° Sulphur content Sour Sour Sour Color Brown Black Dark green ARCHER COUNTY SCHOOL LAND ARCHER cou'N'T'Y ''s'c';:t'oo'L'.'''L'.'AND 21 '6 -ZH4 32 1 ' .J "oo 31 34 33 52 50 21 • Oil we ll .d Ory hole • PRODUCTIVE-Yates '6 -Upper Qu een f .D. 70l4 32 -Middle Queen Son Andres 31 ~,$~0 ii '-"e .r,,.~ . 34 >-~...e -1 .r~"'11\ftllr11 ""~'-im, 1 oil'-'-" IQ ' ''"oo'-'­ •o •o74 ;.::•I l •l.Q I I .. r.. ,,,~ I •"'" ~ I --==--~~~ \)~~'"~ 1111 ,, ~ 33 '"' ,f.111 N l ~2 ~ I 40 IQ TDU IO ~o 41 SCAL E 0 THOUSAND ' EXPLANATION i:f Gos L!Discovery AREA ~ mm !IIIlIIl ~ f~l well wel J Wolf comp Cisco East Cisco West Canyon ci l.) C> . :::.:::' . (.) a: "' o LL:o 0 (/)_J or ~ d:SCD u ci -.....] N () !:"'"" :x:o­::0 :x:o­ () 0 c () ::r: '"Tj .._ M !:"'"" t:1 - ~ () ~ <1> ...... ...... ~ ::s ...... '.:< r CLARA COUCH FIELD, Crockett County, Texas TYPICAL SECT I ON OF ROCKS PENETRATED NOTE : This TYPICAL SECTION is based on a composite log It shows all reservoi rs which are productive within t he area of the field. There is no single location at which all reservoirs are productive. z ELECTRIC 8 RADIOACTIVITY CURVES o LITHOLOGY ~ ~ ~ GAMM A RAY RESISTIVITY ~ ~ ~ DE PTH AND $. P. ELEVATION 2900 -•oo 3000 -550 3200 -750 3300 -80 _,, 3400 3500 -10~ 3600 -1150 0 3700 -125 3800 -13 3900 -145 4000 >­ 4 100 Q; Q; " al 4200 " 4300 ·'400 4500 -4600 4 700 4800 4900 5000 5 100 0 '" 5200 5300 5400 5500 5600 57 00 " z ­ 0 5800 "> J >­ 5900 z 2: w ._ 6000 6040 ­ ':/ : g zi....:..+-+---_:::,,,_i:;:r::;::i--~-----~ " z - z ;t -3850 6300 "" > .J .... -3950 6400 >-"' "' Zi--1-+---_;~-+'-T:':::l--~-----i z w ._ z > 0 Q; 0 ELECTRIC CURVES "' C> " 6500 6600 6 700 6800 6900 7000 7 100 7200 7 3 00 740 0 HOO 7600 7700 7800 7900 000 8 100 200 H EXPLANATION • Sandstone Ootomile ~ Limestone Anhydrite E55l ml ~ Shal e Cheri ~ •0 ~Limestone Rock indicated, and shale sondy ~ Cit produc1ion Gos production l·I ~I Gos producTion, probably not commercial ~¢~ CLARA COUCH FIELD, Crockett County, Texas WATER PRODUCTION Upper Queen and Middle Queen: No water has been produced from either of these reservoirs. Plans for water flooding Middle Queen for secondary recovery are under considerati on. San Andres : Although only 3 wells produced water during completion tests, many WE:lls now produc e various quantities . Generally, water constitutes less than 40'}". of the gross production of such wells as produce it, but a few wells produce a higher per.centage. Remarkably , the water production of most of such wells began abruptly and has continued constantly at essentially the same rate . There seems to be little , if any , water drive in the reservoir.. Wolfcamp: No water has been produced by the lone well completed in this reservoir . Cisco East and Cisco West: Testing prior to com­pletion has demonstrated the presence of water below the oil and gas columns in both reservoir s . Water has been produced by only one well., that which was abandoned in the Cisco East reservoir and is the Wolfcamp discovery well . Canyon: No water has been produced by the lone well completed in this reservoir . The well is a gas-condensate well and is shut in because of iack of commercial outlet. ACID AND OTHER RESERVOIR TREATMENT Upper Queen: Neither acid nor nitroglycerin has been used in this reservoir. Middle Queen: Acid has not been used in this reservoir because of absence of calcareous material. Several wells were completed "natural'', but most wells have been shot with 25 to 60 quarts of nitroglycerin. Some gas has been injected into this reservoir to improve production of oil. .San Andres: Methods of artificial stimulation are varied; some operators use acid exclusively and others depend largely on nitroglycerin shots. Several wells have been both shot and acidized. Jet perforating has been used alone and also in connection with acid treatment. Acid treatments have ranged from 500 gallons in one stage to 8,000 gallons in four stages; the normal treatment has been with 1,500 gallons in one stage. Nitroglycerin shots have ranged from 40 to 350 quarts; average, about 95 quarts. Wolfcamp: The single well completed in this reservoir was not acidized or shot. Cisco East and Cisco West: Most of the wells com­pleted in these reservoirs have been neither acidized nor shot; a few have been acidized with 1, 000 to 2, 500 gallons in a one-stage treatment. Canyon: The one well completed in this reservoir was acidized with 1,000 gallons . PRODUCTION HISTORY OIL PRODUCTION Year WELLS PRODUCING at end of year Flowing P umping OIL PRODUCTION (barrels) Yearly Cumulative F ield totals: 1941 1942 1943 1944 2 2 1 5 6 10 986 10,952 16 ,451 64,835 986 11.938 28 ,389 93,224 1945 ... ·· · ·· · ·· ·· 2 ... .. ....... 14 ... 98,729 . .. ... .... 191.953 1946 I 19 130 ,840 322,793 1947 11 28 238,457 561,250 1948 4 39 323 .972 885 ,222 1949 3 44 252,015 1,137 ,237 1950 ............. 2 .. . . 47 .. ..2 3 7 '9 1 7 ........1 '37 5 ' 15 4 1951 2 48 232 .965 1,608,119 1952 2 47 212,086 1 ,820 ,205 PRODUCTION HISTORY (Continued) OIL PRODUCTION WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Yearly Cumulative Middle Queen: 1944 0 200 200 1945 I . .... 0 . 4 ,209 .. 4 ,409 1946 I 0 4,316 8 ,725 1947 8 2 47,700 56,425 1948 9 22 .099 78,524 1949 I 9 13 ,761 92 ,285 1950 0 ........... 9 . .. 11.847 .. .. 104,132 1951 0 9 8,241 112 ,373 1952 0 9 5 .o13 11 7 ,386 San Andres: 1941 I 986 986 1942 2 5 I 0 ,9 52 11.938 1943 2 6 16,451 28 ,389 1944 0 IO 64 ,635 93 ,024 1945 . . . . . .. . . . . . 1 . 14 94.520. 187 ,544 1946 0 19 126,524 314,068 1947 0 26 157,086 417,154 1948 0 29 231,173 702 ,3 27 1949 0 35 204,806 907 ,133 1950. 0 .. 38 .. 195,367. ... .. . 1,102 ,500 1951 0 39 207 .491 I ,309 .991 1952 0 38 197 ,308 1,507 ,299 Cisco East: 1947 3 0 33,671 33 .671 1948 3 0 70,700 104,371 1949 2 0 33 .448 137 ,819 1950 ........ .... 2. 0 .. 30,703 .168 ,522 1951 2 0 17,233 185 ,755 1952 2 0 9 ,765 195 .520 GAS PRODUCTION Gas production has been limited to supplying gas for local use, particularly including lease and drilling opera­tions. There are no satisfactory records showing quantities produced nor showing the sources from which produced. The records kept by the Railroad Commission are difficult to interpret , particularly as to determining the quantities produced from the respective reservoirs. The following figures have been compiled from Railroad Commission records and appear to represent the reported total gross gas production from all reservoirs . GAS WELLS GAS PRODUCTION PRODUCING (Mcf) Year at end of year Yearly Cumulative 1942 1,448 1.448 1943 I I.818 3 ,266 1944 2 1 .656 4.922 1945 .. .. ... .... 2. ........ ... ...... 2 ,333 ... 7 ,255 1946 2 2 ,842 10 ,097 1947 2 3 .859 13,9 56 1948 3 41,092 55 ,048 1949 3 32 ,372 87 ,420 1950 3 .. 37 ,352 ·········· ·· 124,772 1951 3 37 ,345 162 ,117 1952 4 34 ,433 196 ,550 COX FIELD Crockett County, Texas J . B. COX Geologist, Southern Production Co., Ir.c . , Midland, Texas March 11, 1953 LOCATION The Cox field is 29 mile.s west of Ozona and 4 miles north of Ft. Lancaster . It is 2! miles southeast of the Clara Couch field and 3 miles west of the Lancaster Hill field. METHOD OF EXPLORATION LEADING TO DISCOVERY Shallow core drilling led directly to the discovery of this field. The discovery well was being drilled for the purpose of obtaining samples of near-surface rocks when it discovered oil. DISCOVERY Queen: January 18, 1948; Gulf Oil Corp . #1 H . B . Cox Mineral Fee ''C''. The well was being drilled for samples of rock when it showed oil from depth of 894-911 feet . It was drilled to total depth of 1,251 feet and then plugged back to 943 feet for completion. Pumped at the rate of 152 barrels of 26.8° gravity oil per day after being shot; GOR, 182 :1. ELEVATION OF SURFACE At location of discovery well , 2, 165 feet; at location of the other productive well, 2 ,140 feet . STRATIGRAPHIC SECTION Readers are referred to accompanying papers on near­by fields . The productive zone is in the Queen formation of the Whitehorse group of the Guadalupe series of the Permian system. The exact position of the productive zone within the Queen formation is not determinable from infor­mation available to the writer . OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the immediate vicinity of the two productive wells is in the Grayburg formation. This penetration was in the dry hole near the discovery well where the total depth is indicated as 1,373 feet on the accompanying map. NATURE OF TRAP Queen: Either convex fold or updip reservoir due to either lensing or change irock . termination n character of of PRODUCTIVE AREA Queen and Field: 40 acres. THICKNESS OF RESERVOIR ROCK Queen : Net productive, about 6 feet. LITHOLOGY OF RESERVOIR ROCK Queen: sandstone; gray to tan, dolomitic, fine grained, thin bedded and lenticular . CONTINUITY OF RESERVOIR ROCK Queen: The reservoir rock cannot be correlated be­yond the limits of the field . The Queen formation is wide­spread and contains sandstones which are productive at several places . Whether the sandstone which is productive in this field correlates with productive sandstone elsewhere cannot be determined from information now available . CHARACTER OF on. Queen : Range -cravity, A .P.I.@ 60° F. 23°-26.8° WATER PRODUCTION Queen: No water was ever produced. PRODUCTION HISTORY Queen and Field total: Oil was discovered on January 18, 1948 and production was continued until about the end of 1951. The two productive wells were finally abandoned on March 12, 1952 without having produced any oil during 1952 . There were 2 wells, both producing by pumping, at the end of each year until operation was no longer profitable at the end of 1951. The production of oil by years was as follows : 1948, 9,929 barrels; 1949, 4,821 barrels; 1950, 1,830 barrels; 1951, l ,120 barrels; total, 17 ,700 barrels . The production during the last two months of 1951 was 26 barrels during November and 36 barrels during December . CRAVENS FIELD Lubbock County, Texas MARVIN T. CARLSEN Geologist, 5tandard Oil Co. of Texas, Lubbock, Texas April 16, 1954 LOCATION The Cravens field (two wells, both abandoned) is in north-central Lubbock County 2t miles northwest of the town of New Deal (formerly called Monroe) and 5 miles south-southwest of the town of Abernathy. METHOD OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph surveying. DISCOVERY Clear Fork: February 28, 1945; Seaboard Oil Co. of Delaware and Stanolind Oil & Gas Co. #1 L. M. Cravens. ELEVATION OF SURFACE At discovery well, 3,279 feet; at other well, 3,283 ft. SURFACE FORMATION Apparently Ogallala formation of Pliocene series. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in either of the two productive wells was penetrated in the discovery well, which apparently was drilled into basal Wolf­camp. The oldest horizon penetrated in the vicinity of the field is 271 feet below the top of the Missis­sippian system. This penetration was in Standard Oil Co. of Texas #1 G.G. Flinn, located 2.1 miles northwest of the discovery well where the total depth of 11,171 feet is indicated on the ace ompanying map. The accompanying TYPICAL SECTION is based on the log of that dry hole. PRODUCTIVE AREA Clear Fork: Approximately 80 acres. NATURE OF TRAP Clear Fork: The trap appears to be due to eastward (~pdip) decrease of porosity on a westward plunging structural nose. THICKNESS OF RESERVOffi ROCK Clear Fork: Feet From top to bottom, approximately 90 Net productive, approximately 30 Small fluid recovery during drill-stem tests, zones of rock which yield bleeding oil on cores, layers of dense dolomite, and a relatively low initial potential after considerable acidization, all suggest discontinuous porosity and permeability vertically. Bleeding cores were recovered from the discovery well between the depths of 6,066 feet (-2,787) and 6,148 feet (-2,869). LITHOLOGY OF RESERVOffi ROCK Clear Fork: Gray to brown, slightly porous and fossiliferous, fine to medium crystalline dolomite with inclusions of anhydrite and black shale partings. CONTINUITY OF RESERVOffi ROCK Clear Fork: The stratigraphic equivalent of the productive zone appears to be continuous throughout the area of the accompanying map, but the degree of porosity which occasions commercial production is probably not continuous far beyond the immediate area of the two abandoned wells. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Clear Fork: Feet No free gas cap Highest known elevation of oil -2 ,774 Lowest known elevation of oil -2 ,869 Known relief of oil column CRAVENS FIELD , Lubbock County, Texas TYPICAL SECTION OF ROCKS PENETRATED -241 -341 '700 GAMMA ANO RAY SP RESISTIVITY ELEVATION -2341 5800 -2441 -2541 3800 -441 6000 -2641 ./ w 0 0. ,. 3900 -'41 6100 -2741 1.$ I! se.t.t.E.+~r+ w .. .. a: " a: 0 -641 6200 0 """' -2841 z " a: z 4100 -741 6300 -2941 " ...J 00 6700 -3341 ' ,. z 0 " > >­ 4600 -t24 1 6800 :-3441 z u" 0 -1341 6900 a: " z 0 7000 '.-3641 ...J -1541 -16 41 7200 ...J "'z >­ z -1741 7300 2 ,. 7400 -1841 a:" I­ -1941 7500 7600 -2041 7700 -2141 -224 1 7ll00 -234 1 7900 " "' 0 >­ EXPLANAT ION " Dolomite ~Limestone 8100 Sholy dolomite ~Anhydri~i~ ond ~do1om1t1c shale 8200 . o· ' · . • Rock indicated, Calcareous dolomite · : ·. ; · . •• • • • . sandy 8300 Anhyd rit1c dolomite ~Chert Shaly onhydritic 8<00 Dsolt dolomite .. 8450 • Oil production ELECTRIC 81 RADIOACTIVITY CURVES LITHOLOGY ELECTRIC 81 RADIOACTIVITY CURVES GAMMA RAY RESISTIVITY ...J AND $.P. Q ELEVATION 0. z "" ~ ,. ::; a: ...J -5091 -524 1 -5341 -5441 -5'541 ? ---5641 -5741 -5841 CRAVENS FIELD, Lubbock County, Texas EXPLANATION ---2880--Contour on top of Cleor Fork porous zone -2012 Elevotion ot top of Clear Fork porous zone • 6144 Total depth + Abondoned oil well ,r:1 Dry hole ·~Discovery SCALE 0 10 THOUS AND FE ET p CHARACTER OF OIL Clear Fork: Gravity Oil produced by Seaboard & Stanolind #1 Cravens 27° Slick & Moorman #1 Cloud 28 ° WATER PRODUCTION Clear Fork: During the initial potential test, the discovery well produced at the daily rate of 136 barrels of oil and 34 barrels of water; i .e. , water constituted 20% of gross fluid. During a test two months before abandonment in 1952, water constituted more than 50% of the gross production. Slick & Mooreman #1 Cloud, during its initial potential test, produced at the daily rate of 35 barrels of oil and 82 barrels of water; i.e., water constituted 70% of gross fluid. This well was abandoned in 1951. ACID TREATMENT Clear Fork: The discovery well was treated in three stages; first with 1, 000 gallons, then with 3 ,000 gallons and then with 6, 000 gallons. The other well was treated with 10 ,500 gallons in one treatment. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Pumping Yearly Cumulative 1945 4,055 4 ,055 1946 0 0 4,055 1947 1,724 5 ,779 1948 5 ,850 11 ,629 1949 2 6 ,304 18,167 1950 2 6'111 24,278 1951 5'1 06 29 ,384 1952 0 3 ,506 32,890 The di scovery well was not operated between June 1945 and \'July 1947; was abandoned on November 19, 1952. The only other well in the field, Slick Oil Co. and Moorman Oil Co. #1 Cloud, was completed on September 9, 1949 and was abandoned in 1951. CROSSETT FIELD Crane and Upton Counties. Texas B. DAVID BUTHMAN Geologist, The Texas Company, Midland, Texas July 14, 1954 LOCATION The Crossett field is located on the common line of Crane and Upton counties about 5 miles west of the town of McCamey and about 25 miles south­east of the town of Crane, the county seat of Crane County. It is about 2t miles southwest from the nearest portion of the McCamey field. It is one of several fields along the eastern edge of the Central Basin platform. METHOD OF EXPLORATION LEADING TO DISCOVERY Interpretation of subsurface data led to the drilling of the exploratory test which became the discovery well of the field and also of the first Devonian pro­duction in Texas. DISCOVERIES 3000-foot: April 11, 1952; The Texas Company #1-C C.W .Hobbs. 3200-foot: January 16, 1945; The Texas Company #3-B C.W.Hobbs. 3400-foot: August 25, 1950; Union Sulphur Co., Inc. #1 R.B.Robbins et al. 5100-foot: March 6, 1950; The Texas Company #6-B C. W. Hobbs. This well was abandoned in this reservoir and plugged back and completed for production from 3000­ foot reservoir on July 23, 1952. Devonian and Field: August 3, 1944; The Texas Company #1-A C.W .Hobbs. SURF ACE FORMATION Undifferentiated Quaternary sand. ELEVATION OF SURF ACE At well locations: Highest, 2,421 ft.; lowest,2,328 ft. PRODUCTIVE AREAS Acres 3000-foot (2 wells) -so 3200-foot (2 wells, 1 abandoned) 80 3400-foot ( 1 well, abandoned) 40 5100-foot ( 1 well, abandoned) 40 Devonian 840 Crossett field 1,040 OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 145 feet below its top. This penetration was in the discovery well of the 3200-foot reservoir. NATURE OF TRAPS 3000-foot, 3200-foot, 3400-foot and 5100-foot: The trap in each of these reservoirs is due to decrease of porosity and permeability in a sloping reservoir rock. In each of the reservoir rocks, the degrees of porosity and permeability are generally very low and only locally are they adequate for commercial production. Devonian: The trap is due to erosional truncation of a sloping reservoir rock and sealing by relatively impervious overlying rocks. LITHOLOGY OF RESERVOIR ROCKS 3000-foot, 3200-foot, and 3400-foot: Dolomite; white to tan with fair to good, fine, vuggy porosity. 5100-foot: Dolomite; generally gray to brown, finely crystalline with slight to fair porosity in the form of fine vugs lined with calcite crystals. Devonian: Limestone; white to tan, somewhat silicious and containing thin interbedded layers of chert. Cores have shown considerable fracturing. CONTINUITY OF RESERVOIR ROCKS 3000-foot, 3200-foot, 3400-foot and 5100-foot: Each of these reservoir rocks is continuous through­out the area of the field and far beyond. However, the degrees of porosity and permeability which occasion commercial production do not appear to be continuous beyond the immediate vicinity of each respective well. Devonian: Rocks of the Devonian system strike generally north-south and dip eastward. They have been truncated by erosion throughout the area of the field. The reservoir rock, which is at the top of the Devonian system, has been entirely removed throughout the northern portion of the field where the shallower reservoirs have been found productive at scattered locations. Even in the area which pro­duces from the Devonian reservoir, only the bottom portion of the reservoir rock extends throughout the Devonian productive area; the higher portions having been removed by erosion, as indicated on the accompanying cross section. CR 0 SSE TT FIELD, Crane ahd Upton Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED ,,, I p' TO 5~l0 T0 5HO EXPLANATION • Oil well, producing from 3000-foot reservoir I• Oil well, producing from 320 0-foot reservo ir 1+ Abandoned oil well, formerly productive in 3200-foot reservoir +~ Abandoned oil well, formerly productive in 3400-foot reservoir ~ Oil well, producin9 from 3000-foot, abandoned in 5100-foot • Oil well, producing from Devonian reservoir ff Ory hole •L:lJ Discovery PRODUCTIVE AREAS ~3000-foot iii3200-foot . 3400-foot ~~'!fi~W~~f~i s100-foot D Devonian SCALE THOUSAND FEET WEST EAST GENERALIZED CROSS SECTION A - A' ElEVATtOll , [[T l l l \IAT IO ll HU CR 0 SSE TT FIELD, Crane and Upton Counties, Texas THICKNESSES OF RESERVOIR ROCKS CHARACTER OF GAS F r om top to bottom, feet Max. Avg . 3000-foot 60 SS- 3200-foot 20 20 20 3400-foot. ............................ 12 ......... 12 ......... 12 5 100 -foot 25 25 25 Devonian 37 135 94 Data are not available for satisfactory estimates of net pr oductive thicknesses . CHARACTER OF on. Gravity, A.P .I. Sulphur Base 3000-foot 41 6 Sweet -Mixed 3200-foot 45" 0.5% Mixed 3400-foot ............. .... 41 ° ........... .... Sweet............... Mixed 5100-foot 44° Sweet Mixed Devonian 45° 0.12% Mixed For analysis of Devonian oil see: U.S. Bureau of Min es Lab.ref.No. 46102 Analyses of Crude Oils from Some West Texas Fields. R.I. 4959 (1953) Item 21 ELEVATION AND RELIEF OF PRODUCTIVE ZONES Elevation of oil Oil (feet) column Top Bottom (feet) 3000-foot ----:s5'9± -619! ~ 3200-foot -813 -833 20 3400-foot ........... ...... ...... -1,061....-1,073 .... ............. 12 5100-foot -2,664 -2,689 25 ])evonian -2,790 -3,049 259 The above figures represent conditions as of respective discover y dates. WATER PRODUCTION 3000-foot and 3200-foot: At time of completion, each well produced a small percentage of water . In general, there has been only a slight increase in the ratio of water to oil, but, in one of the four wells, water increased con­siderably and the well was abandoned in 1954. 3400-foot and 5100-foot: Excessive water production occasioned the abandonment of the well completed in the 3400-foot reservoir and the recompletion of the' well origi­nally completed in the 5100-foot reservoir . Devonian: Water constituted a small percentage of the gross production ofa few of the wells at times of completion. In general, there has been a slight increase in the ratio of water in the production of such wells. ACID TREATMENT 3000-foot: Each well was washed with 500 gallons of mud acid. 3200-foot: Each well was washed with 4,000 gallons of mud acid. 3400-foot and 5100-foot: Each well was treated with 500 gallons of acid. Devonian: The normal treatment has been with 500 to 1,000 gallons of acid, but some wells have been completed without acid treatment and the quantity has ranged up to 8,000 gallons used in the treatment of one well. The only gas production has been incidental to oil production. No analysis of the gas from any reservoir is available, but it is known that the gas from the 3 ,000 -foot reservoir and also that from the Devonian reservoir is sweet and relatively dry . PRODUCTION HISTORY WELLS P RODUCING OIL PRODUCTION at end of year (barrels) Year Flowing P umping Yearly Cumula tive FieTcftOtals 1944 3 3 32 ,534 32 ,534 1945 11 0 164,533 197 ,067 1946 ..... ..... ... 11. ............ 2 .. ... .. ... 116,41 3... ..... 313,480 1947 13 3 155 ,1 46 468,626 1948 17 3 213,849 682,475 1949.............. 13............. 9 .......... 150,171. ....... 832,646 1950 20 5 177,463 1,010,109 1951 20 5 207,359 1.21 7 ,468 1952 ............. 20.... ········.7 .......... 205 ,504 ..... 1.422 ,972 1953 19 6 209,258 1,632 ,230 1954* 19 5 170,813 1.803,043 3000-foot 1952 19 ,635 19 ,635 1953 33,359 52 .994 1954* 20.930 7 3,924 3200-foot 1945 l 0 10,126 10,126 1946............... 0............. 1 ............. 3,590.......... 13,716 1947 0 1 4,307 18,023 1948 0 2 5,662 23,685 1949 ............... 0 .............2 ............. 5 ,264..........28,949 1950 0 2 3,922 32,871 1951 0 2 3,452 36 ,323 1952............... 0............. 2 ............. 3,446 ..........39,769 1953 0 2 3,481 43,250 1954* 0 3,156 46 ,406 3400 -foot 1950 0 865 865 1951 1 0 1,165 2 ,030 1952 ............... 0............. 1. ................ 28........... 2 ,058 1953 0 0 0 2,058 1954* 0 0 0 2,058 5100-foot 1950 0 3,573 3,573 1951 0 1 1,016 4,589 1952..... .......... 0............. 1. .... .. ... ...... 265.. ......... 4,854 1953 0 0 0 4,854 1954* 0 0 0 4,854 Devonian 1944 3 3 32 ,534 32 ,534 1945 10 0 154,407 186,941 1946.............. 11. ............ !. ......... 112,823........ 299.764 1947 13 2 150 ,839 450 ,603 1948 17 1 208,187 658,790 1949 .............. 13 ...........,.7 ·········· 144,907 ········ 803,697 1950 19 2 169.103 972,800 1951 19 2 201,726 1.174,526 1952 .............. 19 .............2 .......... 182,130...... 1,356,656 1953 18 3 172,418 1,529,074 1954* 18 3 146 ,727 1.675,801 * 1954 data added by amendment. DIXIELAND FIELD Reeves County, Texas JOE R. HORKEY Geologist, Phillips Petroleum Company, Midland, Texas January 3, 1953 LOCATION The Dixieland field is in northeast Reeves County about 2 miles south of the town of Dixieland. It is in sections 12, 13, 17 and 18 of block 2 of H.&G.N.R.R. Co. survey. The field is near the geographical center of the Delaware basin; on the west limb of the asymmetrical basin about 1,500 feet higher than the axis . METHODS OF EXPLORATION LEADING TO DISCOVERY Random drilling in the vicinity had discovered shows of oil before the beginning of the exploration which led directly to the discovery of commercial production. In 1922, Dixieland Syndicate in its #1 Bell in Sec. 20 found a particularly promising show, and that show led to the drilling of several other tests in the vicinity. It appears that the op­erators who drilled the discovery well in 1948 were guided by the data afforded by the several tests pre­viously drilled in the vicinity. DISCOVERY Bell Canyon : April 20, 1948; C & B Oil Co . (Cosby andBectel) #1 OllieP.Anderson,which is now designated as Indiana Farm Bureau Co-operative Association, Inc., #1 Ollie P . Anderson. On initial potential test, the well flowed at rate of 7 3 barrels of oil per day; 6/64-inch choke; tubing pressure, 290 psi.; casing pressure, 945 psi.; gravity, 35°, total depth, 3 ,939 feet; plugged back to 3 ,906 feet. Within a few weeks, the well was put on pump. ELEVATION OF SURFACE At well locations : Highest, 2 ,787 ft.; lowest, 2 ,736 ft. SURFACE FORMATION Recent Quaternary alluvium and gravels. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field. is in the Bell Canyon formation 75 feet below the base of the Lamar member . This penetra­tion was in the discovery well. Other wells in the vicinity, but beyond the limits of the field, have been drilled considerably deeper and have demonstrated that the average thickness of the Bell Canyon forma­tion is about 1,200 feet . NATURE OF TRAP Bell Canyon: Accumulation of oil appears to have been occasioned by a combination of terracing on an eastward dipping monocline and a decrease in degree of porosity and permeability both updip and along strike. PRODUCTIVE AREA Bell Canyon and Field: About 300 acres proven by development to da~ THICKNESS OF RESERVOIR ROCK Bell Canyon Feet, average From top to bottom, gross 60 Net productive 60 LITHOLOGY OF RESERVOIR ROCK Bell Canyon: Very fine-grained, tight, clean to shaly, homogenous sandstone with partings of shale and sandy shale. DIXIELAND FIELD, Reeves County, Texas ..... "' >­ "' "' z ~ a 0:: ... 0.. CONTINUITY OF RESERVOIR ROCK z z RADIOACTIV I TY CURVES Bell Canyon : The reservoir rock 0 RADIOACTIVITY CURVES Q a: 2 LITHOLOGY L I THOLOGY ~ 0.. is a blanket sandstone occurring "' ~ ID "' 2 "' ..... "' ::> ~ 2 GAMMA RAY NEUTRON "' a: 2 a: a: 0 GAMMA RAY NEUTRON throughout the whole of the Delaware -' 0 "'>-a: a: 0 ... 0 C> ... "' "' 2 DEPTH ELE VATI ON "' DE P TH ELEVATIO N basin. "' "' "' WATER PRODUCTION Bell Canyon: Only a small amount of water has been produced. Such z water as has been produced appears to C( C( have been distributed in the reservoir 0 2 :z: a: rock with the oil rather than to have 0 ... 0 0.. occupied a position below any definite oil-water contact. CHARACTER OF OIL Bell Canyon: ... 3 Gravity, A .P .I. @ 60 ° F. ~ DELAWARE MOUNTA IN Range , 31 . 9 • to 40 • ~ BELL CAN YON Wtd . Avg ., 35° C> EXPLANATION Sondston~ ~Solt CHARACTER OF GAS Sholo ~Anhydrite Bell Canyon: The only gas pro­duced is that which comes out of solu­ Oolom ltu • 01 1 produc ti on tion as the oil is produced . Analysis is not available . ttr~ Grovol, sond, and shaly alluvial deposits D ELEVATION AND RELIEF OF PRODUCTIVE ZONE Bell Canyon: Feet "'0 :z: 0 0 No free gas cap· Highest known elevation of oil -1,041 Lowest known elevation of oil -1.132 Known relief 91 The above figures represent the extremes in pro­ ductive wells completed to date . No oil-water contact has been found . PRODUCTION HISTORY W ELLS PRODUCING O I L P R O DU CTION at end of year (barrels} Year F lowing Pumping Yearly CnmuJative 1948 0 3 12 ,2 31 12 ,2 31 1949 2 3 18 ,670 30,901 1950 2 3 15 ,565 46 .466 1951 2 6 26 ,760 7 3 ,326 1952 2 6 28,293 10 l ,619 ..,'?. ~ 00 ,o ~ waNWRR co BLOCK 2 p T04~1t T8P RR CO BLOCK 55 TWP3 ~I 0 ,_. :>< ,_. t'T] r< >­z 0 "Tj ,_. t'T] r< 0 ::u :c"' ... >­ >­ .. :c 0: llOO 3: "' ... z Q. .. ::> " .. 0.. 400 1500 1600 ... "' 0: 1700 z .. 0 1600 ..z "' 1900 2000 3500 -1335 3700 -1535 "' 3900 -1635 -1735 4100 4200 -1835 -1 935 -2035 4400 -2235 Q. " _, 0 3: 4500 4600 4700 4600 4900 5000 -2335 -2435 -2535 -2635 -Z735 EXPLANATION ---5800---Contour on top of Ellenburger group -s:• Elewtion of top of Ellenburger groop Toto! depth • Oil well P Ory hole •\JDisc ove ry SCALE ELECTRIC a RADIOACTIVITY CURVES LITHOLOGY Q. => GAMMA RAY RESISTI VI TY ~ AN O S. P. Cl 0£PTH ELEVATION 2260-----;~--i::==-----95 i~ -135 2>00 -2352400 ~-.._ --· -335 ~ ,-"> }­ 2600 -435 ) " 2700 -535 ~ 2aoo -6 35 0 2900 -735 .. ... _, 3000 -63 <.) ~00 -935 a: 3200 -1035 .. z 0 3>00 -11 35 3400 -1235 0 5100 -Z935 ~ ~ z.. :; I 5200 -3035 >­"' z z ... z0 >­z 5300 ;c-~----.,;~ ­_, -~­_-­ -31 35 Q. .. <.) ....,.­ -~ 5400 -3235 -~~ 5450 -3285 ELECTRIC a RADIOACTIVITY CURVES LITHOLOGY GA MMA RAY ANO S.P. DEPTH 5450 5500 5600 5700 5600 6000 100 6 200 6300 z "' 0 <.) "' -I z > 0 _, >­>­z"' ..z <.) z ... 6500 6600 6700 6600 6900 7000 7100 7200 7>00 7400 7500 7600 z 3: "' 0: >­"' 7700 7600 ~ MISSISSIPP IAN ---;~; "',::>" ORDOVI CIAN 8004 ELLENBURGER RESISTIVITY _, ELEVATION 6 -3285 -3335 -3435 -3535 -3635 -3735 -39 -4035 -4135 -423.5 -·= -4535 -47 -4835 -4935 f_ Wt ISondSlooo § 001om11e m;Anhydrile * DEVONIAN OI" MISSISSIPPIAN EXPL ANATION ~=~====~ G ...J • z u > 0 0 0: 0 EXP LANATI ON ~Limestone ~Dolomite E£EDolomite and ~\/:}/\)Sandstone ~limestone ~Dolomite and E=~==3 Shale ~shale ~Sandstone ~Dolomite and ~and shale ~anhydrite • 011 production mAnhydrite mmSal t and . mm anhydrite Chert ~ D Rock indicated, red ,;. .., \ I \ 0 ~ 0 0 !? 0 ~ 0 0 2 0 ~ 0 ~ 0 ~ 0 0 ~ 0 0 ~ 0 ~ 0 0 :;: 0 ~ 0 ~ 0 ~ ' ' ' ' ' ' ' ' RESERVOIR PRESSURES Datum At time Saturation At indicated recent date elevation of discovery pressure Pressure (feet) (psi.) (psi.) (psi.) Date -550 I, 36 1t 689 Nov. 1955 -3, 400 Z,890 2, 190 8 17 Nov. 1956 -4,600 3,300 2,830 1,356 Nov. 1956 -5,200 3, 555 793 2,655 Aug. 1956 -5, 524 3, 300• 395 3,062 March 1956 -6,800 4,295 1,492 Z,688 Aug. 1956 -7,080 3,630• 2, 730 March 1956 Queen Leonard Devonian Texas Fusselman-Montoya New Mexico Fusselman-Montoya Texas Ellenburger New Mexico Ellenburger * The fac t that the discovery press ures in the New Mexico Fusselman-Montoya and in the New Mexico Ellenburger were lower than the discovery pressures in the Texas reservoirs in the same reservoir rocks is attributed to the later discovery dates of the New Mexico reservoirs. The New Mexico discovery pressures, when adjusted for differences in datum elevations, were slightly higher than corresponding pressures at the same dates in the respective Texas reservoirs. 90 DOLLARHIDE FIELD, Andrews County, Texas, and Lea County, New Mexico UTHOLOGY OF RESERVOIR ROCKS Queen: The productive portion of the Queen for­mation consists of sandstones which are interbedded withanhydritic dolomite and thin beds of red or gray shale. The sandstones are medium grained, with the grains subangular to subrounded; color is typically light gray; the upper part of the reservoir rock commonly contains frosted quartz grains. The foregoing description applies in the northwest part of the field where the Queen formation is commer­cially productive; southeastward, there is less sand and the formation is not productive. Leonard: The productive rock consists of scattered layers occurring throughout the section between the base of the Drinkard (Tubb) member of the Clear Fork group and the base of the Permian system, generally a thickness ofabout 1,400 feet. As indicated on the accompanying TYPICAL SECTION, the Clear Fork portion of this section is dolomite and the Wichita portion is limestone and dolomite. Both portions contain numerous thin shale partings and some anhydrite streaks. The lower 120 feet of the Clear Fork portion is generally favorably porous, but otherwise the distribution of favorable porosity is very irregular and is scattered throughout the dolomite and limestone beds in thin streaks. The zones of favorable porosity are generally regarded as adequately inter-connected to constitute a single reservoir, but the effectiveness of the inter­connection is questionable as to some portions of the reservoir. It is difficult to correlate the individual porous layers from well to well, but certain.ones, such as the aforementioned 120-foot zone, are recognizable throughout the northern portion of the field and a basal Permian zone is prominent in the southern portion of the field. The porosity of the productive rock averages about 10.4% and the perme­ability averages about 9.2 millidarcys. Devonian: This reservoir rock generally consists of (a) an upper member of about 60 feet of white, fine to medium, crystalline limestone and dolomite with varying amounts of gray translucent chert; (b) a middle member of 75 to 100 feet of white, medium crystalline limestone which is somewhat granular near the base and commonly contains con­siderable glauconite; and (c) a lower member of 20 to 70 feet of chert which normally grades from a light colored opaque chert into a dull brown, earthy, calcareous weathered chert. The porosity of the productive rock averages about 13.5% and the perme­ability averages about l 7 millidarcys. Fusselman-Montoya, (Texas and New Mexico): The Fusselman portion of this reservoir rock is a white to light buff coarsely crystalline limestone which grades locally into dolomite. It commonly contains glauconite and varying amounts of light colored vitreous opaque chert. The Montoya por­tion is a coarsely crystalline dolomite with abundant light colored vitreous chert. Good intergranular porosity is present through the entire thickness of the reservoir rock. Cavernous porosity occurs locally. Open caverns, 2 to 16 feet in height, were encountered in 15 wells in the central part of the field, mainly in Sec. 24, Blk. A-52. While the dis­covered open caverns are mainly in the Fusselman formation, one such cavern is in rock definitely above the Fusselman. Exclusive of the cavernous portion, the productive rock has an average porosity of about 5.8% and an average permeability of about 8.9 millidarcys. Ellenburger, (Texas and New Mexico): The reservoir rock is gray to brown, medium to coarsely crystalline dolomite containing zones with frosted quartz grains, some chert and small amounts of glauconite and pyrite. The porosity is dominantly of the vuggy and fracture types with visible inter­stitial porosity limited to some of the coarsely crystalline dolomites. Horizontal and vertical permeability is sufficiently continuous that water drive provides a significant part of the reservoir energy. Analyses of full diameter cores indicate that the porosity averages 2.2% and the perme­ability averages 4.9 millidarcys. CHARACTER OF OIL Gravity, Sulphur, Volume A. P. I. % Base Color factor* Queen 34 ? ? ? ? Leonard 38. l 0.4 Mixed Green 1.40 Devonian 39.7 0.6 Mixed Green 1.65 Texas Fusselman-Montoya 44.2 0.4 Asphalt Black 1.20 New Mexico Fusselman-Montoya 38 ? Asphalt Black ? Texas Ellenburger 43 0.2 Mixed Green 1.29 New Mexico Ellenburger 42 ? Mixed Green ? expressed ratio of volume in reservoir at saturation pressure to volume at surfaceas at atmospheric pressure and temperature of 60 ° F. For analysis of sample from the Devonian reservoir see: U. S. Bureau of Mines Analyses of Crude Oils from Some West Texas Fields. R.I. 4959 (1953) Lab. ref. Item No. 46092 22 * Volume factor DOLLAR1IIDE FIELD, Andrews County, Texas, and Lea County, New Mexico 25 (/) v C\J ._; 36 (/) I() C\J ._; 12 19 20 DEVELOPMENT MAP .... 30 29 28 1 I p ol TD 8995 u 15 14 .. .. PUBLIC SCHOOL LANDT. 24 S., R. 38 E. '"' I '"' .. ... BLOCK A-52 31 32 "+ ,.., 331 ,.. ... I '"' .. •' .. .... .. FUSSELMAN-MONTOYA /~LEONARD •' ~NEWMEXICO .... . 4' ~ ~ .. I ~ """ __., I .. ... .. .. _. ---.. -....---.. ----~~ • 4.. ,1--,..--,,-.-..---.-..-~--,.-. .~ ~6+----~-.. /..,1=1t--,s,-------.,,1s=-' .. .. Y . I 1s A' 12 13 14 15 I _t---~•'-__19,,,___Jl_ _/91•'---/•1 •'---~ ,,,....--_ ;.al•' ­ -i----­ 2 ;p ..4 -5" 6 I -~ :A --·I ~. -.-·---.~~--:~---,-" .. i-•..1. .._..1.• ·~ /•" I T " ... T .... I ~NEW ME XICO ELLEN BURGER TO 5002 " .. ... .... I /.... ,..·' /.... ~-­ QUEEN 1C7'0 ... •I e .. . p .. TD 3767 T. 25S., R.3BE. 8 7 p TO 9670 (TD 11014 P;,-..._TD 3975 SCALE a 4 THOUSAND FEET TiilCKNESSES OF RESERVOIR ROCKS Feet, average Top to Net bottom productive Queen l2o 30 Leonard 1,400 125 Devonian 180 75 Texas Fusselman-Montoya 300 300 New Mexico Fusselman-Montoya 376 376 Texas Ellenburger 513+ 513 New Mexico Ellenburger 320+ 320 ELEVATION AND RELIEF OF PRODUCTIVE ZONES The following figures represent conditions at the respective discovery dates. There was no free gas cap in any reservoir. Elevation of oil Oil (feet) colwnn ~ Bottom (feet) Queen -400 -600 200 Leonard* • l,ooo! Devonian -4, 300 -5, 300 1,000 Texas Fusselman-Montoya -5,000 -5,520 520 New Mexico Fusselman-Montoya -5, 135 -5,600 465 Texas Ellenburger -6,450 -7,000 550 New Mexico Ellenburger -6, 734 -7, 140 406 *In the Leonard, the highest known oil is at the elevation of -2,945 feet and the lowest known oil is at the elevation of -4,200 feet. However , it should be remembered that the productive rock is in the form of scattered local beds totaling generally ~ess than 10% of the gross thickness of the reservoir rock and that the oil-water contact was as high as -3,500 feet in one of these local beds. While it appears probable that inter-connection between the productive beds is adequate for migration of fluids in geologic time, the indicated oil column is not of the usual significance. ....... 25 I ,, Ii'.: 4 TO 8533 )--Z I-:'.) /ol.. ~18 01 u1"' :;:: "' E XPLANATION ----5100---Contour on top of Fusselman formation + + + + + + •Oil-water contact ot time of discovery • Oil well, producing from Fusselman-Montoya Oil well which hos produced from Fusselman -Montoya only, now abandoned ~· Oil well, previously productive from Fusselman-Montoya, now producin9 from another reservoir • \:JI Di scovery THIS MAP SHOWS ONLY SUCH WELLS AS HAVE BEEN COMPLETED IN FUSSELMAN -MONTOYA SCALE THOUSAND FEET CHARACTER OF GAS There was no free gas in a ny reservoir at time of dis­covery of commercial production. Such gas as has been produced has come out of solution as oil has been produced. The specific gravity and condensate content have averaged about as indicated below. Specific Condensate, gravity ~al /Mcf Quee n ? Leonard 0 .978 Z.58 Devonian 0.957 Z.33 Texas Fusselman-Montoya 1.1 70 3.Z6 New Mexico Fusselman-Montoya Texas Ellenburger 0 .989 3.10 New Mexico Ellenburger DOLLARHIDE FIELD, Andrews County, Texas, and Lea County, New Mexico PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION WATER PRODUCTION at end of year {barrels) {Mcf) (barrels) Year Flowing Art. Lift Yearly Cumulative Yearly. Cumulative Yearly Cumulative Field totals 1945 1 0 12,093 12,093 26,434 26,434 0 0 1946 6 0 146,864 158,957 244,308 270, 742 0 0 1947 27 1 569,239 728,196 659,951 930,693 552 552 1948 85 3 3,550,579 4,278,775 2,449,647 3,380,340 31,285 31,837 1949 165 5 4,537,467 8,816,242 3,177,032 6,557,372 148,891 180, 728 1950 227 16 6,315,297 15,131,539 5,462,970 12,020,342 203,364 384,092 1951 267 28 8,173,528 23,305,067 8,680,428 20, 700, 770 419,747 803,839 1952 313 43 8,095,977 31,401,044 9,601,347 30,302, 117 666,518 1,470,357 1953 328 101 10,006,887 41,407,931 16,277,228 46,579,345 1,245,576 2, 715,933 1954 333 150 9,956,570 51,364,501 19,867,546 66,446,891 1,638, 101 4,354,034 1955 301 191 9,052,301 60,416,802 22,579,607 89,026,498 1,313;549 5,667,583 1956* 277 218 7,971,040 68,387,842 22,582,242 111,608, 740 1,531,022 7,198,605 Queen ---r952 6 2 21, 337 21,337 8,979 8,979 991 991 1953 36 4 322, 681 344,018 207,209 216,188 5,292 6,283 1954 45 14 643, 178 987,196 564,576 780, 764 16, 774 23,057 1955 31 32 619,399 1,606,595 1,544,544 2,325, 308 35,222 58,279 1956* 15 48 391, 713 1,998,308 1,298, 122 3,623,430 28, l 16 86,395 Leonard, total 1949 10 0 81, 786 81, 786 58,265 58,265 0 0 1950 30 l 408,272 490,058 325,060 383,325 1,510 1,510 1951 71 5 1,286,387 1, 776,445 1,266,152 1,649,477 17,931 19,441 1952 75 15 1, 757,255 3,533,700 1,841, 781 3,491,258 50, 783 70,224 1953 96 34 2,'809,835 6,343,535 4,006,433 7,497,691 57,620 127,844 1954 101 64 3, 723,079 10,066,614 7,200,368 14,698,059 107,045 234,889 1955 93 76 3,432,428 13,499,042 9,145,456 23,843,515 95,856 330,745 1956* 95 79 3,005,270 16,504,312 9,138,310 32,981,825 82,414 413,159 Leonard, Texas 1949 10 0 81, 786 81, 786 58,265 58,265 0 0 1950 30 408,272 490,058 325,060 383,325 1,510 1,510 1951 70 5 l,284,376 1, 774,434 1,262,370 1,645,695 17,871 19,381 1952 71 14 1, 715,967 3,490,401 1,813,433 3,459, 128 49,980 69,361 1953 61 25 2,243,120 5,733,521 3,548,664 7,007, 792 49,572 118,933 1954 70 26 2,187, 783 7,921,304 5,422,296 12,430,088 47,087 166,020 1955 68 30 1,949,880 9,871,184 6,123,843 18,553,931 32,771 198,791 1956* 64 33 1,410,693 11,281,877 5,537,277 24,091,208 30,095 228,886 Leonard, New Mexico 1951 l 0 2,011 2,011 3, 782 3, 782 60 60 1952 4 l 41,288 43,299 28,348 32, 130 803 863 1953 35 9 566,715 610,014 457, 769 489,899 8,048 8,911 1954 31 38 1,535,296 2,145,310 1,778,072 2,267,971 59,958 68,869 1955 25 46 1,482,548 3,627,858 3,021,613 5,289,584 63,085 131,954 1956 31 46 1,594,577 5,222,435 3,601,033 8,890,617 52,319 184,273 Devonian, total 1945-51 Same as Devonian, Texas. 7,882,246 13,009,504 29,023 1952 135 9 2,679,417 10,561,663 5,998,817 19,008,321 16,525 45,548 1953 123 22 3, 364, 019 13,925,682 10,201,863 29,210, 184 16, l 29 61,677 1954 123 23 2,604,923 16,530,605 10,307,204 39,517,388 31,547 93,224 1955 117 29 2,139,990 18,670,595 10,208, 562 49, 725,950 28,446 121,670 1956* 115 30 1,809,499 20,480,094 10,569,335 60,295,285 30,808 152,478 Some entries for 1956 are based in part on estimates for last few months. * DOLLARHIDE FIELD, Andrews County, Texas, and Lea County, New Mexico PR 0 DUCT I 0 N HIST 0 RY (Continued) WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION WATER PRODUCTION at end of year (barrels) (Mcf) (barrels) Year Flowing Art. Lift Yearly Cumulative Yearly Cumulative Yearly Cumulative Devonian, Texas 1945 l 0 12, 093 12,093 26,434 26,434 0 0 1946 6 0 146,864 158,957 244,308 270,742 0 0 1947 22 0 449,009 607,966 613,276 884, 018 552 552 1948 41 l 1,148,266 l, 756, 232 1,378,688 2, 262, 706 2, 128 2,680 1949 73 1,177,209 2,933,441 1,594,402 3,857, 108 3,233 5,9U 1950 105 5 2,088,408 5,021,849 3,521, 731 7,378,839 6,358 12, 2 71 1951 104 22 2,860,397 7, 882, 246 5,630,665 13,009,504 16, 752 29,023 1952 126 9 2,545,163 10,427,409 5,829, 723 18, 839. 22 7 16, 525 45,548 19~J 112 22 2, 948, 830 13,376,239 9,589,920 28,429, 147 16,129 61,677 1954 113 22 2,236,693 15,612,932 9,409,697 37,838,844 31, 547 93,224 1955 107 26 l, 780, 134 17,393,066 8,975,596 46,814,440 28,446 121,670 1956* 106 25 1,412,534 18, 805, 600 8,984,402 55, 798,842 30,808 152,478 Devonian, New Mexico 1952 9 0 134, 254 134,254 169,094 169. 094 0 0 1953 11 0 415,189 549,443 611,943 781, 037 0 0 1954 10 1 368, 230 917,673 897,507 1,678,544 0 0 1955 10 3 359,856 l,277,529 1,232,966 2,911,510 0 0 1956 9 5 396,965 1,674,494 1,584,933 4,496,443 0 0 Texas Fusselman-Montoya 1947 2 90,375 90, 375 29,866 29,866 0 0 1948 21 2 726,913 817, 288 233, 380 263,246 8,363 8,363 1949 41 4 1,331,212 2, 148,500 448, 610 711,856 70,495 78,858 1950 53 4 1,918,961 4,067,461 616,543 1,328,399 53, l 99 132,057 1951 50 7 2,275,901 6,343,362 761,671 2,090,070 106,822 238,879 1952 49 9 2,044,903 8,388,265 823, 325 2,913,395 296,640 535,519 1953 37 19 1,856,818 10,245,083 793,121 3, 706,516 369,680 905,199 1954 33 23 1,522, 126 11, 767,209 712,289 4,418,805 627,357 1,532,556 1955 30 25 1,440,651 13,207,860 758,027 5, l 76,832 392,352 1,924,908 1956* 25 30 l,405, 770 14,613,630 754,898 5,931, 730 593, 691 2,518,599 New Mexico Fusselman-Montoya 1952 4 0 132,214 132,214 10,013 10,013 50,314 50,314 1953 4 2 191,923 324,137 61,113 71, l 26 228,939 279,253 1954 6 232,424 556, 561 404,288 475,414 192,694 471,947 1955 7 235, 825 792, 386 271,636 747,050 302,828 774, 775 1956 8 287,540 1,079,926 208, 345 955,395 267,179 1,041,954 Texas Ellenburger 1947 3 0 29,855 29,855 16,809 16,809 0 0 1948 23 0 1,675,400 l, 705,255 837, 579 854, 388 20, 794 20, 794 1949 41 0 1,947,260 3,652,515 l,075, 755 1,930, 143 75, l 63 95,957 1950 39 6 1,899,656 5,552,171 999, 636 2,929, 779 142,297 238,254 1951 37 11 l, 712,900 7,265,071 987,947 3,917,726 277,392 515,646 1952 36 8 1,007,696 8,272, 767 698,458 4, 616, l 84 243, 636 759,282 1953 25 19 921, l 77 9,193,944 783, 722 5,399,906 427,091 l, 186,373 1954 24 20 763,437 9,957,381 550, 384 5,950,290 . 473,709 1,660,082 1955 23 21 749,949 10, 707,330 542,464 6,492, 754 398,578 2, 058, 660 1956* 21 21 704,861 11,412, 191 511,024 7,003, 778 404,627 2,463,287 New Mexico Ellenburger Some entries for 1956 are based in part on estimates for last few months. 1951 1952 1953 4 8 7 0 0 37,943 453,155 540,434 37,943 491,098 1,031,532 33,993 219,974 223, 767 33,993 253,967 477, 734 850 7,629 140,825 850 8,479 149,304 1954 1955 1956 7 6 5 0 l 2 467,403 434,059 366, 387 1,498,935 l,9 32,994 2,299,381 128,437 108,918 102,208 606,171 715,089 817,297 188,975 60,267 124, 187 338,279 398,546 522, 733 * 96 DOLLARHIDE FIELD, Andrews County, Texas, and Lea County, New Mexico CONTINUITY OF RESERVOm ROCKS Queen: The sandstones with favorable porosity and per~ityare limited to flank positions on the New Mexico portion of the anticline. Eastward, the sandstones terminate because of facies change. Leonard: This reservoir rock is continuous throughout the area of the field and throughout a large portion of the Permian basin. However, the individual beds which produce in this field are local and cannot be correlated generally beyond the locations of a few wells. Devonian: As indicated on the accompanying Devonian map, the continuity of the Devonian reservoir rock is interrupted by faults and by truncation. With these excep­tions, the reservoir rock is continuous throughout the area of the field. However, the degree of porosity is quite vari­able. Where the reservoir rock was exposed to erosional truncation, the nature and degree of porosity was determined largely by weathering. Fusselman-Montoya (Texas and New Mexico): This reservoir rock is continuous throughout the area of the field except that it is broken by faults as indicated on the accompanying Fusselman-Montoya map. Porosity and permeability are definitely continuous between the two reservoirs and are generally sufficiently continuous that there is an effective water drive in each of the two reser­voirs. The consistency of the elevation of the oil-water contact in all segments of the Texas reservoir indicates continuity of lithologic conditions favorable for freedom of migration of reservoir fluids. Ellenburger (Texas and New Mexico): This reservoir rock is continuous throughout the area of the field except that it is broken by faults as indicated on the accompanying Ellenburger map. Porosity and permeability are con­tinuous between the two reservoirs and are generally sufficiently continuous that, in each of the two reservoirs, there is a partially effective water drive and the elevation of the initial oil-water contact is consistent within all parts of each reservoir (about 140 feet higher in one reservoir than in the other). WATER PRODUCTION Queen: Approximately one-half of the wells produce some water. Water now constitutes 10 to 20% of the gross fluid produced by the water-producing wells; as much as 50% of the gross fluid produced by a few wells. The total quantity of water produced from the reservoir has gradually increased until itnow amounts to 6.5% of the gross production. Leonard: As indicated in the following tabulation headed PRODUCTION HISTORY, a small amount of water is pro­duced from this reservoir. Currently, the water amounts to about 2.1% of the gross liquid. The wells along the western edge of the Leonard productive area, either at times of completion or early in their productive lives, have produced water in amounts ranging from a trace to 15% of gross liquid. Tests have indicated that this water is not bottom water; that it is from water-bearing stringers within the gross thickness of the reservoir rock and at elevations above the general elevation of the oil-water contact. Devonian: Water production has been limited to struc­turallylow wells and a few other wells where it appears that faulting has afforded migration channels. Water encroach­ment has been negligible; reservoir energy has been essen­tially all due to expansion of gas released from solution as pressure declines. Texas Fusselman-Montoya: Water encroachment has been an important factor in reservoir performance. Cur­rently, water constitutes about 21%of the gross liquid pro­duced; from a few individual wells, the water amounts to as much as 45% of gross liquid. Since the time of discovery, the elevation of the oil-water contact has risen generally almost 100 feet (from about -5,520 to about -5,430). Water encroachment within the extensive cavern system mentioned under LITHOLOGY OF RESERVOIR ROCKS has been erratic; water has entered some wells at elevations about 50 feet higher than the general elevation ci. the oil-water contact; at other wells, even currently, the oil is free of water down to elevations only about 10 feet higher than the elevation of the oil-water contact at time of discovery. New Mexico Fusselman-Montoya: From soon after dis­covery, as indicated in the following tabulation presenting PRODUCTION HISTORY, the total quantity of water has been about equal to the total quantity of oil produced from this reservoir. One well, producing more than three barrels of water per barrel of oil, accounts for two-thirds of the water production. Five wells, including the flowing well, are reported to be producing no water. Texas Ellenburger: Currently, water constitutes about 37% of the gross liquid produced. Of the 44 wells producing from this reservoir, 27 are producing water in varying ratios. Water constitutes more than 60% of the gross pro­duction of several individual wells. Although the rise in the elevation of the oil-water contact has beengenerallyuniform throughout the field, coning has occurred at the locations of several wells. Water drive is an important factor of reser­voir energy. New Mexico Ellenburger: Only one well produces water; that well produces 15 barrels of water per barrel of oil. That well is in the extreme southeast corner of the produc­tive area and is near the fault which determines the limit of the productive area. The fault may provide channels for migration of reservoir fluids. ACID TREATMENT Queen: Data are not available. LeOnard: Nearly all wells have been treated with acid. The normal procedure is to treat promising portions of the gross thickness selectively, generally with 5,000 to 10,000 gallons of acid, but as much as 20,000 gallons has been used in some such treatments. Devonian: Acid treatment has been variable largely because the degree of porosity is variable. Where the degree of porosity is high, acid treatment has not been needed. Low porosity has occasioned treatment of many wells with 4,000 to 5,000 gallons of acid. One dry hole surrounded by producers was treated with 26,000 gallons and another dry hole similarly situated was treated with 32,000 gallons, but treatment failed to cause them to produce. Texas Fusselman-Montoya and New Mexico Fusselman­Montoya: While most wells have been completed without acid treatment, small treatments ranging from 500 to 3,000 gallons have proven beneficial in some wells which showed only low productive capacity when completed naturally. Results were quite variable with the few wells where large quantities were used. Texas Ellenburger and New Mexico Ellenburger: Small treatments ranging from 500 to 3,000 gallons have proven beneficial in a few wells, but generally the wells have not been treated. The only well treated with a large quantity of acid is located near a fault and where permeability is low; the use of 19,000 gallons of acid resulted in satisfactory completion. DOSS FIELD Gaines County. Texas CHARLES S. NEEL, Jr. Geologist, Humble Oil & Refining Co., Midland, Texas June 1, 1954 LOCATION The Doss field is in southwestern Gaines County about 8 miles southwest of Seminole, county s eat. It is on the Central Basin platform near its northeast edge and is one of several fields along a regional anticlinal fold trending northwest-southeast. METHODS OF EXPLORATION LEADING TO DISCOVERY Clear Fork and Field: Seismic exploration by Humble Oil & Refining Company in 1935 and early 1936 resulted in the drilling of a dry hole (T.D.,6192) near the northern edge of the area nowproven as the productive area of the Doss field. Although this dry hole was not drilled to the depth of the shallowest zone now productive, it did furnish significant sub­surface information. Subsequent core drilling and subsurface studies resulted directly in the drilling of the discovery well. Canyon: Studies of subsurface data and seismo­graph survey by Ralph Lowe in early 1949 led to the drilling of the Canyon discovery well. DISCOVERIES Upper Clear Fork: December 12, 1945; Humble Oil & Refining Co. #1 M.S.Doss. Pumped through perforations from 6,360 to 6,380 feet and from 6,465 to 6,475 feet at daily rate of 187 barrels of 29.2° gravity oil and 47 barrels of salt water; gas-oil ratio, 144 : 1. Lower Clear Fork and Field: November 7, 1944; Humble Oil & Refining Co./iTHumble fee. Flowed through perforations from 7,030 to 7,080 feet at daily rate of 201 barrels of 33.6° gravity oil; gas­oil ratio, 517 : 1. Canyon: July 8, 1949; Ralph Lowe #1 Helen Cunningham (now, Shell Oil Co. and Ralph Lowe #1 Helen Cunningham). Flowed through perforations from 8,850 to 8,950 feet at daily rate of 528 barrels of 47° gravity oil and 143 barrels of water and water emulsion; gas-oil ratio, 30 l : 1. CLEAR FORK RESERVOIRS Commercial production occurs at several positions in the Clear Fork group. While the pro­duction is mainly from two zones, one at the top of the group and the other just below the Drinkard member, there are reservoirs at other positions in the group. ln prior publications, there has been general recognition of "Upper Clear Fork" production and "Lower Clear Fork" production. The production from the above mentioned zone at the top of the Clear Fork group has been treated as from "Upper Clear Fork", that from below the Drinkard zone as from "Lower Clear Fork", and that from reservoirs between the Drinkard and the above mentioned zone at the top of the Clear Fork group has been treated variously as from either "Upper Clear Fork" or "Lower Clear Fork~, with the result that there is considerable confusion in the records. The dolomite of the Clear Fork group is characterized by irregular porosity. Commercial production occurs only where the degree of porosity is abnormally high. The vertical distribution and the horizontal distribution of rocks of high porosity are both irregular. Presently available data indicate that there is not sufficient continuity of favorable porosity to permit free migration of reservoir fluids between the several Clear Fork productive zones. Even as to production from a corresponding stratigraphic position, it cannot be assumed that it is fr.om the same reservoir merely because it is from the same stratigraphic position. Most Clear Fork reservoirs are of only local extent although the zones in which they occur are continuous and are of the same general character throughout the region. The above described conditions have resulted in confusion in correlations and, consequently, con­fusion in the production records. Since data are not available for determining the relationships of productive rocks in all Clear Fork wells, and since the records are somewhat confused, all production from Clear Fork is reported in the following PRODUCTION HISTORY as coming from a group of reservoirs rather than to endeavor to determine quantities for each reservoir separately. Further­more, entries under other of the following headings should be considered in view of the above described conditions. SURFACE FORMATION ELEVATION OF SURFACE Recent caliche and wind-blown sand. At well locations : Highest, 3,368 ft. ; lowest, 3,334 ft. DOSS FIELD, Gaines County, Texas RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY DEPTH NEUTRON ELEVATION "'.., ~ 0: 0 .., "' "'C> z 0 0:fi w :E"' 0: :E ~ ~ RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY DEPTH NEUTRON ELEVATION "' " C> 0 z 4 ...J 6 :E"' .., .., Q. I­::> "' 0: 0 >­.., "' "'"'"' z 0 ;: "'<( .., :E"' "':E 0 .., ... 2i: RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY NEUTRON ELEVATIONDEPTH ...J Q 0 QUATERNAR Y 3371 2375 2400 996 971 .., Q. ::> ...J ;5 "'.., 0: 0 z ­0: <( ;: 0:.., I­ 100 200 3271 3171 "' z <( "' 0 -2429 -2529 300 3071 "' ...J .., 2700 671 "' z <( 400 2971 l--+-+-+--i=2800~-c-~~-t;.j;..;,.,q.-t-~~~ z 6100 TANS ILL " 500 2871 6200 TYPICAL SECTION OF ROCKS PENETRATED 6300 3000 600 2771 6400 3100 700 2671 '-' 800 2571 3200 171 0: .., Q. "' "' 900 2471 Q. :nqo 71 ::> '-' 1000 2371 3400 -29 0 .., 0: 0 > 1100 2271 0 3500 -129 "' "' 0: 0 .., 1200 2171 3600 -2 29 :i: > 1300 2071 3700 -329 z 0 :i: w '-' 1400 1971 3800 -429 .., ::> ;. 1500 187 1 - ­ ­ z ~Dolomlllo r+•; •jsoll ~limestone + ++ ~ ~shaly z '-' "'" sioo -2329 5 Q. • Oil o Oil show .::(/..Gos show production DOSS FIELD, Games County, Texas OLDF.ST STRATIGRAPIDC HORIZON PENETRATED The oldest horizon penetrated is in the ·Ellen­burger group 110 feet below its top. This penetration was in the Canyon discovery well at its total depth of 11,881 feet. NATURE OF TRAPS Clear Fork reservoirs: Although the known accumulations are along the axis of an anticlinal fold, it appears that the trapping is due largely to variation in degree of porosity and permeability in sloping reservoir rocks. (*) Canyon: Since the only productive wells are at the crest of a dome, it appears that domal folding is the primary trap-forming factor. However, varia­tion in degree of porosity has definitely limited the productive area and has probably served as a minor factor in forming the trap. LITHOLOGY OF RESERVOIR ROCKS Clear Fork: (*) The reservoir rocks in the Clear Fork group are all of the same general character; mainly cream to tan, finely crystalline dolomite. A few thin layers of gray silty dolomite are inter­bedded with the crystalline dolomite and, limited mainly to the upper 500 feet of the Clear Fork group, there are a few thin beds of dark gray to black lignitic shale. Minor amounts of chert and anhydrite are interspersed in the dolomite. The Drinkard member ("Tubb Sand") is less sandy here than it is generally on the Central Basin platform; here it is composed mostly of dark silty dolomite. The porosity of the reservoir rocks is of the small vug type. Favorable porosity is quite general in the upper 100 feet of the Clear Fork group and in a similar zone immediately below the Drinkard member; at other positions, rocks with favorable porosity are of only local extent and are thin. Canyon: The reservoir rock in the Canyon group is white to light tan, finely crystalline and chalky limestone with minor amounts of white crystalline dolomite. Thin beds of green shale are interbedded with the limestone. The favorable porosity is of the vug type and is irregularly distributed and has an aggregate thickness of no more than 12 feet at any one of the locations where total thickness has been determined. THICKNESSES OF RESERVOIR ROCKS Feet From top to bottom: Min. Max. Avg. Upper Clear Fork (*) 185 285 200 Lower Clear Fork (*) 315 400 365 Canyon 80 124 110 Net productive: Because of the irregularity of porosity in each reservoir rock, it is not practical to endeavor to determine net thickness. PRODUCTIVE AREAS Acres, approx. Clear Fork (*) 2,800 Canyon 400 Doss field 2,800 CONTINUITY OF RESERVOIR ROCKS Clear Fork: (*) The Clear Fork group is continuous throughout most of West Texas; however, the individual reservoirs are each of only local extent. Canyon: The reservoir rock in the Canyon group is continuous throughout the area of the field and throughout most of western Gaines County. Due mainly to erosion but partly also to lack of deposition, there are no rocks of corresponding age over most of the Central Basin platform nor in the Midland basin. However, a long, narrow tongue of Canyon limestone extends from western Gaines County along the eastern edge of the Central Basin platform as far south as northern Crane County. Although this limestone includes the stratigraphic equivalent of the reservoir rock in the Doss field, it is unlikely that porosity favorable for migration of reservoir fluids is continuous far beyond the proved extent of the field. ACID TREATMENT Upper Clear Fork: At time of completion, each well was given a single-stage treatment with 1,000 to 5,000 gallons of acid. Lower Clear Fork: With only one exception, each well was treated with acid at time of completion. Thequantityof acidrangedfrom500to 15,000 gallons. The larger quantities were used in many wells in multi-stage treatments. Canyon: With only one exception, each well was treated with acid at time of completion. The quantity of acid ranged from 250 to 12,000 gallons. The larger quantities were used generally in multi­stage treatments. *See entry under the general heading CLEAR FORK RESERVOIRS on first page of this paper. DOSS FIELD, Gaines County, Texas CONTOURS ON TOP OF CLEAR FORK () 0) "' "' ' BLOCK AX N EXPLANATION Contour on indicated ----292o---horizon • Oil well, producing from Clear Fork • ~ Oil well, producing from Canyon Oil well, producing from Cleor Fork, T abandoned in Canyon • Canyon tested, nonproductive ! """''"""""···"""'"'' Boundary of Canyon ~productive area ;:f Dry hole • "'C] Discovery SCA LE 0 4 6 THOUSANO F'EET CONTOURS ON TOP OF CANYON BLOCK A X ELEVATION AND RELIEF OF PRODUCTIVE ZONES 6 Upper Lower Clear Fork Clear Fork Canyon Elev. of highest kno wn oil, ft. -2,874 -3, 390 -5, 487 Elev. of lowest kno wn oil, ft. -3, 240 -3, 790 -5,570 Difference, fe et 366 400 83 As to reservoirs in the Clear F ork group, it appears unlikely that the above differences represent reliefs of oil colunms. In each case, the highest oil and the lowest oil are probably in different r e servoirs . (*) CHARACTER OF OU. and RESERVOIR DATA Upper Lower Clear Fork Clear Fork Canyon Original bottom hole pressure, psi. 2,950 2,625 3,500 Elevation of pressure datum, feet -3, 000 -3, 700 -5,500 Gravity, A. P. I. @ 60'F. 33.2 38.6 46.0 Saturation pressure, psi. 1,540 Solution gas -oil ratio, cf/bbl. 695 CHARACTER OF GAS Upper Lower Clear F ork Clear Fork Canyon Sulphur indication Sour Sour Sweet Orsat analysis of Lower Clear Fork sample Vol.% Hydrocarbons or inert ~ Hydrogen sulphide 1.8 Carbon dioxide 1.8 *See entry under the general heading CLEAR FORK RESERVOIRS on first page of this paper. DOSS FIELD , Gaines County, Texas PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION WATER PRODUCTION at end of year (barrels} (Mcf} § (barrels} §§ Year Flowing Pumping Yearly Cumulative Yearly Cumulative Yearly Cumulative Field totals 1944 1 0 1, 408 1,408 8xx 8xx 3xx 3xx 1945 3 46, 186 47,594 25,xxx 26,xxx 10,xxx 10,xxx 1946 5 4 126,442 174,0 36 72,xxx 98,xxx 8,xxx 18,xxx 1947 14 12 273,940 447,976 207,xxx 304,xxx 8,xxx 26,xxx 1948 13 24 496,954 944,930 231,xxx 535,xxx 43,xxx 69,xxx 1949 8 37 439,398 1, 384,328 216,xxx 751,xxx 95,xxx 164,xxx 1950 6 44 580,409 1,964, 737 211,xxx 962,xxx 74,xxx 238,xxx 1951 3 55 728,664 2, 69 3, 401 265,xxx 1, 227,xxx 110,xxx 349,xxx 1952 56 660,528 3, 353,929 292,xxx 1, 520,xxx 246,xxx 595,xxx 1953 0 58 550,449 3,904, 378 263,xxx 1, 782,xxx 12x,xxx 715,xxx 1954 ** 0 60 409,865 4,314,243 1955 ** 1 62 470,382 4, 784, 625 Clear Fork (*} 1944 0 1,408 1, 408 8xx 8xx 3xx 3xx 1945 3 46, 186 47,594 25,xxx 26,xxx 10,xxx 10,xxx 1946 5 4 126,442 174,036 72,xxx 98,xxx 8,xxx 18,xxx 1947 14 12 273,940 447,976 20 7,xxx 304,xxx 8,xxx 26,xxx 1948 13 24 496,954 944,930 231,xxx 535,xxx 43,xxx 69,xxx 1949 6 36 376,797 1, 32 1, 727 200,xxx 735,xxx 95,xxx 164,xxx 1950 42 360,817 1, 682, 544 156,xxx 89 1, xxx 74,xxx 238,xxx 1951 47 434,555 2, 117,099 192,xxx 1,083,xxx 98,xxx 336,xxx 1952 1 46 401,286 2,518,385 227,xxx 1, 310,xxx 85,xxx 422,xxx 1953 0 48 371,699 2,890,084 227,xxx 1,537,xxx 53,xxx 475,xxx 1954 ** 0 50 318,873 3,208,957 1955 ** 52 388,805 3,597,762 Upper Clear Fork (*} 1946 0 9,670 9,670 3,xxx 3,xxx 4xx 4xx 1947 0 11, 606 21,276 4,xxx 7,xxx 5xx l,Oxx • 1948 0 10,697 31,973 5,xxx 12,xxx 7xx 1, 7xx 1949 0 9,656 41,629 4,xxx 16,xxx 6xx 2,3xx 1950 0 2 14, 724 56, 353 6,xxx 21,xxx 2,xxx 4,xxx 1951 4 32, 481 88,834 9,xxx 30,xxx 3,xxx 7,xxx Lower Clear Fork (*} 1944 1 0 1,408 1,408 8xx 8xx 3xx 3xx 1945 3 46, 186 47,594 25,xxx 26,xxx 10,xxx 10,xxx 1946 5 3 116, 772 164,366 69,xxx 94,xxx 8,xxx 18,xxx 1947 14 11 262,334 426, 700 203,xxx 297,xxx 7,xxx 25,xxx 1948 13 23 486,257 912,957 226,xxx 523,xxx 42,xxx 67,xxx 1949 6 35 367,141 1,280,098 196,xxx 720,xxx 94,xxx 161,xxx 1950 40 346,093 1,626,191 151,xxx 870,xxx 72,xxx 234,xxx 1951 0 43 402,074 2, 028, 265 183,xxx 1,053,xxx 96,xxx 329,xxx Canyon 1949 2 1 62,601 62,601 16,xxx 16,xxx 0 0 1950 5 2 219,592 282,193 55,xxx 71,xxx 3xx 3xx 1951 2 8 294, 109 576, 302 74,xxx 144,xxx 12,xxx 12,xxx 1952 0 10 259,242 835, 544 65,xxx 209,xxx 161,xxx 173,xxx 1953 0 10 178, 750 l, 014, 294 36,xxx 245,xxx 7x,xxx 24x,xxx 10 90,992 1, 105,286 1955 ** 0 10 81,577 1954 ** 0 1, 186,863 § Quantities of gas have been estimated on the basis of gas-oil ratios. § § Quantities of water have been estimated on basis of oil-water ratios. See entry under the heading CLEAR FORK RESERVOIRS on first page of thi s paper. * Data for 1954 and 1955 added by amendment. ''* DUNN FIELD Mitchell County, Texas MARION R. STEPHENSON Geologist, American Trading & Production Corp. , Midland, Texas January 25, 1956 LOCATION The Dunn field {one well, abandoned) is in the northwest corner of Mitchell County within one mile of' the common corner of Mitchell, Scurry, Borden and Howard Counties. METHODS OF EXPLORATION LEADING TO DISCOVERY Studies of seismic and subsurface geological data led to the discovery of this field. DISCOVERY Canyon: October 11, 1949; Standard Oil Co. of Texas #1 B. F. Dunn. Flowed through i-inch choke at daily rate of 499 barrels of 47° gravity oil and 38 barrels of basic sediment and water from depth of 7,550-7,578 feet. Gas-oil ratio, 1,281: I. Total depth, 8,325 feet; plugged back to 7,587 feet. This well, the only well in the field, was abandoned on December 17, 1952. ELEVATION OF SURFACE Surface: About2,239ft. {derrick floor: 2,249 ft.). SURFACE FORMATION Chinle formation of the Dockum group of the Triassic system. OLDEST STRATIGRAPIDC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 40 feet below its eroded top. NATURE OF TRAP Canyon: Domal upper limit of reef-typeporosity. PRODUCTIVE AREA Canyon and Field: 40 acres TIDCKNESS OF RESERVOm ROCK Canyon: From top to bottom of productive zone, 3 7 feet. UTHOLOGY OF RESERVOm ROCK Canyon: Reef limestone; white to tan, fossil­iferous, coarsely crystalline. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Canyon: Feet Elevation of top of oil -5,301 Elevation of bottom of oil -5,338 Relief 37 The above figures represent conditions in the one well at time of discovery. CHARACTER OF OD. Canyon: Gravity, A. P. I. @ 60° F., 47° Sulphur, 0.1% Gas-oil ratio at time of discovery, 1,281: 1 CHARACTER OF GAS Canyon: No analysis is available; probably none was ever made. Gas was not produced in commer­cial quantity. At the time of the initial potential test, the gas-oil ratio was l,Z80: 1. PRODUCTION HISTORY WELLS PRODUCTION (barrels) PRODUCING OIL WATER Pumping Yearly Cum. Yearly 1949 2,552 2, 552 1,629 1950 1 900 3,452 6,002 1951 Shut-in 0 3,452 0 1952 Abnd. 12/17/52 56 3,508 ? DUNN FIELD, Mitchell County, Texas SECTION OF ROCKS PENETRATED 0 z ELECTRIC CURVES ELECTR IC CURV ES AND ~ ~ Q_ ~ AND .... ::> ~ (J) a: 0 a: LITHOLOGY LITHOLOGY >-w a: 0 Cl> CJ) e> lL DEPTH E LEVATION DEPTH U> w 0: 0 ..z w a. ::> ..z -' .. ..0 ::> '-" '3 w '-" ~ z .. U> 0: "' ~ ..z ..0: ~ 0: w w -' a. u .. 0 0: z 0 w -' .. .... r u ~Limestone t==== j Shole l==~j Red shole 4650 -24 01 4700 -24 51 4800 -2551 4900 -2651 z l--+-t-+-~~---,,,;--tr:!-=T::4-"'=:::-~~~~~ .. i 0: w a. ..z w 0 ..z z .. > -' ~ z z w a. 9;;::2+-----J N 89 -·\ IOIO un " " P Dry hole 1{,o EXPLANATION nu p " tH7 t/)}:\j Sandstone ~Dolomite 66 lld~ 666 Chert ti~ Sandy shole 0 0 0 0 0 0 • Oil productio n If±tilShely li~stone EAST POLAR FIELD Kent County, Texas JAMES L. ELKIN, Jr. Geologist, Humble Oil & Refining Co., Midland, Texas March 1, 1956 LOCATION The East Polar field is in southwestern Kent County about 14 miles southwest of the town of Clairemont. It is near the western edge of the Eastern shelf. Its name was derived from the village of Polar, located 3 miles to the west. NEAR-BY NONCOMMERCIAL PROSPECT Drilling & Exploration Co. #1 Wilson Connell, located near the northeast corner of Sec. 19, Blk. 5, was completed March 15, 1950 for production from the San Andres formation and was recognized as the discovery well of a new field called the Connell field. It had been drilled to the total depth of 7, 9 31 feet, where it was in Ellenburger, and was plugged back for production from 2, 340 to 2, 350 feet in the San Andres formation. It pumped at the daily rate of 12 barrels of 33° gravity oil and 68 barrels of water. The northeast diagonal offset was completed April 4, 1950 for production from the San Andres formation and the two wells produced a total of 3,351 barrels of oil before abandonment; 2, 702 barrels during 1950 and 649 barrels during 1951. METHODS OF EXPLORATION LEADING TO DISCOVERY Surface mapping indicated a structural high in the area. Subsurface studies by Kewanee Oil Company prompted it to purchase leases and to drill. DISCOVERY Canyon-Strawn: June 26, 1950; Kewanee Oil Co. #C-1 Wil (fee, Wilson Connell). Flowed 328 barrels of 38.2° gravity oil per day through perforations from 6,853 to 6,870 feet; gas-oil ratio, 394: 1. This well was completed in Canyon limestone. Since its com­pletion, there have been six other productive zones found within the Canyon and Strawn series. The Railroad Commission treats all of these zones as within one reservoir. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is 200 feet below the top of the Ellenburger group. This penetration was in Drilling & Exploration _Co. #D-1 Wilson Connell, a dry hole located near the southwest corner of Sec. 5, Blk. 5, where the total depthof 8,010 is indicated on the accompanying map. NATURE OF TRAP Canyon-Strawn: The trap is formed by anticlinal folding of the reservoir rock. PRODUCTIVE AREA Canyon-Strawn and Field: Development to date indicates a productive ~of approximately 480 acres. Further development may occasion some addition to this estimate. Close estimation is pre­cluded by irregular porosity and permeability. THICKNESSES OF RESERVOIR ROCK Feet Minimum Maximum Average Canyon-Strawn 4 66 24 LITHOLOGY OF RESERVOIR ROCK Canyon-Strawn: The productive rock is fossil­iferous bedded light colored limestone distributed in several layers and characterized by irregular perm­eability. The effective porosity consists primarily of numerous small vugs. CONTINUITY OF RESERVOIR ROCK Canyon-Strawn: The reservoir rock is continuous throughout the area of the field; however, porosity and permeability are ve-ry irregular. COMPLETION TREATMENT Canyon-Strawn: Nine of the 12 producing wells .vere acidized; 3 were completed without treatment of the reservoir rock. Quantities of acid ranged from 500 to 10,000 gallons; average, 2,375 gallons. The mostrecentlycompleted well was given a 3,000­gallon hydraulic fracture treatment. SELECTED REFERENCE. Myers, D. A., Stafford, P. T., and Burnside, R. J. (1956) Geology of the Late Paleozoic Horseshoe Atoll in West Texas: Bureau of Economic Geol., Univ. Texas, Publication 5607, 113pp., 18 plates. EAST POLAR FIELD, Kent County, Texas TYPICAL SECTION OF ROCKS PENETRATED SURFACE FORMATION: Undifferentiated Triassic r ed shales and sandstone s . ELEVATION OF SURFACE: Derrick floor elev.: Highest, 2,351 ft.; lowest, 2,188 It. z ELECTRIC e RADIOACTIVITY CURVES ~ ~ !!; ~ LITHOLOGY (ii o: o: GA!~AS.~AY RESISTIVITY 0 >­ LLI a:: 0 (I) V> C> U.. DEPTH ELEVATION .. 2188 TRIASSIC 100 2088 .. 0 0 0 < 200 1988 r ..J" 0 ..,,, 300 1888 TANS ILL 1788 500 1688 ~ 600 1588 "'> a: 700 1488 "' z > "' ,,, "'"' 1388 :I: ~ 800 "' ... !-+----~......... '--+--+------I r 900 1288 ;t <; : z ~ i~ "' "' => 1000 1188 0 _) ;: ..~­ 1;-.,oi?'-+---+--?--1000 ~ 1; >­ 988 ~ 1200 ___l_ ii 130" .{ ?--l==t--?--ooo ~ 3 .. 0.. 1400 788 ::> "' 1500 ,.. 1600 ,,, a:: 1700 488 "' 0 z 0: .. "' z > ­ w (I) (I) DEPTH ELEVATION Q ~ "o 5200 -3012 5300 -31 12 5400 -3212 5500 -3312 5600 -3412 5700 -3512 0800 -3612 '900 -3712 6000 -3812 6100 -3912 " 0 (/) 6200 -4012 ;:; 6300 -4112 6400 -4212 6500 ....-_-_ -4312 -4412 -4512 z 0 >­ z 6800 -4612 .. 0 6900 ~ . I ; 7100 I -1 I: 4912 I I ' z I: ~ 7200 I -5012 • ... ,,, 0: I:1 I: 7300 -:5112 I:I -5212 -5249 EXPLANATION ~Limestone [}<~Wi}~{J Sandstone Sandstone ond shale ~Dolomite ~Shale ~ Chert ~Anhydritic ~dolomite ~Calcareous ~shale • Oil production EAST POLAR FIELD, Kent County, Texas 26 21 5 12 \ .. 15 6 \ Jf 6884 dlo I ~ S> 0 'b ~ 0 I ~ 0 0 "' 1316 5 H. a G.N. R.R. Co. H. a G.N. R.R. Co. BLOCK 5 BLOCK 4 Jf 7990 00 .,.~ I 24 17 14 .,o -46~0 ,,r." N • Jf 68aot::JJ0 7 165 POLAR 00 iscovtRy p ,,r." • • 7370 7401 7575 23 18 15 18 .,o , r.'" .,o ,,.ro / Jf Jf 2389 2271 .,o ,,r.'o 22 16 17 00r.'O Jf 2352 21 ::0 ... H. a TC. R.R. Co. BLOCK 97 I I EXPLANATION 4650-----Contour on top of Pennsylvanian limestone Jf Dry hole SCALE • Oil well, producing from Strawn-Canyon 74~3 Total depth + Abandoned oil well, formerly productive from Strawn-Canyon THOUSAND FEET I• Abandoned oil well, formerly prod uctive from Son Andres •\=:JIDiscovery G ELEVATION AND RELIEF OF PRODUCTIVE ZONE PRODUCTION HISTORY Canyon-Strawn: Feet Canyon-Strawn: Highest proved elevation of oil -4,613 WELLS PRODUCING OIL PRODUCTION WATER PRODUCTION Lowest proved elevation of oil -5,056 at end of year (barrels) (barrels) The difference of 443 feet does not Flow. Artif. Curnulative Yearly Cumulative represent a continuous oil column. 1950 2 24,418 24,418 0 0 1951 3 6 116,093 140,511 61,xxx 61,xxx CHARACTER OF OIL 1952 2 10 147,070 287, 581 140,xxx 20 1,xxx Canyon-Strawn: 1953 2 10 115,325 402, 906 191,xxx 392,xxx Gravity, A. P. I. @60°F.: 35-39° Base: Paraffin Odor: Sweet 1954 11 78, 704 481, 610 173,xxx 565,xxx Color: Yellowish green 1955 11 66, 730 548, 340 195,xxx 760,xxx ELKHORN FIELD Crockett County, Texas JACKSON B . BROWN Assistant to the Regional Geologist Continental Oil Company, Fort Worth, Texas June 23, 1955 LOCATION THICKNESSES OF RESERVOIR ROCK The Elkhorn field is in north-central Crockett County about 15 miles northwest of Ozona, county seat. It is on the Ozona platform, a dominant structural feature in the southern portion of the Permian basin. METHODS OF EXPLORATION LEADING TO DISCOVERY The discovery of this field was the result of studies of surface geology and subsurface geology, including data afforded by refraction seismograph. An inducement for intensive exploration was ownership of leases covering a large area. DISCOVERY Ellenburger: June 28, 1951; Continental Oil Co. Ill J .M.Shannon "A''. Initial potential capacity was at rate of 2,580 barrels of oil per day. PRODUCTIVE AREA Ellenburger and Field: Development to date proves about 2,700 acres as productive and indicates that there may be some additional productive area northward. Except at the north end of the field, the extent of the productive area is quite definitely defined. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in the Ellenburger group. The maximum known penetra­tion of Ellenburger is 499 feet below its eroded top. This penetration was at the total depth of 1 ,485 feet in Continental Oil Co. #12 J.M.Shannon "A", located as indicated by entry of "MAXIMUM PENETRATION" on the accompanying map. Since the top of the Ellenburger is an erosion surface and since exact stratigraphic positions within the Ellenburger have not been determined, it is possible that some lesser penetration of Ellenburger actually reached an older horizon than was penetrated in the above mentioned well. NATURE OF TRAP and STRUCTURE Ellenburger: Anticlinal folding appears to be the primary trap-forming factor. The trap is due in part also to truncation and sealing by overlying relatively impervious shales and also in part to the down-to-the-east fault on the east limb of the anticline. While the contours on the accompanying map portray an erosion surface, they serve also to indicate the general structural conditions. There is an anticlinal fold with the axis essentially at the location of the erosional ridge. The eastward and westward dips are slightly greater than the corresponding slopes of the contoured surface. The displace­ment of beds cut by the fault is not definitely determinable but appears to be in excess of 1,400 feet. Ellenburger: Max. Avg. From top to bottom, feet 455 Net productive thickness cannot be satisfactorily esti­mated since the reservoir rock consists of highly fractured dolomite. LITHOLOGY OF RESERVOIR ROCK Ellenburger : Dolomite; gray to tan, generally finely crystalline, contains numerous vugs and cavities and is highly fractured throughout. CONTINUITY OF RESERVOIR ROCK Ellenburger: The reservoir rock is continuous through­out the productive area except that the upper portion has been removed by erosional truncation along the apex of the anticline. The eastward continuity is interrupted by a down-to-the-east fault with throw of several hundred feet. CHARACTER OF GAS Ellenburger: There was no free gas cap at time of discovery nor has there been any of importance resulting from operations. The gas production is incidental to oil production as gas comes out of solution with decline in pressure. No analysis of the gas is readily available. Such gas as is produced is processed at the Todd Unit gasoline plant operated by the Continental Oil Company. WATER PRODUCTION Ellenburger : Wells located structurally low are now producing considerable amounts of water. A uniform rise in water level is indicated. The average chloride content of the water amounts to 28,971 parts per million. RESERVOIR ENERGY Ellenburger: Reservoir energy is due to an effective water drive in combination with energy afforded by expan­sion of gas coming out of solution with decline in pressure. ACID TREATMENT Ellenburger : Practically every well has been treated with 500 to 1,000 gallons of acid at time of completion. ELK H 0 RN FIELD, Crockett County, Texas TYPICAL SECT ION OF ROCKS PENETRATED ELECTRIC GAMMA RAY AHO S. P. 100 0: :::> .., zoo 0 " u u u z ---" .., 0 0: u 4 00 soo TRINITY 600 700 8 00 " V'l 900 .., >-­" >­ 0 z ::c: w 1100 > ~ 1200 1300 0 1400 z " " 0 "0: :::> " " :::> 1500 0:" >­ " 1600 1700 1800 0: z 1900 " ex 2000 ZIOO 2200 0 0: 2:300 "z 8 .J 2350 a. RADIOACTIVITY CURVE S L ITHOLOG Y RESISTIVITY n. zz~ 2697 Z587 2487 2387 2287 21 8 7 2087 1887 1787 1687 1587 148 7 1387 1287 118 7 1087 '" 181 687 487 "' '" ~ ~ V'l EXPLANATION ~Limestone mAnhydrite ff{::\{]Sandstone Chert D Rock indicated, ~Sandstone, onhydritic ••d Rock indicated, r::~1 Sandstone, calcareous D [][] gray or black Rock indicated, ~Shale green D Ll Rock indicated, Shale, calcareous brown ~Dolomite Oil production z ~ ~ ~ ~ V) ~ ">­z 0 0: " " 0 "' ELECTRIC a. RADIOACTIVITY CURVES LITHOLOGY GA"~:·s.~~y RESISTIVITY 4 1 50 4200 -1511 4300 -16 13 4400 -171 1 4500 -111 3 4600 -ltll 4700 -ZOil 4100 -Z ii l 4900 5000 -Z l ll 5 100 -Z4 1 l 5200 -Z5 1l 5300 5 4 00 -Z71l 5500 -Ziil 5600 -Z91l 5700 -10 13 5100 -3 11 3 5900 -Hll 6 000 -ll ll 6 100 -3 4 13 &ZOO -35 13 6300 -36 13 6400 -H l l 6500 -3813• ELKHORN FIELD, Crockett County, Texas TYPICAL SECTION 25 24 OF ROCKS PENETRATED ELEVATION OF SURFACE BLOCK Ji TDllTI G.C. a. S.F. BLOCK At well locations: Highest, Z,706 feet; lowest, 2,594 feet. SURFACE FORMATION Undifferentiated limestones of the Fredericksburg g roup. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Ellenburger : Feet Elevation of highest known oil -4,330 Elevation of oil-water contact at discovery date -4,785 Relief 455 RESERVOIR TEMPERATURE AND PRESSURE and Oll. SAMPLE DATA Ellenburger: Original reservoir temperature, F. , Original reservoir pr essure,· psi,, Gravity of oil. A.P.1.@ 60° F., Bubble point, psi., Solution gas-oil ratio, cf/bbl., Volume factor, surface: reservoir The above data were determined samples. 28 27 26 -4H7 Ji . TD1"1 UNIVERSITY LANDS . -001 20 N -·- Ji 19 PRODUCTION HISTORY GAS PRODUCTION ----44,0--Contour on top of eroded Ellenbur9er group at end of year (barrels) (Mc!) Year Cumulative WELLS PRODUCING OIL PRODUCTION -,·~Elevation of top of eroded E llenburoer ,',',, oroup Flow. Pump. Total Yearly Cumulative ~ Total depth ' Ellenburger and Field total Oil well . P Dry hol e 25 ,987 25.987 SCALE 1951 4 0 4 49 ,389 49 ,389 572 ,558 1953 989 ,922 I ,562 ,480 1952 26 28 861,164 910,553 546 ,571 H~OUSANO FEET 37 II 48 1,550,043 2 ,460 ,596 1954 12 39 51 I ,7 35 ,746 4 .196 ,342 I, I02,199 2 ,664,679 179. 3,140 37•_38• 1,714 635 1.4119 from bottom-hole EXPLANATION EMBAR FIELD Andrews County, Texas EDWIN VAN DEN BARK District Geologist, Phillips Petroleum Company, Midland, Texas January 1, 1954 LOCATION The Embar field is in Blocks 10 and 11, Univer­sity Land, in south central Andrews County. It is 18 miles southwest of the town of Andrews, county seat. METHODS OF EXPLORATION LEADING TO DISCOVERY The methods of exploration which led directly to discovery were core drilling and gravity sur­veying. After the completion of a few wells, a reflection seismograph survey was made for the purpose of providing additional data for detailed mapping. The exploration which led to this discovery was of special importance because this field was the first to produce from the Ordovician north of Crane County. It was the fir st major Ellenburger field on the Central Basin platform. DISCOVERIES Lower Clear Fork: November 4, 1942; Phillips Petroleum Co. #22 University-Andrews. This well had been drilled to a total depth of 6,325 feet, where 5i-inch casing was set. Cement was drilled out to 6 ,307 feet and the casing was perforated with 160 shots fr om 6 ,240 feet to 6 ,280 feet. Flowed at rate of 259 barrels of -42.3° gravity oil per day through 1/8-inch choke. GOR, 544: 1. Ellenburger and Field: May 14, 1942; Phillips Petroleum Co. #2 University-Andrews. Ellenburger was encountered at depth of 7 ,746 {-4,500) feet and the well was drilled to total depth of 7 ,855 feet. Flowed at rate of 1,872 barrels of 44.5 ° gravity oil per day through 2-inch tubing with i-inch choke. GOR, 672:1. OLDEST HORIZON PENETRATED The oldest horizon penetrated is in pre-Cambrian granite. Pre-Cambrian granite was penetrated in six wells at the crest of the structure. ELEVATION OF SURFACE At well locations: Highest, 3,307 ft.; lowest, 3,228 ft. SURFACE FORMATIONS Pleistocene windblown sand 0 to 20 feet thick overlying Cretaceous sandstone. NATURE OF TRAPS Lower Clear Fork: While the trap appears to be due primarily to domal folding, the commercially productive area does not extend over the apex of the convex fold. Low porosity and permeability certainly determine locally the boundary of the commercially productive area. Probably the trapping at the particular location of the commercial accumulation is due in part to updip and lateral termination of a degree of porosity and permeability adequate for migration of fluids. Ellenburger: A combination of an anticlinal fold with reservoir terminated locally by two normal faults and also with reservoir terminated around the structural apex by erosional truncation; the truncated surface is overlain by impervious beds of Wolfcamp age. THICKNESSES OF RESERVOm ROCKS Lower Clear Fork: From top to bottom of productive zone is generally about 110 feet. Ellenburger: The thickness of the Ellenburger reservoir rock is quite variable. Throughout an area of about 300 acres at the apex of the structure, there is no Ellenburger; away from that area, the Ellenburger thickens rapidly in all directions. The maximum measured thickness is 710 feet. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Lower Clear Fork Ellenburger No free gas Elevation of top of oil, ft. -2 ,700 -4,440 Elevation of bottom of oil, ft. -3,070 -4,820 Relief, feet 370 The above data represent conditions at respective discovery dates. EMBAR FIELD , Andrews County, Texas TYPICAL SECTION OF ROCKS PENETRATED *The section indicated as Upper Clear Fork is com­monly called Glorieta. In the opinion of the writer, proper usage of the name Glorieta restricts it to the stratigraphic equivalent of the basal portion of the immediately overlying San Andres formatiof\ . **The section indicated as Middle Clear Fork is commonly called Upper Clear Fork. EXPLANATION b}i}}.t\\j Sonds1one t-.:{:!3Solt ~======i Shale ~Limestone ~Dolomite l!A!lchert D Rock indicated,,.dD Rock indicated, green E]Anhydrite [filRock in dicated, sholy • Oil production 0 Oil show ~ Gos show EM BAR FIELD , Andrews County, Texas MASCHO FIELD BLOCK 11 FIELD EMBAR FIELD -LOY!'er Clear Fork -Ellenburoer lttJJ EMMA FIELD ~GOLDSMITH FIELD • ANDECTOR FIELD I• Completed in Lower Gleor Fork ECTOR COUNTY • t Completed in Ellenbur9er Jfo11u ---2600--Contour on top of Drinkard (Tubb) member -zno Elevation of top of Drinkard (Tubb) member • Total depth Boundary of Lower Clear Fork productive area Oil we ll + Abandoned oil well ff Ory hole • ~Discovery ____..... I• Completed in lower Clear Fork • I Completed in Ellenbu rger ECTOR COUNTY EM BAR FIELD , Andrews County, Texas EM BAR FIELD, Andrews County, Texas UTHOLOGY OF RESERVOIR ROCKS Lower Clear Fork: Tan to buff, fine-crystalline dolomite with beds of tan limestone toward the base. Although there is some pinpoint intergranular porosity, the interstitial.space is dominantly due to solution cavities and channels. Ellenburger: Tan, fine-to medium-crystalline dolomite with some persistent beds of white chert. The interstitial space is due to intergranular porosity along with a large number of solution cavities, channels and fractures. CONTINUITY OF RESERVOIR ROCKS Lower Clear Fork: This reservoir rock is continuous throughout the area of the field and is correlative with productive reservoirs in a large portion of the Permian basin in West Texas and New Mexico. In Texas it is sometimes referred to as "the Fullerton pay", while inNewMexico it is called "the Drinkard zone". It is productive in the nearby Goldsmith, TXL and Fullerton fields. Ellenburger: Within the area of the field, the total thickness of this reservoir rock is present in only a narrow band, which almost surrounds the apex of the Embar structure. The Ellenburger was deposited on an eroded surface, with that surface sufficiently high at the apex of the structure that only the uppermost portion of the Ellenburger was deposited there. Post-Simpson erosion removed such Ellenburger as was at the apex and beveled the Ellenburger and overlying Simpson in the surrounding area. The halo of productive Ellenburger is incom­plete in that, at the east end, the Ellenburger is non-productive on the downthrown side of the fault. The Ellenburger occurs throughout most of the Permian basin and is productive in many fields, including the nearby Andector, Martin, TXL, Key­stone and Dollarhide fields. PRODUCTIVE AREAS Acres Lower Clear Fork 1,400 Ellenburger 1,800 Embar field 2,900 RESERVOIR ENERGY CHARACTER OF OIL Lower Clear Fork Ellenburger Gravity, A.P.I.@ 60° F. 42.0° 43.9° Sulphur 0.65% .28% Color Dk. green Dk. green Saybolt viscosity@ 100° F. 39 sec. 36 sec. Initial boiling point 97. 83° Conradson carbon residue test of still residue 3.88% 3.32% For analyses of Ellenburger oil see: U.S. Bureau of Mines Lab. ref. No. 43064 46116 Analyses of Crude Oils from Some West Texas Fields, R. I. 3744 (1944) Page 9 Analyses of Crude Oils from 283 Important Oil Fields of the United States, R. I. 4289 (1948) Item 201 Analyses of Crude Oils from Some West Texas Fields, R. I. 4959 (1953) Item 23 WATER PRODUCTION Lower Clear Fork: Very little water has ever been produced from this reservoir. The rate of water production by any well has remained about constant since the completion of the well. Ellenburger: Normal water encroachment has occurred in this reservoir. Until early in 1951, most of the Ellenburger wells were making water. Recompletions during 1951 have eliminated most of the water production. ACID TREATMENT Lower Clear Fork: At completion, each well has been treated with 3 ,000 to 15 ,000 gallons of acid. Ellenburger: The wells completed in the Ellenburger required little or no acid to bring them on production. Usually they were treated with 500 to 2 ,000 gallons of acid. Lower Clear Fork: Solution gas drive. SELECTED REFERENCE Ellenburger: Water drive. Normal water en­croachment has necessitated recompletions in Cole, Taylor (1943) Embar field, Andrews County, several wells in the upper part of the productive Texas: Arner. Assoc. Petr. Geo!., Bull., vol. zone. 27' p. 538. EM BAR FIELD, Andrews County, Texas PRODUCTION HISTORY Year WELLS PRODUCING at end of year Flowing Pumping OIL PRODUCTION (barrels) Yearly Cumulative GAS PRODUCTION (Mcf @ 14.65 psi.) Yearly Cumulative Field totals 1942 1943 12 30 0 0 115,494 648,627 115,494 764,121 80,301 646 ,265 80,301 726 ,566 1944 1945 34 35 0 3 1,255 ,052 1,484,049 2,019,173 3 ,503 ,222 1,030 ,105 1,271,959 1,756 ,671 3 ,028,630 1946 1947 36 35 2 3 1,597,736 1,807 ,050 5,100,958 6,908 ,008 1,307 ,485 1,364,414 est. 4,336,115 5,700,529 1948 1949 34 34 3 1,782,429 1,074,208 8,690,437 9 ,764,645 1 ,330 ,000 est. 994,474 7 ,030 ,529 8,025,003 1950 1951 34 35 1,006 ,907 1 ,246 ,824 10,771,552 12,018,376 836,675 863,716 8,861,678 9 ,725 ,394 1952 1953 34 33 2 3 1,061,382 1 ,060 ,303 13,079,758 14'140 ,061 810,xxx 892 ,xxx 10 ,5 35 ,xxx 11,427 ,xxx Lower Clear Fork 1942 7 1943 12 0 0 14,040 281,348 14,040 295,388 21 ,450 429 ,569 21,450 451,019 1944 1945 12 11 0 3 279 ,013 251,777 574,401 826,178 450,101 544,266 901,120 1,445 ,386 1946 1947 12 11 2 3 244,255 228,919 1,070,433 1,299 ,352 512 ,520 554,414 1,957 ,906 2,512,320 1948 1949 10 10 3 172,914 118,206 1,472,266 1 ,590 ,472 500 ,000 est. 433 ,565 3,012,320 3 ,445 ,885 1950 1951 10 11 97 ,835 132,219 1,688 ,307 1,820 ,526 297 ,010 335 ,998 3,742,895 4,078,893 1952 1953 11 11 127 ,570 107,361 1,948,096 2 ,055 ,457 364,xxx 440,xxx 4,443 ,xxx 4,883,xxx Ellenburger 1942 1943 5 18 0 0 101,454 367 ,279 101,454 468,733 58,851 216 ,696 58 ,851 275,547 1944 1945 22 24 0 0 976 ,039 1,232,272 1,444,772 2,677 ,044 580 ,004 727,693 855,551 1,583,244 1946 1947 24 24 0 0 1,353 ,481 1,578,131 4,030,525 5,608,656 794,965 810,000 est. 2,378,209 3,188,209 1948 1949 24 24 0 0 1,609,515 956 ,002 7,218,171 8,174,173 830 ,000 est. 560 ,909 4,018,209 4,579,118 1950 1951 24 24 0 0 909 ,072 1,114,605 9 ,083,245 10,197,850 539 ,665 527,718 5,118,783 5 ,646,501 1952 1953 23 22 2 933,812 952 ,942 11 ,131,662 12 ,084,604 446,xxx 452 ,xxx 6 ,093,xxx 6,545,xxx EMMA FIELD Andrews County, Texas J. L. WILLIAMS Geologist, Phillips Petroleum Co., Midland, Texas January 22, 1953 LOCATION The Emma field is in south central Andrews County 12 miles southwest of the town of Andrews. It is in the east central part of the Central Basin platform and is between and in trend with the Mascho and North Cowden fields. METHODS OF EXPLORATION LEADING TO DISCOVERY It appears that discovery was the result of mapping of geological data afforded by wells pre­viously drilled in the region and by utilization of data afforded by geophysical surveys. DISCOVERIES Upper San Andres: January 10, 1937; Sinclair Prairie Oil Co. #1 E.mma Cowden. The initial production of this well is variously reported from 5 to 45 barrels per day by pumping. In its early history it was treated by the Railroad Commission as being in the North Cowden field. It was plugged and abandoned on June 19, 1937, apparently without having produced enough oil to return its cost. Holt zone: October 27, 1950; Forchall Oil Co. #3 Emma Cowden. ELEVATION OF SURFACE Derrick floor: Highest, 3, 178 feet; lowest, 3, 135 feet. SURFACE FORMATION Recent sand. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in the Holt zone 41 feet below its top. This penetration was in one of only three wells which have been drilled to the depth of the Holt zone within the area of the field. The oldest horizon penetrated in the vicinity of the field is in upper Clear Fork. This penetration was inStanolind Oil & Gas Co. #1-F Univer sity, a dry hole located just north of the field which was drilled to total depth of 5, 619 feet. VARIATIONS JN TIDCKNESSES The intervals between certain reliable strati­graphic markers are considerably greater where observed in edge wells than they are in wells at the apex of the anticline. The total thickness of rocks from the top of the Chinle formation to the top of the Rustler formation varies about 100 feet, from about 1, 500 feet to about 1, 600 feet; interval from top of the Rustler formation to the top of Yates formation varies 70 feet, from 1,090 feet to 1,160 feet; interval from top of Yates formation to top of Grayburg formation varies 60 feet, from 1, 160 feet to 1,220 feet; interval from top of Grayburg formation to base of Grayburg formation varies 35 feet, from 230 feet to 265 feet. NATURE OF TRAPS Upper San Andres: The trap is due primarily to an anticlinal fold. The fact that profitable produc­tion extends farther downdip on the northeast limb than on the southwest limb appears to be due to variation of porosity and permeability ~thin the trap area. Holt zone: Since the two productive wells are near the apex of the structural high, it appears that the trap is probably due to a convex fold. However, since this reservoir rock failed to yield commercial production at Forchall Oil Co. #1 Holt (T. D. 5,280 feet) where the Holt zone is equally high and almost between the two productive wells, it appears that variation in permeability may be an important trap­forming factor. PRODUCTIVE AREAS Acres Upper San Andres 1,500 Holt zone 20 Emma field 1,500 THICKNESSES OF RESERVOIR ROCKS Feet Min. Max. Avg. Upper San Andres From top to bottom 5 180 55 Net productive 5 40 25 Holt zone From top to bottom 22 36 29 Net productive 10 10 10 EMMA FIELD , Andrews County, Texas TYPICAL SECTION OF ROCKS PENETRATED z 0 RADIOACTIVITY CURVES :> ;:: LITHOLOGYQ_ w >­:> 0: 0 GA MMA RAY NEUTRON a: w a: "'>­ :;> DEPTH ELEVATION "' "' "' ::; w "' 0 z " -"0 a: :> I a: u --' >­ 0 "' 0 0 "--' " "' z Q >­ :> a: 0 a: w a: :;> "' "' RADIOACTIVITY CURVES LITHO LOGY GAM MA RAY NEUTRON tn DEPTH ELEVAT IO N " •9 00 2000 ZIO O 22 00 Z300 2400 2500 2600 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 38 00 118 EMMA FIELD, Andrews County, Texas 10 e1..oc."­ \ll'1\Jt."-""1i p' T O 4:5 10 EXPLANATION --1000-Contour on top of San Andres formation +++++Boundary of area where upper Son Andres is commercially productive ----Boundary of area in Emma field where Holt zone is commercially productive Oil well ff Dry hole • '""C] Discovery well + Non -commercial well which was abandoned ofter having produced some oil from upper Son Andres • Producing from upper Son Andres !: Producing from Holt zone o Drilled into Holt zone SC ALE • THOUSAND FEET EMMA FIELD, Andrews County, Texas LITHOLOGY OF RESERVOIR ROCKS Upper San Andres: Light colored, non-sandy, crystalline to dense dolomite. The porosity is of intercrystalline type and is quite variable both vertically and horizontally. The top of the zone which is sufficiently porous to yield oil varies in position from the top to 50 feet below the top of the San Andres formation. The degree of porosity is generally greater on the northeast flank than on the southwest flank of the anticline. Holt zone: Brown, saccharoidal, very cherty, glauconitic limestone with irregular intercrystalline porosity. CONTINUITY OF RESERVOIR ROCKS Upper San Andres: The stratigraphic unit which is productive in this field is continuous throughout the area of the field and probably far beyond. How­ever, the degree of porosity is quite variable within the area of the field and determines the western limit of commercial production. Holt zone: Only 3 weUs have been drilled to the depth of the reservoir rock within the area of the field. While the stratigraphic unit appears to be continuous throughout the area covered by the ac­companying map, the degree of porosity is quite irregular. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Upper San Andres: Feet No free gas cap Elevation of top of oil -997 Elevation of bottom of oil, approximate -1,160 Relief, approximate 183 Holt zone: No free gas cap Elevation of top of oil -1,955 Elevation of bottom of oil Unknown* *Only two wells have produced oil from the reservoir in the Holt zone. In one, the productive zone is from -1,955 feet to -1,957 feet, and, in the other, from -1,955 feet to -1,997 feet. Both wells produce water along with the oil. It is not known whether the water is intermingled with the oil in the reservoir or whether it is below the oil in the reservoir. WATER PRODUCTION Upper San Andres: A few wells make very small percentages of water, none make much water, and many make no water. Figures reporting total water production are not available. Holt zone: Both producing wells make consider­able.water along with their oil production. Figures representing quantities are not available. CHARACTER OF OIL Upper San Andres: Range Avg. Gravity, A .P.I.@ 60° F. 31.2 °-35 .8 ° ~ Sulphur 0.2% For analyses see: Railroad Commission of Texas Analyses of Texas Crude Oils (1940), pp. 32 and 64 Holt zone: Range Gravity, A.P.1.@ 60° F. 29.5°-33.0° ACID TREATMENT Upper San Andres: Only a few wells have been completed without acid treatment. The quantity of acid used has ranged from 1,500 gallons to 8,000 gallons; average, about 3,000 gallons, with 5,000 gallons commonly used. Holt zone: Both wells were acidized; one with 2,000 gallons and the other with 3,500 gallons. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Total Yearly Cumulative Upper San Andres: 1937 x x x 1,7 31 1'731 1938 x x 9 60 ,254 61.985 1939 15 10 25 279,031 341,016 1940 17 20 37 248,415 589 ,431 1941 30 30 60 360,761 950,192 1942 16 51 67 286 ,866 l ,237 ,058 1943 9 58 67 380 ,562 1 ,6 17 ,620 1944 9 63 72 849 ,353 2,466,973 1945 x x 76 1 ,021,225 3,488,198 1946 x x 76 863 ,687 4,351,885 1947 3 73 76 762 ,564 5,114,449 1948 x x 77 733 ,683 5,848,132 1949 0 75 75 619 ,442 6 ,467 ,574 1950 72 73 568 ,206 7 ,035,780 1951 72 73 494,326 7,530,106 1952 72 73 421,786 7 ,951,892 Holt zone: 1950 0 2 ,859 2 ,859 1951 0 2 2 18,110 20 ,969 1952 0 2 2 22 ,570 43,539 FLAT ROCK FIELD Upton County. Texas PAUL J. BEAVER Geologist, Cities Service Oil Co., Midland, Texas February 10, 1953 LOCATION and DEFINITION The Flat Rock field is in southeast Upton County, with the western boundary of present development 7i miles east of Rankin. Regionally, the field is in the south-central part of the Midland basin. Its extent has been defined to the north and to the south, but additional drilling to the east and to the west will be necessary to determine the extent in those directions. METHODS OF EXPLORATION LEADING TO DISCOVERY Mapping of data pertaining to shallow beds indi­cated the area as favorable. This mapping was followed by extensive seismograph exploration. The field discovery well was located on the basis of seismograph data and was completed as a producer from Ellenburger at plugged back depth of 10,843 feet. The second well established production from the lower sand member of the Spraberry formation. DISCOVERIES Spraberry: July 21, 1951; Cities Service Oil Co. and Continental Oil Co. #1 -AM University. Drilled to total depth of 11 ,097 feet and plugged back to 7,138 feet. During initial potential test, flowed through perforations at 7,088-7,120 feet at the rate of 103 barrels of oil per day through 22/64-inch choke. Ellenburger and Field: January 23, 1951; Cities Service Oil Co. and Continental Oil Co. #1-AH University. Drilled to total depth of 11,281 feet and plugged back to 10,843 feet. During initial potential test, flowed through perforations at 10,811-10,841 feet at the rate of 2,044.4 barrels of oil per day through 3/4-inch choke. This well produced only 10,163 barrels of oil from the Ellenburger before being plugged back to the Spraberry in October, 1951. An encroaching water cone forced abandonment of Ellenburger. ELEVATION OF SURFACE At well locations: Highest, 2,752 ft.; lowest, 2,721 ft. SURFACE FORMATION Fredericksburg limestone. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 562 feet below its top. This penetra ­tion was in the Ellenburger discovery well. The accompanying TYPICAL SECTION is based on the log of that well. NATURE OF TRAPS Spraberry: Simple convex fold. Ellenburger: Convex fold in combination with a transverse fault. PRODUCTIVE AREAS Acres Spraberry 640 Ellenburger 240 Flat Rock field 640 It is probable that further development will warrant increase of the above estimates as to each. reservoir and as to the field. THICKNESSES OF RESERVOIR ROCKS Spraberry From top to bottom, feet 25 34 28.5 Net productive, feet 12 18 14.8 Ellenburger From top to bottom, feet 130 135 133 Net productive: 30% to 40% of gross from top to bottom UTHOLOGY OF RESERVOIR ROCKS Spraberry: Sand; very fine grained, gray, slightly porous, with small amounts of silty material in the pore space. Ellenburger: Dolomite; medium to coarse crys­talline, brown; contains secondary calcite crystals. The Ellenburger is highly fractured throughout and contains many vugs and cavities at the intersection of fractures and along bedding planes. The reservoir is connected from top to bottom by the fracturing, which is vertical. Very little cementation has been noted in cores. FLAT ROCK FIELD, Upton County, Texas TYPICAL SECTION OF ROCKS PENETRATED z '? ELECTRIC CURVES l­ V> a_ .. w AND ::> " ~ 0 a: L ITHOLOGY w "' :;; >­ V> V> 8 ::> <) ~ w l5 V> w a: w VI w a_ ::> ...J ..0 ::> "' 0 0:.. z 0 ~ 0 a: Cl w V> a: 0 :I: w I­ :I: " 0 w a: a:"' 0 ~ w .J 0 z '? ELECTRIC CURVES 1­ ~ AND a: 0 LI THOLOGY LL DEPTH ELEVATION 3100 z w 3200 ::> 0 3400 -648 IX 3500 ~ m ~ ~ 3600 -84 3700 -948 V> w a: 0 z.. V> -1 448 -1548 -164 -174 -184 -1948 -214 3 5000 w "' z.. z.. ~ 5100 <( 5200 1­w a: 0 5300 .J -2248 -2348 -2548 5400 -2648 5500 -274 5600 -2848 5700 -2'348 5800 -30<1 5900 -3148 -6000 -3248 V> w a: w Vl 0:.. z 0 w a_ " ~ " .J 0 " ~ 0 a: Cl "' a: 0 ..0: w .J .. I­ :I: 0 ~ z 0 ELECTRIC CURVES 1­ AND ~ a: LITHOLOGY 0 LL DEPTH 6000 IOO -3' 6200 -344 6400 -36 6500 -3748 6600 -3848 >­ 6700 -3940: w CD .. 6800 -40'48 0: -4148 -4248 -4348 7200 -4448 1300 7400 -4648 7500 7600 z ~ w Cl 7700 7800 7900 8000 8100 8200 -5448 8300 -5548 8400 -5648 500 8600 -5848 8700 -594 8800 -6048 8900 -6148 9000 -6248 0 .J 6 0 • 0 B ELECTRIC CURVES l­ a_ .. AND ::> " 0 a: LITHOLOGY -' DEPTH ELEVATION 6ffi ~ 100 too 000 -6248 9100 -6348 9200 -6448 ...." a_ i ~ 9300 -6548 a: .J w 0 a_ " 9400 -6648 500 -6742 -6 8 48 z ••oo z 0 0000 > w 0 tOIOO 10200 FUS SHMAN 10400 z 0 10500 V> ,.a_ ;;; 10600 z u > 0 0 a: 0 w "' a: ::> CD z w .J .J 11100 11200 1128 1 -7748 -7848 -7948 -8048 • -8148 EXPLAN ATION $hole Dolomite Colcoreous Anhydritic shole dolomile Dolomiti c shole Anhydrite Sondy Sort shale Sondslone Fbl Ch ert ~ Art;i tloceous Rock indicated, sandstone D ••d DD Rock indicated, Limestone block Arg1lloceous Rock indicated, limestone brown D Dolomitic O Show of oil hmestone • Oil production w V> ~ ~ DEPTH w ~ z ~ >-100 0 x u i 3 ~ ~ 300 ELEVATION . " 2752 2652 2552 2452 2352 2252 2152 2052 1952 1852 1752 1652 1452 1352 1252 1152 1052 952 852 1~ 52:-i 652 552 452 352 252 152 -48 FLAT ROCK FIELD, Upton County, Texas CONTINUITY OF RESERVOIR ROCKS Spraberry: The productive zone is continuous through­out the area of the field and is of essentially the same character at each location where penetrated within the area of the accompanying maps. It is present throughout the Midland basin and produces oil in many fields. Ellenburger: The continuity of this reservoir rock is interrupted by an east-west fault with down-throw to the north. The Ellenburger group, of which this reservoir rock is a part, is present throughout the Permian basin and is a prolific producer of oil in many fields. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Spraberry Ellenburger No free gas cap Elevation of top of oil, feet -4,363 -7 ,962 Elevation of bottom of oil, feet -4,395 -8,097 Relief, feet 32 135 WATER PRODUCTION Spraberry: No water produced to date. Ellenburger : Water which could not be shut off entirely because of the vertical fracturing was found at depth of 10,489 feet(-8,097 feet) in the discovery well, which pro­duced 10,163 barrels of oil and 27 ,646 barrels of water before it was abandoned as an Ellenburger well and com­pleted as a producer from Spraberry. Of the two wells now producing from Ellenburger, one has produced no water; CHARACTER OF OIL Spraberry Ellenburger Gravity, A.P.I. @ 60 ° F . 39° 61 ° Sulphur 0.025% 0.05% Color Green Straw Odor Sweet Sweet COMPLETION TREATMENT Spraberry: Each well was given a hydraulic fracture treatment (3,000 to 6,000 gallons); some were flushed with kerosene. Ellenburger: Two wells with good porosity were washed with 500 to 750 gallons of acid; the other Ellenburger pro­ducer was treated with a total of 63,300 gallons of acid. PRODUCTION HISTORY Year WELLS PRODUCING at end of year F lowing Pumping OIL PRODUC T ION (bar rel s ) Yearly Cum ulative Spraberry 195 1 3 0 20 ,780 20,780 1952 2 52,616 73,396 E llenburger 1951 0 10'163 l 0 ,163 water constituted 84% of the gross production from the other to January 1, 1953. 1952 2 0 67 .999 78 ,162 FRIEND FIELD Reagan County, Texas E. E. LINDEBLAD Geologist, Continental Oil Co ., Midland , Texas February 25, 1953 LOCATION and OTHER NAMES The Friend field is about 6 miles southeast of Big Lake, county seat of Reagan County. It is 3 miles southwest of the Barnhart field and 8 miles northeast of the World field. One of the two wells in the field is in Sec. 1, Georgetown R.R. survey and the other is Sec. 8, Block 49, University Land sur­vey. Although the two wells are about 3 miles apart, they have been considered as in the same field and were so reported on page 970, A.A.P.G. Bull., vol. 32 (June 1948). They have also been treated as in separate fields, the Friend field and the Block 49 field. For proration purposes, the discovery well men­tioned below was treated for awhile as in the World field, as was Moore Exploration Co. #1 M. S. Neal, located about Ii miles southwest in Sec. 2, D . L. Carver survey, Crockett County, which was also a noncommercial well and which occasioned the use of the designation Moore-Neal as a field name. The Moore-Neal well is also listed on the same page in the above mentioned publication as being in the Friend field. METHOD OF EXPLORATION LEADING TO DISCOVERY Core drilling and subsurface geology led to the acquisition of leases and to the test drilling which resulted in discovery. DISCOVERY Grayburg: January 14, 1947; Moore Exploration Co. #1 W. E . Friend. Pumped 10 barrels per day of 26 °oil with no water . Drilled to total depth of 2 ,582 feet and plugged back to 2 ,538 feet . The top of the productive zone is at depth of 2,390 feet, 80 feet below the top of the Grayburg formation. The well was plugged and abandoned on August 21, 1949 with­out having produced enough oil to return its cost. ELEVATION OF SURFACE At well locations: Highest , 2 ,728 ft .; lowest,2,669 ft. SURFACE FORMATION Undifferentiated rocks of the Comanche series. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is in the Ellenburger group 150 feet below its top. This penetration was in Continental Oil Company #1 University 3, a dry hole located near the north edge of the area covered by the accom­panying map and where the total depth of 9,775 feet is indicated . The accompanying TYPICAL SECTION is based on the log of this dry hole . NATURE OF TRAP Grayburg: The trapping of oil appears to be due to variation in degree of porosity and permeability of rock dipping generally westward. It is not known whether there was one accumulation tapped by the two wells or whether there were two separate and distinct accumulations. PRODUCTIVE AREA Grayburg and Field: Any estimate of the area which has contributed to the production of the two wells is necessarily quite arbitrary. It seems un­likely that it was in excess of 160 acres. THICKNESS OF RESERVOIR ROCK Grayburg: Feet From top to bottom 110 Net productive 40 LITHOLOGY OF RESERVOffi ROCK Grayburg: Dolomite; gray, fine to medium grained, crystalline, occasionally sandy with some minor amounts of chert. CONTINUITY OF RESERVOIR ROCK Grayburg: The reservoir rock is continuous throughout the area of the field. The degrees of porosity and permeability are variable. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Grayburg: Feet Highest known elevation of oil 291 Lowest known elevation of oil 181 Apparent relief 110 FRIEND FIELD, Reagan County, Texas TYPICAL SECTION OF ROCKS PENETRATED QRADIOACTIVITY Ix ELECTRIC CURVES >­ LI THOLOGY ":E :E a: 0 a: GAMMA RAY NEUTRON w w a: 0 "' " 0 I u 0 Q_ :> " " :> "' 2615 to 2710 feet: anhydrite, 5; polyho lite, 5~ salt, 10; polyholite, 8~ anhydrite, 8; sandstone, 7 ; red shale, 2; salt, 12; anhydrite, 4; sondstone, 12; anhydrite, 6; and salt, 16. E XPLANATION ~Limestone n~Y\-~t:JSandsTone IIAnhydrite r.:=a ~Coliche t======~ Shole, red ~Dolomite Polyholite ~~~~JS~~~· ~;~!n .:¢-Gos production • Oil production ~Bentonite w Water o Show of oil NOTE: This TYPICAL SECTION is based on the log of Shell Oil Co. and Citi e s Service Oil Co. HB E. F. King, located in Sec . 10, Block A -42 where its total depth of 12,668 feet is indicated on the accom­panying map. The well was drilled to its total depth in Dec ember 1955, after having found a good showing of oil in the Devonian. P. S. · This well was nonproductive in Ellenburger and was plugged back and completed in Devonian on January 10, 1956. Its production to end of 1956 amounted to 47,545 barrels. 0 a:"' a: 0 ""­ z a: 0 " _J _J FUHRMAN-MASCHO FIELD I Andrews County, Texas TYPICAL SECTION OF ROCKS PENETRATED FUHRMAN-MASCHO FIELD, Andrews County, Texas WATER PRODUCTION CHARACTER OF OIL Grayburg -San Andres: Some water has been produced from the deeper wells, especially in the south, southeast and northeast portions of the field. However, the quantity of water has never been a serious handicap to production from this reservoir. The water has a chloride content of about 35,000 parts per million and it is strongly sulphurous. Glorieta: Large amounts of water are produced from this reservoir. Water-drive appears to be an important factor of reservoir energy. NATURE OF TRAPS Grayburg -San Andres: The accumulation of oil was chiefly influenced by a broad struc­tural uplift along the east side of the Central Basin platform. This uplift has two distinct anticlinal axes, one on the northeast in the original Fuhrman area (now known as the Fuhrman sector) and the other in the southern part of the old West Fuhrman area (now known as the Mascho sector). Variation in degree of porosity probably is also an effective factor in trap-forming; it definitely is an important factor in determining productivity. Glorieta: The factors which occasioned the accumulation of oil in this reservoir appear to be essentially the same as those which occa­sioned accumulation in the Grayburg -San Andres reservoir. The Glorieta reservoir is structurally similar to the easternportion of the Grayburg -San Andres reservoir. As yet, Glorieta production has been developed only in the western portion of the north part of the field. This reservoir consists of lenses of porous dolomite in a sandy and shaly section at the base of the San Andres formation and at the top of the Clear Fork group. CHARACTER OF GAS Grayburg -San Andres: Following is an analysis of a typical sample of gas from this reservoir: Component % Methane 73.68 Ethane 17.55 Propane 6.53 !so-butane .65 N-butane 1.15 Iso-pentane .07 N-pentane .28 Heavier .09 100.00 Gravity A. P. I. @ 60°F Sulphur Grayburg -San Andres 28-32° 4.2"/o Glorieta 29° Sour For analyses of Grayburg -San Andres samples see: Railroad Commission of Texas Analyses of Texas Crude Oils (1940), pp. 32 and 64 U.S. Bureau of Mines Laboratory Reference No. 38145 Tabulated Analyses of Texas Crude Oil. T. P. 607 (1939), Group 2 Item 44 Analyses of Crude Oils from Some West Texas Fields. R. I. 3744 (1944) Page 12 Analyses of Crude Oils from 283 Important Oil Fields of the United States. R. I. 4289 (1948) Item 205 PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION GAS at end of year (barrels} PRODUCTION OIL GAS (Mcf} Flow Pump Yearly Cumulative Field totals:----­1930 -1949 Same as Grayburg -SanAndres 1950 31 251 1 1,375,935 13,417, 195 19,433 1951 .. . . 30 .. 263 . . . 2 .... 1,559,607 .. 14,976,802 ... 164,442 1952 27 266 3 1,444,472 16,421,274 150,373 1953 28 283 3 1,483,860 17,905, 134 175,899 1954 .... 52 .. 299 ... 3.. 1, 656,921 .. 19,562,055 ... 132,309 1955 74 330 3 2,670,892 22,232,947 180,349 Grayburg -San Andres: 1930-1938 941,902 ? * 1939 ... . 48 .... 6 540,387 1,482,289 .. .. 59,400 1940 47 7 504,215 1,986,504 62,400 1941 39 16 462, 744 2,449,248 66, 045 1942 .... 47 29 ... 2 300, 366 2, 749,614 .. .. 30,960 1943 77 44 2 443,438 3, 193,052 55,229 1944 65 112 1 1, 320,043 4,513,095 25,805 1945 .... 66 128 1 .... 1,676,467 6, 189,562 .... 37,340 1946 54 143 2 1, 497,435 7,686,997 59,588 1947 34 184 1,342,612 9,029,609 29,330 1948 .... 33 .. 237 .... 1,626,553 .. 10,656, 162 28, 002 1949 40 243 1, 385, 098 12,041,260 29,928 1950 30 249 1,342,305 13, 383, 565 19,433 1951 .... 30 259 ... 2 . ... 1,493,884 .. 14,877,449 ... 164,442 1952 27 260 3 1, 386, 919 16, 264, 368 150,373 1953 28 270 3 1, 362, 382 17, 626, 750 175,899 1954 .... 52 .. 267 . .. 3 .... 1,340,452 .. 18,967,202 ... 132,309 1955 74 288 3 2,215,352 21 , 182,554 180,349 Glori eta: 1950 2 0 33, 630 33,630 0 1951 . . .. 0 4 0 65, 723 ..... 99,353 ........ 0 1952 0 6 0 57, 553 156, 906 0 1953 0 13 0 121, 478 278,384 0 1954 . ... 0 ....32 0 316,469 594,853 ... .. ... 0 1955 0 42 0 455,540 1,050,393 0 * Published records for the years prior to 1939 are confusing because Fuhrman was not consistently recognized as a separate and distinct field. Its production was commonly reported with that of other fields, particu­larly, Deep Rock and Parker. Although we do not have the figures for each year separately, we believe that the above entry representing cumu­lative production to the end of 1938 is accurate. It was transcribed from page 337 of TEXAS OIL AND GAS SINCE 1543 by C. A. Warner (1939). THE UNIVERSITY OF TEXAS, BUREAU OF ECONOMIC GEOLOGY, PUBLICATION 5716. FUHRMAN-MASCHO FIELD, Andrews County, Texas FUHRMAN-MASCHO FIELD, Andrews County, Texas (Attach FUHRMAN -MASCHO map) GIB FIELD Crane County, Texas ROY HARRIS District Geologist, Lion Oil Company, Midland, Texas May 18, 1953 LOCATION The Gib field is in east central Crane County 3 miles southwest of the town of Crane, county seat. It is 4 miles west of the McElroy field and 4i miles north of the Crane Cowden field. It is in sections 13, 14 and 24 of Block X, C.C.S.D. & R.G.N.G. R.R. Co . survey. METHODS OF EXPLORATION LEADING TO DISCOVERY The field was discovered by the use of seismo­graph and subsurface geologic studies . DISCOVERY Grayburg: January 31, 1948; Lion Oil Co. #1 G. H . (Gib) Cowden. This well was drilled as an unsuccessful Devonian test to a total depth of 8,575 feet and was then plugged back to 2 ,810 feet. Com­pletion was in a sand and dolomite section of the Grayburg formation through casing perforations from 2,735 to 2,775 feet. During potential test, after treatment with 2 ,000 gallons of acid, the well pumped at the rate of 19 .68 barrels of oil per day. ELEVATION OF SURFACE At well locations (derrick floor) : Highest, 2 ,552 feet; lowest, 2 ,534 feet . SURFACE FORMATIONS Quaternary caliche and wind-blown sand. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in the Devonian system 835 feet below its top . This penetration was in the discovery well. A dry hole three-quarters of a mile south of the field, Humble Oil & Refining Co. #1-B G. H. Cowden, had penetrated about 265 feet of Ellenburger at its total depth of 10,192 feet. NATURE OF TRAP Grayburg : Updip decrease of porosity and per­meability on an anticlinal nose. PRODUCTIVE AREA Grayburg and Field: 120 acres. THICKNESS OF RESERVOm ROCK Grayburg Min. Max. Avg . From top to bottom, feet so Net productive 0 20 11 LITHOLOGY OF RESERVOm ROCK Grayburg: The reservoir rock is a fine-grained to medium-fine-grained, loosely cemented, slightly calcareous sandstone and a finely-crystalline, anhy­dritic, white to gray dolomite containing some vertical fractures . CONTINUITY OF RESERVOm ROCK Grayburg: This porous unit of sandstone and dolomite cannot be correlated beyond the limits of the field . Probably it is of only local extent. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Grayburg : Feet No free gas cap Elevation of top of oil -204 Elevation of bottom of oil -260 Relief 60 CHARACTER OF OIL Grayburg: Gravity, A.P.I. @ 60 ° F . , avg. 29.6 ° WATER PRODUCTION Grayburg: No water is produced. COMPLETION TREATMENT Grayburg: The reservoir rock was shot with nitroglycerin at the time of completion of each well. Two of the wells were also acidized. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year All pumping Yearly Cumulative 1947 1 423 423 1948 6 18,872 19 ,295 1949 5 18,719 38,014 1950 5 12 .691 50,705 1951 5 9' 110 59 ,815 1952 5 6,952 66 ,767 1953* ? 6,038 72 ,805 *1953 data added by amendment. GIB FIELD, Crane County, Texas TYPICAL SECTION OF ROCKS PENETRATED EXPLANATION ---260--Contour on base of upper sand of Groyburg formation Elevation of base of upper sand of Groyburg formation Total depth • Oil well Abandoned oil well ff Dry hole • ~Discovery SCALE · THOUSAND FEET p GOOD FIELD Borden County, Texas CARLS. SCHREINER, Jr. Geologist, Seaboard Oil Co. of Delaware, Midland, Texas April 24, 1953 LOCATION The Good field is in southwestern Borden County about 14 miles southwest of Gail, county seat. It is in blocks 32 and 33, T. 4 N . , Texas & Pacific Rail­road Co. survey and is in the northeastern part of the T. J. Good ranch. METHODS OF EXPLORATION LEADING TO DISCOVERY Regional subsurface studies, core drilling and reflection seismograph. DISCOVERY Pennsylvanian reef: April 14, 1949; Seaboard Oil Co. and Pan American Production Co. #1 T. J. Good. The top of the reservoir was found at depth of 7 ,905 feet and the well was drilled to the total depth of 8 ,0 l 0 feet. Flowed at rate of 488 barrels of oil per day through 1/4-inch choke during initial potential test. OLDEST STRATIGRAPIUC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is 60 feet below the top of the Ellenburger group. This penetration was in the dry hole just east of the field at the location where the total depth of l 0 ,200 feet is indicated on the accompanying map. There was no show of oil or gas anywhere in this dry hole. NATURE OF TRAP Pennsylvanian reef: The trap is due to a reef limestone build-up overlain by a thick section of compacted black shale . The relief on the top of the limestone is in excess of 500 feet . There is no evidence of structural deformation of the beds below the reef limestone. PRODUCTIVE AREA Pennsylvanian reef and Field : 1,940 acres. TIUCKNESS OF RESERVOm ROCK Pennsylvanian reef: The reservoir rock is in the form of a plano-convex lens. At the location of the highest well, the top of the productive limestone is 489 feet above water level. From the maximum thickness of about 490 feet in the center of the field, the reservoir rock thins in all directions to zero within short distances. IJTHOLOGY OF RESERVOm ROCK Pennsylvanian reef: Reef limestone; white to gray, medium crystalline to chalky and containing a few distinguishable fossils. Porosity and permea­bility are very irregular; there is some indication of fracturing, but generally the porosity is vuggy to pin-point. Productivity is not consistently related to position on reef; some high wells are poor pro­ducers and there are a few dry holes which entered the reef limestone far above water level. There are a few local thin black shale beds within the reef limestone. CONTINUITY OF RESERVOm ROCK Pennsylvanian reef: The reservoir rock is continuous throughout the area of the field and only for a very short distance beyond the periphery of the field . ELEV A TION AND RELIEF OF PRODUCTIVE ZONE Pennsylvanian reef: Feet No free gas cap Highest known elevation of oil -5 ,216 Elevation of oil-water contact -5,705 Known relief 489 CHARACTER OF Oll. Pennsylvanian reef: Gravity, A.P.I. @ 60 ° F. 43.5° Sulphur 0.21% Viscosity, Saybolt universal @ l00°F. 36 sec. Color Brownish green For analysis see: U. S. Bureau of Mines Lab. ref. No . 50030 Analyses of Crude Oils From Some West Texas Fields. R. I. 4959 (1953) Item 55 ACID TREATMENT Pennsylvanian reef: The usual completion prac­tice is to set the oil string on top of the reef lime­stone, and the well generally flows without acid treatment after a couple of runs with a swabbing unit. SELECTED REFERENCE Rodan, William B . (1950) Good field, Borden County, Texas : Abilene Geological Society, Geological Contributions -1950, pp. 15-19 and 4 maps and 2 cross sections. GOOD FIELD Borden County, Texas OF EXPLANAT IO N ---5600 --Contour on top of Pennsylvonion reef SCALE Elevation of top of Pennsylvanian reef • Total depth THOUSAND FEET • Oil well Ji Ory hole Year WELLS PRODUCING al end of year Flowing Pumping 1949 PRODUCTION OIL PRODUC T ION (barrels) Cumulative ~ 2 03 ,450 203,450 1950 36 I ,4 02 ,577 I ,606 ,027 19 5 1 46 2,182.9 50 3 ,788 ,977 1952 42 I ,509 ,H4 I 5 ,298 .B 18 HISTORY GAS PRODUCTION (Mcf) Cumulative 155.549 155 ,549 I ,204 ,584 I ,049 ,03 5 I ,747 ,O>B 2 .951 ,642 I ,212 .2 I 2 4.163,854 WATER PRODUCTION Yearly (ba rrel s) Cum ula tive ELEVA TION OF SURF ACE At well locations : feel: lowest , 2 ,460 feet. Highe s t, 2 ,632 2 .318 2 ,318 I 03 ,7 4 I 261 ,408 I 06 ,059 367 .467, SURFACE FORMATION Undi fferentiated red sand and s hales of the Dockum group. TYPICAL SECTION ROCKS PENE T RATED G 0 0 D FIELD , Borden County, Texas TYPICAL SECTION OF ROCKS PENETRATED 0 0: <( z 0 '.'.l 0. ::~ (,!) Q ... <( >" ~ \.i.. ELECTRIC Et RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY OEPTH and S.P. 5450 -2836 5500 -2886 5600 -2986 5700 5800 -3186 5900 -3286 6000 -3386 6100 -3486 6200 -3 565 6300 -3686 6400 -3786 6500 -3886 6600 -3986 6700 -4 086 6800 -4 186 6900 -4 286 7000 -4386 7100 -4486 7200 -4586 7300 -4686 0. " <( ~ -' 0 "" z :l 0 74 00 -4 786 7500 -4 886 7600 -4986 7700 a-5086 ~ 7800 ~1-5186 I 7900 8000 z <( z ~ z ~ 8100 • >­"'z z w 0. "L) 8ZOO 8300 NOTE: The above section is based on the log of the discovery well to the depth of 7 ,830 fpet and below that, with depths and elevations adjusted, on the log of the dry hole where tht• oldest horizon was penetrated. The stratigra phic position of the reser­voir is indicated although there was no production from the rocks at that position at the location where this portion of the above log was made. The r eservoir occupies the upper portion of the reef. While the above symbol in the oil column properly r e presents the approximate position of the rese rvoir, it is recognized that there is some evidence that the age of the reef may extend from within Strawn to as late as early Wolrc.:amp. EXPLANATION ~ Sandstone Sol t LJ Shale 83 Sandstone ond shale ~ Limestone [Zj Chert ~ Siliceous limest one D Rock indicated, " d ~ Dolomite [[] Rock indicated, block ~ Oolitic dolomite [] Rock indicated, gray Rock indicated, Anhydrite qreen ~ D E Polyholire • Oil production HARPER FIELD Ector County. Texas FRED FORWARD Geologist, Phillips Petroleum Company, Midland, Texas April 30, 195Z LOCATION The Harper field is 10 miles west. of Odessa, county seat of Ector County. It is in the midst of several prolific oil fields and is in the approximate center of the Central Basin platform. METHOD OF EXPLORATION LEADING TO DISCOVERY Subsurface geology based on the then scanty well data, and using primarily elevations of tops of Rustler and Yates formations, suggested that the Permian beds are structurally high in this area. As a result of the early subsurface studies, Broderick & Calver~ /II E. F. Cowden was spudded on July 13, 1933. This well was completed as a pumping discovery from the San Andres formation on December 1, 1933. DISCOVERY San Andres: December 1, 1933; Broderick & Calvert Ill E. F. Cowden ELEVATION OF SURFACE At well locations: Highest, 3,1Z4 ft.; lowest, 3,014 ft. SURFACE FORMATION Edwards limestone is at or near the surface throughout the area of the field. A thin veneer of unconsolidated Pleistocene sand covers the lime­stone over part of the field. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated by any well within the area of the field is in the upper part of the Clear Fork. The oldest horizon penetrated by any well in the vicinity of the field is 37 feet below the top of the Ellenburger group. This penetration was in Cities Service Oil Co. #1 J. E. Parker, a dry hole about a mil& west of the field. NATURE OF TRAP San Andres: Updip decrease of porosity on a structural nose. PRODUCTIVE AREA San Andres and Field: 3,800 acres. The field limits appear to be defined in all directions. THICKNESS OF RESERVOIR ROCK San Andres: Feet From top to bottom of reservoir rock 180 Net productive ZS LITHOLOGY OF RESERVOIR ROCK San Andres: Dolomite; tan, medium crystalline, with most of the porosity in the top 30 feet. CONTINUITY OF RESERVOIR ROCK San Andres: The stratigraphic equivalent of the productive dolomite is continuous far beyond the limits of the field. However, sufficiently high poros­ity to yield oil commercially appears to be limited essentially to the presently productive area. ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Andres: Feet No free gas Highest proven elevation of oil -881 Lowest proven elevation of oil -l ,Z60 Proven relief 379 The downdip extent of production is determined by decrease of porosity rather than by oil-water contact. It has not been established that there is a definite oil-water contact in the usual sense. WATER PRODUCTION San Andres: Only a negligible amount of water has been produced. The discovery well, which is the lowest well structurally with one exception, is producing no water although it has been producing oil 18 years. ACID TREATMENT San Andres: Generally at the time of completion of each well, the reservoir rock was shot with Z50 to 900 quarts of nitroglycerin. A few wells w.e·re treated with 1,500 to 6 ,000 gallons of acid either before shooting or as the sole treatment. HARPER FIELD I Ector County, Texas TYPICAL SECTION OF ROCKS PENETRATED HARPER FIELD, Ector County, Texas TYPICAL SECTION OF ROCKS PENETRATED z 0 RADIOACTIVITY CURVES ;:: "' ­ "' ~ "' DEPTH "' "' z -"' "'aJ z z Q. "' z 0 RADIOACTIVITY CURVES a: ;:: Q. w "' LITHOLOGY I­ 0 a: a: " " GAMMA RAY NEUTRON "' >­ ~ "' " DEPTH "' z '.:! <.) > 0 a a: 0 NOTE: Thi s TYPICAL SECTION is based on t he log of Cities Service #1 J, E. Parker , a dry hole one mil e wes t of the field . The stratigraphic: position of the r eservoir rock is indicated although it is not productive a t this locat~on. EXPLANATION ++ ++ Limestone Solt ++ +"+" +•.++ ~ Sandstone Chert LI ~ ~ Rock 1nd1coted,Shale - ShOly ~ -~ indicated,Colcoreous shale E2EJ Rock sandy ~ Rock 1nd1coled, . / »)?) onhydr1!1c Dolomite J>>~~~ ~ Anhydr1!1c Rock md1coted, dolomi te o ~ '"d ~ C,0 · trJ &"' · ~· . ~ ""i . ""i~"' · 2S· s\..\(..A°?> 'Tj ......... trJ r­ 0 trJ () 0 ., 0 g :::s ~ ~ ~ HARRIS FIELD Gaines and Andrew Counties. Texas J. L. WILLIFORD Geologist, Humble Oil & Refining Company, Midland, Texas July 30, 1954 LOCATION The Harris field is 10 miles south of Seminole, county seat of Gaines County. It is on the Central Basin platform near its northeast margin. METHOD OF EXPLORATION LEADING TO DISCOVERY Seismograph. DISCOVERY San Angelo: October 29, 1949; The Texas Co. # 1 E.D.Harris. At the time of completion, the well produced, by pumping, at the daily rate of 41 barrels of 31.9° gravity oil through perforations between 5,965 and 5,980 feet. ELEVATION OF SURFACE At well locations: Highest, 3, 305 ft.; lowest, 3, 255 ft. SURFACE FORMATION Wind-blown sand of Recent age and clays and caliche of probable Quaternary age. OLDEST STRATIGRAPIDC HORIZON PENETRATED The oldest horizon penetrated is in the Clear Fork group 1,030 feet below its top. This penetra­tion was in the discovery well. NATURE OF TRAP San Angelo: The trapping of oil appears to be due to a combination of anticlinal folding and variation in degree of porosity. Porosity pinchout determines the boundary of the productive area except in the vicinity of the discovery well; there, the oil body extends downdip to the oil-water contact. PRODUCTIVE AREA San Angelo: Development to date indicates a productive area of 2,480 acres. Futher development may prove that the productive area is slightly greater. THICKNESS OF RESERVOIR ROCK SanAngelo: The thickness of the productive zone ranges from 6 feet fo 55 feet. The area of greatest thickness is on the east flank of the anticline. Near the edge of the productive area, wells have been completed at locations where there is as little as 6 feet of productive rock. LITHOLOGY OF RESERVOIR ROCK San Angelo: Tan to light brown, finely crystalline to finely granular dolomite with minor amounts of anhyd:i.oite and fine-grained sand. The degree of porosity ranges widely and within short distances. CONTINUITY OF RESERVOIR ROCK San Angelo: The reservoir rock in the San Angelo formation appears to be continuous throughout the area of the accompanying map and considerably beyond its boundaries. However, the degree of porosity which occasions commercial production is probably not continuous far beyond the presently productive area. The carbonate and sand facies of the San Angelo formation is continuous over the Central Basin platform and Eastern shelf; a sand and shale basin facies is present in the Midland basin. ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Angelo: Due to irregularity of porosity, it is difficult to determine the elevation and relief of the productive zone. The elevation of the highest known oil is about -2, 600 feet and the elevation of the oil-water contact is -2, 770 feet, but this does not mean that there is a continuous oil body with relief of 170 feet. CHARACTER OF OD. and RESERVOIR DATA Pressure at -2,650 ft. at discovery date,approx. 2,400 psi. Gravity of oil, A .P.I. @ 60°F. 31° Saturation pressure 340 psi. Solution gas -oil ratio 159 cf/bbl. WATER PRODUCTION San Angelo: Some water has been produced but the quantity has not been enough to be of importance. ACID TREATMENT San Angelo: While the normal treatment is with 4,000 to 6,000 gallons of acid, the quanti ties have ranged from 500 to 11, 500 gallons. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of yea r (barrels } Year Flowing Pumping Yearly Cumulative 1949 0 2,340 2,340 1950 2 38,466 40,806 1951 0 14 172,658 213, 464 1952 27 450, 741 664,205 1953 0 52 6 10,291 l, 274, 496 1954* 0 61 580,8xx l,855, 3xx 1955* 0 67 581,5xx 2,436,8xx *1954 and 1955 data added by amendment. EXPLANATION -----2620----Contour on top of Son • Oil well, producing from San Angelo i' Oil well, producing from Upper Clear Fork -2540 !. Oil well, produci ng from Lower Clear Fork ,P Dry hole 1:20 Total depth • \=:] Discovery ::r: .~?5 )::­ 6'00 ···~ ::0 ::0 -(/) 'Tj - tT:I L' t1 g1 s· CD Ul [ Q >­ [ @ ~ Ul ~ ~ (i)-' _Ul ~ ~ Q Ul p\ls1...1c sc\'\0~~?>4 ....... 81..oc\<. THOUSAND ,[E.T c w """' HENARD FIELD Yoakum County, Texas ARCHIE B . COCKBURN Geologist, Cabot Carbon Company, Midland, Texas September 25, 1953 LOCATION The Henard field (one well) is in west-central Yoakum County, 4 miles northwest of the town of Plains, county seat. It is in Sec. 367 of Block D . John H. Gibson survey MAPS and TYPICAL SECTION Because of the geographic and geologic relationship with the Brahaney field, certain data pertaining to this field are presented on maps included in the foregoing paper on that field . Furthermore, the data pertaining to strati­graphic section presented in the paper on the Brahaney field apply to this field. The TYPICAL SECTION OF ROCKS PENETRATED presented in that paper is included here by reference . METHOD OF EXPLORATION LEADING TO DISCOVERY A study of subsurface geological data, including good shows of oil in two nearby tests, led to the drilling of the discovery well. DISCOVERY San Andres : October 28, 1950; Dunigan Bros. & Bra­haney #1 Alice Henard. Pumped at rate of 57 .7 barrels of oil and 12 .6 barrels of water per day from open hole from depth of 5,150 to 5,285 feet after treatment with 4,000 gallons of acid . ELEVATION OF SURFACE At the one well: 3 ,681 feet (derrick floor, 3 ,691 feet). SURFACE FORMATION Ogallala formation of Tertiary system. OLDEST STRATIGRAPlllC HORIZON PENETRATED The oldest horizon penetrated in the one productive well is approximately 750 feet below the top of the San Andres formation. Two miles south, in the Brahaney field , Signal Oil & Gas Co . #1 J . D. Webb penetrated the upper part of the Devonian system. NATURE OF TRAP San Andres: While the dominating structural feature is a southward plunging anticlinal nose, it appears that the most important trap-forming factor is the distribution of porosity. As indicated on a map presented in the foregoing paper on the Brahaney field , the top of the zone with relatively high porosity is convex in form. PRODUCTIVE AREA San Andres and Field : 40 acres . TlllCKNESS OF RESERVOIR ROCK Feet From top to bottom 80 Net effective San Andres: 30 LITHOLOGY OF RESERVOIR ROCK San Andres : Dolomite; tan, finely crystalline, slightly fractured, with styolitic partings, thin.streaks of dark gray shale , and nodules of blue, fractured chert. CONTINUITY OF RESERVOIR ROCK San Andres : The stratigraphic equivalent of the res­ervoir rock is probably continuous over a large area. However, the degree of porosity and permeability which occasions commercial production is very erratic. While the reservoir rock in the Brahaney field is at the same stratigraphic position, it is not known whether porosity is sufficiently continuous to permit migration of fluids from one field to the other or from a common source to the two fields. ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Andres: Feet No free gas cap Elevation of top of oil -1,504 Elevation of bottom of oil -1,636 Relief 132 The elevation of bottom of oil is estimated on the basis of showings in dry holes in the vicinity. Some of these tests produced small amounts of oil but were plugged rather than being completed as marginal producers . CHARACTER OF OIL San Andres : Gravity, A .P .I.@ 60° F . : 32° Odor: Sour Sulphur : High percentage Color : Dark brown to black WATER PRODUCTION San Andres : Water initially constituted 18% of gross liquid produced, but the ratio has now decreased to between 3and4% . ACID TREATMENT San Andres: A treatment with 4,000 gallons of acid resulted in an increase in potential from 15 to 58 barrels of oil per day. PRODUCTION HISTORY Year WELLS PRODUCING at end of year Pumping OIL PRODUCTION (barrels) Yearly Cumulative 1950 1,999 1,999 1951 8,388 10 ,387 1952 7 ,182 17 ,569 HOMANN FIELD Gaines County. Texas DONALD E. CAUSSEY Geologist, Honolulu Oil Corp., Midland, Texas May 29, 1953 LOCATION PRODUCTIVE AREA The Homann field is in Block G, Waxahachie Tap R . R . Yates : Approximately 2 ,400 acres. Co. survey, in central Gaines County about 6! miles north­ east of the town of Seminole, county seat. LITHOLOGY OF RESERVOIR ROCK METHOD OF EXPLORATION LEADING TO DISCOVERY Yates: Sandstone; fine-to coarse-grained; grains are Mapping of subsurface data indicated anticlinal struc­sub-rounded and are cemented loosely by varying amQunts ture at the depth of the Yates formation . Seismic surveying of salt and shale. confirmed this interpre'tation. CHARACTER OF GAS DISCOVERY Component Mol. '7o G/ Mcf Yates: April 7, 1944; Honolulu Oil Corp. #1 E .B .Homann . Carbon dioxide 0.00 This well was drilled to total depth of 5 ,457 feet and plugged Nitrogen 26.34 back to 3 ,513 feet. The top of productive rock is at depth of Methane 56.49 3,443 feet . The initial production was at the rate of 5 ,512 Ethane 9 .41 Mcf per day. Propane 4.58 1.256 Is a -butane 0.46 0.150 N-butane 1.22 0.384 ELEVATION OF SURFACE lso-pentane 0 .45 0 .164 N-pentane 0.28 0. I 0 I At well locations: Highest, 3,326 feet; lowest, 3,244 feet. Hexane 0.56 0 .230 Heptane 0 .2 1 0.097 SURFACE FORMATION 100.00 2.382 Ogallala formation of Tertiary system. Specific gravity, calculated from composition, 0.811 Heating value, B.t.u./cf 953 Sulphur content, grains per Md 0.3 OLDEST STRATIGRAPl:UC HORIZON PENETRATED The above analysis was made by El Paso Natural Gas The oldest horizon penetrated is in the Devonian Co. of a sample s ecured December 20 , 1948 from Honolulu system about 80 feet below the Woodford shale. This pene­Oil Corp. #1-96 E . B . Homann. tration was in the dry hole near the gas well in the southwest corner of Sec. 75where the total depth of 13 ,282is indicated on the accompanying map. The accompanying TYPICAL ELEVATION AND RELIEF OF PRODUCTIVE ZONE SECTION is based on the log of this well. Yates : Feet NATURE OF TRAP -mghest known elevation of gas ~ Lowest known elevation of gas -240 Yates: Convex fold , as indicated on accompanying map . Known relief 166 Tl:UCKNESSES OF RESERVOIR ROCK Yates: Max . Min . Avg. WATER PRODUCTION ACID TREATMENT ~omtop to bottom, feet 190 175 182 Net productive, feet 92 58 75 None None PRODUCTION HISTORY CONTINUITY OF RESERVOIR ROCK Yates: The stratigraphic equivalent of the productive WELLS GAS CONDENSATE zone has been recognized at each of the twelve well loca­PRODUCING PRODUCTION PRODUCTION tions indicated on the accompanying map. However , the at end of year (Mcf) (barrels) degree of porosity and permeability required for commer­Year Flowing Yearly Cum. Yearly Cum. cial production is not continuous throughout the inclusive area. Lack of adequate porosity and permeability appear s 1946 %,007 96.007 1,431 1,431 to be the explanation for the failure of certain test wells , 1947 I 253 ,478 349 ,485 3 ,443 4,874 particularly that in Sec. 104, to produce commercial gas. 1948 3 404,881 758.964 4,598 9,472 While the reservoir rock appears to be continuous through­1949 4 474,612 I ,233 ,576 4,055 13 ,527 out the area of the accompanying map, the condition (high 1950 4 510,879 1,744,455 3 .930 17,457 degree of porosity and permeability) which occasions 1951 4 842 ,692 2,587 ,147 4,806 22 ,263 commercial accumulation appears to be quite local. 1952 5 908,526 3,495,673 3 ,786 26 ,049 146 IHOMANN FIELD Gaines County, Texas TYPICAL SECTION OF ROCKS PENETRA TED z 0 GAMMA RAY CU RVE ;:: ­ fi' ­ ­ a: ~~ ;:: " ·., [!i 3153 I­ t: '· 200 .......... 3053 CRETACEOUS ·.. ., 300 .-~ 2953 _,. ..:~";::.­ 2053 400 <:..,,. -=-=­ 500 2753 ·\> I-­ 600 '· 2653 ·' ( _1;_ --.--­ .t..-­ :E 700 2553 _J in " "' :;:· 900 2353 ~;-~ .. _..... ;::::. 2253 1000 .,: :.."> -_,, -­ '>. 1100 2153 uoo '­ 2153 · ~.. - 1200 <.-> ~; 2053 ·~--:.: "' _J 1300 "'~,__ 1953 z 'I: -?:i.i::.~"'.n'r=­---= ­ " ;:,~ 1400 ·-­ 1053 ·­ _.. "in ' .: .. 17 53 1653 - " ­ 200 0 2100 <' ,.:·: -~ ·:--: 1253 1153 "' 2150 110 3 ~ 0 E XPLANATION ---100-Con tour on top of Yo tes formation SCALE J:1 Elevotion of top of Votes for motion 0 2 3 • 5 6 7 -1 22 ' r--i ~ Gos well ff Dry hole HOMANN FIELD, Gaines County, Texas TYPICAL SECTION OF ROCKS PENETRATED 1§ >=.. ~ ~ ELECTRICS RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY DEPTH and SP RESIST IVITY ELEVATION _, Q a. ::>0 ~ 5 ELECTRIC S RADIOACTIVITY CURVES \i LITHOLOGY "' a: e GAMMA RAY DEPTH and SP RESISTIVITY ELEVATION ELECTRIC a RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY ordSPOEPTH RESISTIVITY ELEVAT IO N 5350 5400 0 0 8550 6600 5500 6700 -8647 5600 6600 w Q_ 3.. 0.. ::> <.? "' w a: 0 z.. z.. f,/) 5700 5800 5900 6000 -2547 -2647 -2747 6900 9000 9100 9200 -5847 -5947 z .. z.. :; >­"' z ~ Q_ a: 0 o . "0 a: a: 0"' 12,100 12,200 12,300 -~47 -9047 6100 6200 ... \8200 ·­ CISCO (VIRGIL) 11,100 -7847 ~Calcareous sandstone ~=-~-%J Shal e [;~Sil ty shale rµ:l Calcareous silty shale Brffi ~olomi te and dolomitic ~limestone ~Dolomite and ~sandy dolomite l~a ~~I Chert D Indicated rock, red 8300 6400 8500 8550 -s241 -s291 -8,247 -834 7 l~..:.;J Sandy shale ~Shole w11h ~inlerbedded limeslone ~Golcoreous shale with ~interbedded limeslon e § L imeslone OJ Indicated rock, block or 9roy D Indicated rock, siliceous LJlndicoled rock, fossiliferous ~ Gos production Show of oil HOOVER FIELD Crockett County, Texas D.E.DAUGHERTY, H.J.McCOOL and J.A.BODJO Geologists, Sinclair Oil and Gas Company, Midland, Texas May 7, 1954 LOCATION The Hoover field is in west central Crockett County about 25 miles west and slightly north of the town of Ozona, county seat, and is about 3 miles northeast of the Clara Couch field and 1i miles southwest of the Simpson field. It is in Secs. 1 and 2, Blk . 1, G.C. & S.F. R.R. Co. survey. METHOD OF EXPLORATION LEADING TO DISCOVERY Random drilling. DISCOVERY Queen: May 18, 1938; W. L. Bradley et al #1 A. C . Hoover. This well was drilled to total depth of 2,173 feet, where sulphur water was encountered . The well was plugged back to 1 ,440 feet and shot with 110 quarts of nitroglycerin from 1,417 feet to 1,436 feet . Through 2-inch tubing set at 1,438 feet, the well flowed at daily rate of 15 barrels of oil and about 2 ,000 Mcf of gas. No oil was marketed from this well until the second well in the field was completed in 1941. ELEVATION OF SURFACE At well locations: Highest , 2,295 ft. ; lowest, 2,249 ft. SURFACE FORMATION Undifferentiated Fredericksburg limestone. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 233 feet below the top of the San Andres formation. This penetra­tion was in the discovery well. The accompanying TYPICAL SECTION is based on the log of that well. NATURE OF TRAP Queen: Updip lensing on a structural nose. PRODUCTIVE AREA Queen and Field: Approximately 80 acres . THICKNESS OF RESERVOIR ROCK Queen: Feet, avg. From top to bottom 60 Net productive 15 LITHOLOGY OF RESERVOIR ROCK Queen: Gray-green, medium-grained, loosely cemented sandstone. CONTINUITY OF RESERVOIR ROCK Queen: The reservoir rock is a lens which extends only a very short distance beyond the boundary of a small area which includes the four productive wells. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Queen: Feet No free gas cap Elevation of top of oil 839 Elevation of bottom of oil 779 Relief 60 CHARACTER OF OIL Queen : Gravity, A .P .I. @ 60°F., 25.4° WATER PRODUCTION Queen: Very little water has been produced PRODUCTION HISTORY Year WELLS P R ODUCING at end of year F lowing P umping OIL P ROD UCTION (b ar r els) Year ly Cumulative 1941 1942 0 0 2 2 l ,839 4,455 l ,839 6 ,294 1943 1944 0 0 l '1 50 357 7 ,444 7,80 1 1945 1946 0 0 0 0 0 0 7 ,80 1 7 ,80 1 1947 1948 2 2 4,003 7 ,8 2 1 11,804 19 ,625 1949 1950 2 2 2 2 6,466 7 ,49 1 26 ,091 33,582 195 1 1952 2 2 3 7 ,447 6 ,27 4 41,029 47,303 1953 4 5 ,534 52,837 TYPICAL SECTION OF ROCKS PENETRATED I 11 141 41 I " !:2 /fc11 c 0 ,.FIELD I ::_> "' c~ ~ "-~ LI T HOLOGY ~ , d ::_>" I unff ~ c ARCHER §I~ 1~1~ oEPrH ELEv•Tio• ~l,f., 3 J3 ::_>"' I COUNTY .,. 0 22 4 9 Q) SCHOOL ::_> .,. 0 LANO 0 "'a: ( ( ., ~ 0 I p~OLDEST p ., ., 0 ID " UI J -., "' "' :< 0 100 2149 a: w 0 w J + i1 \ ..,,L.... 71 I a: ... 8 "' " w 0 I 200 0 w 0 z ::r: """ ,_ w 0 0 :3 0 0 19 49 x >­ 300 >­ ,_ < - " ~ _, M a:" ,_ Q_ ::::0 400 I I 1849 -I ~ ....... M L' t::l 1749 1 I I r 500 0 ...., ~I l.s;;;' 0 () 600 -~ (J) - 0 0 !I ~,., s:: ::::i SALADO -"<­ TANSILL >-3 1449 ~ (J) >< Q 00 '.: ~ 13 49 900 zl ~ a: " w Q_ w w "' Q_ a: " 0 -' I " 0 12 49 1000w,_ :::> I " ·EXPLANA TI ON !..? ~ ~ w > ktJh\A ~Dolomi te Sandstone a: z 11 49 1100 w > An hydrite ~Sha le m w - "' ~Limeston e So 11 ...... fill 1200 t0 49i 011 pr oduction ~ ;; -6500 z z ::' '--'-­ -7000 -7000 ­ vi "' i -7500 -7500 ­? - ....:.? ­ > -8000 "'0 -8000­ I­ - z -8500 "' ii: -8500­ ::> ..J u; 9000 ­ L--9500 HOR I ZONTAL SCALE PRE-CAMBRIAN THOUSAND FEET I I I 0 NE S RANCH FIELD, Gaines and Yoakum Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED SURFACE FORMATION : Ogallala formation of Pliocene series, 3 a. "' g "' 0 z "' ' ::i 11,200 ' oo -7501 ,. • 11,300 -7601 z 11,400 : -7701 U9\.\C \ 9\.oc\(. c-'2.'2. TO:f.r. 31 32 NEW =M=EXICO TEXAS 33 D D 25 PUBLIC SCHOOL LAND I BLOCK A-56 24 WHITEHORSE MAP sc"oo'­'-"'"o ,._-!>1 v,\.oc'I­,o 29 •Zt T e c •) t> s. \.· 1· 11.,. f>\.\(.. ••~ii,H -\0\ •l'IJ • ·~k.H ·~.H ............ \:. "'" . \ ,.~ '-'"' •J!..H • • 0 ...~~s<;O ~ .l"·"~~.•K \ •• ~-. ~ -~· •UI • •JS.,H •Ji,H O0 ·. . .. \ • • •K H •"\ : ,;f,,~•<'lk ":'k."\ ·-·.H ~ \ ·:•t •K.H .. eK • -+-roo \.,..~o c sc~oo/ . \ t>\)f>\. -V., v,\.oc\(. i.& i1 4 10 c KEYSTONE FIELD, Winkler County, Texas (Attach WHITEHORSE map) KEYSTONE FIELD, Winkler County, Texas NATURE OF TRAPS Yates Sand: Anticlinal folding is the primary trap-forming factor. Variation in degree of porosity and variation in permeability are also important trap-forming factors. Colby Sand: The productive area is related to the area of a pair of anticlinal domes, but the relationship merely suggests that convex folding may have con­tributed to trapping the oil. Surely variation in po­rosity and permeability contributed to trap-forming, but probably not to the extent suggested by the dis­tribution of Colby Sand wells; low porosity and low permeability preclude commercial production at some places where migration and accumulation occurred slowly during geologic time. Keystone Lime: While anticlinal folding appears to be the primary trap-forming factor, variation in degree of porosity and permeability evidently con­tributed to forming the trap. Holt Lime: The trap in the Holt Lime is due to anticlinal folding. Devonian and Silurian Lime: The trap in each of these reservoirs is due to (a) anticlinal folding, (b) termination of reservoir by faulting and (c) erosional truncation and sealing by overlying relatively im­pervious beds. The truncated area of Silurian Lime is much less than that of Devonian. McKee Sand, Waddell Sand and Ellenburger: The trap in each of these reservoirs is due to anticlinal folding and to termination of reservoir by faulting. THICKNESSES OF RESERVOIR ROCKS From top to bottom:* Feet Min. Max. Avg. _l_l_ Yates Sand 145 140 Colby Sand 30 180 11 7 Keys tone Lime 144 162 150 Holt Lime 51 66 58 Devonian 30 125 91 Silurian Lime 110 320 1 75 McKee Sand 105 112 110 Waddell Sand 60 100 80 Ellenburger 73 1,018 650 * The figures include minor partings but are exclusive of the thicknesses of major wide­spread non-productive beds within the reser­voir rocks. Net productive: Available data do not afford an adequate basis for estimating net productive thicknesses. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest stratigraphic horizon penetrated is at the base of the Ellenburger group; i.e., at the base of the sedimentary section. As indicated on an accompanying map, 40 wells have been drilled beyond this horizon and into pre-Cambrian granite. COMPLETION THEATMENTS Yates Sand: Both of the current Yates Sand gas wells were completed "natural"; one for production through open-hole and the other for production through perforations. Colby Sand: A few Colby Sand wells were com­pleted "natural" and a few were completed with light acid treatments; the majority, however, were com­pleted by shooting the open-hole section with 300 to 400 quarts of nitroglycerin. Keystone Lime: The Keystone Lime wells were completed by shooting the open-hole section with 400 to 500 quarts of nitroglycerin. Holt Lime: Acid treatment is a part of the regular completion procedure. Quantities of acid have ranged from 500 gallons to 17,500 gallons; the normal quantity is from 3, 000 gallons to 10,000 gallons. Devonian: Acid treatment is apart of the regular completion procedure. Quantities have ranged from 500 gallons to 19,500 gallons; the usual quantity is 5,000 gallons. Silurian Lime: Many wells have been completed "natural"; where acid was used, the quantity was small, generally 1,000 gallons to 4,000 gallons. McKee Sand: The discovery well was completed "natural". The standard completion procedure in­cludes a light acid treatment (1,000 -2,000 gallons) and then hydraulic fracturing with 5,000 to 10,000 gallons of liquid. Waddell Sand: The regular completion procedure has been to acidize with 2,000 gallons of acid and then to hydraulic fracture with 4, 000 gallons of liquid; however, the reservoir rock in one well was shot with 55 quarts of nitroglycerin and thenhydrau­lically fractured with 1,000 gallons of liquid. Ellenburger: Most of the Ellenburger wells were completed "natural". Such of the wells as have been subjected to artificial stimulation were given a light acid treatment (2,000 -4,000 gallons). KEYSTONE FIELD, Winkler County, Texas TYPICAL SECTION OF ROCKS PENETRATED ELECTRIC CURVES "' " "' LITHOLOGY o RESERVOIR :i DESIGNATION -' DEPTH ELEVATION (5 930 0 0 0 830 " :I: ..J " u 0 " "' 730 630 530 (/) 2500 w .... ,.. " 2600 330 2700 230 2800 130 "' a: w w "' a: > a: 2900 30 0 z :I: w w ~ "' 3000 -70 .... :I: ;< ~+>=<---1-__,= z w w :;) 0 "' ~ 3500 a. al ,.. z :;) a: " 3600 " "' «1--+-+-~~+--t=z~'*-~~~~~-:..i " 0 3700 -7 70 a:" w :;) 3800 -870 a. "' 3900 -970 0 4000 -1070 w a:: 4100 -1 170 D z < 4200 z < 4300 44 00 -1470 4500 -1570 4600 -1670 4700 -1770 ~ w a: 0 ..J "' -2170 D 0: "' a: 0 ".._ ""' w w .... "'a:w ,.. "'"' D a: z " z L.iJ ~ ~ I-~ McKee Sand { ~ :I: > -6770 0 "' :::; ~r-+-----:Tl- Waddell Sand 0 -6970 z "' 10000 -7070 ~ r 10100 -7171 10200 -7270 a: Ellenburger ~ w 10300 "'a: -7371 :;) al z 104 00 w -747r ..J ..J w 10500 -7570 l -7670 PRE-CAMBRIAN c NOTE: The above TYPICAL SECTION is based on a composite of the logs of several wells . This depic tion of the complete st ratig r aphic section results in entering excessive depths and elevations for the lower stratigraphic uni ts . § Within the area of the Keystone field, there are several wells which produce oil and gas from a reservoir in the Seven Rivers formation. Such wells are treated by the Railr oad Commission, and by reporting agencies generally, as in the Kermit field . That practice is followed i n this paper. The area of the Kermit field overlaps with the area of the Keystone field as indicated on the accompanying Whitehorse m ap. §§ The single productive zone in the near-by South Keys tone field is in the Clear Fork group about 250 feet below the base of the Tubb member. EXPLAN ATION §oolomite ~Limestone f~~~~~~~~~l Shale D Sandstone l8:d Salt D.Anhydrite + z a:: 5200 -2270 z ~ ,.. 0 " w w 1: ::1 Chert ~Granite 8 600 -5670 u " ..J ..J 0 ~ u .... > 0 5300 -2370 z 0 ~ Gas production tJ.-Show of gos 0 a: 8700 -5770 5350 -2420 0 " • Oil production o Show of oil KEYS TONE FIELD, Winkler County, Texas LITHOLOGY OF RESERVOm ROCKS Yates Sand: This reservoir rock consists of intermingled beds of sandstone, shale and dolomite with traces of salt at many places. The upper por­tion is primarily a fine-grained sandstone in which frosted quartz grains commonly occur about 20 feet below the top. The greater portion of the sand­s tone is red and is highly argillaceous; it varies in color from gray to red, depending on the amount of shale present. The permeability of this reservoir rock has been differentially decreased by differential compaction. Permeability is higher at structurally low locations than it is at structurally high locations. The sandstone grades updip into shales and anhydrite; dcwndip, it is more calcareous. Colby Sand: This reservoir rock is comprised of gray to tan, fine-to medium-grained sandstone with varying amounts ofdolomite, anhydrite and anhydritic dolomite. Commercial production comes almost exclusively from the sandstone; the dolomite yields some oil locally although generally its permeability is too low for commercial production. A reason for this being one of the better shallow reservoirs is that the sandstone has favorable intergranular poros­ity with very little cementing material. Differential compaction has affected the permeabilityof the sand­stone so that permeability is higher at structurally low locations than it is at structurally high locations. Keystone Lime: This reservoir rock is composed chiefly of buff to brown dolomite with small amounts of anhydrite and sand scattered throughout. It in­cludes some cream colored lithographic dolomite which is not productive. The productive dolomite is dense to finely crystalline. The productivity of the reservoir rock is determined by the ratio ofpro­ductive dolomite to lithographic dolomite, which ratio is quite variable throughout the area of the field. Permeability is higher at structurally low locations than at structurally high locations. The low perme­ability at high locations has occasioned the abandon­ment of many wells for production from this reser­voir; some of such wells have been re-completed for production from other reservoirs. Holt Lime: This reservoir rock is comprised of sand, dolomite and sandy dolomite; silty dolomitic sand at the top and grading downward into sandy dolomite and then dolomite. The sandis fine-grained, silty, and is tightly cemented. Its color ranges from gray to tan, depending on the amount of cementing material present. The dolomite is dense to finely crystalline and ranges in color from cream to brown. Most of the oil yielded by this reservoir comes from the dolomite portion of the reservoir rock. The more productive wells are located where the percentage of dolomite is abnormally high. Devonian: This reservoir rock is composed of limestone, chert and cherty limestone. The lime­stone varies in texture from granular to coarsely crystalline and, in color, from white to cream or light tan. It is a clean limestone, in general, but near its base itis slightlyargillaceous and siliceous. Varying amounts of chert are present throughout the reservoir rock, with the greatest amount near the top. The chert is white to bluish-white, calcareous, and is associated with varying amounts of white crys­talline interbedded limestone. Extensive fracturing connects the reservoir from top to bottom and pro­vides favorable porosity and permeability. Vuggy and cavernous porosity has developed along the fracture planes. In a belt around the area where the Devonian has been removed by erosional truncation (indicated on an accompanying map), the porosity and permea­bility are abnormally low, probably due to cementa­ tion of the fracture zones during the time when that portion of the reservoir rock was near the surface. Silurian Lime: This reservoir rockis a coarsely crystalline limestone, white to light buff with a pink cast in many places. Minor amounts of translucent milky white chert and thin partings of green shale occur throughout. Porosity is of the intercrystalline type commonly associated with coarsely crystalline limestone and dolomite. There is some evidence of fracturing; fracturing, together with resultant vuggy and cavernous porosity, appears to account for the porosity being slightly greater than normal for such limestone. In several local areas, permeability is too low for commercial production, apparently because of cementation in the fracture zones. McKee Sand: The McKee Sand is a very clean white sandstone, nearly free of shale. Occasionally it has a light green cast due to discoloration by green shale. Grain sizes vary from fine to coarse. Inter-granular porosity is almost intact with only negligible decrease by calcareous cementation. Waddell Sand: The Waddell Sand is a medium to coarse, rather hard, white sandstone, cemented to somedegreeby calcareous materialandcontaining a few thin beds of gray and green shale. Ellenburger: The Ellenburger consists of dolo­mite with varying amounts of sand, chert and gray shale partings. The sandy phase is in the upper portion; the cherts and gray shales are mainly limited to the lower portion. The dolomite itself ranges from very finely crystalline gray and tan dolomite to fairly coarsely crystalline white and tan dolomite. Porosity and permeability are generally highly favorable, due almost entirely to fracturing which extends from top to bottom of the reservoir. Intergranular porosity is very low and solution porosity .such as is common in limestones and dolo­mites is rare; however, there is some solution porosity although it is not extensive. A few vugs lined with calcite crystals have been found. At locations where the reservoir rock is not fractured, including some structurally high locations, porosity and permeability are too low for commercial pro­duction, even after repeated acid treatments. KEYSTONE FIELD , Winkler County, Texas PRODUCTIVE AREAS Acres P r oductive Depl eted a rea or inactive Yates Sand 60 20 Colby Sand 7, 396 583 Keys tone Lime 2,940 540 Holt Lime 4,400 120 Devonian 4, 360 840 Silurian Lime 2,080 160 McKee Sand 1,640 0 Waddell Sa nd 640 320 Ellenburger 6, 160 820 Keystone field 14,685 585 Currently producing 40 6,863 2, 400 4,280 3,520 1,920 1,640 320 5,240 14, 100 SECONDARY RECOVERY In July, 1952, a water injection program was begun in the Colby Sand reservoir and is proving to be very successful. As indicated by data presented under PRODUCTION HISTORY, the decline of pro­duction was changed to an increasing rate of produc­tion. The number ofinjection wells and the quantities of water injected are reported below: INJ E C TION WATER INJEC TED WELLS (barrels) at end of year Yearly Cumulative Colby Sand 1952 7 1,096,000 1,096,007 1953 31 5, 71 4,072 6,8 10, 0 79 1954 37 7, 674, 812 14,484,89 1 CONTINUITY OF RESERVOIR ROCKS Yates Sand: The reservoir rock appears to be continuous throughout the area covered by the accom­panying Whitehorse m~p. Although porosity and permeability are too low for commercial production throughout most of that area, it appears likely that permeability adequate for migration, in geologic time, of reservoir fluids (particularly, gas) is continuous throughout that area. Colby Sand: The reservoir rock is continuous throughout the area covered by the accompanying Whitehorse map. However, porosity and perme­ability adequate for commercial production are con­tinuous throughout only a portion of that area; the productive area is indicated by the distribution of Colby Sand wells as shown on the Whitehorse map. Keystone Lime: The productive area of this reservoir rock is indicated by the distribution of Keystone Lime wells as shown on the accompanying Whitehorse map. The reservoir rock is definitely continuous throughout that area. It is probably con­tinuous throughout a much more extensive area. While rocks at this stratigraphic position are of about the same lithologic character throughout an area considerably larger than that covered by the accompanying Whitehorse map, it is known that westward on the east flank of the Delaware basin, instead of dolomite, there are sandstones and shales at this stratigraphic position. Available data do not afford an adequate basis for estimating the extent of the particular rock unit which 'is productive in this field. Holt Lime: The productive area of this reservoir rock is indicated by the distribution of Holt Lime wells on the accompanying Glorieta map. It is cer­tainly continuous throughout that area, but its further extent is not determinable from available data. The Glorieta formation, of which Holt Lime is a member, i s continuous throughout much of West Texas and Southeastern New Mexico, but the particular rock unit which yields oil in the Keystone field probably does not extend far beyond the productive area. Rocks at this stratigraphic position grade westward into dolomite and eastward into coarser sand with quartz and chert pebbles. Devonian: The continuity of this reservoir rock is interrupted by a major thrust fault and by erosional truncation, as shown on the accompanying Devonian map and the accompanying cross section; otherwise, the reservoir rock is continuous and of about the same general character throughout the area covered by the accompanying Whitehorse map. Northward, the limestone grades into light-colored dolomite with less chert. Silurian Lime: The continuity of this reservoir rock is interrupted by a major thrust fault and by erosional truncation in a small area at the apex of the anticlinal fold; otherwise, the reservoir rock is continuous and of about the same general character throughout the area covered by the accompanying Whitehorse map. Northward, the limestone grades into dolomite and the percentage of chert increases. McKee Sand, Waddell Sand and Ellenburger: The continuity of each of these reservoir rocks is inter­rupted by a major fault; otherwise each is continuous and of about the same character throughout the area covered by the accompanying Whitehorse map. The stratigraphic equivalent of each is recognized throughout a large portion of West Texas and South­eastern New Mexico, and it is probable that conditions favorable for migration of reservoir fluids are gen­erally continuous in each throughout that region except for minor local areas. ........ CJ) N ~ "~Q sc\'\oo'-'-'" ~. -ri M --< Ul >--3 0 z M '"""rj ........ M l' tJ ~ s· :>;"" ro ., 0 0 c ::J ~ _,15, Elevation of contoured horizon >--3 ~ H Productive reserv oir o Oldest zone penetrated, nonproductive ~ (Jl• Oil well Abandoned oil well * Gos well , previously produced oil Well drilled too product ive zone deeper than Hott Lime hos not p~oduced from Holt Lime ff Dry hole • \::o Discovery PRODUCTIVE RESERVOIR and OL DEST ZONE PENETRATED K Keystone Lime s Silurian Lime H Holt Lime M McKee Sand o Oevonion E Ellenburger H,~ Producing from Holt Lime, abandoned in Silurian Lime This mop shows only such wells os penetrated the contoured horizon. ~ tT:I .-.::: N C '()) ~\}~\...\ -:3 0 z tT:I "Tj ....... tT:I r-t::J ~ ::r ~ ,_. (J) .., EXPLANATI ON 0 0 c :::1 ...... • 00 , Elevation of contoured • D Productive r eservoir ::< ~ Oldest zone -:3 • Oil well ~ * Gos we ll, previously produced Q t/l Well drilled hos not produced p Ory hole PRODUCTIVE RESERVOIR H Hol t L•me D Devonian s S1lur1on Lime O,f;. Producing from Area where F7l LU This mop penetrated ....... m w KEYSTONE FIELD, Winkler County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES Yates Sand, Colby Sand and Keystone Lime: Irregularities due to variation in porosity and permeability make it impractical to endeavor to estimate elevations of fluids in these reservoirs. McKee Sand and Waddell Sand: The only hydrocarbon in each of these reservoirs was in gaseous state prior to reduction of pressure occasioned by production. Gas and condensate are produced from each of these reservoirs, but it is not practical to endeavor to estimate the elevations at which these fluids occur in the reservoirs. Available data do not afford an adequate basis for estimating the elevation of either upper or lower extent of gas in either reservoir. Holt Silurian Lime Devonian Lime Ellenburger Elevation of top of gas, feet -1,526 -4,277 No free -5,887 Elevation of bottom of gas, feet -1,735 -4,400** gas cap -6,565 Relief, feet 209 123** indicated 678 Elevation of top of oil, feet -1, 735 -4,400 -4,401 -6,565 Elevation of bottom of oil, feet -1,800* -5,500+ various -7,150§ Relief, feet 65! 1,100+ ? 585§ * The elevation of the oil-water contact in the Holt Lime reservoir is irregular; generally it is about -1,800 feet in the upper zone and about -2, 100 feet in the lower zone. ** The gas cap in the Devonian reservoir, relatively small at time of Devonian discovery, has enlarged as a result of gas coming out of solution due to decline in pressure as oil has been produced. The gas-oil contact is now at an elevation of about -4,400 feet. § The oil-water contact in the Ellenburger reservoir has risen about 150 feet from its position at -7, 150 feet at the time of the Ellenburger discovery. Correspondingly, the relief of the oil column is now only about 435 feet. RESERVOm ENERGY Yates Sand: The expulsive force is due to expan­sion of the gas. Colby Sand: The expulsive force is due primarily to expansion of gas as it comes out of solution in oil. There are numerous small areas where there is free gas, but there is no extensive gas cap. Keystone Lime: Gas coming out of solution as pressure declines, combined with an expanding gas cap, provides most of the expulsive force for this reservoir. Water drive is effective, but the influx of water has not been at sufficient rate to maintain reservoir pressure as it was at time of discovery. A few structurally high wells produce gas only. Holt Lime: The major expulsive force is due to expansion of gas as it comes out of solution in oil; water drive contributes, but the rate of the bottom­hole pressure decline indicates that gas expansion is the major expulsive force. Devonian: Expansion of gas as it comes out of solution as pressure declines, combined with an expanding gas cap, provides the expulsive force for this reservoir. The enlargement of the gas cap and the lowering of the gas -oil contact resulted in one oil well being re-completed in 1951 as a gas well. Silurian Lime: Expansion of gas as it comes out of solution provides the expulsive force for this reservoir. There is no free gas cap. No water intrusion has been observed. McKee Sand and Waddell Sand: The expulsive force in each of these reservoirs is due to the ex­pansion of the gas. The decline in pressure which permits expansion of the gas also results in retro­grade condensation. Ellenburger: An effective water drive accounts for most of the expulsive force. Water has en­croached at a fairly uniform rate. The oil-water contact moved up from its position at the elevation of -7,150 feet at time of discovery to about -7,000 feet as of January l, 1955. Although there was a gas cap, there was no noticeable lowering of the gas-oil con­tact during the period when reservoir pressure was reduced from the initial pressure to the bubble-point pressure. The bottom-hole pressure was 4,283 psi. at time of discovery and 3, 195 psi. on January 1, 1955; it reached the bubble-point pressure (4, 230 psi.) during September 1945. These data suggest that water drive has been very effective and that the effect of energy from the gas cap has been minor. KEYSTONE FIELD, Winkler County, Texas RESERVOIR TEMPERATURE and PRESSURE and OIL SAMPLE DATA Original reservoir temperature, °F. Original reservoir pres sur e , psi. 450 1, 393 l , 573 2,130 3, 338 3, 377 4,128 4, 128 4,283 Gravity of oil or conds., A.P.I. @ 60° F . Gas 37 33. 2 39.5 36.2 39.7 58.2 62. l 44.2 Sulphur content of oil or condensate, % Gas 0.78 0.80 0.56 0.44 0.49 Nil 0.05 0. 14 Bubble point, psi. Gas l, 393 1,573 2, 130 3, 338 3, 377 Gas Gas 4,230 Solution gas -oil ratio, cf/bbl Gas 485 580 850 655 1, 178 Gas Gas 1, 311 Volume factor, s urface: reservoir Gas 1.26 1. 3 7 1.50 1. 31 1. 61 Gas Gas 1.68 F or oil analyses see: Railroad Commiss ion of Texas Analyses of Texas Crude Oils (1940), pp. 33 and 63 U.S. Burea u of Mines Laboratory reference No. Tabulated Analyses of Texas Crude Oils . T. P . 607 (19 39) Group 2 Item Analyses of Crude Oils from Some West Texas Fields. R. I. 3744 (1944) Page Analyses of Crude Oils from 28 3 Important Oil Fields of the United States . R. I. 4289 (1948) Item Analyses of Crude Oils from Some West Texas Fields . R . I. 4959 (195 3) Item 37172 (Permian) 60 21 222 46087 (Ellenburger) 33 46105 (Silurian) 32 46108 (Devonian) 3 1 CHARACTER AND UTDJZATION OF GAS Gas produced in this field is of a wide range in character. Some gas has been produced from each of the nine reservoirs, three of which (Yates Sand, McKee Sand and Waddell Sand) originally contained gas only and two of which (Holt Lime and Silurian Lime) have produced gas from oil wells only (i.e., as casinghead gas); and, of course, there is a corres­ponding variation in the character of the gas. Unfortunately, no analysis of any of the gas is available for inclusion in thi s paper. Only the small quantity of gas which has been pro­duced from the Yates Sand has been classified as dry gas. The gas from the other reservoirs is of various degrees of richness and the sulphur content is various. Two gasoline plants and one carbon-black plant are located in the field and process all the gas available for utilization except for small quantities used in drilling and lease operations. Cabot Carbon Company began processing gas through.its carbon-black plant in June, 1937, and within the same year it initiated operations at its gasoline plant. In August, 1948, the Sid Richardson Gasoline Corporation commenced operation of its gasoline plant. Except for minor incompleteness, the following tabulation reports the quantities of the principal products (carbon-black and gasoline) of the three plants; data relative to the other products of the plants are not readily available. UNDERGROUND STORAGE A storage well was drilled near the Sid Richardson gaso­line plant in October, 1949. This well, Richardson & Bass #68 J.B. Walton, the first well drilled for underground storage in West Texas, was drilled to the total depth of 822 feet and completed for use in storing liquified petroleum gas in porous dolomite in the Rustler formation, Ochoa series. The storage zone is approximately 10 feet thick, has sufficient closure to prevent escape of the stored products and has excellent porosity and permeability. OP ERATIONS OF GAS PROCESSING PLANTS CARBON-BLACK GASOLINE Gas Carbon­ Gas Gaso­ burned black processed line Year (Mcf) (pounds) (Mcf) (ba rrels ) 1937 ? ? ? ? 1938 ? ? ? ? 1939 10, 509,080 12, 58 1, 550 10, 663, 840 94,718 1940 ? 8,354,442 ? 137,970 1941 ? 17, 196,020 ? 279,828 1942 ? 12,466,078 ? 266, 306 1943 ? 13, 328, 559 ? 235, 125 1944 ? 11,880,134 ? 222, 549 1945 11, 311 , 102 16,580, 785 ? 323, 4 74 1946 ? ? 20,826,432 38 1,91 1 1947 15,007,442 24, 703,846 19, 149,725 344,925 1948 15,5 15,566 25,8 18,265 22, 189, 704 441, 717 1949 12, 8 10, 252 23, 762, 755 34,948,207 673, 385 1950 12,892, 117 26, 454, 050 35,553, 747 619,346 1951 13, 244,380 26,484,400 40, 643,980 609,085 1952 12, 075,460 24,482,257 35, 8 18,870 602,697 1953 12,035,419 25, 124, 88 0 4 1, 546,928 740,536 1954 11,037, 722 24, 704, 200 44, 823,943 686, 826 , ........ \\ 10 (J) p TO 101~1 p.~Q sc~oo\... \... /~ ,., / e\...oc"-11 sc~oo\... N ~ue\...\C e\...oc"-11 p fDUZS B \...p.~Q I EXPLANATION ,, ----5100 ---Contour on top of -------4200-----Contour on eroded Fusselman -Hn Elevation of contoured horizon ~ S Productive reservoir E Oldest zone penetrated, nonproductive • Oil well * Gos well, previously produced oil Well drilled too productive zone deeper t han S iiu rian Lime ; hos not produced from Silurian Lime JI Ory hate • LJ1 Discovery PRODUCTIVE RESERVOIR and OLDEST ZONE PENE TRATED H Holl Lime S Silurian Lime w Waddell S and o Devonian M McKee Sand E Ellenburger 0,3_ Producing from Oevon1on, abandoned in Silurian Lime EB Upper portion of Fusselman removed by pre-Permian erosion SCALE 0 4 6 8 This map st'lows only such wells as penetrated the contoured horizon . THOUSAND FE ET (J) ~ M ....::: U) o-3 0 z M >-rj ....... M L' t1 ~ s· ?<;"' ct .., 0 0 c ::i ...+ '-<: w Ul ; ORDOVICIAN SI LU RIAN ~ M >-<: N '(/) ~\10'-'c 0'-oC~ 11 ~ 0 z M "Tj ,._ 11 1 M l' ti \..p.~Q ~ s· ~ ro .., 0 0 c ,; ::1 -< -1100----Contour on lop of Ellenburger group _Elevot1on of contoured horizon 6211 1 ~ E 01:~0s~u~~~v: ;:::,rr~~~d, nonproductive Oil well Abandoned oil well r ¢ Gos well * Gos we lt, previously produced oil • 011 and gos well , produces oil and gos from separate reservoirs P Dry hole • ~Discovery PRODUCTIVE RE SERVOIR and OLDEST ZONE PENETRATED w Waddell Sand s Silurian Lime E Eltenburger M McKe e Sand o Devonian P Pre-Cambnon M,g_ Producing from McKee Sand, abandoned in Ellenburger ME Dual completion, producing from McKee Sand and Etlenburger SCALE This mop shows only such wells as 0 4 penetrated Ordovician rocks. ......... THOUSAN 0 FE ET m 'I KEYS TONE FI ELD, Winkler County, Texas KEYS TONE Fl ELD, Winkler County, Texas PRODUCTION HISTORY WELLS PRODUCING at end of year OIL GAS OIL PRODUCTION (barrels) PRODUCTION FROM GAS WELLS GAS LIQUID HYDROCARBONS (Mcf) (barrels) Year Flow. Pump. Total Yearly Cumulative Yearly Cumulative Yearly Cumulative Field totals : 1929 .... 0 ..... 0 . . . . 0 . .... ? .. . ...•. . .... 0 ... .... . ... 0 ....... .. ... ? .. . ....... ? •••....... 0 . ... . . .. . 0 19 30 ? ? 1 ? ? ? ? ? 0 0 1931 ? ? 2 ? ? ? ? ? 0 0 1932 . .. . ? .. .. . ? . 2 .•... ? ............. ? ...... ..... ? . ......... . . ? ...... .... ? .......... 0 ...... . .. 0 1933 ? ? 2 ? ? ? ? ? 0 0 1934 ? ? 3 ? ? 5x,xxx ? ? 0 0 1935 ...• ? ... . . ? .•..13 ..... ? ........111,xxx ..... 16x,xxx ............ ? .••.•. . ... ? . ......... 0 ... ... ... 0 1936 ? ? 35 ? 520,xxx 68x,xxx ? ? 0 0 1937 ? ? 99 2 1,173,xxx l, 85x,xxx 872,745 872,745 0 0 1938 ..•. ? ... . . ? .•.157 .... . 8 ...... 1,207,xxx .. .. 3, lxx,xxx ... ..3, 101, 120 ... 3,973,865 .. .. ... : .. 0 ......... 0 1939 202 11 21 3 8 1,451,xxx 4,5xx,xxx 3,110,408 7,084,273 0 0 1940 212 26 238 8 1,649,197 6,2xx,xxx 3,204,991 10,289,264 0 0 1941 ...248 .... 73 . .. 321 . .... 5 .... .. l , 744, 733 ....7,9xx,xxx ... ... 198, 715 .. 10,487,979 ..... .. ... 0 ......... 0 1942 284 81 365 l , 703,509 9,6xx,xxx 40,499 10,528,478 0 0 1943 264 105 369 3 l ,742,750 ll,4xx,xxx 379,295 10,907,773 0 0 1944 ...272 ... 131 ... 403 ..... 7 ...... 2,455, 799 ...l3,8xx,xxx ...... 971, 779 .. 11, 879,552 . ..... ... . 0 . .. . ... . . 0 1945 316 193 509 7 6,805, 761 26,6xx,xxx 1,040, 180 12,919, 732 0 0 1946 440 162 602 5 15,537,577 36,2xx,xxx 457,932 13,377,664 0 0 1947 •..541 ... 171 ... 712 .. 4 or 5 ....14, 755, 717 ...50,9xx,xxx ... .... 76,614 .. 13,454,278 182 . . ... . . 182 1948 584 223 807 10 to 13 14,561, 195 65,5xx,xxx 206,053 13,660,331 2,576 2, 758 1949 545 268 813 9 10,838,968 76,3xx,xxx 3,855,600 17,515,931 83, 102 85,860 1950 ...453 . . . 40 3 ... 856 .. ll to 14 11,030,217 ...87,3xx,xxx . ....l,974,137 .. 19,490,068 .... . 25,961 .... lll,821 1951 4 37 438 875 14 to 17 12, 676,832 100,0xx,xxx 1,917,445 21,407,513 21,914 133,735 1952 417 447 864 16 to 21 11,187,152 lll,2xx,xxx 2,532,800 23,940,313 ll,265 145,000 1953 ...399 ... 466 ... 865 . . 32 to 37 .. 10,548,662 .. l2l, 8xx,xxx 6,886,559 .. 30,826,872 .... 208,044 353,044 1954 389 476 865 49 to 54 8,939, 78 1 130, 7xx,xxx 15, 71 8, 731 46,545,603 398,251 751,295 1955* 381 478 859 56 to 61 8,2 14, 886 138,9xx,xxx 21,857,944 68,403,547 370,426 1,121,721 Yates: See a following page. (Note that the usual presentation in stratigraphic order is not followed.) Colby Sand: 1930 ? ? 0 ? ? 0 0 0 0 1931 ? ? 2 0 ? ? 0 0 0 0 1932 ..•.. ? • . • • . ? • • • • . 2 . . . 0 . . . . . . . . . . • . . . ? .•••....... ? ..•.....•... 0 .......... 0 .......... 0 . . . . . . . . . 0 19 33 ? ? 2 0 ? ? 0 0 0 0 1934 ? ? 3 0 ? 5x,xxx 0 0 0 0 1935 ..... ? .. . .. ? ..... 4 ... 0 . . ... .. .. 14,xxx ... . .. 6x,xxx ...... · .. · ·. 0 .......... 0 .. . .. ..... 0 . ... ..... 0 1936 ? ? 11 0 lOx,xxx 17x,xxx 0 0 0 0 1937 ? ? 48 0 37x,xxx 54x,xxx 0 0 0 0 1938 ..... ? ..... ? .... 91 ... 3 ........ 60x,xxx .... l,lxx,xxx ...... 546,347 .... 546,347 .......... 0 .. ....... 0 1939 128 9 137 3 83x,xxx 2,0xx,xxx 1,011, 752 1,558,099 0 0 1940 136 18 154 3 981, 798 3,0xx,xxx 1,344, 120 2,902,219 0 0 1941 .. 181 .... 49 ... 230 ... 0 ....... 1,187,174 ... -4,lxx,xxx · · · · · · · 13,643 · · · 2,915,862 · · · · ...... 0 ....... . . 0 1942 204 57 261 0 l,249,523 5,4xx,xxx 0 2,915,862 0 0 1943 192 73 265 0 l,219, 785 6,6xx,xxx 0 2,915,862 0 0 1944 .. 186 .... 91 ... 277 ... 0 ....... l,368,637 .... 8,0xx,xxx · · · · · · · · · · · · 0 · · · 2,915,862 · · · · ·. · · ·. 0 ......... 0 1945 183 133 316 0 1,395,928 9,4xx,xxx 0 2,915,862 0 0 1946 203 99 302 0 1,281,062 10, 7xx,xxx 0 2,915,862 0 0 1947 .. 211 ... 103 ... 314. l or 2 ..... 1,084,088 ...11, 7xx,xxx · · · · · · · · 4,002 · · · 2,919,864 · · · · · · .... 0 ......... 0 1948 198 131 329 2 to 5 1,036,286 l2, 8xx,xxx 45,309 2,965,173 0 0 1949 163 155 318 0 851,637 13,6xx,xxx 0 2,965, 173 0 O 1950 ... 91 . .. 257 ... 348. 2 to 5 .... . .. 863, 710 .. -14,5xx,xxx .. ..... 30,446 ... 2,995,619 .. ..... . .. 0 ......... 0 1951 75 278 353 3 to 6 720,421 15,2xx,xxx 38,303 3,033,922 0 0 1952 65 284 349 4 to 9 607,895 15,8xx,xxx 93,587 3, 127,509 0 0 1953 . .. 59 ... 300 ... 359. 3 to 8 ....... 991,660 .. 0 l6,8xx,xxx · · · · · · · 76,041 · · · 3,203,550 · · · · ......o ......... 0 1954 47 324 371 3 to 8 1,359,668 18,2xx,xxx 42,382 3,245,932 0 0 1955* 44 327 371 3 to 8 1,017,532 19,2xx,xxx 35, 759 3,281,69 1 0 0 * 1955 data added by amendment. KEYS T 0 NE f·I ELD, Winkler County, Texas PR 0 D UC TION HIS TO RY (Continued) WELLS PRODUCING OIL PRODUCTION PRODUCTION FROM GAS WELLS at end of year (barrels) GAS LIQUID HYDROCARBONS OIL GAS (Mcf) (barrels) Year Flow. Pump. Total Yearly Cumulative Yearly Cumulative Yearly Cumulative Keystone Lime: 1935 . . .• . ? ..• . ..? .•.. • 9 ... 0 ...... . .. 97,004 ...... 97,004 ..•.....•.. . 0 .......... 0 ...... .... 0 ........ 0 1936 ? ? 24 0 418,xxx 515,xxx 0 0 0 0 1937 ? ? 51 2 801,xxx 1, 316,xxx 872,745 872, 745 0 0 1938 ..... ? • . .. ·? 66 .. . 4 .... . ... 605,xxx l,92x,xxx .... 2,534,300 .. . 3,407,045 .......... 0 ... .. . .. 0 1939 74 2 76 4 621, 773 2, 54x,xxx 2,083, 122 5,490,167 0 0 1940 76 8 84 4 667,399 3,2lx,xxx 1,824, 159 7,314,326 0 0 1941 ... 67 . ... 24 .... 9 1 ... 4 . ....... 557,559 3,77x,x.xx ....... 50,871 ... 7,365,197 .......... 0 ........ 0 1942 80 24 104 45 3,986 4,22x,xxx 40,499 7,405,696 0 0 1943 70 32 102 2 475,192 4, 70x,xxx 329,989 7, 735,685 0 0 1944 ... 64 .. .. 40 ....104 5 ........ 435,191 ... 5,13x,xxx .. .... 824,732 ... 8, 560,417 .......... 0 ...... .. 0 1945 50 60 110 5 400, 126 5,53x,xxx 932,568 9' 492, 985 0 0 1946 52 58 110 4 380, 003 5,9lx,xxx 430,684 9,923,669 0 0 1947 ... 47 .... 56 .. . . 103 ... 2 ........ 301,947 6,2lx,xxx ....... 28,801 .. . 9,952,470 ....... . 182 ...... 182 1948 48 65 11 3 3 301,089 6,52x,xxx 11 3,874 10, 066, 344 401 583 1949 41 74 11 5 4 262,854 6, 78x,xxx 276,893 10,343,237 157 740 1950 ... 24 .... 91 . . ..115 •.. 4 ........ 254,492 ... 7,03x,xxx ...... 429, 718 .. 10, 772,955 . . ...... 164 .. ....904 1951 20 98 118 4 238,415 7,27x,xxx 280, 232 11 ,053, 187 213 1, 11 7 1952 19 97 116 4 191,219 7,46x,xxx 328,469 11,381,656 224 l, 341 1953 ... 19 .... 98 ....117 ... 4 ........ 169,493 ... 7,63x,xxx .... .. 380,593 .. 11,762,249 ........ 126 .... 1,467 1954 21 96 117 3 157, 147 7,89x,xxx 303, 306 12,065,555 205 1,672 1955* 21 97 118 3 151,200 7,94x,xxx 232,872 12,298,427 230 1,902 Holt Lime: See following page. (Note that the usual presentation in stratigraphic order is not followed.) Devonian: 1946 6 0 6 0 113,476 113,476 0 0 0 0 1947 ....32 ..... 3 . ... ,35 ... 0 ........ 686, 98 7 ..... 800, 463 ............ 0 .. ........ 0 .......... 0 ........ 0 1948 61 10 71 0 1,554, 756 2,355,219 0 0 0 0 1949 64 15 79 0 1,373,958 3, 729, l 77 0 0 0 0 1950 .. ,,73 .... 18 .. ...91 .. . 0 ....... 1,430,969 ... 5,160,146 . .... . ...... o .......... 0 .......... o ........ o 1951 80 23 103 1 1,685,600 6,845, 746 7,884 7,884 14 14 1952 79 25 104 1,301,906 8, 147,652 56,244 64,128 69 83 1953 .. ..72 .... 27 ... ,,99 ... 2 ........ 915,467 ... 9,063,119 ...... 109, 027 .... 173,155 ......... 36 ...... 119 1954 69 21 90 1 644,525 9, 707,644 9,317 182,472 5 124 1955* 66 19 85 504, 713 10,212,357 52,574 235,046 36 160 Silurian Lime: See following page. (Note that the usual presentation in stratigraphic order is not followed.) McKee Sand: 1948-1950 0 0 0 0 0 0 0 0 0 0 1951 0 0 0 0 0 30, 456 30,456 1, 710 1,710 1952 0 0 0 0 0 184, 745 215,201 1, 798 3,508 1953 .. . . 0 ..... 0 ..... 0 .. 16 ... .. .. . .. .... 0 ........... 0 . .. . 4,909, 792 .. 5, 124,993 •....197,284 .. 200, 792 1954 0 0 0 38 0 0 14,447,408 19,572,401 392,497 59 3, 289 1955* 0 0 0 45 0 0 20, 626, 023 40, 198,424 361,981 955,270 Waddell Sand: 1948 0 0 0 5 0 0 46,870 46,870 2, 175 2, 175 1949 0 0 0 5 0 0 3,578, 707 3,625,577 82,945 85, 120 1950 .... 0 ..... 0 ..... 0 ... 5 .............. 0 .......... 0 ..... 1,513,973 ... 5,139,550 25, 797 .. 110,917 1951 0 0 0 5 0 0 1,560,570 6, 700, 120 19,977 130, 894 1952 0 0 0 5 0 0 1, 842, 259 8,542,379 9. 174 140,068 1953 .... 0 ..... 0 ..... 0 ... 5 .............. 0 .......... 0 ..... 1,345,587 ... 9,887,966 ..... 10,598 .. 150,666 1954 0 0 0 3 0 0 879' 902 JO, 767,868 5,544 156,210 1955* 0 0 0 3 0 0 851 ,380 11,619,248 8,179 164, 389 * 1955 data a dded by amendment. KEYSTONE FIELD, Winkler County, Texas PRODUCTION HISTORY (Continued) WELLS PRODUCING OIL PRODUCTION WELLS PRODUCING GAS PRODUCTION at end of year (barrels) at end of yea r (Mcf) Year Flow. Pump. Yearly Cumulative Year Gas Yearly Cumulative Holt Lime: Yates Sand: 1943 l 0 6,745 6,745 1929-1936 ? ? ? 1944 9 0 .. .• .. . 191,340 ...... . 198,085 1945 22 0 441,560 639,645 1937 0 0 0 1946 48 5 1,002,551 1,642,196 1947 ....... 71 5 ..... l, 779, 767 3,421,963 1938 ... ..... .. . . .... .. .. ... 20,473 .. . .. . .. 20,473 1948 96 5 2,579,900 6,001,863 1949 96 9 1, 782,498 7, 784,361 1939 15,534 36,007 1950 1951 ... . . .. 93 92 ....... 14 15 ..... 1,370,727 ..... 9,155,088 1,453, 774 10,608,862 . 1940 36, 712 72, 719 1952 94 13 1,316,643 11,925,505 1953 ....• .. 92 ....... 14 ..•.. 1,222,270 ..... 13, 147, 775 1941 . . ........ .... ..... ... 134,201 206,920 1954 94 13 876,288 14,024,063 1955* 94 12 876, 769 14,900, 832 1942 0 0 206, 920 1943 49,306 256, 226 Silurian Lime: 1944 ... . ..... . 2 ....... ... .. 147,047 403, 2 73 1945 0 5,857 5,857 1946 0 16,218 22,075 1945 2 107,612 510,885 1947 ....... 27 ..... ... 4 ..•.. . . 501,610 . . . . ... 523,685 1948 33 8 1,246,266 1, 769,951 1946 27,248 538,133 1949 39 9 1,028,606 2, 798,557 1950 ...•. .. 37 . ... . .. 11 ...... . 975,471 .. .. .. 3, 774,028 1947 ... . . . . ... 1 ......... . ... 43,811 581,944 1951 36 12 1,084, 775 4,858,803 1952 34 14 934,677 5, 79 3,480 1948-1951 0 0 581,944 1953 ....... 34 . .. ... . 14 .. .....853,124 6,646,604 1954 36 12 751,895 7,398,499 1952 27,496 609,440 1955* 34 14 760,001 8, 158,500 1953 ... ..... .. 2 .......... .. . 65,519 674,959 Ellenburger: 1954 36, 416 711,375 1943 l 0 41,028 41,028 1955* 59,336 770,711 1944 .. •.... 13 ........ 0 .... . . . 460,631 ....... 501,659 1945 60 0 4,562,290 5,063,949 1946 130 0 12, 744,267 17,808,216 § For the years prior to 1937, records of the number 1947 ...... 153 ........ 0 .... 10,401,318 ..... 28,209,534 of wells producing at the end of each year and of the quan­1948 148 4 7,842,898 36,052,432 tity of gas produced are not readily available. All above 1949 142 6 5,539,415 41,591,847 entries reporting cumulative production omit an unknown 1950 .•.... 135 ....... 12 .. ... 6,134,848 .. ...47, 726,695 quantity of gas produced by the two wells completed in Yates 1951 134 12 7,493,847 55,220,542 Sand prior to 1937. Four wells in the Keystone field have 1952 126 14 6,834,812 62,055,354 been completed in Yates Sand. Since 1953, no production 1953 ...... 123 ..... . . 13 ..... 6,396,648 .... . 68,452,002 has been reported from one of the two wells indicated as 1954 122 10 5,150,258 73,602,260 currently productive from Yates on the accompanying 1955* 122 9 4,904,671 78,506,93 1 Whitehorse map. * 1955 data added by amendment. WATER PRODUCTION Estimates of quantities of water produced are not available. The Ellenburger. Analyses indicate that the average operators do not keep records of observations which would afford a basis chloride content of such water as has been pro­for making such estimates. It is known, however, that some wells duced from each reservoir was as follows : producing from each of eight of the nine reservoirs have produced some Parts per million water. No water is known to have been produced by either of the two Colby Sand 82,400 wells indicated as Yates Sand wells Qn the accompanying Whitehorse Keystone Lime 50,200 map nor from the Yates Sand reservoir by any of the few wells which Holt Lime 81,600 have produced only temporarily from this reservoir. Only a few of the Devonian 100,000 McKee Sand wells and the Waddell Sand wells have produced any water; Silurian Lime 138,000 the quantities of water produced by these gas wells have been negligible. McKee Sand 91,680 There is a wide range in water production of wells producing oil from Waddell Sand No analysis Colby Sand, Keystone Lime, Holt Lime, Devonian, Silurian Lime and Ellenburger 65,600 LANCASTER HILL FIELD Crockett County, Texas CHARLES R. GRICE Consulting Geologist, Midland , Texas June l , 1953 LOCATION The Lancaster Hill field is in west central Crockett County, about 5 miles northeast of the site of the ruins of Fort Lancaster and about 25 miles w.est of the town of Ozona, county seat. It is in Seq;. 14 and 15 of Block 29, University Lands survey. METHOD OF EXPLORATION LEADING TO DISCOVERY The discovery of this field resulted directly from core drill exploration conducted by Gulf Oil Corporation during 1947 and 1948 . The discovery well was being drilled for the purpose of obtaining samples of near-surface rocks when it discovered oil. DISCOVERY Grayburg : April 10, 1947; Gulf Oil Corp. #1-R University. The top of the productive rock was found at depth of 1,667 feet (1,004 feet above sea level) and the well was drilled to total depth of 1,685 feet. During initial potential test, the well pumped 108 barrels of 33.3° gravity oil in 24 hours through Z-inch tubing set 1,682 feet; gas-oil ratio, 591 to l. Surface elevation, Z,671 feet. ELEVATION OF SURFACE At well locations : Highest,2,700 ft .; lowest , 2,417 ft. SURFACE FORMATION Undifferentiated Cretaceous . OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is 661 feet below the top of the Ellenburger group. This penetration was in the dry hole in Sec . 10 where the total depth of 8 ,626 feet is indicated on the accompanying map. NATURE OF TRAP and STRUCTURE Grayburg : The oil accumulation is due to updip decrease of porosity on a structural nose. There are indications of the possibility of structural closure immediately we st of the field, but it appears that within the area of such indic ated closure the degree of porosity is too low for commercial production. PRODUCTIVE AREA Grayburg and Field: Estimated 120 to 160 acres . THICKNESS OF RESERVOIR ROCK Feet Grayburg : Min. Max. Avg. --10-__1_8_ --1-5­ Gross, t op to bottom LITHOLOGY OF RESERVOIR ROCK Grayburg: Buff to tan , medium crystalline, anhydritic dolomite alternating with thin mediurn­grained sand and anhydrite stringers. CONTINUITY OF RESERVOIR ROCK Grayburg : The reservoir rock appears to be continuous throughout the area covered by the accompanying map. However, the degree of porosity adequate for commercial production appears to be limited to the immediate vicinity of the productive wells . ELEVATION AND RELIEF OF PRODUCTIVE ZONE Grayburg: Feet Elevation of top of oil 1,004 Elevation of bottom of oil 976 Relief 28 CHARACTER OF on. Gravity: 33 .3 ° Base: Asphalt Color : Black WATER PRODUCTION Grayburg: It is known that some water is produced with the oil, but details are not available. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year Year Pumping 1947 3 1948 3 1949 3 1950 2 1951 2 1952 3 1953, Jan. & Feb. 3 {barrels) Yearly Cumulative 13,479 13,479 10 ,607 24,086 3' 136 2 7 ,222 1,891 29,113 2,672 31,785 3,372 35,157 701 35 ,858 LANCASTER HILL FIELD, Crockett County, Texas TYPICAL SECTION OF ROCKS PENETRATED z z RADIOACTIVITY CURVES RADIOACTIVITY CURVES 0 0 "' ,. LITHOLOGY >= LITHOLOGY >= " Cl. w ­ 0 w a: "'>­ 0 " "' DEPTH ... ELEVATION 0 ... "' "' "' " w ... " >­ 1481 -t1­ 100 "' a: w > 1381 a: z w 200 w a:" > :;, "' w "' :;, "' 0 1281 "' 0 :c "' z Cl. :c w u u :;, w z a: 300 " ... - ...J w " ­ ­ Oil production .>:;. Show of gos • 6 16 21 15 22 110 0 LANCASTER HILL FIELD p ~ ~M ) TOlll2~ ­ ~ • • • l----------~-f-----------,f-T~0~2~0'~0---• I087 --• 1070 ----<--+------' _....-11 .../'? • /. p 14 23 ~ iV PTDl77~ /9 o""-~ ! l BLOCK 29J. TURNER UNIVERSITY LANDS ~· IOSo N EXPLANATION 1075 -1100-Contour on top of Groybur9 formation 24 +1087 • Eleva tlon di top of Groyburo formation • Oil well +Abandoned oil well d Ory hole SC ALE d T08230 THOUSAMO FEET LEE HARRISON FIELD Lubbock County. Texas WILLIAM H. CARTER District Geologist, Midstates Oil Corporation, Midland, Texas November 22, 1955 LOCATION and OTHER NAMES The Lee Harrison field is in central Lubbock County about 3 miles east of the city of Lubbock. It is about a mile northwest of the Fort Worth&: Denver railway and immediately southeast of U.S. Highway 62, which is parallel to the railway through the area covered by the accompanying map. Throughout the several years when there was only one well in the field it was generally known as the Lubbock field. In some publications, the field was first designated as the Nairn field, but this name was soon superseded by the more widely used name. Following the completion of the second well on October 9, 1948, the field was given its present name in memory of the late Lee Harrison of Lubbock, who drilled the discovery well. Effective February l, 1949, the Railroad Commission changed its official designation from Lubbock field to Lee Harrison field. METHOD OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph. DISCOVERY Clear Fork: August 20, 1941; Lee C. Harrison et al #1 W.G.Nairn Estate. After treatment with 2,000 gallons of acid, the well produced by pumping through casing perforations from 4,885 to 5,002 feet at the daily rate of 160 barrels of oil and 8 barrels of water; gas-oil ratio, 300 : 1. The well was tem­porarily abandoned in October of 1945 after having produced a total of 11,527 barrels of oil; production was started again in June of 1947. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is in the Bend shale of Lower Pennsylvanian age. This penetration was in Texas &: Pacific Coal & Oil Co. #1 F. W. Austin, a dry hole located near the northwest corner of the area covered by the accompanying map (TD 10,030) . NATURE OF TRAP Clear Fork: The accumulation of oil is due partly to a convex fold and partly to variation in degree of porosity and permeability. ELEVATION OF SURFACE At well locations (derrick floor) : Highest, 3,208 feet; lowest, 3, 198 feet. SURFACE FORMATION The surface formation is sandy loam of the Ogallala formation of the Pliocene series. THICKNESSES OF RESERVOIR ROCK Clear Fork: Feet Min. Max. Avg. From top to bottom 90 132 115 Net productive ? ? 45 LITHOLOGY OF RESERVOIR ROCK Clear Fork: Dolomite; tan, brown or gray; intermittently finely granular and finely porous; locally oolitic and locally cherty; low permeability; contains a few partings of dense gray dolomite and also of shale. CHARACTER OF OIL Clear Fork: Gravity, A.P.I. @ 60° F. : 23.6° -28° ; avg., 25°. Base: Asphalt Color: Black WATER PRODUCTION Clear Fork: Water constitutes a material portion of the gross production of each well; the range is about 3% to about 75%. ACID TREATMENT Clear Fork: Each well was treated with acid during completion operations. The quantity of acid used during each treatment ranged from 2,000 gallons to 19,000 gallons. The large quantities were occasioned by the low permeability of the reservoir rock. LEE HARRISON FIELD, Lubbock County, Texas TYPICAL SECTION OF ROCKS PENETRATED z RAD IOACTIVITY CURVES !2 >-LITHOLOGY w a_ ::> " 0 GAMMA RAY NEUTRON a: a: " -' w a: V> ~ w a_ "-' 0 " ::> " "' PRODUCTIVE AREA Clear Fork and Field: 560 acres. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Clear Fo rk: Feet No free gas cap Highest known oil -1,664 Lowest known oil -1,829 Kno wn r elief 165 PRODUCTION JilSTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) All pumpin13: Yearly Cumulative Clear F ork: 1941 I, 764 I, 764 1942 2, 353 4, 117 1943 1,467 5,584 1944 3,520 9, 104 1945 2,425 II, 529 1946 0 11, 529 0 1947 1,489 13,018 1948 4,506 17, 524 a: z " 1949 41, 186 58,710 -' I950 10 63,281 I 2I ,991 NOTE: The above TYPICAL SECTION is based 8 1951 IO 49,889 171,880 on a composite log . 1952 IO 44,641 21 6,521 EXPLANATIO N 1953 10 40,073 256, 594 1954 I 2 41,928 298, 522 1955• 14 90,360 388,882 ~Dolomite t======i Shale *1955 data added by amendment. ~~tfif{~ Sandstone [~1 Sandy shale OD R~~ indicated, m Operation of the discovery well was suspended tem­porarily from time to time until after the second well was Anhydrite • Oil produc tion completed late in 1948. No production was reported for the period from October 1945 to June 19 47. LEHN-APCO FIELD P8COll County. Texas JAMES P. MURPHY and JAKE W. HODGES Geologists, Sinclair Oil & Gas Company, Midland, Texas and Roswell, New Mexico, respectively October 1, 1955 LOCATION and DEFINITION The Lehn-Apco field is in north-central Pecos County about 5 miles southwest of the town of Buenavista. It is on the Central Basin platform near its southwestern edge. The Lehn-Apco field is in the midst of an area spotted closely with oil and gas fields. The random distribution, the lean production and the generally small extent of the continuously productive areas have contributed to confusion in applying field names and in keeping records of development and operation. Certain parts of this field are about as closely re­lated to certain parts of near-by fields as they are to other parts of this field. The definition of the field is not determined as much by geologic facts as it is by geography and history. For the purposes of this paper, the Lehn-Apco field is defined as including all of the productive area within the area of the accompanying map except a portion of the area of the Apco field at the southeast corner and also portions of the areas of the Lehn-Apco North field and the Pecos -Shearer field, both in the north­central portion of the area covered by the accom­panying map. This definition coincides with the current definition of the Lehn-Apco (1600 ') field of the Railroad Commission except that the productive portion of Sec. 46 at the northwest end of the field is treated by the Commission as in the Pecos Valley (Low Gravity) field and, furthermore, our defini­tion includes the Commission's Lehn-Apco (Ellen­burger) field. METHOD OF EXPLORATION LEADING TO DISCOVERY Interpretation of subsurface geological data. ELEVATION OF SURFACE At well locations: Highest, 2, 490 ft. ; lowest, 2, 400 ft. PRODUCTIVE AREAS IDSTORY and FIELD NAMES The first commercial well within the area of the Lehn-Apco field was completed on July 20, 1939, at a location near the east corner of Sec. 71 and indicated on the accompanying map by a discovery symbol. Under the name of Lehn field, development spread to include portions of Secs. 47, 48, 69, 70, 71, 72, 73 and 74. On October 22, 1943, E.R. Lloyd #1 Mrs. E.C.Powell (now, Burke Royalty Co. #1 E.C.Powell) was completed in Sec. 76 and was recognized as a discovery well. Development spread into Sec. 75 and the name Apco 1600' field was applied to the producing area in Secs. 75 and 76. On May 20, 1944, Debs Patillo #1 Iowa Realty Trust (now, Burke Royalty Co. #1 Iowa Realty Trust), located in Sec. 61, was completed as a producer in the Seven Rivers formation. Although the producing zone is considerably higher than the producing zone in the wells then in the Lehn field, this well and two additional wells subsequently completed in the same reservoir were added to the Lehn field schedules and treated as if they were producing from the same reservoir as other Lehn wells. For purposes of regulation, the Lehn field was consolidated with the Apco 1600' field on October l, 1945, under the name Lehn-Apco 1600' field. Wells located 3 to 5 miles north of the herein defined Lehn-Apco field subsequently were completed and treated as in this field. The first of such wells was completed on March 6, 1946; there were 20 such wells on April 1, 1949, when they were removed from the Lehn-Apco 1600' field schedules and set up as in the Lehn-Apco 1600' North field. As wells were completed in Sec. 47, near the northwest end of the field, they were added to either the Lehn schedule or the Lehn-Apco ,1600' schedule, whichever was effective at the time. However, only a short distance westward, in Sec. 46, there were previously completed wells which were carried on the schedules for the Pecos Valley (Low Gravity) field. Now that the productive area is continuous, for the purposes of this paper, the wells in Sec. 46 are considered as in the Lehn-Apco field although they are currently treated by the Railroad Commis­sion as in the Pecos Valley (Low Gravity) field, the main portion of which occupies an area beginning 2 miles westward. Acres Seven Rivers 80 Queen-Grayburg 2,100 SURFACE FORMATION Ellenburger 40 Lehn-Apco field 2,220 Quaternary sands. LEHN-APCO FI ELD, Pecos County, Texas TYPICAL SECTION OF ROCKS PENETRATED z 9 ~ ~ Cl. ~ >­(/') a:: ""O et:: ~ ~ ~ ~ 0 0 "0 :r: .J u 0 " "' .J .J "' ">-z "'w >­" >­ z "'cc w " > er: w a. w w > "' cc"'w 0 :z: ~ :z: 3' w a. .J " 0 " " " "' ~ "'cc " "' >­ cc " "' w ~ z " z " "' RADIOACTIVITY CURVE LITHOLOGY GAMMA RAY .J DEPTH i5 500 1954 600 1654 700 1754 800 1654 900 1554 1000 1100 1200 1300 1400 1500 1454 1354 1254 115 4 1054 954 1700 -'-:.:::;;:::;~}!: _-­_.. 754 ~~;;::: 554 2000 454 2100 354 2200 254 2250 204 "'a. w " ~ ~ w a. " .J "0 " " "' ~ ~ "z cc 0 " w .J .J u z ELECTRIC a RADIOACTIVITY CURVES 0 >­ LITHOL OGY " GAMMA RAY RESISTIVI T Y " ANO S. P. ~ DEPTH ELEVATION '" 40 ~·?O 2250 204 2300 154 2400 54 2500 w a:: 2600 0 z " z ~ F 2700 -246 2800 -346 -446 3100 ':::"~­ ~~~~:: 3200 J' 3300 ::~ ......_,. -846 3400 -946 3500 3600 ?°--= ~­, 3700 3800 L'[ I r­4000 ~ " w"' g; "' a: 0 >­ w cc "'"'"' "'cc ~ cc w " .J u z 0 " cc -" " z cc 0 w w " a. .J >­:z: u 3' z 9 I­ ELECTRIC a RADIOACTIVITY CURVES LITHOLOGY ~ er GA MMA RAY AND 5 . P. RESISTIVITY ~ DEPTH ELEVATION 4 000 " ' " ' --? 4IOO . 42:00 4 300 4400 -1946 4500 -20 46 4600 -21 46 4 700 -2246 4800 -2346 4900 <- -2446 "' w w cc u z _J 0 5000 -2546 0 :i' " z " ~ t--t-~~---,_.-~-cl=~-"'--t~~t--'._""""~~~ '::' 5 100 ~­ -2646 > "' 0 z 0 cc !:; 0 5300 5336 NOTE: This TYPICAL SECTION is based on the log of Houston Oil Co. Hl Wm. E. O'Neil, locat ed near the south corner of Sec. 74 where TD 5338 is indicated on the map. The positions o f the three reservoir rocks are indicated although no one of them is productive in this well. The lack of production is significant only as to Ellenburger since the drilling operator owned interest in production above the depth of 2,500 feet. EXPLANATION ~Alternating thin beds of shole, Dolomi te ~sandstone end dolomile Dolomite with thin ~Anhydrite and dolomi le beds of sondstone ~thin beds of sondsl one Allernating thin • beds of sondy Anhydrilic dolomite wilh dolomite and shale thin beds of sondstone Dolomite ond ~Anhydrite ond sell with limestone ~thin beds of sandstone • Oil production with .J LEHN-APCO FIELD, Pecos County, Texas RESERVOIRS Oil in commercial quantities has been found in three stratigraphic zones; one is in the Seven Rivers formation, one is partly in the Queen formation and partly in the Grayburg formation, and the other is in the Ellenburger group. For the purposes of this paper, each of these productive zones is treated as a strati­graphic unit designated as the reservoir rock. The Seven Rivers reservoir rock has produced in only three wells. It appears that those three wells have produced from one and the same reservoir. The Queen-Grayburg reservoir rock has been the source of all production except the minor amount p,roduced by the three above mentioned wells and the small amount produced in 1955 by the one Ellenburger well. The Queen-Grayburg reservoir rock consists of interbedded dolomite, shale and sandstone with a .small amount of anhydrite. The major portion of the production is from sandstones in the basal portion of the Queen formation. While the accompanying TYPICAL SECTIONindicates aproductive sandstone at each the top and the bottom of the productive section, it is not to be understood that such relation­ship is consistent. The sandstones are lenticular, are at various positions in the zone and are not subject to definite correlation except locally. Migration of fluids through the zone has not been sufficiently free that all production should be considered as from one reservoir. Not only is there lack of communication across strata, but, also, there is lack of continuity of adequate porosity and permeability in correlative beds to permit migration of fluids along strata at present temperatures and pressures. There are probably several distinct reservoirs in the Queen-Grayburg productive zone within the area of this field. Since it is not practical to determine the extent of each reservoir separately, the following data have been compiled to apply to the several reservoirs collectively. The Ellenburger reservoir has been found productive in only one well to date. DISCOVERIES Seven Rivers: May 20, 1944; Debs Pattillo Hl Iowa Realty Trust (now, Burke Royalty Co. Hl Iowa Realty Trust). Queen-Grayburg and Field: July 20, 1939; H.L.Cain Hl M.M.Lehn (later, W.E.Kenney HI M.M.Lehn; now, Burke Royalty Co. Hl Masterson Lehn "A"). Queen-Grayburg: Apco 1600': October 22, 1943; E.R. Lloyd Hl Mrs. E.C.Powell (later, Major Drilling Co. Hl Mrs. E.C.Powell; now, Burke Royalty Co. HI E.C.Powell). This well is at considerable dis­tance from any previously completed well; it was recognized as a discovery well at time of completion and itled to the designation of Apco 1600' field. This well and other wells in Sec. 76 along with those in the north half of Sec. 75 are producing from a res­ervoir which appears to be separated from other reservoirs by lack of permeability adequate for migration of fluids. EJlenburger:Jan. l 7, 1955; Vega Oil Corp.HI J.B.Rayner OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in the Ellenburger group 281 feet below its top. This penetration was in W.R. Weaver Hl Iowa Realty Trust, completed as a dry hole on 11/24/54 and locatednear the west corner of Sec. 73, Block 10, where the total depth of 5, 786 feet is in­dicated on the accompanying map. Pre-Cambrian rocks have been penetrated by several wells located immediately east and southeast of the area covered by the accompanying map. NATURE OF TRAPS Seven Rivers: Updip termination of favorable porosity in a sloping reservoir rock. Queen-Grayburg: Each of the traps in this zone is due to updip termination of favorable porosity in a sloping reservoir rock. Most of the traps are formed in part because of the termination of favor­able porosity being in a curved position on a structural nose. Ellenburger: Available data are inadequate for determining nature of trap. THICKNESSES OF RESERVOIR ROCKS Net productive, average, approx. Feet Seven Rivers 12 Queen-Grayburg 20 Ellenburger 10 UTHOLOGY OF RESl:::RVOIR ROCKS Seven Rivers: Interbedded sandstones, shales and dolomite containing some anhydrite. Queen-Grayburg: Interbedded sandstones, shales and dolomite containing some anhydrite. The sand­ stone in that portion of the reservoir rock in the Queen formation is fine grained and is white to gray in color. For additional description, see preceding entry under RESERVOIRS. Ellenburger: Fine-to medium-grained, tan to dark gray, crystalline dolomite. CONTINUITY OF RESERVOIR ROCKS Seven Rivers: The productive member of the Seven Rivers formation is not subject to positive correlation beyond the immediate vicinity of the three wells where it is productive. Queen-Grayburg: The zone which is locally productive is continuous throughout the area covered by the accompanying map. However, as reported above under RESERVOIRS, the individual productive lenses are of only local ex~ent. Ellenburger: Available data do not afford a basis for determination of continuity of this reservoi r rock. LE HN-APCO FI ELD , Pecos County, Texas LEHN-APCO FIELD, Pecos County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES Seven Rivers : Feet Elevation of top of oil, approx. 1,300 Elevation of bottom of oil, approx. 1,262 Relief, approx. 38 Queen-Grayburg: Highest proven elevation of oil, approx. 835 Lowest proven elevation of oil, approx. 721 The difference of approximately 114 feet does not represent relief of oil in single re"servoir. There are several distinct reservoirs in this stratigraphic unit and these figures merely re­present the extreme elevations of oil in the several reservoirs. Ellenburger: (one well) Elevation of top of oil -4. 772 Elevation of bottom of oil -4,800 Relief 38 CHARACTER OF on. Gravity, A. P. I. @ 60° F. Max. Min. Avg. Seven Rivers ? ? ? Queen-Grayburg 36.6° 26° 34° Ellenburger 35.5° 35.5° 35.5° WATER PRODUCTION Seven Rivers andQueen-Grayburg: Wells in these reservoirs initially produced very little water. Data relative to present water production are not available. Ellenburger: The one well initially pumped at the rate of 15 barrels of oil and 18 barrels of salt water daily. COMPLETION TREATMENT Seven Rivers and Queen-Grayburg: The majority of the wells in these reservoirs were each shot with from 40 to 150 quarts of nitroglycerin. Ellenburger: The reservoir rock in the one productive well was treated with 1,000 gallons of regular acid. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Flowing Pumping Yearly Cumulative Field totals 1939 13 0 23,572 23,572 1940... 34 . . ....... 1 133,195 ... 15 6,767 1941 44 3 134,871 291,638 1942 27 23 91, 714 383, 352 1943 19 34 83,369 466,721 1944 28 38 97,688 564,409 1945 ...28 .. . . . ... 45 ...... 101,233....665,642 1946 25 51 8 1,xxx 747,xxx 1947 20 56 59,xxx 806,xxx 1948 13 60 51,xxx 857,xxx 1949 22 5 1 53,xxx 910,xxx 1950.. . 24 ........ 66 ........85, 407.. . . 99 5,xxx 1951 20 71 67,822 1,063,xxx 1952 22 63 55,343 1,118,xxx 1953 22 62 52,801 1, 171,xxx 1954 26 64 71,979 1,243,xxx Seven Rivers 1944 2 0 l,lxx l,lxx 1945.... 2 ......... 1 .........1, 7xx ..... 2, 8xx 1946 2 1 2,5xx 5, 3xx 1947 l, 7xx 7,0xx 1948 1 1, 7xx 8, 7xx 1949 1 l,6xx 10, 3xx 1950 1 ......... ....... . l ,6xx . .. . l l,9xx 1951 1 l,4xx 13, 3xx 1952 1 l ,8xx 15,lxx 1953 0 2 l ,5xx 16,6xx 1954 0 2 9xx l 7,5xx Queen-Grayburg 1939 13 0 23,572 23,572 1940 ... 3 4 . . . . . . . . . 1 1 3 3' 195 . . . 1 5 6' 7 6 7 1941 44 3 134,8 71 291,638 1942 27 23 9 1, 714 383,352 1943 19 34 83,369 466, 721 1944 26 28 96,6xx 563,3xx 1945... 26 ...... .. 44 .. ..... 99,5xx ... 662,8xx 1946 23 50 83,xxx 746,xxx 1947 19 55 57,xxx 803,xxx 1948 12 59 49,xxx 852,xxx 1949 21 50 51,xxx 903,xxx 1950. .. 23 ... . . ... 65 • . .... . 83,8xx ... 987,xxx 195 1 19 70 66,4xx 1,053,xxx 1952 21 62 53,5xx 1,107,xxx 1953 22 60 51,3xx 1.158.xxx 1954 26 62 71,lxx 1, 229 , xxx Ellenburger 1955 0 l 1,072 1,072 (to Oct.) The above figures do not include such wells as are in section 46 nor the production from those wells. Under Field totals and under Queen-Grayburg, the correct number of wells is 1 to 3 greater than above indicated and the correct quantities of oil are greater by the amounts produced by such well or wells in section 46 as were producing. Since the respective times of their completion, those wells have been reported as in the Pecos Valley (Low Gravity) field. LION FIELD Ward County, Texas C. K. HOLLOWAY Geologist, Lion Oil Company, Midland, Texas January 21, 1954 LOCATION The Lion field is in central Ward County about 4 miles west of the town of Pyote. METHOD OF EXPLORATION LEADING TO DISCOVERY This field was discovered as a result of sub­surface geologic studies . DISCOVERIES Bell Canyon gas sand: March 17, 1945; Lion Oil Company #B-4 University Bell Canyon oil sand and Field: October 3, 1944; Lion Oil Company #B-1 University ELEVATION OF SURFACE At well locations (derrick floor): Highest, 2,675 feet; lowest, 2,649 feet . SURFACE FORMATION Wind-blown sands of Quaternary age. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Bell Canyon formation 1,545 feet below its top . This penetration was in Lion Oil Co. #B-7 University at its total depth of 6,490 feet. NATURE OF TRAPS Bell Canyon gas sand and Bell Canyon oil sand: Some structural closure is indicated in each of the two reservoirs. However, accumulation appears to be controlled by lenticularity of sandstones in the uppermost twenty feet of the Bell Canyon formation. THICKNESSES OF RESERVOIR ROCKS Bell Canyon gas sand: Net productive, average, about 10 feet. Bell Canyon oil sand: Net productive, average, about 10 feet. PRODUCTIVE AREA Bell Canyon and Field : Total proven for gas and oil, 360 acres. --­ LITHOLOGY OF RESERVOIR ROCKS Bell Canyon gas sand: Very fine-grained, tight sandstone. Bell Canyon oil sand: Fine-grained sandstone containing thin shale laminae . The two reservoirs are separated by a thin zone of relatively impermeable sandstone or, as at Lion Oil Co. #7-B University, by a thin limestone. CONTINUITY OF RESERVOIR ROCKS Throughout the Delaware basin, there are sand­stones at the stratigraphic positions of the reservoir rocks, but the particular lenses of sandstone which produce in this field may not extend far beyond the presently proven productive area of this field. CHARACTER OF Oll. Gravity, A.P.I.@ 60° F. 37 . 1 ° Sulphur indication Sweet CHARACTER OF GAS The sulphur content is sufficiently low that the gas is satisfactory for domestic usage . As the gas is produced at the two productive gas wells, a small amount of condensate is yielded at the surface. WATER PRODUCTION The current daily production of well #B-1 is 10 barrels of oil and 5 barrels of water; of well #B-7, 7 barrels of oil and 2 barrels of water. Wells #B-2, #B-3 and #B-5 each produced salt water prior to abandonment. COMPLETION TREATMENT In wells #B-1, #B-2, #B-3 and #B-8, the reser­voir rock was shot with nitroglycerin. In well #B-7, the reservoir rock was treated with 1,000 gallons of acid. There was no treatment of the reservoir rock in either of the gas wells, #B-4 and #B-6. LION FIELD, Ward County, Texas tll I><: u 0 1%4 0 "" z 0 (/) w > :J "' u ~ ~ 5 ~ ~::; -O 6 n C"' i : -2'60 ~ $900 ( ~I : -2&10 ..> ' CC (I) 430 0 • -IOI() a: Zl-----f----1 e "'"' .. 0 ~ 44 00 ; -1110 "' '4$00 I -1210 I I I I I • &oo ~ I I I.....__ I ' -1310 -1 I I I I I I I I I ooo I I I ~ ! . -1•10 I I "' "'a: 0 I I~I ( I I ~ : _,'° I I I I I I I Hooo r•OO I I I ~ '9oo I I I ~i : _,.,o I I I I I I ~ 6600 1111 [ j $ .::1I I ." >... ·- ~ ' ' ~' 'JI 1111 ~ { I I,£ "'' ;! I I~i -·j I 1 11 1 rt I \ "00 ? I I> I -2"0 I I I 1-1100 $$00 -2210 I =:? I I 7200 J I I < :_ ,,,o ~1 I I ••oo l I I :=J> :_,,,o t7300 J I I ~:_,0 ,0 '!11 r:~ i LJ t ;~" ..... »·· . . . ... .i::.. ~ >o :::0 t-3 ,_. z '-rj ,_. tTl L' t:J >o :::1 ~ ~ Ul ~ :::1 ~ ~ Q Ul This TYPICAL SECTION is based on the log of Atlantic & Phillips Hl Univer sity A-11, located in Sec. 1, Block 11 , as indicated on the accompanying GRAYBURG MAP. • Oil production MART IN FIELD, Andrews County, Texas MART IN FIELD, Andrews County, Texas nDCKNESSES OF RESERVOm ROCKS From top_ to bottom, feet Min. Max. San Andres 100 120 Wichita 90 160 McKee 20 30 Ellenburger 20 445 LITHOLOGY OF RESERVOm ROCKS San Andres: Dolomite; tan to brown, finely crystalline dolomite with shreds of organic matter and grading to a white or buff, medium crystalline to saccharoidal dolomite, rarely anhydrite-bearing; locally, gray, sandy or oolitic . Where anhydrite ~foes not fill the space between the dolomite crystals , the interstitial space constitutes effective porosity. The San Andres is only rarely vuggy . Wichita: Dolomite; white to tan, ranging from dense, near lithographic, to fine-and medium­crystalline. The porosity is intercrystalline. McKee: Mainly quartz sand, the sand consisting of medium to coarse quartz grains, generally well­rounded and frosted. The upper part of the sand is commonly shaly; locally glauconitic and tightly cemented. The lower part of the sand is loose and friable and has high porosity. There are thin beds of green, fine-grained pyritic shale commonly con­taining sand grains and locally containing sandy limestone laminae . Ellenburger: Dolomite; white to tan or gray with texture ranging from near lithographic, very finely crystalline , to coarsely crystalline, sacchar­oidal. The uppermost part commonly contains coarse sand grains; stringers of sandy dolomite occur lower in the section. A small amount of white chert, locally incLuding brown oolites, is generally distributed throughout the entire thickness. The porosity is intercrystalline to vuggy with large fractures common. ELEVATIONS OF TOPS OF RESERVOIRS IN WELLS Feet Highest Lowest Relief San Andres -981 -1,057 76 Wichita -3,464 -3 ,488 * McKee -4,825 -5,370 545 Ellenburger -5,171 -5,676 505 *Both the highest elevation and the lowest eleva­tion were observed in edge wells . The excess of the McKee relief over the Ellen­burger relief is not to be interpreted as indicating greater structural relief on the McKee. The differ­ence is due merely to the fact that completed wells provided opportunity for measurement further down­dip on the McKee. CONTINUITY OF RESERVOffi ROCKS San Andres: The San Andres dolomite is one of the most widespread producing zones on the Central Basin platform. It is commercially productive where there are traps and where the absence of an­hydrite permits sufficient porosity and permeability. Wichita: The Wichita dolomite is extensively distributed throughout the Central Basin platform. It is a major oil reservoir in the Fullerton field , ten miles to the north. Although it is presently pro­ductive in only three wells in the Martin field , it has been found capable of commercial production in numerous wells completed in deeper zones . McKee: The degree of pre-Permian erosion is an important factor in determining the distribution of the McKee sand. However , within the area of the Martin field , this sand has not been eroded. It is continuous throughout the area of the field . Locally, its continuity is interrupted by faults at the east and north limits of the field . Regionally, changes in facies, as well as erosion, are important in deter­mining distribution. It is absent over a wide part of the Northern Shelf area of Texas and New Mexico and over some of the uplifts on the Central Basin platform. It is commercially productive in severa.l fields in a broad area; confined principally to anti­clinal structures on the Central Basin platform Ellenburger : The Ellenburger is of essentially uniform lithologic character over a very extensive area. It is a prolific producer in many fields in North and West Texas , and its equivalent, the Arbuckle , is productive in Oklahoma and Kansas . CHARACTER OF OIL San Andres Wichita McKee Ellenburger Gravity, A .P.I. 37-38 ° 35 ° 41° 44° WATER PRODUCTION San Andres, Wichita and McKee: Negligible; definite data not available. Ellenburger : Cumulative water production to June 1, 1951, amounted to 1,546,505 barrels or 15.5% of the gross fluid produced. The water con­tains considerable sulphur . ACID TREATMENT San Andres and Wichita: Generally before being placed on production, each well is acidized with 5 ,000 to 20 ,000 gallons . McKee : Not acidized. Ellenburger: Most of the Ellenburger wells are completed without acidization; however, treatment with only a 500-gallon acid wash appears to be necessary for proper completion of some wells . MART IN FIELD, Andrews County, Texas GLOR I ET A MAP N EXPLANATION --2000-Contour on top of Gtorielo formation -l'JZs Elevation of Top of Glorieto formation • 011 well Jf Dry hole • \::J Discovery well ~ Producing from Son Andres ! Abandoned ; formerly producing from Son Andres 9 Producing from Wichita • I Producing from McKee I• Producing from Ellenburger SCALE THOUS AND FEET MART IN FIELD, Andrews County, Texas ELLENBURGER MA P p TD78e3 N EXPLANATION --6000-Contour on top of Ellenbur9er 9roup -!i:'26 Elevotion of top of E1lenbur9er oroup -8~4 nt. This estimate is determined by adding -2240 feet to the observed elevation of the top of the Devonian • Oil well p Dry hole • -O Discovery wel1 .!. Producing from Son Andres ! Abandoned; former ly producin9 from Son Andres e Producing from Wichitca • I Producin9 from McKee 1 • Producing from Ellenbur9er SCALE THOUSAND FEET MARTIN FIELD , Andrews County, Texas D PR ODU CTION HIST O RY OIL PRODUCTION OIL PRODUCTION OIL PRODUCTION WELLS* {barrels) WELLS* {barrels) WELLS* {barrels) Year Oil Yearly Cumulative Year Oil Yearly Cumulative Year Oil Yearly Cumulative Field totals San Andres {Continued) Ellenburger 1940 3 4,553 4,553 1950 14 20 ,446 269,931 1946 7 169,901 169.901 1941 7 18,369 22 .922 1951 13 29 ,751 299.682 1947 18 708,626 878,527 1942 22 45' 107 68,029 1952** 11 24 ,656 324,388 1948 38 2' 139 ,483 3,018,010 1943 9 42,327 110,356 1949 45 2,203,029 5 ,221 ,039 1944 18 23 ,507 133 ,863 Wichita 1950 45 2,234,758 7 ,455 '797 1945 19 70 ,919 204,782 1951 45 2,981,733 10,437 ,530 1946 27 301,024 505 ,806 1945 30,833 30 ,833 1952** 45 2,602,517 13,040,047 1947 38 825,474 1,331,280 1946 2 35 ,520 66 ,353 1948 65 2 ,353 ,832 3,685,112 1947 2 24,757 91, 110 1949 79 2 ,638,776 6,3~3.888 1948 2 17 ,599 108,709 *Number of wells producing at end 1949 2 15 ,70 l 124,410 of year. 1950 79 2,637,342 8,961,230 1951 79 3,306,296 12,267 ,526 1950 3 15,438 139 ,848 **1952 data added by amendment. 1952** 77 2,852 ,101 15,119,627 1951 3 15 .953 155,801 1952** 3 16,328 172,129 San Andres 1940 3 4 ,553 4,553 McKee 1941 7 18,369 22 ,922 Development of the Ellenburger 1942 22 45' l 07 68,029 1945 l 10 ,080 10,080 followed rapidly after The Atlantic 1943 9 42 ,327 110,356 1946 2 70 ,6 16' 80,696 Refining Co. completed a stepout l!2 1944 18 23,507 133,863 1947 2 70,192 150,888 miles southeast of the Ellenburger dis­ 1948 10 177 ,094 327 .982 covery well. McKee sand development 1945 17 30 ,006 163 ,869 1949 19 400 ,972 728,954 has been largely subsequent to Ellen­1946 16 24,987 188 ,856 burger development as m ost of the 1947 16 21,899 210,755 1950 17 366,700 l,095,654 McKee wells have been drilled as twins 1948 15 19,656 230,411 1951 18 278 ,859 l ,374,513 to previously completed Ellenburger 1949 13 19 ,074 249,485 1952** 18 208 ,600 1,583,113 producers. MARVIN FIELD Sterling County, Texas R . L. THARP and C . F . SKRABACZ Geologists, Anderson-Prichard Oil Corp . , Midland, Texas January 30, 1953 LOCATION The Marvin field is in south-central Sterling County about 8 miles south of Sterling City, county seat. The two presently productive wells are in the southwest quarter of Section 12, Block 15, H.& T . C.R . R. Co. Survey. The field is on the western edge of the Eastern platform. METHOD OF EXPLORATION LEADING TO DISCOVERY Seismic data indicated a structural high on pre­Permian s trata. DISCOVERY Wolfcamp: May 10 , 1948; Anderson-Prichard Oil Corporation and Vickers Petroleum Company #1 M. F. Foster. ELEVATION OF SURF ACE The surface at the discovery well is 2,470 feet above sea level; at Humble Oil & Refining Co. #1 R. T. Foster (abandoned oil well), 2 ,524 feet above sea level. SURFACE FORMATION The only formation exposed within the area of the field is limestone of the Fredericksburg group. OLDEST STRATIGRAPHIC HORIZON PENETRATED About thirty feet below top of Ellenburger. This penetration was in the discovery well. NATURE OF TRAP Wolfcamp: It appears that a convex fold forms the trap . However , as indicated on the accompanying map, closure is not proven . PRODUCTIVE AREA Wolfcamp and Field: 80 acres . Future develop­ment may warrant increasing this estimate. THICKNESS OF RESERVOIR ROCK Wolfcamp: The n et productive thickness of the reservoir rock is about 30 feet in the discovery well and about 20 feet in the other currently producing well. LITHOLOGY OF RESERVOIR ROCK Wolfcamp: White, oolitic and fossiliferous limestone. This limestone is interbedded in a brown, argillaceous limestone. CONTINUITY OF RESERVOm ROCK Wolfcamp: The limestone member which is productive cannot be proven to be continuous beyond the wells where its elevation is indicated on the accompanying map . This member was not recognized in the most eastern well on the map. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Wolfcamp: Feet No free gas Elevation of top of oil -1,783 Elevation of bottom of oil -1,823 Relief of oil column 40 CHARACTER OF OIL Wolfcamp: Gravity , A .P .I. @ 60 ° F. 28° Base, Paraffinic WATER PRODUCTION Wolfcamp: Each well has produced only a very small amount of water. ACID TREATMENT Wolfcamp: Each of the two presently productive wells was treated with 1,000 gallons of acid through perforations. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of ye ar (barrels) Year Pumping Yearly Cum ulative 1948 2 10 ,820 l 0 ,820 1949 2 33,402 44,222 1950 2 34 ,3 15 78 ,537 195 1 2 31,793 110,330 1952 2 14,205 124 ,535 Although three wells have been completed in the field, nearly all of the production has been by two wells . Humble Oil & Refining Co. #1 R. T. Foster was completed Nov . 3, 1948, and was abandoned in 1949 after having produced only little oil. MARVIN FIELD , Sterling County, Texas TYPICAL SECTION OF ROCKS PENETRATED NOTE: Above the depth of 4200 feet this TYPICAL SECTION is based on the log of Humble Oil and R efg. Co. HI R. T. F oster (abandoned oil well in Sec. 19) a nd below the depth of 4200 feet., it is based on the log of the d iscovery wel l with arljusted d(~pths and elevations. ~ ~ L imestone Oolomi le EXPLANATION B Shole D Anhydr ite LlITill Sands lone ~Cheri ~ Soll ~Grovel ELECTRIC CURVES GAMMA RAY CURVE LI THOLOGY ..J SCA LE THOUSAND FEET ELECTRIC CURVE S AND LITHOLOGY DE PTH ELEVATION -3262 -336 7 -3467 -3567 ~3667 -)767 -3867 -3967 -4067 -4167 -4 267 -4367 -44 67 -4567 -4667 -4 767 -4867 • Oil producl 1on MASON FIELD Loving County. Texas GORDON S. KNOX Geologist, Phillips Petroleum Co., Midland, Texas January 4, 1953 LOCATION The Mason field is in northwestern Loving County 3 miles south of the Texas -New Mexico border and 9 miles northeast of the hamlet of Orla in Reeves County. It is in Secs. 8, 17, 20 and 21 of Block 55, T. 8t P. R.R. Co. Survey. It is in the cen­tral part of the Delaware basin. METHODS OF EXPLORATION LEADING TO DISCOVERY On November 20, 1934, O. M. Mason and associates acquired a block of oil and gas leases covering an area which now includes the Mason field, They later organized the Loving County Oil Company, which drilled the discovery well. The writer does not know the nature of the information which induced the Loving County Oil Company to locate the discovery well where it did. Subsurface geology is given credit for the northward extension of the field. DISCOVERY Bell Canyon: March 3, 1937; Loving County Oil Company 112 Mrs. Minnie Kyle. ELEVATION OF SURFACE At well locations: Highest, 3,101 ft.; lowest, 3,030 ft. SURFACE FORMATION Quaternary gravels and alluvium. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is in the Bell Canyon formation about 382 feet below the base of the Lamar member. This penetration was in Argo Oil Corp. /11-C TXL at its total depth of 4,274 feet. This well is located near the northwest edge of the field. NATURE OF TRAP Bell Canyon: Accumulation of oil appears to be due to differential porosities and permeabilities in a sloping reservoir rock. PRODUCTIVE AREA Bell Canyon and Field: 800 acres. THICKNESS OF RESERVOIR ROCK Bell Canyon: The productive rock is limited to a zone about 7 feet thick, the top of which is about 20 to 30 feet below the base of the Lamar member. It is a portion of a sandstone several hundred feet thick. LITHOLOGY OF RESERVOIR ROCK Bell Canyon: Very fine grained, gray, tightly cemented to soft, porous sandstone with a few thin black shale partings. CONTINUITY OF RESERVOIR ROCK Bell Canyon: The reservoir rock is a portion of a thick blanket sandstone which contains some inter­bedded shale and which is continuous as a remark­ably homogenous sandstone throughout the Delaware basin. The continuity of the locally productive por­tion cannot be proven beyond the extent of the field. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Bell Canyon: Feet No free gas cap Elevation of top of oil -841 Elevation of bottom of oil -912 Relief 71 WATER PRODUCTION Bell Canyon: From the time of first production, a small amount of water has been produced with the oil by most of the wells, regardless of structural position. No encroachment of water has been ob­served. MAS 0 N FIELD , Loving County, Texas CHARACTER OF OIL Bell Canyon: G ravity, A.P.J. @ 60° F . , average, 40.9. Sulphur , 0.12'}'. Base, Intermediate For analyses sec: Railroad Commission of Texas Analyses of Texas Crude Oils ( 1940} pp. 33 and 65 U.S. Bureau of Mines Lab. ref. No. 381 42 Tabulated analyses of Texas Crude Oils, T. P. 607 (1939) Item 62, Grnup 2 PRODUCTION HISTORY Year WELLS PRODUC ING at end of year OIL PRODUCT ION (barrels) Yearly Cumulati v e 1937 19 38 1939 194 0 84 .892 12 I ,329 89 ,014 79 ,540 84 ,892 206 ,22 1 295 ,235 374 ,775 1941 1942 194 3 1944 1945 7 6 62,536 58,9 13 54 ,83 2 49 ,7 17 50 ,871 437 .311 496 ,224 551 ,056 600,773 651 ,644 1946 1947 1948 1949 1950 49 ,557 54 ,238 56 ,867 59 ,192 90 ,449 70 I ,201 755,439 812,306 87 I ,498 961 ,947 1951 1952 II 63 ,316 65 ,486 I ,025 ,263 I ,090 ,749 i§ RADIOACTIVITY CURVES ~ l/l ~ LITHOLOGY t-..,"' ~ ~ ~ GAMMA RAY NEUTR ON l/l l/l ....._ OEPTH ELE V4TION >­ "' "' z ..,"' t­ ::> 0 "' .., z "' "' _J 0 "'"' i " 0 :<: >­ .., .., "' 0 "' TYPICAL SECTION OF EXPLANATION SCALE --70 0-Contour on top of Lomor member -1\1 Elevation of top of Lomor memb er THOUS/I NO f £( T Oil well ff Dry hole .., " t­ >­ z "' "' .., "' Q_ ROCKS PENETRATED .., a: .., "' 0 J: "0 .., Q_ 3 0 "' "' ::> "' Q_ => 0 a: "' ~ ~ w ! ~ EXPLANATION k/·;\:):JSondston' • Dolomitic Anhydrit' ~==~=~ Shole mAnhydrite g:~:S Cooglomerote ~Dolomit' ~Gypsum • Oil production ~. Solt McCAMEY FIELD Upton and Crane Counties. Texas E. S . HUGHES Geologist, Gulf Oil Corporation, Fort Worth, Texas July 15, 1954 LOCATION and FIELD NAMES The McCamey field is mainly in southwestern Upton County. It occupies an area almost 15 miles long in a northwest-southeast direction, with the northwest end extending into southeastern Crane County. At the nearest point, it is about Ii miles northward from the town of McCamey. It is one of several fields along the eastern edge of the Central Basin platform. The area treated herein includes the area treated in some publications as the Herrington field (4 producing wells) in Sec. 4, Blk. 3i. C.C.S.D. & R.G.N.G. survey and Sec. 16, Blk. 3, M.K.&T. survey. The northwestern end of the McCamey field has been called the Taylor area in some publications and the name McCamey-Taylor was commonly applied to the entire field during several years. The map presented as a part of this paper serves also for the accompanying paper on the Hurdle field and for the accompanying paper on the Webb Ray field. The map indicates the area of the Crossett field and a part of the area of the Crane-Cowden field, both of which fields are treated in other papers in this volume. The map also indicates the location of Buffalo Oil Co . # 1 King Ranch Oil & Lignite Co., which was completed June 7, 1953, as the discovery well in a new field designated by the Railroad Commission as the South McCamey (Wichita) field; also, the location of Brown & Thorp and John Parker #1-A J.W.Robbins,whichwas completed February 13, 1953, as the discovery well in a new field designated by the Railroad Commission as the Webb Ray South­east (San Andres) field . METHOD OF EXPLORATION LEADING TO DISCOVERY The mapping of surface exposures, which reveal a gentle anticlinal fold, led to the discovery of the field. ELEVATION OF SURFACE At well locations : Highest, 3,121 ft.; lowest, 2,421 ft. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 223 feet below its top. This penetration was at the total depth of 8 ,653 feet in Sinclair Oil & Gas Co. #5-A J .F .Lane, located in the southeastern part of the field at the location indicated as No. 2 on the line A-A' on the accompanying map. SURFACE FORMATIONS Rocks exposed at the surface are mainly of the Comanche series of the Cretaceous system. The northeast portion of the field is situated on King Mountain, a large mesa capped by rocks of the Fredericksburg group with rocks of the Trinity group exposed along the slopes. Recent Quaternary deposits fill the lowlands. To the north and north­west of the field, red beds of the Dockum group of the Triassic system are exposed at the surface. DISCOVERIES Grayburg: September 25, 1925; George B. McCamey, J.P. Johnson and Marland Oil Co. #1 M .L.Baker (now, Reno Oil Co. #1 M.L.Baker). The initial production was at the rate of 70 barrels of oil per day from a total depth of 2, 19 3 feet. This well was soon sold to Republic Production Co. and was deepened to the total depth of 2 ,350 feet and plugged back to 2 ,267 feet after encountering sulphur water . It was re-completed on March 13, 1926, with a potential pumping capacity of 60 barrels of fluid, 30 to 40% of which was water; gravity of the oil was 33.0° A.P.I. Fusselman: November 25, 1943; Texas Pacific Coal & Oil Co. #52-A J. F. Lane. This well was formerly a producer from the reservoir in the Grayburg formation and was deepened to 8,358 feet and tested water in the Ellenburger. It was then plugged back and perforated for production from Fusselman. Through perforations at 7 ,125 -7 ,160 feet and 7 ,190-7 ,200 feet, it flowed 44° gravity oil at rate of 398 barrels per day; gas-oil ratio, 1,732: l. A steady increase in gas-oil ratio led to early classification of the well as a gas-condensate well. The rate of production of condensate quickly declined to 50 barrels per day, then to 13 barrels per day and the well was shut-in within a short time. The writer has been unable to find any record of the quantities of fluids produced. The only other well completed in this reservoir is the Ellenburger discovery well, which produces gas and condensate from this reservoir. Ellenburg er : May 19, 1948; Texas Pacific Coal &OilCo. #62-A J.F.Lane. During initial potential test, flowed at rate of 54 barrels of 43.1 ° gravity oil and 37 barrels of sulphur water per day through perforations at 8 ,070 -8,130 feet; gas-oil ratio, 1,025: 1. This well is the only dually completed well in the field; it produced oil from the Ellenburger and gas and condensate from the Fusselman for about eighteen months before excessive water production forced abandonment in the Ellenburger. McCAMEY FIELD, Upton and Crane Counties, Texas NATURE OF TRAPS Grayburg : The trap is due primarily to anti­clinal folding .. Variation in degree of porosity and permeability has functioned as a secondary trap­forming factor . Fusselman and Ellenburger : The trap in each of these reservoir rocks is due to a small, prominent anticline or dome with approximately 650 feet of structural closure. TIUCKNESSES OF RESERVOm ROCXS From top to bottom, feet Min. Max. Wt. avg. Grayburg, estimated 20 ~ 85 Fusselman 75 110 93 Ellenburg er 74 90 82 Data are not available for satisfactory estimates of net productive thicknesses. CONTINUITY OF RESERVOm ROCKS Grayburg: The reservoir rock in the Grayburg formation is certainly continuous throughout the area of the field and probably throughout a large portion of the area of Central Basin platform. Its top is an important datum horizon in the eastern half of that platform. Fusselman and Ellenburg er: The Fusselman and Ell~nburger reservoir rocks have been found in each of the 9 wells which have been drilled to suffi­cient depth to test the Ellenburger; no additional wells have penetrated Fusselman. It appears likely that these reservoir rocks are continuous throughout the area of the accompanying map. However, there is a possibility that the Fusselman is truncated locally along the axis of the dominant anticline. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Grayburg : Feet No free gas cap Elevation of top of oil 638 Elevation of bottom of oil 378 Relief 260 Fusselman : Elevation of top of gas -4,399 · Elevation of bottom of oil -4,602 Relief 203 Most of the productive relief is oc­cupied by gas. Ellenburger: No free gas cap Elevation of top of oil -5 ,352 Elevation of bottom of oil -5,564 Relief 212 PRODUCTIVE .AREAS Acres Grayburg 20 ,000 Fusselman 160 Ellenburger 160 McCamey field 20,000 LimOLOGY OF RESERVOm ROCKS Grayburg : The reservoir rock in the Grayburg formation consists of three members, each with dis­tinctive lithology. The upper member, locally 10 to 20 feet thick, is predominantly a finely crystalline, tan to brown dolomite with medium to large, dark brown dolomite rhombs. The brown color is due to oil which is thoroughly disseminated throughout the dolomite . This member is one of the most persis­tent and widespread stratigraphic units in the Guadalupe series; its top is an important datum horizon throughout the eastern half of the Central Basin platform. The middle member, approxi­mately 100 feet thick, is predominantly elastic and is characterized by a gray-green fine-to medium­grained well cemented sandstone, a gray fine­grained calcareous argillaceous sandstone, and light green b entonitic shale. The upper 10 to 40 feet contains varying amounts of white granular to massive anhydrite. The highest oolitic zone in the reservoir rock occurs about 60 to 70 feet below the top of the middle member . Commercial oil pro­duction is yielded by this middle member wherever the sandstone is of sufficient thickness and with a sufficiently high degree of porosity. The lower member is the principal productive portion of the Grayburg reservoir rock. It is dolomite with one to three producing zones, generally two, where porosity is adequate for commercial production. The top of the highest porous zone in the lower member is 130 to 180 feet below the top of the reservoir rock and the top of the lowest porous zone is approximately 200 to 225 feet below that datum . In general, the vertical permeability of the lower member is of low order . The effective porosity is of the secondary solution type . Fusselman: The reservoir rock in the Fusselman formation is a white to pink, coarsely crystalline, crinoidal to chalky limestone. Varying amounts of gray to brown, vitreous chert are scattered through­out its thickness and a very thin zone of medium to coarse, oolitic limestone occurs at the base. The rock is uniformly porous throughout with the exception that the degree of porosity is higher in the basal portion. Intercrystalline porosity, fossil-cast por­osity and secondary solution cavities constitute the effective pore space. Ellenburger: The reservoir rock, which is approximately the upper 70 to 80 feet of the Ellen­burger group, is predominantly gray to brown finely crystalline fractured dolomite containing a few thin gray shale partings. The effective porosity is due to fracturing and to secondary solution cavities. m~ D Dfilm Llfild "'x " r J> z *" J> -4 Dim 1lilit 111111 0 z 1!1!1 1 Flm~ ITJ~~ ~ " R M I A N TR I ASSIC c R ETACEOUS GU ADALUPE c 0 MANCHE WHITEHORS E 0 C H 0 A y I -4 A T E S s A L A 0 0 J> 12! I . ~ g 0. ~ ~ . 0 ;:; 0 0 0 0 00 ~ 1-~ ~ or ~­ ~ 0 ~ I g 0 0 0 0 0 0 0 0 0 0 0 0 g 0 Or 0 0 0 0 0 0 lI SYSTEM SERIES GROUP FORMAT ION 0 ,.. "' () . "' .. ~ ... :! "' ~ () ~; II> c"' ... l> ro o­ ,.. 0 0 l>"' () -< ... < z -< »m -< mo ~" ~~ () c ~s < "' (/) "' "" I,~ '\ /'; \ ,"'"\ .. ~I/\ "'y,. /\f\ (,/'~I \II v.,...,......,.,, ~ ~,,,.,""•./~../ '"\' "'•/~ \'\ ,\fr\,,.~""···/'V"~/"~i....~ 1 ../"·..,41 i,/~ i \/ ~/~~ /'...,.,,.; 1 ..,...>J'~\ ,/\ i1 "IV'I V'~ w, ,\ 11 . ~ SYS TEM I ........ 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(-.,,"-"\ ~ ..~ W f I I I II I h I I j ~ I I VI u ( I \J 'I ., ~· ~ , I I ~ \ 11! , I w \ I "'.: ~~-""----" 1: 11 I I ~~ ~ I . · : *.* : • ~ . t :1 : ::.( :1:\ l-, /~I"" "'" 11!'1 1 ::::: ~11::: ~ ~ t~ \ I~" I f \(~ lt:1: l,1rr~ ~\; ;; ~ r.(, r\:\/ t ~~(1\ ! '~tJ\v1t1./ ~ \:,\[ --~-------------------------------------- _,·:t-"""'"'' I ~ I\} ~ 1\r t:: j I •1~: ~ r I~ i, U ~ l \ '\ ' 1 ~ ~ _ ' I \' ~ 0 . ' N . . . . . ti T . . . . ~ ~ ~ ~ I~ = Q 0 ::; (1 0... ~ C/l ~ "'ti ::; CD t'1 z t'1 ~ 0 0 c ::; = ...... (j)" > :(fl ~ ..., t'1 CD >< Q (/l OIL McCAMEY FIELD, Upton and Crane Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED JI EXPLANATION M. K. a T. R. R. Co. BLOCK --•450-Con1011r on top of Oil we ll COfflp leled In Groybur9 + Oil well obondoned in Groyburo Groybuq1 formation "JI • Oil wel l compt1!1d In Son Andru (one well) l• Oil we ll comple!td In Wichita (one. well) Oil welt abandoned in Groybur9 and tf Fune lmcin (one we ll) ~ Oil well completed In Ell1nbur91r (one we ll} Ouol completion, (I01-cond1nsot1 we ll In Funtlmon, oil welt obondoned in Ell 1 nbur91r {one well) Orlll t d Into Ell en bur9 1r 11roup Ory hol e · ~ Ol1covuy M. K. 6 T. R. R. Co. BLOCK I \ \ ,r \ ""sso -.. . .,.ro ro">o \ ·"&\ I / g J • '1 ""'~$¥ /? BROWN 8 THORP ond JOHN PARKER / Jr100 / / / I I I / JI UPTON COUNTY CROCKETT COUNTY JI I-' CD ~ () 0 ::x:.o ~ M >-<: >-rj ........ M L' t:J c:: "d 0 :::1 0 :::1 0.. ~ :::1 (1) ~ :::1 - (ii' _rn o-j ~ Ul McCAMEY FIELD, Upton and Crane Counties, Texas CHARACTER OF GAS WATER PRODUCTION Fusselman: Following is an analysis made by Texas Pacific Coal & Oil Co. of a sample of gas from Texas Pacific Coal & Oil Co. #62-A J.F.Lane, the only gas well in the field; a dual completion, formerly with oil production from Ellenburger. During the Fusselman potential test at time of completion, this well produced condensate of 58° gravity at rate of 17 barrels per day; gas-liquid ratio, 126,771:1. Component Mol. % Carbon dioxide 0.10 Nitrogen 2 .52 Methane 69.40 Ethane 14.44 Propane 7 . 31 !so-butane 0 .66 N-butane· 2 .7 3 Iso-pentane 0 .32 N-pentane 0 .58 Hexanes 0 .81 Heptanes 1.13 Total 100 .00 Specific gravity @ 58 ° F. 0.76 Sulphur indication Sweet RESERVOIR ENERGY Grayburg: Expulsion of oil from the reservoir is due to expansion of gas corning out of solution as pressure declines and also to water drive. Depletion has advanced to the stage where water drive is now the more important of the two types of reservoir energy. Fusselman : The reservoir energy is of gas-expansion type. £llenburger: There is an effective water drive in this reservoir. Texas Pacific Coal & Oil Co. #6~A J .F .Lane was abandoned in this reservoir because of water encroachment. Grayburg: Throughout the field, water constitutes a large percentage of the gross production. During April 1953 ab~\lt 80% of the gross production of most wells was water. For analysis of the water see: Berger, W.R . and Fash. R.H. (1934) Relation of water analyses to structure and porosity in the West Texas Permian basin: Amer . Assoc . Petr . Geol., Problems of Petroleum Geology, pp. 869-889. Fusselman: No water production. Ellenburger: During October 19 54 water constituted about 15 % of the gross production of the one Ellenburger well. Excessive water production forced abandonment of Ellenburger production in the Ellenburger discovery well after operating about eighteen months . ACID TREATMENT Grayburg: Most of the recent completions have included acid treatment; a few wells have been completed «natural" and others have been shot with nitroglycerin. Generally, each well is treated with 1, 000 to 3,000 gallons of acid, but the quantities have ranged upward to as much as 10,000 gallons. Fusselman: Both of the wells completed in the Fussel­man reservoir were treated with acid. Texas Pacific Coal & Oil Co. #52-A J .F .Lane was treated with 12,000 gallons in four stages; 1,000 gallons, 8,000 gallons, 2,000 gallons, and 1,000 gallons. Texas Pacific Coal & Oil Co. #62-A J.F.Lane, the presently producing gas well, was treated with 4, 500 gallons. Ellenburger: Both of the wells completed in the Ellen­burger reservoir were treated with acid; Texas Pacific Coal & Oil Co. #62-A J .F.Lane, with 13,000 gallons and Texas Pacific Coal & Oil Co. #63-A J.F.Lane with 4,000 gallons. CHARACTER OF OIL Grayburg Fusselman Ellenburger Gravity, A.P.I. @ 60 ° F. 28° 44° 46 ° Sulphur, % 2 .23 0.58 0.35 For ana lyses of samples from the Grayburg reservoir see: Railroad Commission of Texas Analyses of Texas Crude Oils (1940), pp. 32 and 61 U.S . Bureau of Mines Laboratory reference No. 26178 26265 27593 27863 27864 Analyses of Crude Oils from the West Texas District. R. I. 2849 (1927) P a g e 14 15 Tabulated Analyses of Texas Crude Oils. R.I. 3252 (1934) Group 2 Item 40 41 42 43 44 Tabulated Analyses of Texas Crude Oils . T .P . 607 (1939) G roup 2 Item 64 65 66 67 68 Analyses of Crude Oils from Some West Texas Fields. R .I. 3744 (1944) Pag e 23 Analyses of Crude Oils from 283 Important Oil Fields of the United States. R.I. 4289 (1948) Item McCAMEY FIELD, Upton and Crane Counties, Texas PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flow Pump Yearly Cumulative 1926 ? ? l ,617 ,158 l ,617 ,158 1927 ? ? 6,663,444 8,280,602 1928 ? ? 4,29 3 ,927 12 ,574,529 1929 ? ? 3,195,374 15 ,769 .903 1930.... . .. ? . ... ? .. .....2,601,478 .. .. .. 18 ,371 ,38 1 1931 ? ? 2,298,062 20,669,443 1932 0 253 l,356 ,887 22 ,026 ,330 1933 0 260 1,291,329 23,317,659 1934 6 300 1,328 ,09 3 24 ,645,7 52 1935 .... 6 ..... ... . 296 1.961.719......26,607,471 1936 5 543 3,124,153 29,731 ,624 1937 0 717 4,586,953 34,318,577 1938 3 838 5,683,217 40,001,794 1939 l 881 5,180,729 45 ,182 ,523 1940. . ....2 869 ..4,226,117. . .49 ,408 ,640 1941 2 854 4 ,156,649 53 ,565 ,289 1942 13 841 3,264,274 56,829,563 1943 0 832 3 ,211 ,799 60 ,041,362 1944 l 811 3,350,671 63 ,392,033 1945. ... . 9 .. .836. ... 3,224,725 .. . .. .66,616,758 1946 3 855 3,303,437 69 .920,195 1947 869 3,352,054 73 ,272,249 1948 899 3,408,193 76,680,442 1949 0 872 3 ,046 ,635 79 '727 ,077 1950. ....0 .... ... ...89 5......3 ,586 ,829 ... . ..83 ,313 .906 1951 0 925 3,382,231 86,696,137 1952 3 936 3,029,043 89.725,180 1953 2 961 2,786,500 92.511,680 1954* 0 953 2,396,245 94,907,925 Fusselman: One well, Texas Pacific Coal & Oil Co. #62-A J.F .Lane , has flowed gas and condensate since May, 1948 . Another well, the discovery well , produced oil during a short period and then some gas and condensate. While the writer has been unable to determine quantities of fluids produced by that well, it is apparent that the quantities were small. CONDENSATE GAS PRODUCTION PRODUCTION (barrels) (Mcf) Year Yearly Cumulative Yearly Cumulative 1948 5 ,904 5 .904 122 ,730 122,730 1949 6 ,361 12 ,265 124,437 247 ,167 1950.... 4,871 .. 17'136. 99.376 ...... . 346,543 1951 3 ,680 20 ,816 103 ,949 450,492 1952 4,409 25 ,225 123 ,597 574,089 1953. 4,085. 29 ,310 ..... . 106,201 680 ,290 1954* 2 ,984 32,294 115,458 795,748 Ellenburger: WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flow Pump Yearly Cumulative -2---0­ 1948 7 ,659 7,659 1949 2 0 29 ,346 37 ,005 1950 0 2 3 ,309 60 ,314 1951 0 17 ,858 78,172 1952 0 l 0 ,200 88 ,372 1953 0 8,097 96,469 1954* 0 6,642 l 03'1 11 *1954 data added by amendment. McCUTCHEN FIELD Coke County. Texaa J.B. JORDAN Exploitation Geologist, Union Oil Co. of Calif., Midland, Texas June I, 1954 LOCATION The Mccutchen field is 3 miles east of the town of Robert Lee, county seat of Coke County. METHODS OF EXPLORATION LEADING TO DISCOVERY Geophysical exploration led to the location of the well which discovered the field. That well is the discovery well of the Mccutchen pool. The West Mccutchen pool was discovered by a well which was located on the basis of subsurface geological data. DISCOVERIES Graham: McCutchen pool: July 17, 1950; Union Oil Co. of Calif. #1-B Daisy Mccutchen. West Mccutchen pool: January 17, 1951; Union Oil Co. of Calif. #3 Jim Mccutchen. ELEVATION OF SURFACE Derrick floor: Highest, 1,978 ft.; lowest, 1,909 feet. SURFACE FORMATION San Angelo formation at base of Guadalupe series. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 395 feet below the top of the Ellenburger. This penetration was in the McCutchen pool discovery well. The accompany­ing TYPICAL SECTION is based on the log of that well. NATURE OF TRAPS Graham: Each of the two traps is formed by draping of the overlying shale over a thick, relatively local, sand body and by lateral updip gradation of the sand to shale. PRODUCTIVE AREAS Graham Acres Mccutchen pool 2% West McCutchen pool 80 Mccutchen field 376 THICKNESSES OF RESERVOm ROCK Graham: Net productive, feet Min. Max. Avg. McCutchen pool -8-3018 West McCutchen pool 15 21 18 LITHOLOGY OF RESERVOIR ROCK Graham: The reservoir rock consists of fine to coarse sand with some shale and chert pebbles and interbedded thin shale streaks. In the southwest part of the Mccutchen pool, there are some con­glomerate zones within the reservoir rock. CONTINUITY OF RESERVOm ROCK Graham: The reservoir rock grades laterally into shale in all directions. The exact extent of sand is not known. However, at the location of the dry hole near the north edge of the area covered by the accompanying map, the reservoir rock is very shaly and, at a location only a mile further north, sand is completely absent. There is no sand at a location 3% miles to the northwest. Pure limestone occupies the corresponding stratigraphic position at a loca­tion 4 miles to the east. Southward, the zone grades from predominantly sand to predominantly shale at a distance of about 7 miles. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Graham: West Mccutchen Mccutchen Elevation of top of oil, ft. -2,003 -2,056 Elevation of bottom of oil, ft. -2,049 -2,077 Relief 46 21 CHARACTER OF OIL Graham: Gravity, A.P.I. @ 60 ° F .: 46 ° Sulphur: 0.15% Color: Yellow WATER PRODUCTION Graham: None of the wells produced water initially but as oil was withdrawn some of the edge wells started producing small amounts of water. McCUTCHEN FIELD, Coke County, Texas TYPICAL SECTION OF ROCKS PENETRATED ~Dolomite end ~Limestone ~dolomitK: limestone ~Limestone and kt·~~~~{iWI SondstoM ~dolomitic: limestone ~Sh.ale end limestone ~Rock indicated, ~=~====~ Shale ~ ~Dolomite ~sholy ~Ddomite ond • Oil production ~ anhydrite 438 436 435 McCUTCHEN POOL SCALE 445 446 N ---2030 --Contour on top of reservoir rock ~1 Elevation of top of reservoir rock 443 ... Total depth S. LEWIS • Oil well P Dry hole • ~Discovery p z ELECTRIC CURVES 0 ANO " ~ LITHOLOGY 0: ...J fr OEPTH ELEVATION Q ELECTRIC CURVES ANO LITHOLOGY z "' z "' > ...J ,,, .."' >­z z z a:"' CD,. <.) "' PRODUCTION HISTORY Year WELLS PRODUCINat end of year G OIL PRODUCTION (barrels) Yearly Cumulative Graham: -mo Fie ld totals 5 36 .9 58 36,958 1951 161,256 198 ,214 1952 178,371 376 ,585 1953 144,008 520 .593 Graham: -mo Mccutchen pool 5 0 36,958 36,958 1951 145 ,799 182 ,757 1952 172 ,320 355 ,077 1953 140,661 495,738 Graham: ~ West McCutchen pool 0 2 15 ,457 15 ,457 1952 6 ,051 21,508 1953 3,347 24,855 McELROY FIELD Crane and Upton Counties, Texas A . B . McINNIS and F. H . HARTMAN Geologists, Gulf Oil Corporation, Fort Worth, Texas November 15, 1955 LOCATION and FIELD NAMES The McElroy field is in northeastern Crane County and west-central Upton County. It is elongated in a northwest­southeast direction with the central portion occupying an area along the Crane-Upton County line immediately east of the town of Crane. It is in the midst of several fields on the eastern edge of the Central Basin platform. It is continuous with the Dune field; separated merely by an arbitrary line. Presently known conditions of nature indicate that the adjacent portion of the Dune field would be more appropriately considered as a part of the McElroy field than as a part of the Dune field. Adoption of the more nearly natural boundary does not appear practical for the purposes of this paper. During early development, three portions of the McElroy field were treated as individual fields : namely, Church­Fields field, Gulf-McElroy field and McClintic field. Extension and merging ofproductive areas led to designations by various combinations of these names and, finally, to general recognition that the three units should be treated as one field and to general adoption of the use of the one name with its present significance. The Railroad Commission consolidated its rules and records effective March l, 1941. The first well drilled in the northeast quarter of Sec. 3, Blk. X, C.C.S.D. & R.G.N.G. survey was treated during several years as in a separate field, the South Crane field, and that name has been used in many publications. George F . Getty #1 Hallie C. Day, located 330 feet south of the north line and 990 feet west of the east line of said section, was completed in the Grayburg formation on June 24, 1948, and its oil production of 1,883 barrels during 1948, 319 barrels during 1949 and 163 barrels during 1951 (total, 2,365 barrels) was reported as from the South Crane field. The well was temporarily abandoned and produced no more oil until after a workover which was completed on March 14, 1955, when it was designated as E. Q . Echols #1 Hallie C . Day and was treated as in the McElroy field. It is now designated as R. L. Dameron #1 Hallie C. Day and treated as in the McElroy field. Other wells in the immediate vicinity have been treated generally by administrative authorities and in petroleum publications as in the McElroy field. In this paper, the production of said first well, along with the production of the subsequent wells, is treated as in the McElroy field. DISCOVERIES Grayburg: Church-Fields: April 19, 1926; Church & Fields #1 University (later, Magnolia P etroleum Co. #1 University). Completed with open hole from 3, 028 to 3, 040 fe et; estimated potential, 190 barrels of oil per day. Grayburg: Gulf-McElroy: July 22, 1926; Gulf Produc­tion Co. #1 J . T. McElroy. Completed with open hole from 2,675 to 2, 750 feet (later deepened to 2,917 feet); estimated potential, 500 barrels of oil per day. Grayburg · McClintic: November 28, 1928; Keck Investment Co. #1 H. L . McClintic (later, Mabee Petroleum Corp. #1 H . L. McClintic). Top of reservoir, 2,890 feet; total depth, 2,944 feet; shot with 400 quarts of nitroglycerin from 2,874 to 2,934 feet; swabbed 140 barrels of oil during first day after shot. METHODS OF EXPLORATION LEADING TO DISCOVERY Trend drilling in conjunction with interpretation of a limited amount of surface geological data led to the drilling of Church & F ields #1 University, which was the first discovery well within the present area of the field. ELEVATION OF SURFACE The surface generally is about 2,625 feet above sea level; the highest elevation is about 2,800 feet and the lowest is about 2, 550 feet. SURFACE FORMATIONS Quaternary sand and caliche cover the surface within the area of the field. Rocks of the Fredericksburg and Trinity groups are exposed in m e sas east and southeast of the field. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellenburger group 400 feet below its top. This penetration was in Gulf Production Co. #103 J. T. McElroy, located in Sec. 197, Blk. F, where the total depth of 12, 786 feet is indicated on the accompanying map. There were several shows of oil below the Grayburg formation, but no commercial production. The well was plugged back and completed in the Grayburg reservoir. At the time this well was drilled to its total depth (May 25, 1935), it was the deepest well in the world. As reported in the two papers cited below under SELECTED REFERENCES, this well established several records and provided considerable technical information. LITHOLOGY OF RESERVOIR ROCK Grayburg: The upper portion of the reservoir rock is only locally commercially productive. This member is sandy, gray to tan, anhydritic, bentonitic (green), shaly dolomite. The average thickness is about 100 feet. It yields oil and gas locally from thin oolitic zones where porosity is favorable. The porosity is primary and is oolitic and intergranular. This sandy upper portion of the reservoir rock is generally recognized by its fine, angular, even-grained texture. It is immediately below a widespread brown dolomite zone, generally about 15 feet thick, which is the first widely correlative carbonate rock below the evaporite series. The above described sandy upper portion of the reservoir rock immediately overlies the main productive zone, which is oolitic, anhydritic, fossiliferous dolomite. The oolites are spherical and nearly uniform in size; about l I 32-inch in diameter. Fragments of fusulinids are common. This main productive zone, 10 to 100 feet thick, is the main source of production in the McElroy field. It is relatively homogeneous and, due to its oolitic and granular dolomitic texture, is an excellent reservoir rock. It has both primary and secondary porosity; the primary porosity is of the oolitic and inter-crystalline types and the secondary poros­ity is of the solution vug and fossil cast types. Mc EL R0 Y FIELD , Crane and Upton Counties, Texas NATURE OF TRAP Grayburg: The trap is due primarily to anticlinal folding. Variation in degree of porosity and permeability has functioned as a s econdary trap-forming factor. THICKNESSES OF RESERVOffi ROCK F eet Grayburg: Min. Max. Avg. Top to bottom ToO 400 225 Data are not available for determining net thicknesses of productive rock. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Grayburg: F eet No free gas cap Elev. of top of oil -198 Elev. of bottom of oil, approx. -600 Relief, approx. 402 The above figures represent conditions at time of discovery. CHARACTER OF GAS Component Mo l. % Hydrogen sulphide 2lT Methane 34.5 Ethane 26 .55 Propane 12.9 7 Butane 3.41 P entane .70 Hexane .20 99.93 CHARACTER OF OIL Gravity, A.P.I. @60 ° F . : 31 -33° Sulphur: 2.5% Base: Intermediate Color: Greenish-and brownish-black Component Mol. % Hydrogen sulphide ----s.99 Methane 8 .98 Ethane 6.92 Propane 5.67 Butane 4. 37 P entane 3. 74 Hexane 4.49 Heptane and heavier 60.34 100.50 For other analyses see: Railroad Commission of T exas Analyses of Texas Cr ude Oils (1940), pp. U.S. Bureau of Mines Lab. ref. No. 27860 27861 27862 30343 43112 Analyses of Crude Oils from the We st Texas District. R.I. 2849 (1927) Page 11 12 13 Tabulated Analyses of Texas Crude Oils. R . I. 3252 (19 34) Group 2,Item 19 46 47 20 Petroleum Engineering Report, Big Spring Field and Other Fields in West Texas and Southeastern New Mexico. R. I. TYPICAL SECTION OF RADIOACTIVI TY CURVES L I THOLOGY GAMMA RAY NEUTRON 32 and 62. ROCKS PEN E TRATED " w ... V> 1;; z "' O'. " w z RADIOACTIV ITY CURVES <::> ... V> 0. LITHOLOG Y w ::> "' O'. 0 O'. GAMMA RAY NE UTRON " --' O'.w 0 V> "­ "' "' 0 :z: u 0 w 0. ::> --' 0 "' ::> " "' - EXPL ANA TION Sandstone Coliche ~ ~-Shale m Anhydrile . Con9lomerole Halite 3316 (1936) Page 144 ~ -D + ~ ~+ Ta bulated Analyses of Texas Crude Oils. Dolomite Polyholite T. P. 607 (1939) Group 2,ltem 37 38 39 40 • ~ Analyses of Crude Oils from Some West Rock indicated,Oolitic dolomi te T exas Fields. R. I. 3744 (1944) Page 24 ben l onitic Analyses of Crude Oils from 283 Important Oil F ields of the Anhydritic dolomite .Oil produc tion United States. R. I. 4289 (1948) Item 232 Mc EL R 0 Y FIELD , Crane and Upton Counties, Texas ---+100--Contour on top of Groyburg format ion Oil wel l + Abandoned oi I we ll Orillinq well P' Ory hole 12;u Total depth • -C:U Discovery SCALE 10 15 THOUSAND FEET Mc EL R 0 Y FI ELD , Crane and Upton Counties, Texas PRODUCTIVE AREA RESERVOIR ENERGY Grayburg and Field: Approximately 21,000 acres . Grayburg: Oil expulsion is due to expansion of gas as it comes out of solution because of declining pressure. The reservoir be ­ havior is characte rized by lack of free gas cap, low rate of water CONTINUITY OF RESERVOIR ROCK influx, increasing gas-oil ratios and decreasing bottom-hole pressures. Grayburg: The rese r voir rock is continuous throughout the area of the field. SELECTED REFERENCES WATER PRODUCTION Carpenter, C. B . , and Hill, H. B. (1936) Church-Fields, McElroy oil field; in P etroleum Engineering R eport, Big Spring and Grayburg: As indi cated by figures in a column other fields in West Texas and Southeastern New Mexico: U. S. in the following PRODUCTION HISTORY, water Bureau of Mines, R. I. 3316, pp. 136-149. production constituted less than 2% of the total West Texas Oil Scouts (1936) Church-Fields -McElroy; in chapter re fluid production during the first 16 years, less than West Texas ­Year 1935: National Oil Scouts Assoc., Year 10% during the next 5 years, and more than 12% Book -1936, pp. 218-219. Presents detailed data afforded by but less than 20% during the last 7 years . It is the then de epest well in the world. estimated that water production through 1955 totals about 14,000,000 barrels, or about 5.6% of the gross quantity of fluids removed from the reservoir. Following is an analysis of a typical sample of the PRODUCTION HISTORY water. The sample was taken 9/27/55 from the flow line of Gulf Oil Corp. #55 J.T. McElroy, which Grayburg is located in Sec. 200, Blk. F, and which was WELLS P RODUCING OIL PRODUCTION WATER completed on 10/22/28 at the total depth of 2,990 at end of year (barrels) (%of total feet for production from 2,800 -2, 990 feet. Year F low. Artif. Total Yearly Cumulative liquid; est) ANALYSIS 1926 ? ? 19 427,020 427,020 Neg . 1927 ? ? 221 23,42 1,270 23, 848, 290 Neg. Salinity: Primary, 76.42%; Secondary, 15.88% 1928 ? ? 255 21,456,390 45,304,680 Neg. Alkalinity: Primary, 0.00%; Secondary, 15.88% 1929 ? ? 282 13,841 ,477 59,146,157 0.02 Specific gravity: 1.0133 pH: 6.98 Resistivity @24°C. : 0.412 ohmmeters. 1930 ? ? 320 11,564,274 70,7 10,431 0 .05 1931 ? ? 335 6,341,942 77,052, 373 0.04 Parts/ Reaction Reaction Reaction 1932 ? ? 344 5, 648, 998 82, 701 ,371 0 .03 Radical million coeff. value value, % 1933 ? ? 345 4,646,597 87,347,968 0.03 Na 5,985 0.0435 260.36 38.21 Ca l , 160 0.0499 57.88 8.50 1934 ? ? 351 4,500, 160 91, 848, l 28 0.04 Mg 273 0.0822 22.44 3.29 1935 65 312 377 4,062,666 95,9 10, 794 0.05 OH 0 0 .0588 0.00 0.00 1936 86 328 414 4,474, 135 100,384,929 0.07 C03 0 0.0333 0.00 0.00 1937 130 290 420 4,520,758 104,905,687 0.08 HC03 1,598 0.0164 26.21 3.85 S04 3, 100 0.0208 64.48 9 .46 1938 129 344 473 3,657,959 108, 563, 646 1.24 Cl 8,865 0.0282 249.99 36.69 1939 176 317 493 3,696,244 112,259,890 1.07 H2S 754 0.00 0.00 1940 212 313 525 5,063,9 15 117,323,805 1.01 Total 21, 735 681. 36 100.00 1941 154 428 582 4, 797~ 089 122 , 120,894 1.05 Hypothetical Parts per 1942 108 487 595 4,9 10,238 127,03 1,132 1.51 recombination million 1943 79 523 602 6,147,530 133, 178,662 2.32 Ca(HC03)2 2, 124 1944 87 529 6 16 10,458,736 143,637,398 4.47 CaS04 2, 154 1945 11 5 538 653 10,932,952 154,570,350 5.00 MgS04 1,344 NaS04 735 1946 83 586 669 9,8 12, 707 164,383,057 6. 10 NaCl 14,616 1947 67 666 733 10,38 1, 131 174, 764, 188 6.50 1948 48 761 809 10,627, 787 185,39 1,975 9.10 1949 30 824 854 8, 135,442 193,527,41 7 12. 10 COMPLETION TREATMENT 1950 27 876 903 7,495,252 20 1,022,669 14.91 Grayburg: Acidizing has played a subordinate 1951 14 907 921 8,412,540 209,435, 209 15.86 rol e in both workovers and initial completions. The 1952 9 9 15 924 7,442,090 216,877,299 15. 70 general completion practice has been to shoot the 1953 11 898 909 7, 165,838 224, 043, 13 7 18.90 reservoir rock with 100 to 300 quarts of nitroglycerin. Large volume, high inj ection rate, sand-oil fracture 1954 11 946 957 6,679,230 230, 722, 367 19.78 treatments have recently r eplaced shooting during 1955 * 33 1,033 1,066 6,827, 197 2 37,549 ,564 16.85 both workovers and initial completions. Generally, a fracture treatment consists of injecting 15,000 * 1955 data added by amendment. gallons of refined oil containing 20,000 pounds of sand down the 7-inch casing with injection rates GAS PRODUCTION: Incidental to oil production, some gas has ranging between 15 and 40 barrels per minute, been produced throughout the history of the field, but since the gas followed by an overflush of approximately 175 barrels was sour and had very little value, records of gas production are of crude oil. too fragmental to warrant entry here. McKEE FIELD Crane County, Texas BARBARA M. CREAGER Geologist, Humble Oil &: Refining Co., Midland, Texas February 1, 1956 LOCATION and FIELD NAME The McKee field is in southwestern Crane County one mile north of the Pecos River. It is in the approximate center of the southernportion of the Central Basin platform. The field name was derived from the name of the McKee sandstone, which was the first zone found productive in the field. METHODS OF EXPLORATION LEADING TO DISCOVERY Study of subsurface geological data led to the exploratory drilling which resulted in the discovery of commercial production in the McKee sandstone. The nearest McKee production at that time was in the Abell field about two miles to the southwest. A leak in the casing in the third well in the field prompted workover operations during which it was found that oil was flowing from the Tubb Dolomite. This well was then completed as the Tubb Dolomite discovery well. DISCOVERIES Tubb Dolomite: January 9, 1950; Magnolia Petroleum Co. #3 D.K.Glenn. After having produced from the McKee sandstone for six years, this well was plugged back to 4, 136 feet and completed for production from the Tubb Dolomite member, where its daily initial flowing potential was at the rate of 124 barrels of 35.8 ° gravity oil through perforations from 4,050 to 4,075 feet; GOR, 1,317 : 1. McKee: September 5, 1942; Magnolia Petroleum Co. #1 D.K.Glenn. The daily initial flowing poten­tial was at the rate of 225 barrels of 43. 2 ° gravity oil from open hole from 6,125 to 6,185 feet. This well has been plugged and abandoned and the only other wells (two) which have produced from McKee have been abandoned in this reservoir and are now producing from Tubb Dolomite. ELEVATION OF SURFACE At well locations: Highest, 2,461 ft.; lowest, 2,419 ft. SURFACE FORMATION OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is 249 feet below the top of the Ellenburger. This penetration was at the total depth of 7,204 feet in Magnolia Petroleum Co. #1 N.M. Tucker, a dry hole just east of the field. NATURE OF TRAPS Tubb Dolomite: The trap is due to variation in degree of porosity and permeability on a north-south trending anticline. McKee: Anticlinal folding appears to be the primary trap-forming factor . PRODUCTIVE AREAS Tubb Dolomite 600 acres McKee (depleted) 120 acres McKee field 625 acres THICKNESSES OF RESERVOm ROCKS From top to bottom: Feet Min. Max. Avg. Tubb Dolomite 15 85 43 McKee 10 60 37 Net thicknesses : Available data do not warrant estimates of net productive thicknesses. LITHOLOGY OF RESERVOm ROCKS Tubb Dolomite: Gray to brown, slightly shaly, dense to crystalline dolomite with pinpoint to vuggy lenticular porosity and a small amount of fracturing. McKee: Fine-to medium-grained, white to green, loosely consolidated sandstone with scattered shale partings. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Tubb Dolomite McKee Highest known elev. of oil,ft. -1,614 -3,660 Lowest known elev. of oil,ft. -1, 718 -3, 749 Undifferentiated Quaternary sand. Known relief, ft. 104 McK EE F IELD , Crane County, Texas TYPICAL SECTION OF ROCKS PENETRATED EXPLANATION .i..++ +!~m~W.}}j sandstone ~Dolomite :~+-+-++ Solt [illSandstone .Anhydritic .Polyholile ___ and shale dolomite ~Calcareous . Chert t:=:=::jShale dolomite D ~Limest IIAnhydrite f.\:!\<.}lRos~~di~dicoted, one ~Limestone .Dolomitic Q Rock indicated, and shale anhydrite sholy .Oil production 0 Oil show * Gas show CHARACTER OF OIL Tubb Dolomite McKee Gravity, A.P.L @ 60°F. 31.s• 39.6° Sulphur, % by weight 1.16 0.22 Base Interme diate Viscosity at I00°F. Sa ybolt sec. 42 44 Odo r Sour Sour Color B r o wnis h-Brownish­green black F or analyses of McKee oil see: U.S. Bureau of Mines Lab. ref. No. 46097 Analyses of Crude Oils from Some West Te xas Fields. R.I.4959 (1953) Item 38 McKEE FIELD, Crane County, Texas CONTINUITY OF RESERVOIR ROCKS Tubb Dolomite: The reservoir rock in the Clear Fork group is continuous throughout the area of the field and throughout a large portion of the Central Basin platform. However, generally the degree of porosity and permeability are not adequate for commercial production. A reservoir rock at the same stratigraphic posi,tion is productive in the South Sand Hills field, 3 miles north, and in the Sand Hills field, 7 miles north, and also in several othe r fields on the Central Basin platform. Within the area of the McKee field, the top of the porous zone is from 15 to 130 feet below the base of the Drinkard member, which is characterized by being sandy. McKee: The reservoir rock is continuous over most of the southern portion of the Central Basin platform except in areas of extreme pre-Permian erosion and except in local areas where continuity is interrupted by faulting. WATER PRODUCTION Tubb Dolomite: Water production has increased gradu­ally since the time of discovery. Water now constitutes less than 15% of the gross liquid production. McKee: No water was produced at time of discovery. No record of water subsequently produced is available. ACID TREATMENT Tubb Dolomite: Of the 14 wells completed in this res­ervoir, 13 were acidized; one was completed "natural". Quantities of acid ranged from 250 gallons to 9, 000 gallons ; average, 1, 750 gallons. McKee: Of the 3 wells completed in this reservoir, 1 was acidized; 2 were completed "natural". RESERVOIR ENERGY Tubb Dolomite: The reservoir energy is due primarily, if not wholly, to expansion of gas as it comes out of solu­tion in the oil due to decline in pressure. There appears to have been some free gas present at time of discovery, but whether it was in this reservoir or in a lens slightly higher is not determinable. The gas-oil ratio has increased from 1,317: 1 at time of discovery to the present ratio of 5,989: 1. McKee: The reservoir energy was due to expansion of gas which came out of solution as pressure declined. DEVELOPMENT AND PRODUCTION HISTORY NUMBER OF WELLS OIL PRODUCTION Completed Producing oil (barrels) during year at end of year Flow Pump Yearly Cumulative Tubb Dolomite 1950 3 2 14,656 14,656 1951 3 4 2 32, 1 76 46,832 1952 5 9 2 94,435 14 1,267 1953 3 9 5 100, 704 241,9 71 1954 0 8 6 70,965 312,936 1955 0 7 6 68, 529 38 1,465 McKee 1942 1 0 8,768 8, 768 1943 2 2 34, 618 43, 386 1944 0 0 3 41, 797 85,1 83 EXPLANATION 1945 0 0 3 19,253 104,436 --­--1650 ---­• Oil well + Abandoned Contour oi l well on top of Tubb Ootomite* Gos well, shut In 1946 1947 0 0 0 0 3 2 11 , 600 9,609 11 6,036 125,645 p Dry hole • '-c:D Discovery 1948 0 0 2 7,218 132, 863 e Produc ing from Tubb Dolomite ·~ Abandoned in McKee 1949 0 0 2 5,289 138, 152 PRODUC TI VE AREA BOUNDARIES --­---­--- Tubb Dolomite · · •· ·• · • •• •• · ••• •• • McKee 1950 1951 0 0 0 0 8,670 l, 393 146,822 148,215 SCALE THOUSAND n:n 1952 1953 -55 0 0 0 0 0 0 435 0 148,650 148,650 MIDWAY LANE FIELD Crockett County. Texas JOHN M. SWEET Geologist, The Atlantic Refining Co., Midland, Texas March 15, 1953 LOCATION The Midway Lane field is in northeast Crockett County, about 14 miles north northwest of Ozona, county seat. METHODS OF EXPLORATION LEADING TO DISCOVERY Refraction seismograph surveys were conducted in the general area by The Atlantic Refining Co. and Sinclair Oil & Gas Co. On the basis of these sur­veys, the two companies collaborated in the selec­tion of the location of the exploratory test which became the field discovery well. DISCOVERIES Queen: August 22, 1950; Sinclair Oil & Gas Co. and~tlantic Refining Co. #7 University 67. Ellenburger and Field: July 31, 1947; Sinclair Oil & Gas Co. and The Atlantic Refining Co . #1 University 66. ELEVATION OF SURFACE Derrick floor elevations: Highest, 2 ,683 feet ; lowest, 2 ,642 feet. SURFACE FORMATION Undifferentiated limestones of Fredericksburg group. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 20 feet below the top of the Riley formation . This penetration was in the well in the southeast corner of Sec . 21, Block 46, University Lands survey. Below the depth of 7 ,600 feet, the accompanying TYPICAL SECTION is based on the log of that well. It is the only well in the field which penetrated pre-Ellenburger rocks . NATURE OF TRAPS Queen: Low relief anticlinal fold . Ellenburger: Anticlinal fold with irregularities as indicated on an accompanying map. Fracturing influences productiveness within the anticlinal trap . The vertical distribution of productive rock within the Ellenburg er is variable due to the distribution of fractures. PRODUCTIVE AREAS Queen Ellenburger Midway Lane field Acres ~ 1,400 1,405 It appears likely that further warrant increase of the above development estimate for will the Queen reservoir. It is not likely that there will be any further development of the Ellenburger reser­voir . THICKNESSES OF RESERVOIR ROCKS Net productive, feet Min. Max . Avg. Queen 7 20 est. 13 est. Ellenburger 55 75 65 LITHOLOGY OF RESERVOIR ROCKS Queen: Sandstone; gray to white, fine to medium grained, soft to unconsolidated. There are a few local anhydrite partings less than 5 feet thick. Ellenburger: Dolomite; white to tan, fine to coarsely crystalline, hard, with vuggy, interstitial and fracture porosity, porcelaneous chert and large round sand grains. CONTINUITY OF RESERVOIR ROCKS Queen: This reservoir rock has been readily recognized at the location of every productive well and dry hole within the area of the accompanying map. It is continuous for many miles in all direc­tions from the field. Throughout such indicated area, porosity and permeability are favorable for migration of reservoir fluids. Ellenburger: With reservoir rock defined to include all of that portion of the section which yields, or has yielded, commercial oil and/or gas within the area of the field, it is entirely accurate to say that the reservoir rock is continuous throughout the area of the accompanying map. However, the strati­graphic position of the productive zone is quite variable within the section included in this definition. A zone which is prolific at one loq1tion may be non­productive nearby because of low permeability; but another zone may be productive there. The degree of permeability is dependent upon fractures, and fracturing is quite irregular. MIDWAY LANE FIELD, Crockett County, Texas WATER PRODUCTION ELEVATION AND RELIEF OF PRODUCTIVE ZONES Queen Ellenburger Elevation of top of oil, feet 1,737 -4,832 Elevation of bottom of oil, feet 1,516 -4,980 Relief, feet 221 148 In the Ellenburger discovery well, there was a column of 122 feet of free gas above the oil. Testing of other Ellenburger wells has not been adequate for determination of extent of free gas above the oil. So far as known, there is no free gas cap in the Queen reservoir. CHARACTER OF on. Queen Ellenburger Gravity, A.P.I. @ 60° F. 30° 50.2 ° Sulphur ? .18% Base ? Intermediate Color Black Red-green Viscosity@ loo• F. ? 33 sec. Queen: Three wells produced small amounts of water during initial production tests. At the date of the last available records (July, 1952), water con­stituted 14% of the gross liquid produced from this reservoir. Ellenburger : The encroachment of salt water occurred very rapidly. Water was first produced in May, 1948, when 0 .2610 was recorded . From then the water percentage increased at a steady rate up until the time of the last available records (January, 1953), when water constituted 79% of gross production. ACID TREATMENT Queen: This reservoir has been acidized in two wells; in one well, with l ,000 gallons of acid and, in the other, with 150 gallons of acid. Ellenburger : This reservoir has been acidized in most wells where it is productive . Only 500 gallons of acid were used in treating each of more than half of the wells acidized; varying amounts up to 9 ,500 gallons of acid were used in treating each of the others . PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION at end of year (barrels) (Mcf)* Year Flowing Pumping Yearly Cumulative Yearly Cumulative Queen 1950 2 0 2 ,8 74 2 ,874 1951 0 7 24 ,9 77 27 ,851 1952 0 6 25,761 53,612 Ellenburger 1947 0 0 44 ,781 44 ,78 1 100 ,774 100 ,774 1948 29 0 1,270 ,252 1,315,033 2,408,775 2 ,509 ,549 1949 25 10 1,310 ,1 37 2,625,170 5,792,099 8,301,648 1950 17 14 666 ,567 3,291 ,737 6.162 ,052 14,463 ,700 1951 15 13 402 ,016 3 ,693 ,753 6 ,440 ,718 20,904,418 1952 16 10 191,021 3 ,884,774 4,973 ,884 25 ,888 ,302 *GAS PRODUCTION: The above figures represent net gas production; i.e. , the difference between the amount produced and the amount returne d to the reservoir . A pres­ sure maintenance plant was installed in 1949 and has been operated sol ely to maintain pressure . The gas is not processed before being returned to the reservoir. GRAY BURG MAP N UNIVERSITY BLOCK 46 . 7 .. .,s. ~ •361301 ff'/ 7 -~ .....,•.._ \"" 1 LAND~ I FIELD .,,,~ "":/ .,.,, t.-..,,, \, ,, ;:LLENBURGER a::;_....,--• ~ Jl:'". UNIVERSITY 45 °~ ' I '• \ ....\,., I , .. 0 I \ ..... .......,,•.-.;._ BLOCK"·"'· l ouEEN a:;-• ! ·!n • I}~ ·~3'6 +IS~"'i .,..,,0 ! ! T !'.370 · ·~"' .. 1314 jf, W'-----L~-+:...-.------.J'-----"'""--'·o.10•3 ...,:/.,00 ci u ci > ci => >­ "' ~ _J ·u "'"" 0 _J 0"' " "' vi0 er 0 " -+ 1350-Contour on top of Groyburg formation · •j;• Elevation of top of Groyburg formation 'i Completed 1n Oueen ~ Completed in Ellenburger ~ Abandoned 1n Ellenburger !./ Injecting gos into Ellenburger • Oil well Ji Dry hole • -0 Discovery well ·11~ ··r' ....!.. ...!'' ·•~l .. , £ .. '.!~' •,, 'o CHAMBERS COUNTY SCHOO L L AND LEAGUE 4 ••in ii 0.,. 1;.111\: 1D7~73 00 '•.. , 'o EXPLANATION MIERS FIELD Sutton County. Texas JOE M. NICHOLS Geologist, Stanolind Oil & Gas Co., Midland, Texas February 10, 1955 LOCATION and OTHER NAMES The Miers field is in southeastern Sutton County about 20 miles southeast of Sonora, county seat. It i s in the general area of the juncture of the Eastern shelf to the northeast, the Midland basin to the northwest and the Kerr basin to the south. Physio­graphically, the location of the field is within the area of the Edwards Plateau. During its early history this field was commonly known as the Wilson field and as the Shell-Wilson field. However, sinee the time of the fir st marketed production in 1949, it has be en more generally des­ignated as the Miers field. METHOD OF EXPLORATION LEADING TO DISCOVERY Refraction seismograph. DISCOVERIES Canyon: July 18 , 1952; Phillips Petroleum Co. #1 Libb "A" (fee, Libb Wallace). Initial open flow capacity, 13,000 Mcf of gas per day through perfora­tions from depth of 3,976 -4,018 feet. This is the only well completed in this reservoir. Strawn and Field: May 5, 1946; Shell Oil Co. #1 Duke Wilson et ar:-lnitial open flow capacity, 9 ,200 Mcf of gas per day through perforations from depths of 4,195-4,215 and 4,220-4,245 feet. OLDEST HORIZON PENETRATED The oldest stratigraphic horizon penetrated is at the base of the Riley formation, Cambrian. system. The Riley formation unconformably overlies pre­Cambrian granite. The oldest horizon penetrate d is in the pre­Cambrian granite. Granite has been penetrated in two wells. The greater penetration was 169 feet and was in Shell Oil Company #3 W. A. Miers (total depth, 5,009 feet) located in Sec. 53, Blk. 14, about 3,200 feet southeast of the Canyon discovery well and identified as No. 4 on the line of the accompany­ing cross section. The other penetration of granite was in the Canyon discovery well, which, at its total depth of 5 ,489 feet, was drilled 23 feet into pre­Cambrian granite. NEAR-BY NONCOMMERCIAL PROSPECTS The location of the well which prompted the designation of Wallace field is near the northwest corner of the area covered by the accompanying maps. Ashland Oil & Refining Co. #1 W.D.Wallace Est. was completed on August 24, 1953, in Strawn limestone with an initial daily flowing potential of 87 barrels of 33 .2 °gravity oil and 11 barrels of water through perforations between 5,006 and 5 ,026 feet. It was generally recognized as a discovery well and was so treated in several publications. Oil produc­tion decreased and water production increased so that operation soon became unprofitable. Operation was suspended in November of 1953 and the well was later plugged and abandoned after having produced only 2 ,292 barrels of oil. Subsequent to the com­pletion of that well, the Strawn limestone was found nonproductive in four dry holes in the immediate vicinity. Another near-by noncommercial prospect oc­casioned erroneous recognition in some publications as a field discovery and was designated by the Rail­road Commission as the Son Ross field. Stanolind Oil & Gas Co. #1 Joe B. Ross, located in Sec. 26, ·Block 14, was completed for production from a zone in the Canyon series. After having been drilled to the total depth of 4,950 feet by Lockhart & Nichols, the well was acquired by Stanolind Oil & Gas Co. with the hope that further testing might result in profitable production from zones which had made good shows of oil. The new operator set 5!--inch casing at 4,755 feet and then, after two unsuccessful attempts at completion, perforated with 120 shots from 4,450 to 4,470 feet and then applied hydraulic fracturing treatment with use of 3,000 gallons of fluid. The zone from 4,450 to 4,462 feet was later re -perforated with 48 shots and given hydraulic fracturing treatment with an additional 12,000 gallons of fluid. On August 19, 1954, the well was completed for production. It indicated initial potential of 7 .56 barrels of 29 ° gravity oil per day; gas-oil ratio, 11,750: l. On February 9, 1955, the well was plugge d and abandoned after having pro­duced a total of only 311 barrels of oil. ELEVATION OF SURFACE At well locations (derrick floor): Highest, 2 ,305 feet; lowest, 2,186 feet. MIERS FIELD, Sutton County, Texas ~r.2• Total depth ,0 60 62 "\ I -<[ I <[ z 0 I­ (.) w Cf) Cf) Cf) 0 0::: (.) 0 0 0 0 0 0 0 0 0 w 0 0 0 0 0 ' 0 ~ ~ ~ ~ ~ ~~ " MIERS FIELD, Sutton County, Texas SURF ACE FORMATIONS The rocks at the surface consist of limestones of the Washita ·and Fredericksburg groups and also of caliche of Recent, Quaternary, age. Certain of these limestones form prominent escarpments throughout the area covered by the accompanying map. VARIATIONS IN THICKNESSES The accompanying isopachous map shows the variations in thicknesses of the Strawn reef. Within the map area, thicknesses range from less than 600 feet to nearly 1,400 feet. The reef is less than 600 feet thick over the apex of the granite knob over which the Miers field is located. The reef was deposited on·· an eroded surface of truncated older rocks, in­cluding pre-Cambrian granite, so that thicknesses of the remaining portions of each of the pre-Strawn stratigraphic units range from zero to complete normal thickness. NATURE OF TRAPS Canyon: Updip decrease of porosity. Strawn: Convex upper limit of reef limestone which is covered by relatively impervious shale. THICKNESSES OF RESERVOIR ROCKS Canyon: The interval from the top to the bottom of the reservoir rock in the one productive well is 60 feet. Within this total thickness, there is a net thickness of 41 feet of porous sandstone which yields gas into the bore-hole. Strawn: The characteristics of the Strawn reservoir rock are such that its upper and lower limits cannot be correlated with precision throughout the area of the field; therefore, its range of thick­ness is not accurately determinable. In the eight productive wells, the gross interval from the top of the productive rock to the gas-water contact ranges from 31 to 124 feet. It appears probable that the maximum thickness of the reservoir rock, from top to bottom, is only slightly greater than the thickness indicated by the larger of these figures. Data are not available for estimating net thicknesses of rocks which yield gas and condensate into the bore-holes. ACID TREATMENT Canyon: The one well was not treated with acid. Strawn: With one exception, all wells have been completed without acid treatment. UTHOLOGY OF RESERVOIR ROCKS Canyon: Sandstone; medium to large grains of clear quartz in a white to gray cement; friable; large spots of green glauconite are common. Strawn: Limestone; brown to tan, fine-to medium-grained crystalline, fossiliferous; porosity is mainly due to vugs of fine to medium size. CONTINUITY OF RESERVOIR ROCKS Canyon: The reservoir rock in the one produc­tive well cannot be correlated with any particular stratum in any other well. The reservoir rock appears to be a local lens of sandstone, merely one of such as are common in this portion of the Canyon series. Strawn: The reservoir rock is at the apex of a reef. The reef appears to be continuous far beyond the present extent of the field, but it is doubtful whether conditions favorable for migration of res­ervoir fluids are continuous in any direction more than a few miles beyond the present extent of the field. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Canyon: {One well) Feet Elevation of top of gas -:-1,741 Elevation of bottom of gas -1,80 l Known relief of gas 60 No oil known Strawn: Highest known elevation of gas -1,926 Elev. of gas-water contact, approx. -2,050 Known relief of gas, approx. 124 No oil in this reservoir The elevation of the gas-water contact in the Strawn reservoir has not been determined definitely. It appears that at the time of dis­covery of commercial production in this reservoir, the gas -water contact was within 20 feet either above or below the indicated elevation of -2,050 feet. CHARACTER OF GAS Canyon and Strawn: The gas in each reservoir is sweet and is rich in heavy hydrocarbons which condense when reservoir pressure is decreased. The production of gas is accompanied by production of considerable condensate. The weighted average gravity of the condensate is 48° A.P.I.@ 60° F. The stripped gas is of quality satisfactory for domestic utilization. MIERS FIELD, Sutton County, Texas TYPICAL SECTION OF ROCKS PENETRATED ELECTRIC 8',RAOIOACTIVITY CURVES PRODUCTION HISTORY W ELLS GAS PRODUCTION PRODUCING (Mcf) Y1·ar at ..,. nd of yf'ar ~CumulativP Fi eld tot<-il s 1949 9. I 47 9' 147 19 50 0 9 , 147 1951 9 ,l 47 1952 83 ,740 92 ,887 1953 3.724,910 3,817 ,797 1954 3 ,532,934 7,350,73 1 Canyon ----r9'53 120,969 120,969 1954 656 ,586 777 ,555 Strawn -­19-49 9, 147 9 ' 147 1950 0 9 ' 147 195 I 9' 147 9 ' 147 1952 83 ,740 92 ,887 1953 3,603 ,941 3 ,696 ,828 1954 2 ,876 ,348 6 ,573 ,1 76 GAS PRODUCT!ON o Until February 1953, there was no market for the gas except for local consump­hon. A pipe line connecting with San Angelo was completed in February 1953, and since then the field has supplied gas to that line for marketing in San Angelo. At no time has the market demand been eq ual to the capacity of the field. Had market been avail­able for greater quantities of gas, more wells would have been drilled. CONDENSATE PRODUCTION o The only records of condensate production indicate that the production from Canyon amounted to 208 barrels during 1953 and 937 barrels during 1954; from Strawn, 2,490 barrels during 1953 and 1,250 barrels during 1954. w "' .... ~ z LITHOLOGY LITHOLOGY -' -' 0 "'>-cc OEPTH ELEVATION (5 DEPTH ELEVATION 0 Pleistocene a nd Recent alluvium and sand dunes. "'"' w 3300 -560 "' ,_.,.....,.........,....,...._ 1210~~,.....,==...,,.~~~~-4530cc 0 7300 -4 560 :c z w 3 400 ­660 >:: ~ J-+-+--+-,-00--~r: .­ :c -4 660 0 ELEVATION AND RELIEF OF PRODUCTIVE ZONES cc gj " f2 7500 -4760 0 gj 0 E levation, feet Relief 3600 0 Top of oil Bottom of oil feet " 7600 -4860 " Clear Fork -1,957 -2,150 to -2,IBO 193 to 223 3700 7700 -4960 Tubb -2,B07 -2.932 125 E llenburger -7 ,326 -7,700 374 3800 z '.'! 7800 -5060 w z The above data represent conditions at res pective Q_ 0 => "'w 3900 discovery dates. ;;:; -' 5600 -2B60 0 t- cc 9600 -6860 No. of well s W ATER PRODUCTION producing water {barrels) 0 9700 0 Year Tubb Ellenburger Tubb Ellenburger cc WADDELL z 5800 -3060 "'z 6400 -3660 w ci -7660 6500 -3760 WA TER ANALYSES -7760 Milligrams per liter 6600 Cons titu ent Clear Fork Tubb Ellenburger 6700 EXPLANATION Calcium 7 ,746 5 ,741 3 ,375 Magnesium 1 ,472 692 516 6800 f/.:)~{///j Sandstone ~Limestone Sodium 45' 192 60 .440 29 ,B43 6900 ~Shary ~Dolom1t1c ~sandstone ~limestone Bicarbonate 36 395 I ,236 7000 --? ~Dolomite t=E=E==~ Shale Carbonate Q_ " 7100 No€:l'-soN \ e. N ~ ~ 0 z ~ ::r: z ~ (/} "Tj ........ M L' t1 ~ Q a Q :::s Q... ~ ff :><;-' BLOCK I w.a N.W. R.R. d - / Z659 ----~/ \ 2 669 2172 -1983 • -2016 -20 41 -198 1 ff -2018 -2 031 -2078 ,,,. Dis c ./,.,,-Ovt Ryrr--.._: 2 658 -1984 • -2017 / ./ u.........r 26117 -2030 / -1973 • -2 007 / '\, / ,q1'> 2. 56 -•t7t • -2009 2. 62 -2011 -1984 • -2020 I 2658 -2027 -1t11_20~3 -2000~.'~.,,e 6 oo• 265 1 EX PLAN AT ION • -2003 -1916 -2016 --2000-Contour on top of Lomor member El evation of top of Lamar member I 2657 -Elevation of surface -1973 • -2001 -Elevation of top of productive rock -201& -Elevation of total depth -1957 • Oil well Dry hole -211 4 + Abandoned oil well CHARACTER OF OIL PRODUCTION HISTORY Bell Canyon: WELLS PRODUCING OIL PRODUCTION Gravity, A.P.1.@ 60 ° F., 32 ° to 34• at end of year {barrels) Sulphur , 0.14% Year Flowing Pumping Yearly Cumulative Base, Intermediate 1931 0 2 ,350 2,350 For analyses see: 1932 0 ? ? U. S. Bureau of Mines Lab. ref. No. 32208 1933 0 ? 14,834 Tabulated Analyses of 1934 0 3 ,733 18,567 Texas Crude Oils. 1935 0 8,275 26 ,842 R. I. 3252 (1934) Item 1, Grp . 2 Tabulated Analyses of 1936 0 9 ,155 35 ,997 Texas Crude Oils . 1937 0 8,850 44 ,847 T. P . 607 (1939) Item 70, Grp. 2 1938 0 8,266 53,113 1939 2 0 6,344 59.457 1940 0 6,726 66 ' 183 WATER PRODUCTION 1941 2 0 8,690 74,873 1942 0 5 ,953 80 ,826 Bell Canyon: Only one well, Anderson-Prichard Oil 1943 0 5,709 86,535 Corp. #1-E Monroe , is making water . This well is at a 1944 0 6,123 92 ,658 lower structural position than any other well in the field. 1945 0 5,804 98.462 It is at the location where top of Bell Canyon formation is indicated as at the elevation of -2 ,022 feet on the accom­1946 0 5,630 104 ,092 panying map. 1947 0 5 .911 110 ,003 1948 0 6 ,008 116 ,011 1949 2 0 7 ,302 123,313 SELECTED REFERENCE 1950 9 65,925 189 ,238 Adams, J. E . (1936) Oil pool of open reservoir type: 195 1 9 64 ,780 254 ,018 Arner. Assoc. Petrol. Geol., Bull., vol. 20, pp. 780-796. 1952 11 56 ,804 310,822 MONROE FIELD, Ward County, Texas TYPICAL SECTION OF ROCKS PENETRATED NELSON FIELD Andrews County. Texas C. G. COOPER and B. J. FERRIS lieologists, Shell Oil Company, Midland, Texas January 1, 1954 LOCATION and OTHER NAME The Nelson field is in west-central Andrews County about 28 miles west of the town of Andrews, county seat. It is in the northern part of the Central Basin platform. The north end of (he field was designated as the Freund field during a few months after the comple­tion of the first well in that area, the Humble Oil &t Refining Co. #2 H. 0. Sims et al., located in NE cor., Sec. 25, Blk. A-39, Public School Land. This well was completed on November 27, 1946, with potential production at rate of 704 barrels per day from the Ellenburger. METHOD OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph. DISCOVERIES Wichita: December 21, 1948; Humble Oil &t Refining Co . #3 H. 0. Sims Ellenburger and Field: June 10, 1946; Shell Oil Co. #IA. Nelson ELEVATION OF SURFACE At well locations: Highest, 3,385 ft. ; lowest, 3,326 ft. SURFACE FORMATION Quaternary sand. OLDEST ZONE PENETRATED Pre-Cambrian granite. NATURE OF TRAPS Wichita: Updip deer ease of porosity and permeability. Ellenburger: Anticline. LITHOLOGY OF RESERVOIR ROCKS Wichita: Light gray to light brown, finely sac­charoidal, slightly cherty dolomite with some white to gray, compact limestone. This zone has yielded commercial production in a local area restricted so far to the northwest part of the field . Throughout other parts of the area of the field, apparently due to low porosity and permeability, this zone has either failed on tests to yield significant amounts of oil or has failed to make shows of oil sufficiently encourag­ing to warrant testing . Generally, throughout the area of the field, the rock at this stratigraphic position is dense, nonporous limestone. Ellenburger : White to light brown, cherty, slightly sandy dolomite, commonly coarse-grained, but occasionally showing a fine saccharoidal texture. The reservoir is overlain by a variable thickness of dense limestone . CONTINUITY OF RESERVOIR ROCKS Wichita: The reservoir rock is continuous throughout the area of the field but the degree of porosity which occasions its being productive is limited, so far as now known, to a local area. Ellenburger: This reservoir rock is continuous and is of fairly uniform lithologic nature throughout the area of the field . However, on the northwest closure, a gradation to limestone has resulted in the rock being sufficiently dense that there are erratic accumulation conditions with dry holes at favorable structural positions . ELEVATION AND RELIEF OF PRODUCTIVE ZONES Wichita Ellenburg er No free gas Elev. of top of oil, feet -3,783 -6 ,807 Elev. of bottom of oil, feet -4,008 -7 ,251 Relief, feet 225 444 ACID TREATMENT Wichita : Acidization has varied from a single treatment of 1,000 gallons to a total of 13 ,000 gallons of acid in five stages. Ellenburger : Acidization has varied from single treatments of 1,000 gallons to a total of 8,000 gal­lons given in three stages . NELSON FIELD I Andrews County, Texas TYPICAL SECTION OF ROCKS PENETRATED ELEVAT ION ELEVATI ON -3000 3000 ~-4000 -4000 ~ - -5000 -5000 I­ -6000 -6000 L--7000 -7000­ I­ - J PRODUCTIVE AREAS CHARACTER OF OIL 18 1 19 161 171 ~ J ~ -~'V I I N \' I ,..,. Acres Wichita ~ Ellenburger I ,200 Nelson field 1,520 nilCKNESSES OF RESERVOIB ROCKS Top to bottom , avg . g ross Wichita Ellenburg e r Feet ---us 160 PU BLIC SCHOOL LANO ~~ (/) \ ' ~1' "'o\ .... 1---I BLOCK A-39 wr :i; x UJ ~) t 22 ~r 24r 231:;:::-'\ ~,2sr'°"~ \ \ :\ \ I ~ \ ~U,, ~ Ji ';:/00 ''m~~~~~ '6'~ ~ • ""'o 5 3 2 • ~ ~,,..-;~ .... ::;) >~~ z 0 <:,::;) u <:-"<:, 0 ~ I' u Vl PUBLIC SCHOOL LANO .. ~~ A-40 BLOC K w a: ' ~),,, _J ~~ I EXPLANATION ---7050--Contour on top of Ellenburger group • Oil well completed in Wichita ~ Oil well completed in Ellenbur9er ff Ory hole • \=:tJ Discovery SCALE THOUSAND FEET WATER PRODUCTION No. of wells producing water z tr:l r-­ en 0 z '"Tj I-< tr:l r-­0 ->­ ~ 0... @ ~ t/) () 0 c ~ .-+ "< >--:3 (!) >< Q t/) N N '-] Year Wichita Ellenburg er 1947 1948 1949 1950 1951 1952 1953 Wichita E llenburg er Gravitv, A .P .I. @ 60• F. ~ 43.0 Color Green Da rk g r een Sulphur , by weig ht 0.631o 0.141o For analyses of sample from Ellenburger see: U. S. Bureau of Mines Lab. ref. No. 46089 Analyses of Crude Oils from -­Some West Texas Fields. R. I. 4959 ( 1953) Item 41 Wichita 3 ,887 1,344 I ,612 4 ,317 ? PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels} Year Flowing Pumping Yearly Cumulative Field totals 1946 1947 1948 1949 1950 1951 I 0 1952 14 1953 17 Wichita 1949 1950 1951 1952 1953 Ellenburg er 1946 1947 1948 1949 1950 1951 1952 13 1953 13 51,677 2 16 ,055 51,677 267,732 285 ,847 279 ,470 553 ,579 833 ,049 259 ,257 325 ,536 1 ,092 ,306 I ,4 !7 ,842 431.697 527 ,513 1,849,539 2 ,402 .955 13,770 13,770 12' 133 10,747 25 .903 36,650 21,583 56 .392 58 ,233 114 .625 51,677 216 ,055 51,677 267 ,732 285.847 265 ,700 553,579 819,279 247 ,124 314,789 1,0 66 ,403 1.407 ,095 410,114 471'121 l ,817 ,209 2 .28 8 ,330 WATER PRODUCTION (barrels) Ellenburg er 1,859 18.485 21,481 20 ,480 28 ,445 13 ,082 54, 170 GAS PRODUCTION (Mcf) vearly CurOU.Iatlve 18 ,780 68 .607 18,780 87 ,387 88 ,7 19 59 .110 176 ,106 235,2 16 73,725 117.986 308 ,94 1 426 ,927 203 ,932 257 ,995 630.859 888,854 13 ,522 13 ,52 2 14,378 8 .952 2 7 .900 36 ,852 17 .978 51 ,3 16 54,830 106,146 18 ,780 68 ,607 18,780 87 ,387 88 ,719 45 ,588 176 ,106 221,694 59 ,347 109,034 281,041 390 ,0 7 5 185 .954 206 .679 576,029 782 .708 NORTH GAIL FIELD Borden County, Texas BILL C. OGDEN Geologist, Union .Oil & Gas Corp. of Louisiana, Midland, Texas January 25, 1956 LOCATION The North Gail field (one well, now abandoned) is in northwest Borden County 11 miles northwest of Gail, county seat, and 4 miles southeast of the common corner of Lynn and Garza Counties on the north boundary of Borden County. METHOD OF EXPLORATION LEADING TO DISCOVERY Seismic work led to the drilling of the discovery well. DISCOVERY Spraberry: March 29, 1949; H. L. Hunt #B-1 Clayton&: Johnson. Pumped through perforations from 5, 730-5,745 feet at daily rate of 40 barrels of 37.5° gravity oil and 15 barrels of salt water. Gas-oil ratio, 400 : 1. Total depth 8,237 feet; plugged back to 5, 760 feet. ELEVATION OF SURFACE Derrick floor: 2,626 feet SURFACE FORMATION Chinle formation of Dockum group of Triassic system. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated, as indicated on the accom­panying SECTION OF ROCKS PENETRATED, is in the Strawn series 114 feet below its top. The oldest horizon penetrated in the vicinity of the field is in the Ellenburger group 319 feet below its top. This penetration was in H. L. Hunt #B-3 Clayton & Johnson located in Sec. 16 where the total depth of 9,294 feet is indicated on the accompanying map. NATURE OF TRAP Spraberry: The trap appears to be due to updip and lateral decrease of porosity in a sloping reservoir rock. Porosity of the reservoir rock decreases with increase of shale content. PRODUCTIVE AREA Spraberry and Field: 40 acres THICKNESS OF RESERVOIR ROCK LITHOLOGY OF RESERVOIR ROCK Spraberry: Gray to white-and-tan, very-fine-grained, dense, calcareous, silty sandstone with some fractures. CONTINUITY OF RESERVOIR ROCK Spraberry: The reservoir rock appears to be continuous throughout the area of the accompanying map and considera­bly beyond. It is at or near the same stratigraphic position of reservoir rocks in several fields in the Midland basin in a north-south belt from southern Lynn County to south­eastern Upton County and southwestern Reagan County. Whether conditions throughout the area of said belt are favorable for migration of reservoir fluids is not determin­able from data now available. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Spraberry: Feet Elevation of top of oil -3, 104 Elevation of bottom of oil -3, 124 Relief 20 The above figures represent conditions in the one well at time of discovery. CHARACTER OF OIL Spraberry: Gravity, A. P. I. @ 60° F., 37.5° Sulphur, 0.27% Gas-oil ratio at time of discovery, 400: 1 WATER PRODUCTION Spraberry: During the initial potential test, water con­stituted 23% of the gross production. Records of subsequent water production are not available. ACID TREATMENT Spraberry: The reservoir rock in the one well was treated with 500 gallons of acid. PRODUCTION HISTORY WELLS OIL PRODUCTION PRODUCING (barrels) Pumping Yearly Cumulative Spraberry: 1949 1,980 1,980 1950 767 2, 747 1951 373 3,120 1952 * 109 3,229 Spraberry: From top to bottom of productive zone, 20 ft. *The well has not produced since April 1952. NORTH GAIL FIELD , Borden County, Texas SECTION OF ROCKS PENETRATED z z ELECTRI C CURVES ELE CT RIC CURVES <::> ~ (I) ~ AND ::;; "' 1­ AND w w 0.. ::;; ~ ~ g~ LITHOLOGY LITHOLOGY (/) er o a:: _J >-w er o >­ w a:: 0 rJ'J fl) l!> U... DEPTH ELEVATION U> (I) t.!:l U... DEPTH ELEV AT ION 0 LlmJSandstone ~Limestone mlAnhydrite ~Sandstone ~Reef limestone ~Solt~andshole Rock indicated, GS@ shaly sandstone mL~~~s~~~~e (] red ~Anhydritic 0 Rock indicated,ITTLlShale and sandy shale ~dolomite gray • Oil product ion z <::> ::;; "'I­ ~ w ; "' >­ a:: UJ a:0 (I) (I) LI.. z Q. " _J z >­ 0 "'>­ z z z -­ 8237 "' 14 38 H. E. 6 W. T. R.R. Co. ~---,~,r------B-L-K~·-3-1--.'°"-----I 1 EXPLANATION Abandoned oil well .P Ory hole SCALE 10 12 T HOUSAN D FEE T NORTH GOLDSMITH FIELD Ector County, Texas EDWIN VAN DEN BARK District Geologist, Phillips Petroleum Co., Midland, Texas November 28, 1953 LOCATION and OTHER NAME The North Goldsmith field is in the extreme northwest corner of Ector County about 30 miles northwest of Odessa, county seat. It is one of many multi-pay fields on the Central Basin platform. It was known as the Cummins field until in 1940 when the present name was officially established. METHODS OF EXPLORATION LEADING TO DISCOVERY Interpretation of subsurface data led to the discovery of this field. The production of both the first well and the second well was such that there was doubt through several years whether commercial production had been discovered . The first well, C . J . Davidson and Atlantic Refining Co . #1 H . E . Cummins was completed in the San Andres reservoir on August 20, 1934, when initial potential test indicated a daily capacity of 35 barrels of oil and 1 ,500 Mcf of gas . However, during subsequent operations the well produced very little oil; has been operated intermittently as a gas well. On November 5, 1936, the second well, Grisham­Hunter Corp. #1 R . B. Cowden was completed with capacity of 10 barrels of oil per day from San Andres at depth of 4 ,265 feet to 4 ,430 feet. The location of this second well, now abandoned, is 1~ miles north of the gas well and may be identified on accompanying maps as the abandoned oil well twinned by a Devonian producer. Further development did not follow until 1940, when there were additional wells drilled to develop San Andres production. The field pro­duced from only the San Andres reservoir until in 1946 when commercial production was discovered in the Devonian reservoir and in the Fusselman reservoir. DISCOVERIES San Andres : August 20, 1934; C . J. Davidson and Atlantic Refining Co. #1 H. E . Cummins Devonian: April 21, 1946; Stanolind Oil & Gas Co. #1 Grisham-Hunter Corp. (now designated as Stanolind Oil & Gas Co. #1-A R . B . Cowden) Fusselman: October 10, 1946; Phillips Petroleum Co. #1 Bum ELEVATION OF SURFACE At well locations: Highest, 3 ,325 feet; lowest, 3 ,280 feet. SURFACE FORMATION Sandstone of probable Trinity age. In the upper part of this sandstone, to depths varying up to 50 feet, there is a secondary deposit of caliche. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest stratigraphic horizon penetrated in the vicinity of the field is in Ellenburger dolomite about 95 feet below the top of the Ellenburger formation. This penetration was in Stanolind Oil & Gas Co. #1 J . M. Williamson, a dry hole ju~t west of the field. NATURE OF TRAPS San Andres : Updip decrease of porosity and permea­bility on a northwest plunging structural nose. Devonian and Fusselman: Each of these reservoirs is terminated updip by truncation. The North Goldsmith field is on the west limb of a general structural high on which the nearby Andector field is located. For an understanding of the structural and stratigraphic relationship of the reservoirs in this field, please see the map and cross sections in the accompanying paper on the Andector field. PRODUCTIVE AREAS Acres San Andres 400 Devonian 400+ Fusselman 600+ The San Andres productive area is fairly well defined. The limits of the Devonian and Fusselman productive areas have not yet been determined . THICKNESSES OF RESERVOIR ROCKS Feet Min. Max. Avg. San Andres From top to bottom 60 200 150 Net productive 30 60 50 Devonian From top to bottom 40 Net productive 20 Fusselman From top to bottom 50 Net productive 20 LITHOLOGY OF RESERVOIR ROCKS San Andres: The reservoir rock is a brown dolomite, aphanitic to finely crystalline with a few oolitic layers. Porosity occurs as zones of fine-grade pores separated by impervious beds. Devonian: The reservoir rock is a light gray to white chert, smooth to very finely granular. Reservoir space is furnished by fractures and by zones of finely porous chert. Fusselman: The reservoir rock is a white calcareous chert and white cherty crystalline limestone. Porosity occurs in thin zones scattered through the Fusselman for­mation but most conspicuously at the top. NOR TH GOLDS MITH FIELD, Ector County, Texas CONTINUITY OF RESERVOIR ROCKS San Andres: This upper San Andres reservoir rock extends throughout and far beyond the field, and is, in fact, practically the same unit which produces in the nearby Goldsmith field. The two fields, however , are separated by an area in which the porous layers are either of non­commercial grade or have been elevated so high that they contain only gas. Devonian: This thin unit rises monoclinally to the east and is terminated by truncation a short distance east of the producing wells. However, northward along strike the reservoir rock can be traced a considerable distance into the Block 11 and Three Bar fields where the same unit of the Devonian is productive under similar geological conditions. Fusselman: This reservoir rock has the same attitude as the Devonian reservoir and in a similar manner is terminated by truncation to the east of the producing wells . RESERVOIR ENERGY San Andres and Devonian: The energy operating to expel the oil from each of these reservoirs appears to be that occasioned by gas coming out of solution due to decrease in pressure. Fusselman: An effective water drive serves to expel the oil from the reservoir. ELEVATION AND RELIEF OF PRODUCTIVE ZONES San Andres Devonian Fusselman Highest known elevation of oil, feet -976* -4,586 -4,718 Lowest known elevation of oil, feet -1,180+ -4,755 -4,978 Known relief, feet 204 169 260 *Above this elevation, all porous zones in the upper part of the San Andres formation throughout the Goldsmith­North Goldsmith-Andector structural high contain gas . CHARACTER OF OIL San Andres Devonian Fusselman Gravity, A.P .I. @ 60° F. 37 ° 43° 36.2 ° WATER PRODUCTION San Andres and Devonian: There is a small quantity of water produced by certain wells fo each of these two reservoirs . Fusselman: This reservoir has produced a consid­ erable amount of water. ACID TREATMENT All wells have been treated with acid either at time of initial completion or at time of recompletion. The quan­tities of acid used have ranged from 300 gallons to 5 ,000 gallons. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year F lowing Pumping Cumulative F ield totals 1936 0 2 ,400* 19 37 0 2,000 * 4 ,400* 1938 I ....... .... .. . 0 1,500* 5 ,900 1939 I 0 I ,000* 6 ,900 1940 5 0 12 ,443 19 ,343 1941 9 ... ... ........ I 49 ,71 1 .. 69 ,054 1942 6 8 32 ,628 101 ,682 1943 7 3 27 ,930 129,612 1944 7 ...... ... . . .. 2 24 ,393 154 ,005 1945 7 2 21,274 175,279 1946 11 2 111 ,564 286 ,843 1947 11 . " ...... ..... 6 .... 262,71 8 549,56 1 1948 8 9 324 ,948 874,509 1949 5 12 197 , 777 I ,072 ,286 1950 7 .............. 12 .. 164,458 .... . 1,236,744 1951 12 7 J66 ,384 1,403'128 1952 II 9 150 ,942 1,554 ,07 O* San Andres 1936 0 2 ,400* 1937 0 2 ,000* 4 ,400* 1938 ........ ... .. . 0 I ,500* ........ 5 ,900 1939 I 0 1,000* 6 ,900 1940 5 0 12,443 19,343 1941 9 ......... .. ... I 49.711 ... 69 ,054 1942 6 8 32,628 101,682 1943 7 3 27 ,930 129,612 1944 ... 7 .............. 2 24 ,393 ....... 154,005 1945 7 2 21,274 175,279 1946 7 2 23 .961 199 ,240 1947 5 .............. 4 26,814 ....... 226,054 1948 8 26 ,493 252,547 1949 8 19,318 27 1,865 1950 I .............. 8 .. 18,276.. 290.141 1951 6 3 19 .857 309 .998 1952 6 3 17 ,879 327,877* D evonian 1946 3 0 77,587 77,587 1947 3 ................ 2 17 3,167........ 250,754 1948 3 148,151 398.905 1949 3 88,174 487,079 1950 3 ...... ......... I .. 78,67 5. 565 ,754 1951 3 86.920 652 ,674 1952 4 88,057 740 ,7 3 1 F usselman 1946 1 0 10,016 10,016 1947 3 ............. . 0 ......... 62,7 37 ....... 72,753 1948 4 0 150,304 223,057 1949 1 3 90,285 313,342 1950 3 .............. . 3 . .... .. " 67 ,507 ........ 380 ,849 1951 3 3 59 ,607 440 ,456 1952 5 45 ,006 485 ,462 *The above figures reporting quantities produced from San Andres during 1936, 1937, 1938 and 1939 are merely estimates . These estimates represent portions of all cumulative quantities for San Andres and Field. GAS PRODUCTION: The single gas well, which produces from the San Andres, had produced prior to January 1, 1953, slightly over 1,000,000 Mcf of gas. N 0 R TH GOLDSMITH FI ELD, Ector County, Texas TYPICAL SECTION OF ROCKS PENETRATED THOUSAND FEET EXPLANATION [\{:\:::] Sandston e g-=-=-=3 Shole ~Sandstone ~ond shale ~Dolomite B Limestone Solt + ~ ~Anhydrite ~Dolomitic ~anhydrite ~Chert D Rock indicated, D red Rock indicated, "* Qreen Gos production • Oil production NORTH GOLDSMITH FIELD I Ector County, Texas TYPICAL SECTION OF ROCKS PENETRATED NORTH POLAR FIELD Kent and Garza Counties. Texas JOHN E. SCHERER Geologist, Union Oil & Gas Corp. of Louisiana, Midland, Texas January 25, 1956 LOCATION The North Polar field consists of two offsetting wells, one in Kent County and the othe r in Garza County, about 8 miles north of the south boundaries of these counties. It is about 5 miles northwest of the town of Polar in Kent County. METHODS OF EXPLORATION LEADING TO DISCOVERY Studies of seismic and subsurface geological data led to the discovery of this field. DISCOVERY Ellenburger: October 15, 1950; Star Oil Co. and Moore­Cook # A-1 Blanche Young. Flowed through 3/4-inch choke at daily rate of 1,477 barrels of 41.2° gravity oil from depth of 7, 780-7,822 feet. Gas-oil ratio, 960:1. Total depth, 7,822 feet. ELEVATION OF SURFACE Elevation of ground: 2,312 feet at the discovery well and 2, 291 feet at the other well. SURFACE FORMATION Chinle formation of Dockum group of Triassic system. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellenburger group 42 feet below its eroded top. This penetration was in the discovery well at its total depth of 7,822 feet. NATURE OF TRAP Ellenburger: The trap appears to be due to updip and lateral decrease of porosity in a sloping reservoir rock. The degree of porosity is locally high because of differential solution at an erosion surface. PRODUCTIVE AREA Ellenburger and Field: 80 acres THICKNESS OF RESERVOIR ROCK Ellenburger: The reservoir rock is at least 42 feet thick, as the total Ellenburger penetration in the discovery well yielded oil and only oil. The total thickness is proba­bly not much greater than 42 feet because the oil-water contact is at an elevation only 6 feet below the total depth of the discovery well; as to upper extent, it is unlikely that there is much productive rock stratigraphically higher than thatat the top of the productive section in the discovery well. LITHOLOGY OF RESERVOIR ROCK Ellenburger: Predominantly brown-to-gray micro-crystalline dolomite with small amount of white chert. CONTINUITY OF RESERVOIB ROCK Ellenburger: The Ellenburger dolomite is continuous throughout most of West Texas and, although it is truncated at many places and to various degrees, there is almost everywhere a zone at the top which is sufficiently porous to permit free migration of reservoir fluids. The condition of low porosity which affords a trap at this location is very local. Most Ellenburger reservoirs are in anticlinal traps rather than being limited by change in degree of porosity. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Ellenburger: Feet Elevation of highest known oil -5,458 Elevation of oil-water contact -5,506 Known relief 48 The highest known oil is at the top of the productive sec­tion in the discovery well. The elevation of the oil-water contact is established by its position in the other well, where water was yielded 15 feet below the top of the reservoir. The oil body may extend slightly higher than -5,458 feet at some near-by undrilled location, but it is unlikely that it extends much higher. CHARACTER OF OIL Ellenburger: Gravity, A . P . I. @ 60° F. , 41.2° CHARACTER OF GAS Ellenburger: No analysis is available; probably none was ever made. This field has not produced gas in commercial quantity. At time of completion, the gas-oil ratio in the dis­covery well was 960: l; in the other well, 512: 1. WATER PRODUCTION Ellenburger: No records of water production have been kept. At time of completion, the gross production of the second well was 5% water. ACID TREATMENT Ellenburger: In the discovery well, at time of completion, the reservoir rock was treated with 1, 000 gallons of acid. The other well was completed "natural". NOR TH POLAR FI ELD , Kent and Garza Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED EXPLANATION PRODUCTION HISTORY ~Sandstone and i?t?:W.JSandstone limestone WELLS PRODUCING OIL PRODUCTION at end of rear (barrels) Flowing Pumping Yearly Cumulative ~Sandstone ond shale F=====~ Shale I 95D 13, 324 13, 324 1951 55,482 68,806 ~Dolomite ~Limestone and shale 1952 38,875 107,6.81 1953 33,598 141,279 Chert ~Dolomite 1954 27,039 168, 318 .Oil production 1955 25,47 1 19 3, 789 NORTHWEST BLOCK 31 FIELD Crane County, Texas JOHN FUSZEK Geologist, The Atlantic Refining Company, Midland, Texas April 8, 1953 LOCATION The single well comprising the Northwest Block 31 field is located 1,980 feet from the south and east lines of Sec . 6, Block 31, University Lands survey, in the north central portion of Crane County about 10 miles northwest of Crane, county seat. It is about Z miles west of the south end of the University Waddell field and about 3t miles northwest of the Block 31 field. It is near the eastern edge of the Central Basin platform. METHODS OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph work led to the drilling of the discovery well by The Atlantic Refining Company. Stanolind Oil & Gas Company acquired a half-interest in the well prior to its completion. DISCOVERY Connell: November ZS, 1950; The Atlantic Re­fining Co. #1-LL University Block 31. Drilled to total depth of 11,915 feet and plugged back to 11,SZO feet. On initial production test, flowed at rate of Z6Z barrels of oil per day through perforations from 11,470 to 11,510 feet. It was temporarily abandoned in February, 1953. ELEVATION OF SURFACE Derrick floor elevation at well location: Z,645 feet. STRATIGRAPHIC SECTION The rocks penetrated in the one well in this field are similar to those penetrated in the Block 31 field and reported in the TYPICAL SECTION in the accompanying paper on that field. However, the only zone which is productive in this well is in the Con­nell member of the Oil Creek formation. The top of the Connell member is at the depth of 11 ,465 feet and the top of the zone which yielded oil is at 11,470 feet. SURFACE FORMATION Recent and Quaternary sands . OLDEST STRATIGRAPffiC HORIZON PENETRATED The oldest stratigraphic horizon penetrated is 345 feet below the top of the Ellenburger group. PRODUCTIVE AREA Connell and Field: Approximately 40 acres. THICKNESS OF RESERVOIR ROCK Connell: There is about 6 feet of net productive sand in the Connell member, which member is about 35 feet thick at this location. LITHOLOGY OF RESERVOIR ROCK Connell: Sandstone; light colored, medium-to coarse-grained, loosely cemented, slightly calcar­eous. The sand grains vary from subangular to well-rounded. CONTINUITY OF RESERVOIR ROCK Connell: While the continuity of the reservoir rock cannot be positively determined, that rock appears to be a blanket sandstone. It is a portion of the Connell member of the Oil Creek formation, which member has been found at widely distributed locations and is best developed on the southern portion of the Central Basin platform, with commer­cial production limited, up to now, to fields in Crane and northern Pecos counties. CHARACTER OF OIL Gravity: 46.6 °@ 76 ° F . Sulphur: 0 .1% Base: Paraffinic Color: Green WATER PRODUCTION The amount of water produced was negligible. PRODUCTION HISTORY OIL PRODUCTION GAS PRODUCTION (barrels) (Mcf) Year Yearly Cumulative Yearly Cumulative 1950 5,000 5,000 4,957 4,957 1951 lZ,163 17,163 10,792 15,749 1952 3,139 Z0,302 Z,680 18,429 1953 56 Z0,358 35 18,464 The only well in the field made its entire pro­ duction by flowing and was temporarily abandoned in February, 1953. OATES FIELD Pecos County. Texas DONALD R. RANEY Geologist, The Pure Oil Co., Fort Worth, Texa~ June 19, 1955 LOCATION The Oates field is in western Pecos County about 20 miles southwest of Fort Stockton. METHODS OF EXPLORATION LEADING TO DISCOVERY Surface mapping of Cretaceous beds led The Pure Oil Company in 1930 to drill to the depth of 5 ,000 feet to test the Delaware Mountain sandstone. In 1947, this hole was deepened to 11,805 feet. The discovery well was drilled as a water supply well for the deepening operations. DISCOVERY Rustler: April 10 , 1947; The Pure Oil Co. #1-B J.S. Oates. Initial production was at the daily rate of 39 barrels of oil and 501 barrels of water. ELEVATION OF SURFACE At well locations: Highest, 3,6 17 feet; lowest, 3,479 feet. SURFACE FORMATIONS Undifferentiated limestones in the Fredericksburg group and sandstones of the Paluxy formation, Trinity group. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is in the Pennsylvanian system 1,580 feet below its top. This penetration was in The Pure Oil Co. #1 C .B.Harrison, located about 1,700 feet northeast of the discovery well where the total depth of 11,805 feet is indicated on the accompanying map. The accompanying TYPICAL SECTION is based on the log of this dry hole. NATURE OF TRAP Rustler : Closed anticline. PRODUCTIVE AREA Rustler and Field: About 320 acres proved productive. The extent of the productive area is not completely defined, particularly to the north and northwest. THICKNESS OF RESERVOIR ROCK Rustler : From top to bottom , approximately 10 feet. CONTINUITY OF RESERVOIR ROCK Rustler: The reservoir rock appears to be continuous throughout the area of the field and considerably beyond. The dolomite member of the Rustler formation is continu­ous throughout most of the Delaware basin. LITHOLOGY OF RESERVOIR ROCK Rustler: Light gray to buff calcareous sandy dolomite. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Rustler: Feet Elevation of top of oil 2,706 Elevation of bottom of oil 2,660 Relief 46 CHARACTER OF OIL Rustler: Gravity, A.P .I. @ 60' F., 18.6 ° WATER PRODUCTION Rustler: A considerable amount of water is produced with the oil. Several of the wells produced some water at time of completion. 174 175 T. a P. R.R. Co . --+2620-­ - p G.c.a S.F. R.R. Co. T O 955 BLOCK 121 EXPLANATION ----+2720-----Contour on top of Rustler formation • Oil well • Abandoned oil well p Ory hole SCALE THOUSAND q:[T B O ATES FIELD , Pecos County, Texas _, 6 .. TYPICAL SECTION OF ROCKS PENETRATED E L ECTRIC CURVES ANO LITHOLOGY " "' >­ "'"' ­ "'a: >-"' "'"' .::::/---­ :;."·:.---­ ·:-:;'.---­ :-.·.-:.---­:·:.·.-.----­ ··.·.-:---­ ..·...:;---­ ·.·.-:---­ "' Q. 0 "' z z z -n oo N PRODUCTION HISTORY EXPLA NATI ON at end of yea r {barrels) Year Pumping Yearly Cumulative NO. OF WELLS OIL PRODUCTION Red fi:///{(fj Sandstone sandston e I947 3,403 3 ,403 1948 9 .393 12,796 E===~ Shal e ~Redshole ~ 1949 5 ,888 18 ,684 F==I Calcareous 1950 22 ,580 41 ,264 §oolomit e ~shale 1951 34,449 75 ,7 13 ~Limestone ~Anhydrite 1952 29 ,281 I04 ,99 4 1953 28,464 133,458 1954 24, 110 157,568 • Oil produc tion O'DONNELL FIELD Lynn County, Texas E . C . RISLEY Geologist, Continental Oil Co . , Midland, Texas February 1, 1953 LOCATION The O'Donnell field is near the southeast corner of Lynn County, about 15 miles southeast of the town of Tahoka and about 13 miles northeast of the town of O' Donnell. The three presently productive wells are all in Sec . 431 , Block 9, East Line & Red River R.R . Co. survey. METHODS OF EXPLORATION LEADING TO DISCOVERY Seismograph surveying by Magnolia Petroleum Co . led to the drilling of the field discovery well. DISCOVERIES Strawn and Field: May 20, 1950; ---"M"agnolia Petroleum Co . Ill Garza Land & Cattle Co . Mississippian: October 8 , 1950; Humble Oil & Refining Co . Ill W. C . Dulin Ellenburger : November 1, 1952; Round Top Oil Co. Ill Garza Land & Cattle Co . SURFACE FORMATION Ogallala formation of Pliocene system. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 68 feet below the top of the Ellenburger group. NATURE OF TRAPS The known elevations on each reservoir prove at least a nose, as indicated by the accompanying maps . Further development may prove that the traps are due to structural nosing in combination with updip decrease in permeability. PRODUCTIVE AREAS Acres Strawn ~ Mississippian 120 Ellenburger 40 O'Donnell field 120 THICKNESSES OF RESERVOIR ROCKS Strawn Miss. Ellenburger _1_5_ From top to bottom, feet 46 -58 16 Net productive, feet 15 22 16 LITHOLOGY OF RESERVOIR ROCKS Strawn: Limestone; gray to brown or black, fossilif­ erous, finely crystalline to dense, with a minor amount of vuggy porosity throughout its thickness. Fracturing is apparent toward the base of the productive reservoir rock. Mississippian: Limestone; gray to tan, finely crys­ talline, containing gray to white vitreous chert and also some interstitial porosity locally. Apparently, there is a wide divergence in permeability. Toward the bottom, frac ­ tures increase permeability. Ellenburger: Dolomite; gray, generally dense, contain­ ing blue chert inclusions; good porosity locally; fracturing increases permeability. CONTINUITY OF RESERVOIR ROCKS Each of the three reservoirs appears to be continuous throughout the area of the field and beyond to include the immediately adjacent area tested by two dry holes . Within this small area, however, there is considerable variation in porosity and permeability of each of the three reservoir rocks . The degree of fracturing is quite variable and may determine the boundaries of productive areas. Each of the three reservoirs is at a stratigraphic position corres­ponding to the stratigraphic position of productive reser­voirs elsewhere in the Permian basin. However, it is highly conjectural whether conditions favorable for migration of reservoir fluids are continuous from any reservoir in this field to any reservoir in any other field. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Elevation of oil, feet Strawn Miss . Ellenburger Highest known Lowest known Known relief, feet -5,695 -5 ,710 15 -6 ,063 -6,157 94 -6 ,395 -6 ,411 16 CHA RACTER OF OIL Strawn Miss. Ellenburger Gravity, A .P .I.@ 60° F . 42.2° 37.2°avg. 42 .2 ° (33.9 -40.5) Odor Sweet Sweet Sweet WATER PRODUCTION Barrels Strawn Miss. Ellenburger 1950 0 152 0 1951 2,529 163 0 1952 11.611 l ,266 * *Some water was produced from Ellenburger during December; amount, unknown . ACID TREATMENT Strawn: The one well completed in the Strawn reser­voir was washed with 250 gallons of wash acid and then treated with 500 gallons of regular acid. Mississippian: In the Mississippian discovery well, this reservoir was treated four times with acid during the course of completion; with 3,000 gallons during each of three treatments and then with 5 ,000 gallons during the fourth treatment. In the other Mississippian producer, this reservoir was washed with 1,000 gallons of acid and then treated with 2 ,500 gallons of acid at the time of completion in this reservoir in February, 1953, after the well had been plugged back from Ellenburger . Ellenburger: The one well which was completed in this reservoir was washed with 5 ,000 gallons of acid at the time of that completion. Subsequently the Ellenburger was plugged off and the well was completed in the Mississippian. 0' D 0 N NELL FIELD, Lynn County, Texas CONTOURS ON TOP OF STRAWN CONTOURS ON TOP OF MISSISSIPPIAN CONTOURS ON TOP OF ELLENBURGER -50 49 ;. .\ ff ~ + + + + ---..... A-E 430 EXPLANATION Elevation of contour horizon Oil we ll , producing from Strawn Oil welt, producing from Mississippian Oil well, abandoned in Ellenburoer Dry hol e •~Discovery \#ell Productive area of Strawn Boundary of productive area of Mississippian Boun dary of productive area of Ellenburger (depleted) Identification in followin9 tabulation SCALE 12 THOUSAND FEET s ELEVATIONS AT INDICATED LOCATIONS A B c D E Surface 2 .924 2 .920 2,920 2 ,915 2 .91 1 Top of Yates formation 836 805 8 15 835 855 Sa n Andres formation -348 -348 -343 -326 -321 Spra berry forma tion -3,023 -3 ,023 -3,022 -2 .967 -2 .995 Dea n formation -4,446 -4 ,439 -4,404 -4 ,405 -4,419 Strawn series -5 ,748 -5 ,75 3 -5 ,700 -5 .695 -5,735 Mississippian system -6 ,096 -6,105 -6 ,07 0 -6 ,093 Ellenburge r group -6,416 -6 ,4 15 -6,384 -6 ,401 Total depth -6,436 -6 ,440 -5 ,710 -6 ,452 -6.41 1 O'DONNELL FIELD , Lynn County, Texas TYPICAL SECTION OF ROCKS PENETRATED ELECTRIC 8t RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY RESISTIVITY and SP OEPT H ELEVATION ffi 1400 1'20 ...J >­ "'::> 1500 1420 a: 1600 1320 1l :z: " 1220 0 1120 1900 1020 2000 920 TANSILL 2100 020 w "' ti. 2200 720 >­ 2300 620 "' a: ~ 2400 '20 ii1 z ~ 2500 '20 "' 2600 3!0 "'~ 2700 220 0 :z: z "' ~ 2 2800 120 " i a: "'i!j w ::> a. 0 2900 20 >000 -80 -180 -280 3300 -380 3400 -480 3500 -580 3600 -680 "' ~ 3700 -180 z " z J800 -880 " "' 3900 -980 4000 -1080 4100 -1180 4150 -1230 NOTE : This TYPICAL SECTION is based on the log of the dry hole offsetting to the west the Strawn discovery well . The position and extent of each reservoir is indicated although none is productive at this l ocation. EXPLANATION ~Limestone ~ Calcareous sandstone ~ Dolomite ~Shale Im Anhydrite r~ Calcareous shale [i/./)~:\:j Sandstone ~ Chert Oil production ELECTRIC 8t RADIOACTIVITY LITHOLOGY GAMMA RAY RESISTIVITY DEPTH and SP ""' 4200 w "' a: 0 4l00 w " z z a. ::> ...J g (f) 4 400 " § "' 4500 ;:. 4600 w ii1 3 C> 4700 4800 4900 5000 5100 '200 5300 "' a: ~ 5400 ~ "' ...J " 5600 '700 5800 6100 ­ 6200 6300 6400 >­;:. ~ 6500 i w ~ ~ a. 6600 "' 6700 6800 ­ 6900 7000 7100 ­ 7200 a. 7300 " " ~ ...J 74000 z "' w 7500 " " 7650 CURVES ELEVATION -1230 -1280 -1380 -1480 -1580 -1680 -1780 -1880 -1980 -2080 -2180 -2280 -2380 -2480 -2580 -2680 -2780 -2880 -2980 -l080 3190 -3280 -3380 -34 80 -3580 -3680 -3780 3880 -3980 -4080 4 190 -4280 -4380 -4480 -4580 -"730 ELECTRIC 8t RADIOACTIVITY CURVES LITHOLOGY a. ::> GAMMA RAY RESISTIVITY ....J 0 a: and SP DE:PTH ELEVATION (5 7650 -47l0 7700 -4780 <.!> a. 7800 -4880 ~ ~ j Ii a: ...J "' 0 ti. ~ 7900 -4980 8000 -5080 8100 -5180 200 -5280 8300 -5380 0 " "' 0 8400 -5480 -5880 z ~ er tn 8900 -5980 9000 -6080 • -6180 -6280 ffi 9360 z "'a: 0 " ffi > 0 0 ~ "' ...J w 0 PRODUCTION HISTORY WELLS PRODUCING at end of year Yea r Flowing Pumping Field totals I950 1951 1952 Strawn 1950 1951 1952 Mississippian 1950 1951 1952 Ellenburger 1952 E ar ly in 1953, the one well from the Ellenburge r reservoir was OIL PRODUCTION (barrels) Yea rly 23,437 23,197 9 ,792 21 ,268 18 ,'688 4 ,470 2' 169 4 ,509 3 ,514 I ,808 which Cumulative 23 ,437 46 ,634 156 ,426 21 .268 39 .956 44 ,426 2 ,169 6 ,678 10 ,192 I ,808 had produced plugged back and was completed for production from the Missis­sippian reservoir. OLSON FIELD Crockett County. Texas J. D. HOLME Geologist, Sun Oil Company, Midland, Texas May27, 1954 LOCATION The Olson field is in northwest Crockett County, approximately 10 miles southeast of Iraan in Pecos County and approximately 10 miles northeast of Sheffield in Pecos County. It is at the we stern dissected edge of the Edwards Plateau. METHODS OF EXPLORATION LEADING TO DISCOVERY Core drilling and subsurface geology. DISCOVERIES Soma: March 17, 1947; Sun Oil Co. #7 J.M. Shannon Estate. Initial potential, after acidization, 114 Mcf of gas per day. Queen: Gas: August 29, 1943; Plymouth Oil Co. #2.-M J.M.Shannon Estate. Initial potential, 14 Mcf of gas per day. Queen: Oil: May 17, 1950; H & F Oil Co. #1 J.M.Shannon Estate. Initial potential, after shot, pumping at rate of 160 barrels of oil per day. San Andres and Field: June 22, 1940; Moore Exploration Co. #1 W. T.Nolke. Initial potential, after acidization, pumping, 130 barrels of oil per day. ELEVATION OF SURFACE At well locations : Highest, 2,719 ft.; lowest,2,433 ft. SURFACE FORMATIONS All surface rocks within the area covered by the accompanying map are in the Fredericksburg and Washita groups of the Comanche series. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 436 feet below the top of the Ellenburger group. This penetration was in Plymouth Oil Co. #l-A-0 A.C.Hoover, located in Sec. 11, Block 66 as indicated on the accompanying map, at the total depth of 6 ,970 feet. Sulphur water at that depth prompted plugging back and completion in the reservoir in the San Andres formation. NATURE OF TRAPS Soma, Queen: Gas and Queen: Oil: Updip de­crease of porosity on the east flank of an anticlinal fold. San Andres: The accumulation is along the apex of an anticlinal fold, as indicated on the accompanying map. LITHOLOGY OF RESERVOIR ROCKS Soma: Sandstone; gray and brown, fine-grained. ~:Gas and Queen: Oil: Sandstone; red and gray, fine-to coarse-grained, with rounded, frosted quartz grains. San Andres: Dolomite; white, crystalline. CONTINUITY OF RESERVOIR ROCKS Soma: Shows of gas in several wells indicate, but do not prove, that this reservoir rock is con­tinuous throughout the northeastern part of the field. Queen: Gas and Queen: Oil: The productive reservoir in any well can not be proved to be continuously open for migration of fluids beyond the patterned area in which the well is represented on the accompanying map. San Andres: The reservoir rock in the San Andres formation appears to be continuous throughout the area of the accompanying map and considerably beyond its boundaries. However, the degree of porosity which occasions commercial production is probably not continuous far beyond the presently productive area. WATER PRODUCTION San Andres: Most of the San Andres wells are currently producing some water. At times of initial potential tests, at least 11 of the wells produced some water. As indicated above, the elevation at which water is yielded is quite irregular. COMPLETION TREATMENT Queen: Oil: Most of the Queen oil wells were given hydraulic fracture treatments. San Andres: 12 wells were acidized only; 16 were shot only; 4 were acidized and shot. 0 LS 0 N FIELD, Crockett County, Texas PRODUCTIVE AREAS Soma Queen: Gas Queen: Oil San Andres Olson field Acres __3_0_ 30 85 900 l ,020 THICKNESSES OF RESERVOIR ROCKS Soma Queen: Gas Queen: Oil San Andres Thickness, feet Top to bottom Net productive 40 15 30 12 20 20 40 20 ELEVATION AND RELIEF OF PRODUCTIVE ZONES Soma: --m_ghest proven elevation of gas Lowest proven elevation of gas Known relief Queen: Gas : Highest proven elevation of gas Lowest proven elevation of gas Kn own r elief Queen: Oil: Highest proven elevation of oi l Lowest proven elevation of oil Known relief San Andres: Highest proven elevation of oil Lowest proven elevation of oil Known relief Feet 1,275 I, 134 141 692 661 31 679 577 102 62 1 425 196 The oil-water contact in the San Andr e s reser ­voir is very er ratic. \"'late r has been found as high as 506 feet above sea level. In order to avoid water production, wells at locations where the r e servoir is relatively low have been completed with as little penetration oil produc ti as on. necessary for a commercial rate of CHARACTER OF OIL Queen: Oil San Andres Gravity, A.P.I. 30° 25° @ 60° F. TYPIC AL SECT I ON OF ROCK S P ENETRATED PRODUCTION HISTORY PRODUCTIVE WELLS OIL PRODUCTION GAS PRODUCTION at e nd of year (barre ls) (Mcf) Oil Wells Ga s Well s Year F low Pump Total Shut-in Yearly Cumulative Yearly Cumulative 1941 0 1 4,634 4,634 1942 0 3 5 ,843 10,477 1943 0 15 ,326 25 ,803 1944 14 45 ,645 71,448 1945 20 59,592 131,041 0 1946 0 29 7 0,095 20 I, I 35 1947 0 32 2 161,445 362 ,580 37,758 48,364 1948 0 40 2 226 ,720 589 ,300 18,985 67,349 [}/X·:):J 1949 0 49 229,835 819' 135 10 ,138 77,487 1950 54 z 257 ,728 1,076 ,863 17 ,164 94,65 l I![.-_~~-= --_ ~ 1951 0 59 375 ,661 I ,4 52 ,524 27 ,740 122 ,391 1952 0 66 2 406 ,076 I ,858 ,600 22 ,558 144,949 ~ EXPLANATION Dolomi te Sondston@ Anhydr i t@ R@dshol@ + ... ++ + So If u m ..tooe :+ ++ 1953 0 68 2 388,123 2,246,723 30 ,985 175,934 • Oi I production -i} Go 3 produ ction ~ ~ p' N 2;~;;0so"'~ '~~~,w ff l!S IO ..,. o'\... ff ~001'-I°-''. ff 2 197 ARCHER COUNTY SCHOOL LAND '!J:::@$'it~',,:(J\j)[t,~t[1~i~,~l~~iif;D 20 10 ~1;o"'" -?-0 0"­0<,; o" BLOCK GG 2 ) 1!1 0 r-' (/) 0 z 'Tj ...... M r-' t:J ~ (l ~ CD ::::: 0 g ::s -:< r 19 12 EXPLANAT ION • Oil ,.,11 p Ory hole * Go• we ll 'i~,ll~'~*.!. PRODUCTIVE AREA <::':':. ~Somo • o"""' 011 [iliiliJ D Ouun: Go~ ~:.).~Son Andrtc s.~·1 SCAL E THOUSAND FEET B OWNBY FIELD Yoakum County, Texaa C. G. COOPER and B. J. FERRIS Geologists, Shell Oil Co., Midland, Texas January 1, 1953 LOCATION The Ownby field is in the east central part of Yoakum County about 8 miles southeast of Plains, the county seat. It is at the extreme northeast end of a lobe on the continuously productive area which includes also the Wasson and Waples-Platter fields . Wasson, Waples-Platter and Ownby appear to con­stitute one continuously productive area and could logically be considered as one field. METHODS OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph and interpretation of subsurface data. DISCOVERY San Andres : April 22, 1941; George P. Livermore, Inc. #1 E.Ownby ELEVATION OF SURFACE At well locations: Highest, 3,608 ft.; lowest, 3,556 ft. TYPICAL SECTION OF ROCKS PENETRATED For information relative to the stratigraphic sec­tion penetrated in this field, the reader is referred to the accompanying paper on the Waples -Platter field. The stratigraphic section is essentially the same in the two fields . SURFACE FORMATION Caliche and surface sand overlying Ogallala sand (Pliocene). OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the San Andres group 1,000 feet below its top. NATURE OF TRAP Anticlinal fold MAP Because of geographic and geologic relationships with the Waples -Platter field, the map data are presented on one map, which is included in the accompanying paper on the Waples-Platter field. PRODUCTIVE AREA San Andres and Field: 2 ,040 acres. THICKNESS OF RESERVOIR ROCK San Andres: From stratigraphic position of highest production to stratigraphic position of lowest production: Average, 65 feet. LITHOLOGY OF RESERVOIR ROCK San Andres: Dolomitic limestone; gray, tan and brown, compact to saccharoidal, fine-grained cherty. The porosity and permeability are quite variable both vertically and horizontally. The extent of this portion of the San Andres group constituting the reservoir rock is determined by the stratigraphic range of rock sufficiently porous to yield oil into the wells. Since the porosity is so variable, a large portion of the reservoir rock is not productive. CONTINUITY OF RESERVOIR ROCK San Andres: The lithologic unit considered as reservoir rock is continuous throughout the area of the field; the porosity within the unit is quite variable. Generally at the apex of the structural fold, the stratigraphically higher portion of the reservoir rock is sufficiently porous to yield oil, whereas downdip that portion is non-porous and impermeable; at lower structural positions, the porosity is lower in the section. CHARACTER OF OIL San Andres : Gravity, A.P.I.@ 60 ° F. Average 29.9• Sulphur, by weight: 2.26% Color: Dark green OWNBY FIELD, Yoakum County, Texas ELEVATION AND REIJEF OF PRODUCTIVE ZONE San Andres: Elevation of highest known gas Elevation of bottom of gas Known relief Elevation of top of oil Elevati on of l owest known oil Known relief Feet -1,617 -1,665± 48± -1,665± -1,830 165± It appears that at the time of discovery of the Waples-Platter field in 1939, the oil-water contact at the south side of that field was at the elevation of -1,720 feet and that the contact sloped regularly northward to -1,830 feet at the north end of the Ownby field . ACID TREATMENT San Andres: All wells were treated with acid at time of completion. Treatments, in either one or two stages, ranged from 500 gallons to 15 ,000 gallons. WATER PRODUCTION Barrels Year 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 At the end of 1952, Yearly Cumulative 93 93 1,369 1 ,462 2,350 3 ,812 12,467 16,279 27 ,042 43,321 22 ,469 65,790 19,745 85,535 27 ,845 113,380 21,973 135 ,353 16 ,886 152 ,239 20,923 173,162 39 ,835 212,997 23 of the 52 wells were pro­ ducing no water; water constituted 2% to 95% of the gross production of the other 29 wells. An analysis of the water shows milligrams of constituents per liter of water as follows : calcium, 4,816; magnesium, 37 ; sodium, 77 ,548; bicarbonate, 87; carbonate, none; sulphate, 1,760; chloride, 126,844; total, 211,092. PRODUCTION HISTORY Year WELLS PRODUCING at end of year Flowing Pumping OIL PRODUCTION (barrels) Yearly Cumulative GAS PRODUCTION (Mcf) Yearly Cumulative 1941 5 0 25 ,415 25,415 44,560 44,560 1942 5 0 45 ,338 70,753 55,039 99 ,599 1943 10 0 52 ,898 123,651 65 ,130 164,729 1944 17 7 168,719 292,370 159,560 324,289 1945 26 22 352,578 644,948 285 ,612 609 ,901 1946 26 22 413 ,343 1,058 ,291 339 ,130 949,031 1947 27 21 437,083 1,495,374 492 ,170 1,441,201 1948 24 24 449 ,245 1,944,619 629 ,622 2 ,070 ,823 1949 18 27 309 ,892 2,254,511 473 ,9 02 2 ,544,725 1950 18 32 295 ,649 2,550,160 402 ,276 2,947,001 1951 18 33 358,739 2,908,899 435 ,509 3,382,510 1952 15 37 308 ,606 3,21 7 ,505 386 ,375 3,768,885 1953* 12 40 284,450 3,501,955 502,135 4,271,020 * 19 5 3 data added by amendment. PAGE FIELD Schleicher County, Texas SAMUEL P . ELLISON, Jr. Professor of Geology, The Unive rsity of Texas, Austin, Texas September 22, 1955 LOCATION The Page field ' is in south-central Schleicher County 7 miles east and 2 miles south of Eldorado, the county seat. It is near the southern margin of the Eastern platform. METHODS OF EXPLORATION LEADING TO DISCOVERY Surface mapping of the Cretaceous rocks shows a northwestward-plunging irregularly shaped nose near the discovery well. Presumably, this surface structure, accompanied by ownership of a relatively large block of leaseholds, led to the drilling of the discovery well. DISCOVERIES Strawn: Gas: June 1934; John H. Cooper #1 Bert Page (now, Cooper Gas Co. #l-A-40 Bert Page) . In November 1929, this well was commenced by Geo. T. Wilson et al, who ceased drilling in January 1931, at the depth of 5,053 feet. The well was acqui red by John H. Cooper and deepening was commenced on May 15, 1934. Sweet gas with a condensate content of 0. 7 gallon per Mcf was encountered in June 19 34, at depth of 5,402 feet. Drilling was continued inter­mittently to the total depth of 6,257 feet. The well was plugged back to 5, 550 feet and after being shot with 200 quarts of nitroglycerin and after acidiza­tion, it was completed as a gas -condensate well in January 1936. Initially, it produced at rate of 6,000 Mcf of gas per day through separator and against a back pressure. Railroad Commission tests in 1940 indicated an open flow capacity of 16, 000 Mcf per day. Strawn: Oil: June 18, 1939; Lone Star Gas Co. #1 Humble-Page (now, Cooper Gas Co. #l-C-30 Bert Page). After acidization, the well flowed 42° gravity oil through 12/64-inch choke at the rate of 158 barrels per day. It was rated as having a potential capacity of 259 barrels per day. ELEVATION OF SURFACE At well locations : Highest, 2,411 ft.; lowest, 2, 265 ft. SURFACE FORMATIONS Lower Cretaceous (Fredericksburg and Washita) limestones and calcareous shales. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellenbur­ger group 572 feet below its top. This penetration was in Cooper Gas Co. #l-D-39 Bert Page at its t otal depth of 7 ,022 feet (-4,645). NATURE OF TRAPS Strawn: Porosity zones in the reef limestone mass are on a broad terrace and disappear updip to the north and east. Limestone grades into shale updip. The accompanying map showing the topogra­phy of the top of the Strawn reef indicates approxi­mately 300 feet of relief. PRODUCTIVE AREAS Strawn: Acres Gas 400 Oil 1,480 Page field 1,600 THICKNESSES OF RESERVOIR ROCKS Strawn: Range, feet Top of highest productive zone to bottom of lowest productive zone 210to470 Net productive Total for gas bearing zones 80 to 120 Total for oil bearing zones 10 to 60 LITHOLOGY OF RESERVOIR ROCKS Strawn: Limestone; granular, paurograined, gray, calcitic, with porosity ranging up to l l .2o/o and permeability ranging up to 5.3 millidarcys. Individ­ual porous and permeable zone s are rarely more than a few feet thick and are separated by layers of dense, granular, light gray, non-permeable, calcitic limestone., On the basis of recorded core analyses, the maximum known oil saturation for any one porous zone is 46.7o/o. CONTINUITY OF RESERVOIR ROCKS Strawn: Two porosity zones containing gas and two porosity zones containing oil can be recognized throughout the field. A possible third oil zone below the two main producing zones may be recognized, but it is not continuous throughout the field. All porosity zones have greater irregularity in the southern part of the field. PAGE FIELD, Schleicher County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES CHARACTER OF OIL Strawn: First gas zone: Elevation of top of gas Lowest known elevation of gas Known relief No oil in this reservoir Second gas zone: Highest known elevation of gas Lowest known elevation of gas Known relief No oil in this reservoir Fir st oil zone: Elevation of top of gas Elevation of bottom of gas Relief Elevation of top of oil Elevation of bottom of oil Relief Second oil zone: No free gas cap Elevation of top of oil Elevation of bottom of oil Relief Third oil zone: No free gas cap Elevation of top of oil Elevation of bottom of oil Relief WELLS PRODUCING at end of year Oil G as & Year F low. A rtif. Condensate 19 34-38 1 19 39 2 1940 3 194 1 4 1942 5 1943 5 1944 1 5 1945 1 6 1946 5 7 1947 17 1 7 1948 32 0 5 19 49 5 29 4 1950 5 29 4 1951 5 29 4 1952 3 33 7 1953 0 32 7 1954 0 33 9 Feet -2 ,861 -3,038 177 -3,021 -3,200 179 -3 ,168 -3,198 33 -3 ,198 -3 ,282 84 -3,198 -3 ,311 113 -3,350 -3 ,388 38 Gravity, A.P.I.@ 60° F. : 37°to43° CHARACTER OF GAS No analysis of the gas is available. However, the gas is known to be sweet and known to be rich since condensate in large quantity is produced. The gravity of the condensate averages about 61 ° A.P.I. The stripped residue is sold to the city of Eldorado and to the Lone Star Gas Company for domestic utilization. WATER PRODUCTION Negligible. ACID TREATMENT Acid treatments range from 1,500 to 16,000 gallons per well; average about 4,000 gallons . SELECTED REFERENCE Simpson, Roscoe (1941) Page field, Schleicher County, Texas : Arner . Assoc . Petr. Geol., Bull., vol. 25, pp . 630-636 . PRODUCTION HISTORY OIL CONDENSATE P RODUCTION PRODUCTION (barrels) (barrels) Yearly Cumulative Yearly Cumulative None 10 '361 12 ,520 9 ,677 7 ,859 8,469 8 ,263 6 ,386 56,875 324,691 None Neg. Neg. 10,361 ? ? 22 ,881 ? ? 32,558 ? ? 40,41 7 ? 4,634 48 ,886 24,384 29,018 57 '149 18 ,879 47 ,897 63 ,535 17 ,540 65 ,437 120,410 13,325 78,762 445,101 14 ,219 92,981 589 ,078 1,034,179 6'111 99 ,092 455 ,458 1,489 ,637 849 99,941 3 11 ,885 1,801 ,522 796 100,737 227 ,287 2 ,028 ,809 1,337 102,074 210,600 2 ,239 ,409 1,321 103,395 250 .959 2 ,490 ,368 1 ,23 1 104,626 268 ,589 2,758,957 1,577 106,203 GAS P RODUCTION (Mcf@ 14 .65# & 60° F) Yearly Cumulative Neg. Neg . 78,998 78 ,998 58 ,784 137,782 1,726,631 1,864,413 2 ,556 ,747 4,421,160 3 ,035 ,908 7 ,457 ,068 2 ,625 ,511 10,082,579 2 ,410 ,444 12,493,023 2,277, 125 14,770 ,148 2,253,485 17 ,0 23,633 l ,024,655 18,048,288 419,784 18 ,468 ,072 . 157 .462 18,625 ,534 199,875 18,825,409 363 .960 19 ,1 89 ,369 401,640 19,591,009 511,501 20,102,5 10 PAGE FIELD , Schleicher County, Texas TYPICAL SECTION OF ROCKS PENETRATED NOTE: This section is based on the log of Cooper Gas Co. #5-A-32 Bert Page to the depth of 5,690 feet and, below that depth, on the log of Cooper Gas Co. 111 -0 -39 Bert Page with depths and elevations adjusted. EX PLA N AT ION ~Limestone t:,{{~·}./j Sondsfone E=====3 Shore ~==::i Calcareous shale f-1:3 Block shale i'.f Gos produclion ~Dolomite Oil production D [ r =< I 0 1~ i r m m ~ . I 0 "' N 0 z ~ r ~ r 0 (/) "' "' 0 "' (/) "' "' g <"' Q I "' ~ SDX8J, I AlUTI08 l8lp~ayq::>g a1 ::r Id ::r D vd I osz ------2350 ----Contour on top of Polo Pinto formation • Oil well Abandoned oi I well SC ALE -Jil-Gos well *Abandoned QOS well p' Dry hole ·~Discovery 'l:J :;r:,. 0 M "Tj ........ M l' t:J "(/) g. a> () ' ::r CD .., 0 ' \ \ }\ *=QI\:R•WN GAS i~o 0 s:: ~ \ \;, 000 \ '.J 00 \ , ~O '-', -< 0 "' * \ .,"'00 -3 / ~ Q 30 27 UI •,0::0STRA,WN :01L ;0 rof.L ,. 28 -3100 • Oil we ll *Gos well p' Ory hole Contour on top of Strawn reef + Abandoned oil well SCALE * Abandoned Qas well ·~Discovery l:'V (/'1 ....... PARKER FIELD Andrews County, Texas L. G. BYERLEY, Jr. Geologist, Honolulu Oil Corporation, Midland, Texas April 30, 1956 LOCATION The Parker field is in central Andrews County about three miles south of the town of Andrews, county seat. It is in the midst of several fields on the eastern edge of the Central Basin platform. As indicated on an accompanying map, it overlaps slightly with the Andrews field. In the overlapped area, the wells which produce from San Andres are classified as in the Parker field and those which produce from Wolfcamp and/or Pennsylvanian are classified as in the Andrews field. METHOD OF EXPLORATION LEADING TO DISCOVERY The San Andres discovery well was drilled on the basis of evidence afforded by subsurface methods. DISCOVERIES San Andres: January 2, 1935; Honolulu Oil Corp. and Llano Oil Co. #1 J.E. Parker (later, Honolulu Oil Corp. and Woodley Petroleum Co. #A-1 J.E. Parker). Wolfcamp: September 19, 1953; Fred Turner #1 J.E. Parker. Pennsylvanian: July 14, 1954; Fred Turner #2 J.E. Parker. SURFACE FORMATION Undifferentiated sands, gravels and caliche of the Tertiary system. OLDEST STRATIGRAPIDC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen· burger group 322 feet below its eroded top. This penetration was in Honolulu Oil Corp. #H-2 J . E. Parker, located in Sec. 20, Blk. A-43, where the total depth of 12,867 feetis indicatedon an accompa­nying map. The accompanying TYPICAL SECTION is based on the log of this well. ELEVATION OF SURFACE At well locations: Highest, 3,219 ft. ;lowest, 3,17lft. NATURE OF TRAPS San Andres: It is believed that the high areas indicated by contours on an accompanying map are high because of local increases in thickness of the San Andres formation. These high areas are be­lieved to be depositional features rather than struc­tural features. Variation in permeability within these features appears to be the most important trap-forming factor . Wolfcamp: The highs and lows caused by de­position over buried Pennsylvanian topography appear to have some effect on the accumulation of oil and gas, but the distribution of porosity and permeability is believed to be the most important trap-forming factor. Pennsylvanian: The trap is probably due to a combination of folding and lensing of porous zones. PRODUCTIVE AREAS Acres San Andres 280 Wolfcamp 480 Pennsylvanian 480 Parker field 760 THICKNESSES OF RESERVOIR ROCKS Feet Min. Max . Avg. San Andres: From top to bottom 35 141 79 Net p roductive ? ? 10-15 Wolfcamp: From top to bottom 93 105 100 Net productive 4 30 13 Pennsylvanian: From top to bottom 25 200 90 Net productive 8 29 23 PARKER FIELD, Andrews County, Texas IJnlOLOGY OF RESERVOIR ROCKS ELEVATION AND RELIEF OF PRODUCTIVE ZONES San Andres: White crystalline dolomite containing inclusions of anhydrite and with scattered zones of tan porous dolomite; greater granularity and more oolites in zones of higher porosity. Wolfcamp: Light-gray to tan crystalline very fossiliferous limestone with porous lenses. Algal colonies have been noted in several cores. Dark­grey to black shale partings and stylolites are scattered throughout the section. Glauconite occurs near the base. Pennsylvanian: Buff to tan crystalline fossili­ferous limestone with porous lenses. Red and green shale partings and scattered oolitic zones occur in the upper portion. CONTINUITY OF RESERVOIR ROCKS San Andres: The San Andres reef facies, of which this reservoir rock is a portion, occurs all along the east edge of the Central Basin platform and the southeast edge of the North Basin platform. It also forms an arc through northern Andrews, Martin and Howard counties and along the west edge of the East­ern shelf. Along the eastern edge of the Parker field the San Andres dips rapidly basinward and an abrupt facies change occurs. This facies change marks the eastern extent of reef migration and is represented by an interfingering of the basin sand­stones into the reef. The San Andres productive area in the Parker field is limited eastward in part by this facies change and in part by the dipping of the reservoir rock to below the elevation of the oil­water contact. In other directions, the productive area is limited by extent of porosity adequate for commercial production. Wolfcamp: It appears that the reservoir rock is continuous throughout the area of the accompanying map and sufficiently beyond to include the whole of the Andrews field to the north, the Wemac field five miles to the east and the University Block 9 field two miles to the south. However, porosity adequate for commercial production is probably not continuous throughout the above indicated area. Pennsylvanian: The reservoir rock is present and productive to the north in the Andrews field and to the south in the University Block 9 field. West­ward it has been removed by erosional truncation which followed closely the end of Pennsylvanian time. The eastward continuity of the reservoir rock into the Midland basin haij not yet been determined; it is known to extend downdip eastward to below the elevation of the oil-water contact in this field. San Andres: Feet No free gas cap Elevation of top of oil 1,435 Elevation of lowest commercial oil production 1,540 Relief 105 Wolfcamp: No free gas cap Elevation of top of oil 5,406 Elevation of lowest commercial oil production 5,560 Relief 154 Pennsylvanian: No free gas cap Eloevation of top of oil 5,834 Elevation of lowest commercial oil production 5,988 Relief 154 CHARACTER OF OIL San Andres: Gravity, A:P. I. @ 60°F: 30° Sulphur indications: Sour Wolfcamp: Gravity, A. P. I. @ 60°F: 37.3° Base: Intermediate Viscosity at reservoir conditions of 129°F. and 3,555 psi: 0.92 centipoises Pennsylvanian: Gravity, A. P. I. @ 60°F: 39.6° Base: Intermediate Viscosity at reservoir conditions of 130°F. and 3, 700 psi.: 0.694 centipoises WATER PRODUCTION San Andres: Some water is being produced. The quantity has not yet been sufficient to cause any serious operating problems. Wolfcamp and Pennsylvanian: Each of these res­ervoirs yields a negligible amount of water. COMPLETION TREATMENT San Andres: The first two wells were shot with 200 to 260 quarts of nitroglycerin. All subsequent wells have been treated with 3,000 to 7,000 gallons of acid, except that one well was treated with 2,000 gallons of acid and the reservoir rock was hydrauli­cally fractured with 3,000 gallons of oil and sand. Wolfcamp: Each well except one, which was completed "natural", has been treated with 250 to 5,500 gallons of acid. Pennsylvanian: Each well has been treated with 300 to 13,000 gallons of acid. PARKER FIELD , Andrews County, Texas TYPICAL SECTION OF ROCKS PENETRATED >­ 0: ">= " / 3192 " ffi .... \ '~ 100 3092 CRETACEOUS 200 2992 300 2892 400 2792 500 2692 600 2592 w ...J z :i: 0 700 2492 800 2392 (.) 900 2292 ::> "' "' "' "'(.) " 0: 0 0 .... 1000 2192 2092 1200 1992 1300 1892 " "'0 a:: 1400 1792 .... " z " (/) 1500 1692 1600 1592 TECOVAS 1700 1492 "' "' ­ w 3: w 1900 1292 0 RUSTLE~ -=~~ 11 92 2000) < z 2100( 1092 "" i ~ 0: (.) w 0 a. 2200 992 0 0 892 ~ 2300.,._; " ~ 7922400 --­ z~­ 692 667 z 0 0: ~ w w w 5 a. "'"' "'­ w 0: fi'"' "'"'" 0 0 0" :i: ...J " (.) 0 " "' ...J ...J z "' .... " "' w .... " >­ "' 0: w > ii' z w > z w w "'"' " 0: "' 0 :i: 0: w w .... a. :i: 3: ELECTRIC 8 RADIOACTIVITY CURVES ELECTRIC 8 LITHOLOGY GAMMA RAY ANO S P. RESISTIVITY GAMMA RAY AND $. P. DEPTH ELEVATION RADIOACTIVITY CURVES LITHOLOGY RESISTIVITY ELEVATION "'-1858 -1908 -2008 -2108 -2208 -2308 I I -2408 I I I I -2506 -2608 -2708 I -:2808 I I I ' -2908 I I ~3008 -3108 I I -13208 I I I I -3308 I : I g -34 08 I I I I I -3508 -3608 I -' 13708 I I I I -3808 I I I I I I I -4008 I I -4 108 ' 1 -4208 I ~4306 I -4363 G 2525 ;:-_ }. 2600 ~ c-­ ', 2700 ~-o.~­ ~7 2800 ~~._~ ;",,_ } 2900 -t ~ "~ 667 -=­ 592 492 ~- 392 292 w a. ::> ...J Cl 3000 ::> 192 " " 5600 3100 92 w "-6500 ::> a. -808 4000 ~~-:: 0: ...J w " 0 " YOAKUM ...J (.) 6600 ::> " z 4 100 -908 w " w ::> 0 4200 -1008 0 0: "z 0 w ...J " 6900 4400 0: ::> ­ " 7000 0: " 7100 r 7200 47001 ' -1508 } w"' 'I 0: 4800~: ''-1608 t:" 7300 0 1 :i: z (.) " 3: z 7400 4900 ~ " "' 7500 t 5000~ -t808 ~-­ 5050~ -1858 7575 , 5700 -~-: -8 3200 ...~---­ ,,;' -~~~ 5800 3300 ~--:: -108 5900 -208 6000 -308 6100 -408 6200 -508 z " 6300 -608 0:"' w a. 6400 -708 0: r­ "' 0 PARKER FIELD, Andrews County, Texas TYPICAL SECTION OF ROCKS PENETRATED ELECTRIC a RADIOACTIVITY CURVES ~ ~ o. GAMMA RAYLITHOLOGY i;; ii: 5 AND S.P. RESISTIVITY =! 0 PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year {barrels) Flow. Artif. Yearly Field totals 1935-1952 Same as San Andres 1953 1954 1955 12• San Andres: 1935 1936 19 37 1938 1939 1940 194 1 1942 1943 1944 19 45 1946 19 47 1948 1949 1950 195 1 1952 1953 1954 1955 Wolfcamp: 1953 1954 1955 Pennsylvanian: 1954 1955 10 * 12 19• 4!,265 263,052 457,306 11, 647 ! 3,955 12,473 11, 243 9,656 10,882 10, 541 9, 799 9, 738 9,984 9. 301 8,985 9,680 l 2, 769 27,074 20, 698 20, 122 17,65 1 2 1,275 26, 889 27, 487 4 10 19,990 16 1, 276 190,271 74,887 239,548 Cumulative 236, l 98 277, 463 540,515 997,821 11 ,647 25, 602 38,075 49,318 58,974 69,856 80,39 7 90, 196 99.934 109,918 119, 219 128,204 137,884 150, 653 l 77, 727 198,425 2 18,547 236, l 98 257,473 284, 362 31 1, 849 19,990 18 1, 266 371,537 74,887 3 14, 435 There are 25 producing wells , 7 of which produce from San Andres only, 6 from Wolfcamp only, 6 from P ennsylvanian only and 6 from bolh Wolfcamp and P ennsylvanian . PARKER FIELD , Andrews County, Texas ~ 11 :.....;e· ---r~ -US& -~ \ I \ ~ ~\ , I \( I I EXPLA NATION ---1425 ---Contour on top of Son Andres formation -•"_1' Elevation of top of Son Andres formation 121111 Total depth • Oil well JI' Ory hole + Abandoned oil well o Location or drilling well • ~Discovery /. Producing from Son Andres I+ Prev iously productive from Son Andres •\ Producim;J from Wolfcomp ....!..._ Producing from Pennsylvanian ~o;;~lf~;;:~e~i~~· p~r0o0d5~~~~~;~~om ://///////////////////////////////////, Boundary of Son And res productive area SCALE THOUSAND FEET PARKER FIELD , Andrews County, Texas 6 ... WOLFCAMP MAP ~ .A ~ ..£. ~ ANDREWS FIELD ~ EXPLANATION ----5425---Contour on top of Wolfcamp reservoir -5 : os Elevation of top of Wolfcomp reservoir 1tu1 Total depth • Oil well +Abandoned oil well P Ory hole o Location or drilling well • ~Discovery / • Producing from Son Andres I+ Previously productive from Son Andres .\ Producing from Wolfcomp _!.._ Producing from Pennsylvanian ~D~~lf~~~~le~i~~, :e~~~~l~~~ia~rom ://///////////////////////////////.-Boundary of Son Andres productive area SCALE THOUSAND FEET \\ \ \ I \ I I J I 2 u~\\1€.~s\°t'< 9 'O'--ocV... PARKER FIELD , Andrews County, Texas 6 ~ PENNSYLVANIAN MAP _l:, ~ ~ ~ ~ ANDREWS FIELD ~ 9 iO EXPLANATION ----5725---Coo1our on top of eroded Pemsylvonion system ·~;10 Elevation of top of eroded Pennsylvanian system 121'7 Total depth • Oil well +Abondoiied oil well ff Dry hole o Location or drilling well • ~Discovery /. Producing from San Andres f+ Previously productive from Son Andres .\ Producing from Wolfcomp _..!.__Producing from Pennsylvanian ~Duo\ completion, producing .from Wolfcomp and Pennsylvanian W///////////////////////////////////// Boundary of Son Andres productive area SC ALE THOUSAND FEET 0 PARKS FIELD Midland County, Texas JAMES RUSSELL COTTON Geologist, Houston Oil Co. of T exas, Midland, Texas January 1, 1954 LOCATION The Parks field is in west central Midland County, about 10 miles southwe st of the town of Midland. METHODS OF EXPLORATION LEADING TO DISCOVERY Subsurface and seismic . DISCOVERIES Strawn: September 23, 1951; Magnolia Petroleum Co. #1 A.B.Harrington Bend: December 6, 1950; ----"Magnolia Petroleum Co. #1 H.F.Timmerman Ellenburger and Field: June 30, 1950; Magnolia Petroleum Co. #2 Roy Parks ELEVATION OF SURFACE Average, 2,835 feet . SURFACE FORMATION Trinity sandstone, overlain by a thin veneer of Pleistocene-Recent wind-blown sand. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 367 feet below the top of the Ellenburge r group. This penetra tion was in Magnolia Petroleum Co. #1 H .S.Collins , which was drilled to the total depth of 13 ,302 feet at the location indicated on the accompanying map. The only other wells which have been drilled to the Ellenburger are the Ellenburger dis covery w ell and the Bend discovery well . CONTINUITY OF RESERVOIR ROCKS Strawn, Bend and Ellenburger : The continuity of each of the---re'Servoir rocks is interrupted by a normal fault which parallels the axis of the anticline. Except for this interruption, each of the reservoir rocks appears to be continuous throughout the area of the field and far beyond. NATURE OF TRAPS Strawn: The wells producing from this r e servoir are a t various positions on a faulted anticlinal fold. The primary trap-forming factor is probably the anticlinal fold ; however, updip decreas e of porosity appea rs to have been an important factor in occa­sioning accumulation. Bend: The trap is at the apex of a faulted anti­cline, as indicated on the accompanying map. It appears likely that the trap is formed, in part, by termination of the reservoir rock against the fault. Ellenburg e r : The three wells which have tested the Ellenburger are near the apex of an anticlinal fold. It appears that the trap which occasioned the accumulation of oil i s due to anticlinal folding. LITHOLOGY OF RESERVOIR ROCKS Strawn: Lime stone; tan to gray to brown , finely crystalline to densely crystalline, fossiliferous, slightly cherty in part and shaly near base. Bend: Limes tone, dark gray to gray-brown, fin ely crystalline to densely crystalline , slightly cherty and fossiliferous , with intermittent thin gray shale beds . Ellenburger: Dolomite; tan to gray-white, finely crystalline to m e dium crystalline. CHARACTER OF OIL Str'awn Bend Ellenburger Gravity, A .P .I.@ 60° F. 43 ° 44° 54° WATER PRODUCTION Strawn: Negligible Bend: Negligible ~burger: Large percentage of gross production ACID TREATMENT Strawn: The quantity of acid used in each well ranged from 250 gallons to 30, 500 gallons. Bend: Some wells were completed "natural". The quantity of acid used in the treated wells ranged up to 70,250 gallons. Ellenburger: No one of the three wells completed in Ellenburger was treated with acid. PARKS FIELD, Midland County, Texas PRODUCTIVE AREAS Strawn Bend Ellenburger P a rks (depleted) field 2 ,880 20 3,280 THICKNESSES OF RESERVOIR ROCKS Feet Min. Max. Avg . Str awn 10 60 30 Bend 20 79 46 Ellenburger 28 28 28 ELEVATION AND RELIEF OF PRODUCTIVE ZONES Strawn Bend Ellenbur ger No free gas in any reservoir Elevation of top of oil, feet -7 ,401 -7,555 -10,107 El evation of bottom of oil, ft . -7,742 -7,877 -10,135 Relief, feet 341 322 28 I compl e ted in Be nd P Ory hole • ~Discovery .\ Oil well, obondoned in Ellenburoer, PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year All flowing Yearly Cumulative Field totals 1950 62 ,840 62 ,840 195 1 14 470,072 532,912 1952 29 789 ,002 I ,321 ,914 1953 41 712,554 2 ,034 ,468 Strawn 195 1 49 ,616 49 ,616 1952 4 89 ,543 139 ,159 1953 5 74 ,278 213,437 Bend 1950 5 ,516 5,516 1951 11 420 ,456 425,972 1952 25 699 ,459 1'125,431 1953 36 638,276 1,763 ,707 Ellenburger 1950 57 ,324 57 ,324 '1951 0 57 ,324 Only one well, the discovery well, has been com­pleted for production from Ellenburger . It was abandoned in Ellenburger and plugged back to Bend in January 1951. TYPICAL SECTION OF ROCKS PENETRATED PARKS FIELD , Midland County, Texas TYPICAL SECTION OF ROCKS PENETRATED z 0 RADIOACTI VITY CURVES z RADIOACTIVITY CURVES ~ ;: LITHOLOGY 2 V> w " w ~ " ,_ ,_ w V> ii: " a: GAMMA RAY NEUTRON ii: ';! w >-w 0 V> u. DEPTH ELEVAT ION V> V> :: z z 0 _J • z >-w V> z "' z ~ z V> i z 0 2 > w " i 0 a: w a. z ~ a: => _J - 0 0 a: 0 • z .. -' >­ V> z z [~\?Md Sandstone t:==-===~ Shale ~Calcareous ~ shal e w "-~Limestone EXPLANATION ~Dolomi te mlAnhydrite ~Limestone . Solt ~ond chert D ~Dolomite ond 1:::;:;:;1 Rock indicated, ~ anhydrit e ;:;:;:;: sandy ~Sondston~ and [-_ iRock indic ated , - ~ on hydr1t e -_ -sholy . 011 production D Rock indicated, * Show of oos red PECOS VALLEY FIELD Pecos and Ward Counties, Texas ROSS H. LEY District Geologist, Sun Oil Company, Midland, Texas February 11, 1956 LOCATION and FIELD NAMES The Pecos Valley field occupies an area extending across the Pecos River mainly in northwestern Pecos County and partly in southeastern Ward County. The irregularly shaped a rea extends 11 miles in a north-south direction with the northern tip 7 miles southeast of the town of Grandfalls in Ward County. This field is on the Central Basin platform near its southwest edge. The production from the Yates formation in this field has been treated in publications generally as from three distinct fields under the names of Orient field, Pecos Valley High Gravity field and Pecos Valley Low Gravity field. The area commonly designated as the Orient field is at the north­west tip of the Yates productive area. The Pecos Valley Low Gravity field includes two distinct areas, one in the central portion and the other at the south end of the Yates productive area. These three distinct areas are indicated on an accompanying map. The area of the Pecos. Valley High Gravity field is the remainder of the Yates productive area as that area is indicated by the distribution of well symbols indicating production from the Yates formation. However, until the beginning of 1939, Pecos Valley High Gravity field and Pecos Valley Low Gravity field were treated as one field, the Pecos Valley field, and that field included also such well or wells as were in Sec. 46, Blk. 10, H. & G. N. R.R. Co. survey. At the beginning of 1939, all wells pro­ducing oil heavier than 32 ° gravity were classified as in the Pecos Valley Low Gravity field and all wells producing oil lighter than 32 ° gravity were classified as in the Pecos Valley High Gravity field. Since the time of their first production in 1929, the Railroad Commission has · treated as in either the Pecos Valley field or the Pecos Valley Low Gravity field, which­ever name was currently effective, such producing wells (never more than three) as were in Sec. 46, Blk. 10, H. & G. N. R.R. Co. survey. In this paper, those wells are not considered as within the area of the Pecos Valley field; they are considered as in the Lehn-Apco field. A group of 5 wells in Sec. 36, Blk. 3 and Sec. 21, Blk. l 0, about the center of the Pecos Valley field, has been treated generally in petroleum publications and by the Rail­road Commission as constituting the Jamison & Pollard field. The first of these wells was completed July 24, 1940; all had been abandoned before the end of 1953. They pro­duced from a zone in the Whitehorse Dolomite. At the time of its completion, the well listed under DISCOVERIES as the first Fusselman discovery well, was considered as the discovery well of a new field. The field was named North Heiner field and the well was operated under that name until its abandonment in 1952. It was the only well in the field. In this paper, that well is treated as in the Pecos Valley field. DISCOVERIES Yates and Field: November 20, 1928; Pecos Valley Oil Company #1 Fee. Flowed "natural" from depth of 1,628 feet at daily rate of 105 barrels of 37° gravity oil. Yates: Orient: April 2, 1948; R.R. Herrell #1 W. C. Jackson et al (now, C. N. Smith #1 Jackson-State). After shot, flowed through -!-inch choke at daily rate of 66 barrels of 37.5° gravity oil; gas-oil ratio, 680: l; T. D., l,826 feet. Whitehorse Dolomite: July 24, 1940; Ward-Pecos Pe­troleum Corp. #DE-6 Pecos Valley Oil Co. Flowed at daily rate of 193 barrels of oil and 1,900 barrels of water. Pepth to top of reservoir, 2,037 ft.; T. D., 2,049 ft. At time of completion, this well was classified as in the Pecos Valley Low Gravity field; at the beginning of 1941 it was reclassi­fied and treated as the first well in the Jamison & Pollard field. Ownership was transferred from Ward-Pecos Pe­troleum Corp. to Jamison & Pollard effective January l, 1941; then to Pollard & Davis effective November l, 1948. Wolfcamp: July 10, 1951; Callery & Hurt, Inc. #D-1 Redmond "J". After acid treatment, flowed through 14/64­inch choke at daily rate of 500 Mcf of gas and 3 barrels of condensate; T. D., 8,414 feet. Devonian: May 28, 1953; H. L. Hunt #1 H.J. Eaton. After treatment with 3,500 gallons of acid, flowed through 15/64-inch choke at daily rate of 3,527 Mcf of gas and 65.17 barrels of 61.6° gravity condensate; gas-oil ratio, 54,120: l ; depth of reservoir, ·5,368 -5,404 feet. Fusselman: August 19, 1948; Humble Oil & Refining Co. #1 A. D. Unsicker. Flowed through2-inch tubing at daily rate of 67 barrels of 39.4° gravity oil and 14 barrels of water; gas-oil ratio, 210: l; drilled to total depth of 8,460 feetin Ellenburger and completed for production through perfora­tions from 5, 630 -5, 660 feet. This well was recognized as the discovery well of the North Heiner field and was the only well ever treated as in that field. It was abandoned in l95i. Fusselman: May 17, 1953; Sinclair Oil & Gas Co. #1 Realty Trust. Flowed "natural" through -! -inch choke at daily rate of 452 barrels of 42.1 ° gravity oil; gas-oil ratio, 342: l. This well was drilled to total depth of 8,100 feet in 1950 and completed in Ellenburger; later plugged back to 5, 760 feet; depth of Fusselman reservoir, 5,682 -5, 732 feet. Montoya: February 14, 1951; Callery & Hurt, Inc. #A-1 H.J. Eaton. After mud-acid treatment, flowed through open 2-inch tubing at daily rate of 22, 000 Mcf of gas and 153.6 barrels of 75.2° gravity condensate; gas-oil ratio, 42,300: l; T. D. , 8,061 feet; depth of reservoir, 5,328 -5,470 feet. McKee: March 24, 1951; G. H. Vaughn #1 Iowa Realty Trust. Flowed "natural" through 3/8-inch choke at daily rate of 3,300 Mcf of gas. In Ellenburger at T. D., 8,323 feet. Ellenburger: October 2, 1949; Fullerton Oil Co. #D-1 METHOD OF EXPLORATION LEADING TO DISCOVERY Kone Production Co. Flowed "natural" through 3/4-inch choke at daily rate of 505 barrels of 43.6° gravity oil; gas­Random drilling where the operator owned fee title to a oil ratio, 629: l; top of reservoir at 7,971 feet; T. D., 8,210 large area of land. feet; plugged back to 8, 157 feet. PECOS VALLEY FIELD, Pecos and Ward Counties, Texas YATES RESERVOIRS Generally in prior publications, the Yates production of this field is treated as coming from three fields (Orient, Pecos Valley High Gravity and Pecos Valley Low Gravity) , but there has been no subdivision on the basis of reservoirs. It is recognized that the Yates formation contains several distinct reservoirs within the area here treated as the area of the Pecos Valley field. However, it is not practical to delineate the several reservoirs and to present datafor each separately. Therefore, the Yates reservoirs are treated as a group rather than to endeavor to present data for each reservoir separately. Within the Yates productive area there are multitudes of variations in porosity and permeability, with the result that there are many small erratic accumulations of oil and gas. There are many independent reservoirs with their own inde­pendent gas-oil and oil-water contacts. Many of these reser­voirs appear to contain no water below the accumulation of oil and/ or gas. In some parts of the field, particularly in the southern and southwestern portions, the degree of po­rosity is so low that only gas will flow from the reservoirs. The degree of porosity appears to have a relationship with local structural conditions. There is a tendency for the Yates sandstone to be shaly and have low porosity in locally low areas. This probably indicates that the Yates was de­posited on an irregular surface closely similar in form to that of the top of the Yates at present and as portrayed on an accompanying map. As indicated on the accompanying TYPICAL SECTION, there are two general productive zones in the Yates forma­ tion. In general, the higher gravity oil is produced from the upper zone and the lower gravity oil is produced from the lower zone. At the stratigraphic position of the upper zone, which is sandstone within the area of the field, there is less sand eastward (updip); at the east edge of the area covered by the accompanying map, the rock at this stratigraphic position is principally anhydrite. Likewise, the lower zone contains less sand eastward, where there is a greater per­ centage of shale and anhydrite; at the east edge of the area, the rock at this stratigraphic position is all anhydrite. The eastward decrease of porosity and permeability is such as to constitute barriers to migration of fluids. In the eastern portion of the area, many wells drilled with cable tools encounter no fluids of any kind in the Yates section. West­ ward and southwestward from the producing area, the lower of the above mentioned two zones grades into tight lime­ stone; the upper zone is of the same character as in the productive area. Within and immediately adjoining the Pecos Valley field, the Yates formation has been penetrated at about 780 loca­ tio·ns; at 561 locations where wells were completed in the Yates formation, at locations of 191 shallow dry holes and at 28 locations where penetration was carried into pre-Permian rocks. Of the 561 wells completed in the Yates formation, 130 have either beenabandoned or converted to water injection wells. ELEVATION OF SURFACE Elevations at well locations: Highest, 2,547 feet, at the south end of the field; lowest, 2,401 feet, at the Pecos River. SURFACE FORMATIONS Rocks of the Quaternary system occupy most of the sur­face; rocks of the Fredericksburg and Trinity groups of the Cretaceous system and rocks of the Triassic system occupy minor areas. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellenburger group 575 feet below its top. This penetra tion was in the Montoya discovery well a t its total depth of 8,061 feet. NATURE OF TRAPS Yates : The predominating trap-forming factor is updip dee~of porosity and permeability in sloping res ervoir rocks. However, it appears probable that there are several distinct reservoirs in the Yates formation and that some of the accumulations a re due, at least in part, to other trap­forming factors, particularly, to convex folding and to updip termination due to lensing. Whitehorse Dolomite: Convex folding. Wolfcamp: The trap at the location of the single pro­ductive well appears to be due to anticlinal folding . For approximate structural conditions, see a ccompanying map showing contours on top of Yates formation. Devonian: The trap was formed by updip termination of reservoir rock by truncation and with sealing by over­lying relatively impervious rock. Fusselman, Montoya and Ellenburger: Updip termin­ation against a fault on an a nticlinal nose. McKee: Both updip termination due to lensing and updip dec~fporosity and permeability in a sloping reservoir rock. PRODUCTIVE AREAS Acres Yates 10, 440 Wolfcamp 320 Whitehorse Dolomite 120 Devonian 1,400 Fusselman 400 Montoya 320 McKee 640 Ellenburger (depleted) 160 Pecos Valley field 12, 200 THICKNESSES OF RESERVOIR ROCKS Feet, average Top to Net bottom productive Yates High Gravity area 100 13 Low Gravity areas 120 16 Orient area 62 13 Whitehorse Dolomite 6 2 Wolfcamp (one well) 235 175 Devonian (seven wells) Where only 1 zone is productive 70 20 Where 2 zones are productive 185 60 Fusselman (four wells completed; one abandoned) 75 32 Montoya (one well) 175 90 McKee (two wells) 55 37 Ellenburger ( 4 wells completed; all abandoned) 180 96 TYPI C AL SECTION OF ROCKS PENETRATED z 0 RADIOACTIVITY CURVES ~ ~ a.. ~ LITHOLOGY I--::> :e CJ) cc: 0 a:: GAMMA RAY NEUTRON >-w a: 0 "' DEPTH ELEVATION "' "' "' "'­0 2454 ::> w 0 J: >­ w (.) .... (.) z ­ <( <( ~ .... "a: 100 2354 .... a:w (.)0 (.) 200 2254 > r---s } ~ I I~! I ·~~~~~~~~~ 500 )ri{ "'j 1854 if ... 700 1754 1654 800 :1<( 1554 0 ~r·.. "IJ: a: ~ 1q54 1000 ~1 I I I 1354 1100 I 12.54 ;\"" ,,,.J 1300 1400 } em < 1'143 I ~ NOTE : This TYPICAL SECTION is based on the log of Magnolia Petroleum Co. #1-39 H.J. Eaton, a dry hole located in Section 39, Block 3, H. & T. C.R. R. Co. survey, where its total depth of 9,529 feet is indicated on the accompanying maps. While that log serves satisfactorily for our general purposes, its details, particularly depths and el evations, apply to the one location only. To convey an understanding of the field as a whole, reservoir symbols and fluid symbols are entered at appropriate stratigraphic positions although the l og records conditions in a. dry hole. t-.J O> .;::... 'l:1 tTl () 0 Ul < :i::­ L' L' tTl >-< '"Tj ...... tTl L' t:J 'l:1 < Q Ul PECOS VALLEY FIELD, Pecos and Ward Counties, Texas EXPLANATION ---+1100---Contour on top of Yotes formation Oil well, productive from Yates Abandoned oil from Yates well, previously productive Abandoned oil well, previously productive from Whitehorse Dolomite @ Oil well, productive from pre-Permian th ~ * Abandoned oi1 well, previously productive from pre-Perm ion Gos wel l, productive from Yates Gos well , producing from Wolfcomp, total depth in pre-Permian ro T.C. R.R. Co. BLOCK 112 °!?SON-PECOS FIELD @ Gos we ll, productive from pre-Permian p Dry hole , total depth in Permian ® Dry hole, total depth in pre-Permian 6 ln 1ecting water into Yoles A. 1n1ect 1ng water into Yates, previously productive frvm Yates ·~Discovery ---------+--+---+-Boundary of Orient productive area · · ~---~ ~ ..~ .. ·-Boundary of Pecos Volley Low Gravity productive oreo SCALE 4 6 ro 590 Ji THOUSAND FEET PECOS VALLEY FIELD , Pecos and Ward Counties, Texas PECOS VALLEY FIELD , Pecos and Ward Counties, Texas LITHOLOGY OF RESERVOIR ROCKS Yates: Sandstone; gray to brown, fine-to m edium­gr ained with thin interbedded sha le streaks and numerous rounded frosted quartz grains. See the entry under the heading YA TES RESERVOIRS. Whitehorse Dolomite: Dolomite; brown to tan. Wolfcamp: Dolomite; brown, gray, tan, finely porous. De vonian: Limestone; white to brownish-white, finely crystalline with abundant milky-white or smoky chert. Fusselman: Dolomite; tannish-gray to brown, finely c r ystalline to medium crystalline with tannish-white, fine to very fine, cherty limestone. Montoya: Dolomite and limestone; tan with milky tannish­white smoky chert. McKee: Sandstone ; grayish-white to gray, fine to coa r s e. The composition, particularly the clay content, varies widely in short distances. Ellenburger: Dolomite; brown to tan, finely crystalline to medium crystalline, with scattered embedded sand g rains. CONTINUITY OF RESERVOIR ROCKS Ya tes: The Yates formation is continuous throughout the ma-of the accompanying map; the individual reservoirs are of only local ex tent. As reported under the heading YATES RESERVOIRS, there are many reservoirs in the Yates formation. Whitehorse Dolomite: Available data do not provide a basis for correlating the reservoir rock beyond the immedi­ate vicinity of the wells where it was productive. It is probably continuous throughout a large area, but only locally sufficiently porous to yield oil. Wolfcamp: The reservoir rock is continuous through­out the area of the accompanying m a p. Devonian, Fuss elman and Montoya: Each of these reser­voir rocks has been truncated by pre-Permian erosion. Furthermore, faulting has interrupted their continuity. The details of the continuity of these reservoir rocks are not yet determinable because, within and immediately adjoining the area of the Pecos Valley field, there have been only 28 penetrations into pre-Permian rocks. McKee and Ellenburger: Each of these reservoir rocks app~ be continuous throughout the area of the accom­panying map except for interruptions by faulting. COMPLETION TREATMENT Yates: In practically all wells, at time of completion, the Yates reservoirs have been treated either by shooting with nitroglycerin or, in recent years, by hydraulic frac­turing. Hydraulic fracturing has been used in practically all of the recent completions. Pre-Permian reservoirs : The pre-Permian reservoirs are commonly treated with acid at time of well completion. SECONDARY RECOVERY There are now 10 water-flood projects operating in the Pecos Va lley field, all flushing Yates reservoirs. Three additional similar projects will be started in the immediate future. Results of water-flooding are reflected in the following PRODUCTION HISTORY by the increase in 1953 in Yates Low Gravity and by the increase in 1955 in Yates High Gravity. ELEV A TI ON AND RELIEF OF PRODUCTIVE ZONES Proven e l evation, feet GAS OIL Relief, Highest Lowest Highest Lowest feet Yates 1,274 506 1, 209 469 (*) Whitehorse Doi. No free gas 464 399 65 Wolfcamp -2,685 -2,945 No known oil (**) 260 Devonian -2,915 -3, 121 -3,00 1 -3, 129 214 Fusselman -3, 045 -3,224 -3,206 -3,332 287 Montoya -2, 880 -3,032 No known oil (**) 152 McKee -4, 123 -4,307 No known oil (**) 184 Ellenburger No free gas -5,521 -5, 742 221 The above figures represent conditions as of respective discovery dates . {*) The fluid columns of individual reservoirs in the Yates formation have not been determined. See entry under YATES RESERVOIRS. (**) The liquid hydrocarbons (condensate) produced from Wolfcamp, Montoya and McKee are prob­ably all in the form of gas in the reservoirs. CHARACTER OF LIQUIDS OIL CONDENSATE Gravity, Sulphur Gravity, A. P. I. @ 60°F. indication A. P. I.@ 60°F. Yates High gravity 32-40 Sweet Low gravity 24-32 Sweet Orient 27-37 Sweet Whitehorse Doi. 24 1.14% Wolfcamp . . .... ... ... . . . . . .......... ... .... 50 Devonian 34-38 Sweet 62 Fusselman 42-53 Sweet 72 Montoya . .. ..... . ........... . ........... . . 68 McKee 64 Ellenburger 44 Sweet For analyses see: Railroad Commission of Texas Analyses of Texas Crude Oils (1940), pp. 33, 63 and 64. u. s. Bureau of Mines Lab. ref. No. 311 62 38155 Tabulated Analyses of Texas Crude Oils. T.P. 607 (1939) Group 2 Item 73 72 Analyses of Crude Oils from Some West Texas Fields . R. I. 3744 (1944) Page 27 28 WATER PRODUCTION The quantity of water has never been sufficient to con­stitute a serious handicap to producing operations. PECOS VALLEY FIELD, Pecos and Ward Counties, Texas PRODUCTION OIL PRODUCTION (barrels ) WELLS PRODUCING at end of year OIL GAS Flo w Pump Yates, High Gravity 1928-1938 * 19 39 48 40 ? 1940 46 56 ? 1941 43 58 ? 1942 42 58 ? 1943 42 59 ? 1944 35 64 ? 1945 44 66 ? 1946 50 63 ? 1947 62 59 ? 1948 73 71 ? 1949 152 72 ? 1950 92 150 ? 195 1 69 199 ? 1952 65 201 ? 1953 82 217 ? 1954 79 222 ? 1955 ? ? ? Yates, Low Gravity 1928-1 938 * 1939 52 18 ? 1940 36 42 ? 1941 2 7 50 ? 1942 26 47 ? 1943 26 45 ? 1944 12 54 ? 1945 12 48 ? 1946 9 55 ? 1947 9 54 ? 1948 8 55 ? 1949 5 54 ? 1950 8 48 ? 1951 9 5 1 ? 1952 8 49 ? 1953 9 53 ? 1954 8 63 ? 1955 ? ? ? Yates, Orient 1948 3 6 0 1949 0 5 0 1950 0 5 0 1951 1 5 0 1952 3 6 0 1953 2 8 0 1954 2 8 0 1955 2 8 0 HISTORY GAS PRODUCTION A few wells (on the order of 10) in different parts of the field have been completed for production of gas from Yates reservoirs. Ca pacities range from a few hundred Mcf to 18, 000 Mcf of gas per day. During the early development history of the field, on the structural highcentering on the Pecos River, numer­ous wells encountered strong flows of gas at the top of the Yates formation but were deepened and com­pleted as oil wells. In the early 1930's, a 4-inch gas pipe line was built to supplygas to the town of Fort Stockton, located 22 miles southwest of the field. This line was con­nected to two wells, one in the wes t corner of Sec. 27, Blk. 3, and the other near the north corner of Sec. 23, Blk. 10, and transported a bout 50 Mcf of gas per day. The line was originally operated by Pecos Crude Oil Purchasing Corporation, which later sold the line to Big Bend Pipe Line Compa ny, which, in turn, sold the line to the city of Fort Stockton which operated the line until 1940 when it was abandoned in favor of a gas supply from the Fort Stockton field. Plans to extend the line from Fort Stockton to Alpine and Marfa were never executed. The original Yates gas well, O. J . Perren #1 H . J . Eaton, completed in August 1929, in the west corner of Sec. 27, Blk. 3, is still producing gas. Gas from this well, now designated as Callery & Hurt, Inc. #1 Pickle-Eaton, in addition to gas from the one Montoya well, Callery & Hurt, Inc. #A-1 H . J . Eaton, was used to gas-lift oil from Ellenburger wells t wo miles to the northwest. It is now being used to fuel irrigation pumps. In late 1954, El Paso Natural Gas Company began taking casing head gas from the pre-Permian gas­condensate wells . FOOTNOTE *Prior to 1939, Yates High Gravity and Yates Low Gravity were treated by reporting agencies as a single unit. Because of confusion in the records, the quantities produced annually are not reported herein. The writer believes that the cumulative total to the end of 1938 amounted to l , 073,687 barrels. The allocation between High Gravity and Low Gravity is not readily definitely determinable; however, suf­ficiently accurate for our purposes is the ratio indi­cated by data on pages 362-364, A. I. M. E. Petroleum Development and Technology -1943 (covering 1942). Those data indicate that 62% of the cumulative total was from the Yates High Gravity area and 38% was from the Yates Low Gravity area. On the basis of that ratio, the writer estimates that the production prior to 19 39 a.mounted to 665, 686 barrels from Yates High Gravity and 408,001 barrels from Yates Low Gravity. Yearly 306,936 277,091 240, 328 190,432 146,318 129,003 137,805 180,929 206,962 307,923 521,938 581,066 50 1,650 489,652 532,121 509,249 790,890 171,521 199,411 184,374 110,442 93,963 82, 122 72, 208 75,135 69, 961 67' 593 62,945 58,479 60,789 73,557 110,873 2 13,440 343, 626 15,438 29,441 7,000 9, 725 22,596 24, 573 14, I 78 13,425 Cumulative 666,xxx 973,xxx 1,250,xxx 1,490,xxx 1,680,xxx 1,827,xxx 1,956,xxx 2,094,xxx 2,2 75,xxx 2,48 1,xxx 2, 789,xxx 3,311,xxx 3,892,xxx 4,394,xxx 4,884,xxx 5, 416,xxx 5,925,xxx 6, 716,xxx 408,xxx 580,xxx 779,xxx 9.63,xxx 1,074,xxx 1, 168,xxx 1,250,xxx 1,322,xxx 1, 39 7,xxx 1,467,xxx 1,535,xxx 1,598,xxx 1,656, xxx 1,717,xxx 1, 791,xxx 1, 901,xxx 2,115,xxx 2,458,xxx 15, 438 44,8 79 51,879 61,604 84, 200 108, 773 122,951 136,376 PE C 0 S VALLEY FIELD, Pecos and Ward Counties, Texas PR 0 D UC TION HIS TO RY (Continued) OIL PRODUCTION GAS PRODUCTION CONDENSATE (barrels) (Mcf) PRODUCTION (barrels) Yearly Cumulative Yearly Cumulative Yearly Cumulative Whitehorse Dolomite 1940 4, 324 4, 324 1941 22,975 27,299 1942 .......• .. . . .. 27,247 ........ 54,546 1943 21, 646 76, 192 1944 13, 400 89, 592 1945 ...... ........ 15, 739 .... ... 105,331 1946 42,687 148,018 1947 9,642 157,660 1948 . . . . . . . . . • . . . . 6,618 ....... 164,278 1949 25,027 189,305 1950 4,082 193, 387 1951 ....... . ..... . 1,797 195,184 1952 790 195,974 1953 90 196,064 1954 ...... .. ... . . .... . 0 . ..... . 196,064 1955 0 196,064 Wolfcamp 1953 0 0 3,300 3,300 116 116 1954 ................. . 0 .. .......... 0 ········ 10,251 ······· 13,551 .......• 207 .. ..... 323 1955 0 0 65,018 78,569 1,158 1,481 Devonian 1953 7,714 7,714 0 0 0 0 1954 ...•.......... 47,399 ........ 55,113 ......... 8,676 ........ 8,676 ........ 329 ....... 329 1955 54,91 8 110,031 635,544 644,220 13, 732 14,061 Fusselman (*) 1949 2,270 2,270 0 0 0 0 1950 2,185 4,455 0 0 0 0 1951 ..... .......... 1, 191 . . . . • . . . 5, 646 . . . . . . . . . . . . 0 ............ 0 .. ........ 0 ......... 0 1952 0 5,646 0 0 0 0 1953 22,095 27, 741 0 0 0 0 1954 ........... . .. 19,040 ........ 46,781 .... . ....... 0 ... . ....... 0 ........ . . 0 .... ... .. 0 1955 12,092 58,873 40,692 40,692 274 274 Montoya 1951 . .. . ...• ..... . .... 0 ... •........ 0 . ... ... 291,286 ...... 291,286 ...... 4,588 .. . .. 4,588 1952 0 0 246,888 538,174 3,890 8,478 1953 0 0 193,568 731, 742 3,620 12,098 1954 . ...•..... ... . .... 0 . ... ........ 0 ............ 0 ...... 731,742 .... .... .. 0 . ... 12,098 1955 0 0 462,256 1,193,998 8,462 20,560 McKee 1951 ................. . 0 ......•.•... 0 .... ....•.•. ? ............ ? ....... . 173 ....... 1 73 1952 0 0 0 ? 0 1 73 1953 0 0 0 ? 0 173 1954 ..........•....... 0 ............ 0 ............ 0 .......... .. ? •..•...... 0 ....... 1 73 1955 0 0 262, 604 262,604+ 3,041 3,214 Ellenburger 1949 14,372 14, 372 0 0 0 0 1950 70,250 84,622 0 0 0 0 1951 .... ... .... . .. 25, 777 110,399 ........... . 0 .......•.... 0 0 .. ...... 0 1952 14,997 125,396 0 0 0 0 1953 6,165 131,561 0 0 0 0 1954 ............... 3,351 134,912 ........... . 0 ........• . .• 0 0 ... .... . 0 1955 481 135,393 0 0 0 0 (*) Although the first Fusselman discovery well was completed in 1948, we find no record of production prior to the beginning of 1949. The one well flowed during the first half of 1949 and was operated by pumping until its abandonment in 1951. It was reported generally as in the North Heiner field and was the only well treated as in that field. PEGASUS FIELD Midland and Upton Counties. Texas ROBERT R . HARBISON Geologist, Stanolind Oil & Gas Co. , Midland, Texas January l, 1955 LOCATION The Pegasus field occupies an area which is partly in southwest Midland County and partly in northwest Upton County. It is about 20 miles south of the town of Midland, county seat of Midland County, and about 17 miles southeast of the town of Odessa, county seat of Ector County. It is in the southwestern part of the Midland basin. METHODS OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph surveying and core drilling led to the discovery of the field. DISCOVERIES San Andres: January 20, 1954; Sinclair Oil & Gas Co. #17 J.H.Tippett. Spraberry: January 10, 1952; Republic Nat. Gas Co. #2 Arner. Republics Corp. Wolfcarnp: November 21, 1952; Wilshire Oil Co. #1-12 W.R.Tirnrnons. Bend: February 13, 1951; --C-.W .Murchison #1 Joe Cannon. Devonian: June 19, 1952; Superior Oil Co. #4 J .D.Windharn "16" . Ellenburger and Field: March 15, 1949; Magnolia Petroleum Co. #1-A TXL. ELEVATION OF SURFACE At well locations: Highest, 2,891 feet; lowest, 2,840 feet. SURFACE FORMATIONS Fredericksburg limestone and overlying unconsolidated Quaternary deposits constitute the surface rocks within the area of the field. LITHOLOGY OF RESERVOIR ROCKS San Andres: Sandstone; fine-grained, slightly calcare­ous, light gray in color when not stained; contains partings of dark brown argillaceous limestone and thin streaks of black shale . Spraberry: Limestone; brown, fine-grained crystalline. Wolfcarnp: Limestone; tan to brown, fine -grained crystalline. Bend: Three beds of limestone; tan to brown, chalky and fine-grained crystalline; separated by streaks of shale. Devonian: Limestone; brown, fine-grained crystalline, cherty. Ellenburger: Dolomite; light brown, fine-to medium­grained crystalline. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 800 feet below the top of the Ellenburger group. This penetration was in the discovery well for the field and for the Ellenburger reservoir, the log of which served as a basis for the accompanying TYPICAL SECTION. NATURE OF TRAPS San Andres: The six wells producing from the San Andres reservoir are located in the north part of the field near the axis of an anticlinal fold. Anticlinal folding is evidently the primary trap -forming factor. However, it appears that the reservoir rock is only locally sufficiently porous for fr·ee migration of fluids and that variation in degree of porosity and permeability may have contributed locally to the trapping of the oil. Spraberry: Updip termination of reservoir due to lensing . Wolfcarnp: At the north end of the field, there are three wells producing from a reservoir in the Wolfcarnp series. The accumulation in this reservoir appears to be due partly to convex folding, but probably more importantly to variation in character of reservoir rock. Updip decrease of porosity appears to be an important trap -forming factor. The Wolfcarnp discovery well, located at the south end of the field and now abandoned, probably produced from a separate and distinct lens having favorable porosity. Bend: Convex folding. ne;cmian: Anticlinal folding and updip termination of reservoir due to lensing . Ellenburger: Convex folding. CONTINUITY OF RESERVOIR ROCKS San Andres : The reservoir rock cannot be correlated beyond the immediate vicinity of the six productive wells. It is certain that the degree of porosity favorable for commercial production is not continuous within the area of the field except in the immediate vicinity of the six wells. Spraberry: The reservoir rock appears to be merely a local lens terminating updip on the south flank of the anticlinal fold. Wolfcarnp: The bed of limestone is continuous throughout the area of the field, but the areas where porosity is ade­quate for commercial production are only local. It appears that productivity is determined by degree of porosity in a continuous limestone bed. Bend: The reservoir rock in the Bend series is con­tinuous throughout the area of the field. Devonian: Except where broken by faulting, the bed of limestone is continuous throughout the area of the field, but favorable porosity occurs only in a small area in the north end of the field. Ellenburger: Except where broken by faulting, the Ellenburger reservoir is cDntinuous throughout the area of the field . N -...J N 'tj M 1--,i 0 >< ;:i::.. 'tJ (/) ()-c: > (/) t'"" SERIES 'Tj LEONA R D GUADALUPE ........ GROUP CLEAR FORK WH ITEHORSE en FORMATION t'1 M SAN ANDRES GRA Y BURG QUEEN SEVE N RIVERS ~I rf\ , . ,· • I /"\, , , , /\· ,, ,,••-._,,..----·" ,-,,, , ,----·--,'-,----., ,,. ·~--v~··---·----.-·,,.., ., . , , ., , 1 1-1 'l',.J/,,./ \l'I' " 'I' J..., 1\ ''"' " .._ ... /1 ' .. /'\;"1 >\ ,.,,..~..rl(-°\'-.,'~"' ~ ~,,~, v(w•.,"> .r'.,,.-"J~"" " '.rr•""\.'r,..__...,.,/.,,..,,, ,''\...,, Ii <-<'-i·" •,; ' , , ., ',,.v ''/ v ''"·" \. .-..~., ,-..' / PENNSYLVANIAN BEND STRAWN WOLF CAMP DEAN ,"'\Vr 11-.. • 1 ~t: ./•I' ti \ ,1 ,~ .(:/.,i 1• \;'"''' ,, )I: ~t.'W'>"i\:, (°\ :'~<: :" :: ' \::\I:: . , : :,,: '~ h: : : 'I :/ \: :i1 ~ :'' \, :\ ·"i ,, 1-l -~-~--""''1+':.,....r-~-r..'' 't'!(1' f, t ~ ~ ,•1 "'~!\ '"· 1. 1 1 \I: 1, ,11 ,~ /,1 , !>;::.; >''' 'i r, r1• 1\'''1.\1~~ 1,Jv>~v :, :\~/ ' I "'r: ./v .... , I I ' '"'' ~; · I i" \t "~..-~ I/ ""'~........ /' t '-.,,~ / "\, ' / '/ \. '"\. \ 1·./'-...,.,'\/ '\ I' /"' .I ·~ ~~ \t ... ti \. ,' , ~ " ,_ ..,_, \,' •' '"",• ..-, ,,/'\,.,.,,, ; ·~ \\J r ,, =i ... 0 Q :i: 0 Oo "Tl ::s r " Q.. 0 " "' -i ::D -< ­ Q < m =i 0 "' ::s ~ -< () Q.. ~ c ",, ::io:: < lg ~ en c: "d en "' ...... 0 OIL 'tJ ::s t'1 z 0 PERMIAN SYSTEM t'1 0 1--,i s:: WICHITA LEONARD SERIES ::D :::?. CLEAR FORK GROUP (j)' SPRABE RRY FORMATION > tll I /> ,,/: ,, , .f;, ,\ /: :\.·'~ , , --·-.:-., ·"'''' ,,w\·\--.'·/' ,, . \;~--,;;-( -.~.1·:'.v1\\v'.Jv'>"•'\,...!•','\-----f ,,,,,.., ., ' '•J\y:'\N, •\/•/: '\vvf\f·,.,, I: ./)'" ' , ' ' I '\'I SHALY LIMESTONE, CALCAREOUS SHALE ond SHALE WITH THIN BEDS OF LIMESTONE ! ~ ]~' < ;; en "' OIL () r- r 1--,i t:J ." "' ~ "' -i - ~ ,," 0 ."' < 0 z ~ p> ~ "'r ." ~ . "' . " ~ -i 0 • " ~ ©"' :u ~ r p> -,, -i )> :i: 0 0 ­ ro 0 ... -< -i "' " < =i ",, -< c _ 1--,i tr:I >--j ~ Q Ul PEGASUS FIELD, Midland and Upton Counties, Texas TYPICAL SECTION z 0 0 0 0 0 0 0 0 0 0 0 0 0>­ ~~ 0 0 0 ~ ~ ~ 0 OF ROCKS PENETRATED T ~~ ' ' ' ..J 0 EXPLANATION ~Lomestone t=~==j ImAnhydrite dnOt:I~ 0 NOSdWIS H39Hn8N3113 Shale 0: z " .., S31H3S dW'Q':l.flOM .... "' "' ~Calcareous W31SAS N'l11Wt:l3d NN3d NV ld dlSSISSIW N'Q' I N0/\30 ·11s N'l1l3lAOOt:IO +++ + Solt ~Dolomite +t++ ~Shale H 0 0 0 0 w ~ g ~ ~ • Od producl ion [}//({_jSandstone ~Cher i ~ 'i ~ ~ ~ ~ T T PEGASUS FIELD, Midland and Upton Counties, Texas __ _ Contour on top of Pennsylvanian 7100 limestone, on eroded $urface Oil well , productive in Son Andres 5/ Oil well, productive in Spraberry : Oil well, productive in Wolfcomp Oil well, productive in Bend Oil well, productive in Devonian • Oil well, productive in Ellenbur9er a Oil well, productive in Ellenburg er, • abandoned in Bend \ 'D Dual completion, product ive in Ellenburger \. and reservoir indicated by symbol "­Oil well, productive in Wolf camp, abandoned '----__..../ o Drilling well P Dry hole • L:t1 Discovery SCALE L:t1 WOLFCAMP PEGASUS FIELD, Midland and Upton Counties, Texas EXPLA NATION ____ __Contour on top of 10100 Ellenburoer group Oil well, productive in Son Andres 5/ Oil well,productive in Spraberry : Oil well, productive in Wolfcomp Oil well, productive in Bend Oil well, productive in Devonian Oil well, productive in Ellenburger 'O Dual completion, productive 1n Etlenburger • and reservoir indicated by symbol V Oil well, productive in Wolfcomp, abandoned o Drilling we ll P Dry hole SCAL E PEGASUS FIELD, Midland and Upton Counties, Texas PRODUCTIVE AREAS ELEVATION AND RELIEF OF PRODUCTIVE ZONES Acres San Andr es ---z4o Spraberry 80 Wolfeamp 160 Bend 19 ,200 Devonian 240 Ellenburger 12 ,600 Pegasus field 19 ,200 THICKNESSES OF RESERVOIR ROCKS Feet, average Top to Net bottom productive San Andres 70 ? Spraberry 200 45 Wolfcamp 40 10 Bend 290 60 Devonian 50 20 Ellenburger 450 250 CHARACTER OF OIL Gravity, Sulphur , A.P .I.@ 60° F. % San Andr es 29 ? Spraberry 38 0 .33 Wolfeamp 42 0.12 Bend 44 0 .07 Devonian 48 0 .08 Ellenburger 5 3 0.09 For analyses of Ellenburger oil see: U.S. Bureau of Mines Lab. ref. No. 50048 Analyses of Crude Oils from Some Wes t Texas Fields. R. I. 4959 (1 953) Item 42 COMPLETION TREATMENT San Andres: One San Andres well was completed "natural"; in one well, the reservoir rock was treated with 500 gallons of acid and then hydraulically fractured with 10,000 gallons of oil and sand; one well was treated with 350 gallons of acid; in two, the reservoir rock was fractured with 4,000 gallons of sand and oil; in one, with 12,000 gallons of sand and oil. Spraberry: In the first of the two wells, the reservoir rock was treated with 2, 500 gallons of acid and was hydrau­lically fractured with 2, 250 gallons of sand and oil; in the second well, the reservoir rock was treated with 1,500 gallons of acid and was hydraulically fractured with 18,000 gallons of sand and oil. Wolfcamp: The four Wolfcamp wells were treated with 3,500, 3,000, 2,000 and 1,500 gallons of acid respectively. Bend: Quantities of acid were determined on the basis of information provided by swab tests. Many wells were completed "natural". The quantities of acid ranged from none to 25, 000 gallons. Devonian: The quantities of acid ranged from 500 to 39,000 gallons of acid. Ellenburger: Many wells were completed "natural". The quantities of acid ranged from none to 62,000 gallons. Quantities used in wells at locations structurally low were greater than in wells at structurally high locations beca use the degree of porosity of the reservoir rock is lower at the lower structural positions. E levation of oil, feet Relief, San Andres Top -2 ,7 19 Bottom ? feet -­?- Spraberry -4,897 ? Wolfcamp -5 ,415 ? ? Bend -7' 156 -7,723 567 Devonian -8,935 -9 ,557 622 Ellenburger -9 ,581 -10,410 829 PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Yearly Cumulative Field totals 1949 4 0 260,420 260 ,420 1950 30 0 1,292,744 1,553,164 195 1 68 4,038 ,491 5 ,591 ,655 1952 122 5 4,384,926 9 ,976,58 1 1953 182 11 5,628,010 15,604,591 ,1954 218 II 5,747 ,578 21,352, 169 San Andres 1954 2 4 97 ,76 1 97 ,761 Spraberry 1952 I 8,862 8 ,862 1953 0 2 17 ,5 13 26,375 1954 0 2 18,582 44 ,957 Wolfeamp 1952 4 0 6,695 6 ,695 1953 3 0 8 ,292 14,987 1954 2 0 6 ,210 21,197 Bend -­1-951 16 378,686 378,686 1952 32 3 883 ,858 ] ,262 ,544 1953 66 3 1,573 .998 2 ,836 ,542 1954 95 3 1,75 1,176 4,587,7 18 Devonian 1952 I 0 11,358 11,358 1953 6 0 113 ,483 124,841 1954 5 0 I 05 ,680 230,521 Ellenburger 1949 4 0 260,420 260 ,420 1950 30 0 1,292 ,744 1,553,164 1951 52 0 3 ,659 ,805 5,212,969 1952 84 I 3,474,153 8,687 ,122 1953 107 6 3,914,724 12,601,846 1954 114 2 3,768, 169 16,370,015 REPRESSURING OPERATIONS : R epressuring of the Bend and Ellenburger reservoirs is to be conducted under a unitization plan covering the whole of the productive areas of these reservoirs . Pressure in the Bend reservoir has declined from the initial of 4,567 psi. to about 3,000 psi.; in the Ellenburger reservoir, from 5 ,668 psi. to about 3 ,600 psi. Injection of gas into the Bend reservoir has already been initiated and injection of water into the Bend and into the Ellenburger will be started in the near future . Gas is being injected into the Bend at the unusually high pressure of 3 ,500 psi. and it is anticipated that the pressure may be increased to 4 ,500 psi. Injection of water into Ellenburger at the depth of about 13 ,000 feet will establish a depth record for s uch operations . The gas which i s being injected is residue gas supplied by the Pegasus Unit gasoline plant. About 5 million cubic feet of gas is being injected daily through a pilot well in the southwest part of the field . PETERSBURG FIELD Hale County, Texas B.H.BONEY Geologist, Cabot Carbon Company, Midland, Texas May 19, 1953 LOCATION The Petersburg field (one well) is in south­eastern Hale County about 6 miles northwest of the town of Petersburg . Regionally, it is on the Matador arch between the main Permian basin of West Texas and the shallower Palo Duro basin of the Texas Panhandle. METHOD OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph. DISCOVERY Cisco: February 5, 1947; Stanolind Oil & Gas Co . H1 E. L. Fisher. On potential test, flowed 1 ,008 barrels of oil in 18 hours. ELEVATION OF SURFACE Derrick floor: 3,316 feet. SURFACE FORMATION Ogallala formation of the Pliocene series . OLDEST STRATIGRAPlUC HORIZON PENETRATED The oldest horizon penetrated in the single well in the field is about 434 feet below the top of the Cisco series . The oldest horizon penetrated in the vicinity of the field is in rocks of pre-Cambrian age. Stanolind Oil & Gas Co . #2 E. L. Fisher, the dry hole about two thousand feet northeast of the produc­tive well, drilled 372 feet into pre-Cambrian rocks. The location of this dry hole is in Sec. 5 where the total depth of 8 ,394 feet is indicated on the accom­panying maps. This is the only well in the vicinity which drilled below rocks of Pennsylvanian age. NATURE OF TRAP Cisco: Limestone reef PRODUCTIVE AREA Cisco and Field: Approximately 40 acres. TIUCKNESS OF RESERVOIR ROCK Cisco: In the one productive well, it is 111 feet from top of productive rock to bottom of productive rock . Because of poor core recovery, the portion of the total thickness which yielded oil is not determinable. LiraOLOGY OF RESERVOIR ROCK Cisco: Reef limestone; light gray, fine to medium crystalline with dense streaks, highly fossiliferous . Fossils are predominantly crinoid sterns . CONTINUITY OF RESERVOIR ROCK Cisco: The reservoir rock has been found in only the one well. Evidently it is a small reef with distribution limited to the immediate vicinity of the well. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Cisco: Feet No free gas Elevation of top of oil -3,566 Elevation of bottom of oil -3,677 Relief 111 CHARACTER OF OIL Cisco: Gravity, A.P.I. @ 60 ° F. 39. Base, Paraffin WATER PRODUCTION Cisco: The encroachment of salt water was very rapid. After producing oil only five months, the well started producing salt water and by the end of the first year, water constituted about 103 of the gross production. In May , 1948 , the production was at the rate of 40 barrels of oil and 8 barrels of water per day . The well was then treated with 1,000 gallons of acid and production increased to the rate of 72 barrels of oil and 98 barrels of water per day. In early May, 1953, production was at the rate of 25 barrels of oil and 150 barrels of water per day. PETERSBURG FIELD, Hale County, Texas TYPICAL SECTION OF ROCKS PENETRATED RADIOACTIVITY CURVES LITHOLOGY ~ "' ~ "' "'­ w :' tn Ill DEPTH 0. z "' "" "' :.: ­ z "' z w 0. NOTE: This TYPICAL SECTION is based on a composite log of the productive well and the dry hole where the oldest horizon was penetrated. The depths and elevations below the productive zone ha ve been adjusted. z 0 >­ z 0 " z "a: 0. "' "' iii "' " z ~ a: 0 :c w 1­:c 3' 900 1000 1100 1200 1455 1355 1255 1155 1300 1055 1400 955 855 755 655 1800 555 w :;; z a:"w > z a:" w " w CL 1900 2000 2100 2200 2300 455 '" 255 155 55 2400 -45 0 ~ z ~ _, "'a: ~ a: ~ _, '-' 0 _, w "'z 2500 2600 2700 2800 -145 -245 -345 -445 ~ >- Vl z ~ a: w (f) 0 CL " '-'" "­ _, 0 3' SECTION OF ROCKS PENETRATED g; 0 a: C> "' a: 0 lL a: w " _, 0 1­ " ::c '-' J:; ELECTR IC El RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY ANO S.P. RES ISTIVITY DEPTH ELEVATIO N 2900 "'°' -545 3000 -645 3100 -745 3200 -845 3300 -945 3400 -1045 3500 -I 145 3600 -1245 -1345 -1445 3900 -1545 4000 -1645 4 100 -1745 4200 -1845 4300 -1945 4400 -2045 4500 ' i-2145 ' ' ' ' 4600 ;-2245 ' ' 4700 :-2345 ' ' ' ' ' 4800 J :-2445 :: ~ ' 4900 :-2545 ' ' 5000 :-2645 ' ' ' ' 5100 :-2745 5200 ~ -2845 ELECTRIC El RADIOACTIVITY CURVES " LITHOLOGY ~ ~ g; GAMMA RAY >­ a: w ~ ANO DEPTH S.P. RE SIS TI VI TY ELEVATION _, 0 5800 z CL " ~ "' :;:a:_, 5900 -3545 w CL 0 3' 6000 -3645 6100 -3745 6200 -3845 6300 -3945 6400 -4045 0 '-' <> 6500 -41 45 6600 -424 5 6700 -434 5 z " z " 6800 -4445 >_, >­ - ~ t-"1--t-69_0_0 __ -4 545 z w CL 7000 -4645 z 0 >­ z " 7100 -4 745 '-' 7200 -4845 7300 -4945 z 3' " a: 1­ 7400 7500 7600 77 7800 : ­34 ' -5445 z " <> >0 0 a: 0 er w "' a: ::> "' ~ _,_, w 7900 8000 8055 -5545 -5645 -5700 • 5300 54 00 -2945 -3045 NO TE: The above TYPICAL SECTION i s based on the log of Cosden P etroleum Corp. #1 W.G. Williams, the dry hole which penetrated the oldest horizon penetrated in the vicinity of the field. It was selected because of its depth and because it provides radioactivity and electrical curves. The reservoir symbol and the symbol for show of oil are entered to r eport conditions in other wells. 5500 -3145 EXPLANATION 5600 -3245 Dolomi te Shale Sandstone and sh ale 5700 -3345 Anhydr itic dolomite Colcoreous sha le Chert ..L--­~- • Oil production 2900 -545 5800 -3445 ~L imestone ~~1~1!~t*~il Sandstone o Show of oil CHARACTER OF Oll. Ellenburge r: Gravity, A. P.1. @ 60°F. : 39. 75 ° Sulphur: 0.43"/o Color: Green For analyses see: U. S. Bureau of Mines Lab. ref. No. 46106 Analyses of Crude Oils from Some West Texas Fields. R. I. 4959 (1953) Item 44 WATER PRODUCTION Ellenburger: The quantities of water produced by individual wells at time of completion varied through a wide range; how­ever, before abandonment, water constituted a large portion of the gross production of every well. Data. are not available for determining the quantities of water produced. PRODUCTION IUSTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flow Pump Yearly Cumulative 1946 1 1 26,872 26,872 1947 1 2 36,630 63,502 1948 0 2 17,873 81,375 1949 0 2 9,693 91,068 1950 0 0 8,984 100,052 1951-53 0 0 0 100,052 1954 0 1 3,566 103,618 1955* 0 0 58 103,676 OIL PRODUCTION: All except 2,862 barrels of the above indicated oil was produced from Ellenburger dolomite. On February 28, 1954, King Oil Co. #1 C. E . Cargile, located near the southwest corner of Sec. 25, Blk. 5, was completed in a zone in the Strawn series and produced from this zone 982 barrels during March; 777 barrels during April; 543 barrels during May; 278 barrels during June; 126 barrels during July and 156 barrels during September; total, 2,862 barrels. This well was then deepened to Ellenburger and produced 64 barrels during October; 597 barrels during November and 43 barrels during December; total of 704 barrels from Ellenburger in 1954. (P. S. : It was plugged and abandoned on 4/23/55 after having produced an additional 58 barrels, which brought its Ellenburger production to 762 barrels.) * 1955 data added by amendment. ~ N ""d 0 L' >­ ::0 '"Tj - M L' t:1 ~ (l) ::s .-+ 0 0 c ::s ~ >--3 ~ @ -ss2s EXPLANATION ~~~--5425~~~~ Contour on eroded top of Ellenburger TO 2506/ TD 8055 • Oil well +Abandoned oil wel l ;:f Ory ho le 61 42 SCAL E .. ~ CJ 10 -ssso--L--­ THOUSAND FE ET G PRUITT FIELD Wmd County. Texas EDWARD R. KENNEDY, Jr. Geologist, Argo Oil Corporation, Midland, Texas June 10 , 1954 LOCATION The Pruitt field {one well, now abandoned) is in northwest Ward County, lli miles north of Barstow ana 12 miles southeast of Mentone, the county seat of Loving County. METHODS OF EXPLORATION LEADING TO DISCOVERY The writer has been unable to determine which methods of exploration led to the discovery of this field . It is likely that the discovery resulted from random drilling. DISCOVERY Bell Canyon: July 6, 1942; Fred A. Hyer #1 T . B . Pruitt (commenced as J.E.Fitzpatrick Trust #1 T .B .Pruitt). OLDEST STRATIGRAPHIC HORIZON PENETRATED The qldest horizon penetrated bythe one produc­tive well is in the Bell Canyon formation 11 feet below the base of the Lamar member . The oldest horizon penetrated in the vicinity of the field is in the Bell Canyon formation 168 feet below the base of the Lamar member . This penetration was in Anderson-Prichard Oil Corp. #1 J.D.Campbell,the dry hole located about 1,850 feet northwest of the productive well. The accompanying TYPICAL SEC­TION is based on the log of that dry hole. NATURE OF TRAP Bell Canyon: Data are not adequate for determin­ing the factors which occasioned the trapping of oil. However, it appears likely that the trap is due to updip decrease of porosity and permeability on an eastward plunging structural nose . PRODUCTIVE AREA Bell Canyon: It is impossible to determine the extent of the area, probably less than 40 acres.which contributed to the production of the one well, now abandoned. THICKNESS OF RESERVOIR ROCK Bell Canyon: Approximately 10 feet. LITHOLOGY OF RESERVOIR ROCK Bell Canyon: Clean, gray, friable, porous, fine­grained sandstone. CONTINUITY OF RESERVOIR ROCK Bell Canyon: The reservoir rock appears to be continuous throughout a large area, but probably varies considerably in thickness, porosity and per­meability within relatively short distances . ELEVATION AND RELIEF OF PRODUCTIVE ZONE Bell Canyon: Feet Elevation of top of oil -2,186 Elevation of bottom of oil -2,196 Relief 10 The above figures are based on shooting-line measurements and are believed to be correct. Other reported measurements-to top and bottom of oil are as much as 33 feet less. CHARACTER OF on. Bell Canyon: Gravity, A.P .1.@ 60° F., 32° WATER PRODUCTION Bell Canyon: Water constituted 40o/o of the initial gross production, which was at the daily rate of 15 barrels of oil and 10 barrels of salt water. COMPLETION TREATMENT Bell Canyon: The reservoir rock was shot with 100 quarts of nitroglycerin. PRUITT FIELD I Ward County, Texas TYPICAL SECTION OF ROCKS PENETRATED RADIOACTIVITY CURVES ,. UJ UJ "' >­ "' GAMMA RAY NEUTRON UJ e >­ DEPTH ELE VATION "' "' EXPLANATION Sandstone Anhydrite ~ Im ·+·.,..~:+ Solt $holy sondstone ++ + lliJ .Oil product ion - LJ· $hole above sea level, SURFACE FORMATION Undifferentiated rocks of the Quaternary system . PRODUCTION HISTORY Year WELLS PRODUCING a t end of year Flowing OIL PRODUCTION (barrels) Yearly Cumulative 1942 1943 1944 l ,902 1,428 92 1,902 3 ,330 3,422 The last reported production was in April, 1944. ELEVATION OF SURFACE The surface at the location of the one well is 2,694 feet QUITO FIELD Ward County. THaa EDWARD R. KENNEDY, Jr. Geologist, Argo Oil Corporation, Midland, Texas January 1, 1956 LOCATION NEAR-BY RECENT DISCOVERIES The Quito field is in west-central Ward County, 11 miles west of Pyote, 6 miles northeast of Barstow and about 4i Exploratory drilling in 1955 at two locations within the area covered by the accompanying map resulted in comple­ miles northwest of the railroad siding of Quito. tions as oil wells. With further development, it may be proved that these discoveries should be treated as extensions of the Quito field, but, at least for present purposes, they METHOD OF EXPLORATION LEADING TO DISCOVERY are considered as in productive areas beyond the limit of the Quito field. Both are producing from reservoir rocks of Subsurface geology. about the same character and at about the same stratigraphic position as the Quito reservoir rocks, and the oil is of about the same gravity. One is named West Quito field, DISCOVERY where there are now three wells, and the other is named Regan-Edwards field. Bell Canyon: April 4, 1953; Argo Oil Corp. #1 John Olson. West Quito field: Chambers & Kennedy #1 D.J.Creedon was completed on 5/29/55 and was treated as the discovery well of a new field. Landa Oil Co. #1 G.H. Watt (TD 4850) OLDEST STRATIGRAPHIC HORIZON PENETRATED was completed on 10/18/55 as a northwest offset and Hono­ lulu Oil Corp. #1 J.E.Echols (TD 4902) was completed on The oldest horizon penetrated is in the Cherry Canyon 1/1/56 as a southwest offset. At the end of 1955, there formation 149 feet below its top. This penetration was in were two oil wells in the field, one flowing and one pumping; Argo Oil Corp. #1 Radford Grocery at its total depth of they had produced a total of 5,252 barrels of oil. 5,886 feet. This well is located in Sec. 194 where the total Regan-Edwards field: Ken Regan & Associates #2 P. W. depth 5,886 is indicated on the accompanying map. Edwards et al was completed on 8/19/55 and was treated as the discovery well of a new field. At the end of 1955, this well was pumping and had produced a total of approximately NATURE OF TRAP 1, 400 barrels of oil. Bell Canyon: A complex permeability trap on an east­ THICKNESSES OF RESERVOIR ROCK trending structural nose. Bell Canyon: Feet Min. Max. Avg. PRODUCTIVE AREA From top to bottom 142 194 l7o Net productive 5 50 15 Bell Canyon: Development to date proves that the productive area includes at least 1,200 acres. Further ELEVATION AND RELIEF OF PRODUCTIVE ZONE developmentmay prove that the productive area is consider­ ably more extensive. Bell Canyon: Feet, approx. No free gas cap Elevation of highest known oil -2, 182 UTHOLOGY OF RESERVOIR ROCK Elevation of lowest known oil -2,453 Known relief 271 Bell Canyon: Sandstone; gray, fine-grained, friable, with porosity and permeability varying in a wide range and with The above figures represent approximately the general s.hale interstratified as indicated on the accompanying graph conditions at time of discovery. However, it appears that under the heading TYPICAL DETAIL OF PRODUCTIVE the oil-water contact was not at a uniform elevation in all SECTION. The reservoir rock contains five sandstone zones sandstone lenses. Furthermore, in the uppermost sand­ separated by shales and shaly sandstones. The individual stone, it appears that the oil-water contact slopes eastward; sandstone zones are lenticular and vary considerably in from -2,218 at the western edge of the field to -2,325 at the thickness and permeability within the area of the field. The eastern edge of the field. The position of the oil-water upper-most sandstone, the most important oil-bearing zone, contact has not been definitely determined in any of the other varies from 6 feet of impermeable, shaly sandstone to 39 sandstone members. feet of favorably permeable, non-shaly sandstone. WATER PRODUCTION CONTINUITY OF RESERVOIR ROCK Bell Canyon: Every well produces some water. The Bell Canyon: The reservoir rock is continuous throughout ratio of water to gross fluid produced by individual wells the area of the accompanying map. While the general ranges from 1 % to 85%. Water accompanies oil in the character of the reservoir rock as a stratigraphic unit is production from every productive member of the reservoir about the same throughout the area, the individual layers rock. vary considerably locally with the result that there is interruption of conditions favorable for migration of reser­ COMPLETION TREATMENT voir fluids. Because of the lenticularity of the sandstone members and the variation in the degrees of porosity and Bell Canyon: The reservoir rock in every well has been permeability, from a practical operating standpoint, the subjected to hydraulic fracturing by some one of the several individual lenses determine the extent of continuity. processes now used. QUITO FIELD, Ward County, Texas TYPICAL SECTION SURFACE FORMATION : Undifferentiated Quaternary. OF ROCKS PENETRATED ELEVATION OF SURFACE : At well locations ' Highest, Z, 704 feet; lowest, 2,588 feet. z RADIOACTIVITY CURVES Q ~ ~ g, ~ GA MM A RAY NEUTRON (/) 0::: 0 a:: ...I >­ w 0::: 0 (/) V> <.!'.l I.I. DEPTH ELEVATION Q ----2150---Contour on 1op of Sell Canyon formation Oi l well o Location JI Dry ho le SCALE • \::] Discovery TYPICAL DETAIL OF PRODUCTIVE SECTION EXPLANATION [:'.:/\(] Sandston e t::::::::3 Shale §™ S~~ CHARACTER OF OIL Bell Canyon: Gravity, A . P . I. @ 60° F., 38 . 2° to 39. 1 ° . PRODUCTION HISTORY Year WELLS PRODUCING a t end of year OIL PRODUC TION (ba r rels) Yearly Cumulative 1953 1954 1955 10 13 10 17 42, 522 180,21 7 223,819 42, 522 222, 739 446,558 REINECKE FIELD Borden County, Texas R . LELAND REDLINE Chief Geologist, Great Western Drilling Co., Midland, Texas October 13, 1954 LOCATION The Reinecke field is near the southeast corner of Borden County; 4 miles from the east boundary and 2 miles from the south boundary. It is in Block 25 of Houston & Texas Central R.R. Co. survey. NEAR-BY NONCOMMERCIAL PROSPECTS GARNER: The well which prompted the designation of the Garner field is near the southeast corner of the area covered by the accompanying map. Rowan Oil Co. #1 C.H. Garner was completed on April 3, 1951 in the Clear Fork group with an initial daily pumping capacityof 133barrels of 27° gravity oil and no water through perforations between 4, 242 feet and 4, 272 feet after having been plugged back from the total depth of 7, 520 feet. It was generally recognized as a discovery well and was so treated in several publications. It produced 3,566 barrels of oil during 1951 and 847 barrels during 1952. It was plugged and abandoned on October 26, 1952. REINECKE (CLEAR FORK): D.D.Feldman Oil & Gas #1 A.O.Murphy, located near the north boundary of the area covered by the accompanying map, is the only well ever completed in the field designated by the Railroad Commission as the Reinecke (Clear Fork) field. This well was completed September 26, 1952 with an initial daily pumping capacity of 179 barrels of 38° gravity oil; gas-oil r.atio, 288: 1. It was drilled to a total depth of 6,995 feet and was plugged back to 4, 919 feet. The top of the reservoir rock, which is in the Clear Fork group, is at the depth of 4, 559 feet. The well produced 2,610 barrels of oil during 1952 and 1,055 barrels during 1953 and was plugged and abandoned January 21, 1954. METHOD OF EXPLORATION LEADING TO DISCOVERY The general trend of previously discovered fields in­dicated chances sufficiently favorable to warrant drilling under the terms of an available drilling deal. DISCOVERY Cisco: February 2, 1950; George P. Livermore, Inc. #1 W. Reinecke (now, Great Western Drilling Co. #1 W. Reinecke). ELEVATION OF SURFACE At well locations: Highest, 2,370 feet; lowest, 2,300 feet. SURFACE FORMATION Recent alluvium and undifferentiated red beds of the Trias sic system. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in the Pennsylvanian system. The oldest horizon penetrated in the vicinity of the field is 65 fe et below the top of the Ellenburger group. This penetration was in Chapman & McFarlin #2 A.L.Holley, located near the southwest cor­ner of section 52, where the total depth of 8, 112 feet is indicated on the accompanying map. NATURE OF TRAP Cisco: Convex upper limit of reef limestone which is covered by relatively impervious shale. THICKNESS OF RESERVOIR ROCK Cisco: The maximum gross thickness of the reservoir rock is on the order of 300 feet. LITHOLOGY OF RESERVOIR ROCK Cisco: Reef limestone. In several wells, commercial production has been found in a thin dolomitized zone of limestone above the main white fossiliferous limestone reef. In one well, Cosden Petroleum Corp. #2 LB.Holbein, such a zone occurs several hundred feet above the main limestone reef, but it seems probable that this particular zone is productive merely because it is connected to the main reef by fractures and solution channels. The writer considers it possible that some of these dolomitized zones are of early Wolfcamp age. CONTINUITY OF RESERVOIR ROCK Cisco: The same general reef is continuous northeast­ward through Scurry County and southeastward on an arc which crosses the southeast corner of Borden County, turns northward in Howard County and swings northwestward across the southwest corner of Borden County and into Dawson County. WATER PRODUCTION Cisco: Production of salt water has amounted to about one million barrels to date. At present, seven wells are producing bottom-hole water in varying percentages ranging from 4% to 98% of gross liquid produced. The absence of a gas cap, coupled with a uniform rise of bottom-hole pres­sure whenever the field is shut in for bottom-hole pressure surveys, suggests that water drive may contribute to reservoir energy. Production of liquids is now at a rate faster than migration of water into the productive area. ACID TREATMENT Cisco: There has been no uniform program for acid treatment of the reservoir. Several operators have used small wash-shots (1,000 gallons) to clean mud contamination from the reef limestone, although there has been little difficulty in flowing the wells naturally. REINECKE FIELD, Borden County, Texas TYPICAL SECTION OF ROCKS PENETRATED ,;w ~ ~ "' w a:: ~ § RADIOACTIVITY CURVE >­LITHOLOGY0.. <(6 ~ GAMMA RAY ~ ~ DEPTH ELEVATION ~ ~ ~ ~ g;, ~ z Q ; ~ ~ ELECTRIC a RADIOACTIVITY CURVES GAMMA RAY LITHOLOGY RESISTIVITY DEPTH ANO S. P. ELEVATION "'"' ~ "' "'a: >­"' "'"' z 0 ;:: .. "'0 a: ~ :? ELECTRIC & GAMMA RAY ANO S. P. DEPTH RADIOACTIVITY CURVES LITHOLOGY RESISTIVITY ELEVATION -' (5 100 2349 2249 "' "' a: 0 :i:: "'.... J: "' 2100 2200 249 149 4850 4900 5000 -2501 -2551 -2651 200 2149 -----49 5100 -2751 300 2049 2400 -51 400 1949 2500 -151 0 a: ­a:: 5 a> "' 2800 ~ 2900 a: 0 z a: -' 0 :i:: "' " 1700 649 3800 -1 451 6500 -4151 6600 -4251 1800 54 3900 -1551 6700 1900 2000 44 349 "' a: ~ 4000 4100 -1651 -1751 z z "'.. 0 u "' u 6800 6813 2IOO EXPLANATION 249 a: 0 ­ a: "' a: > a: z "' > a: V> "' ­ i.u CANYON ? <'­ 10100 z 3: 10300 10 400 z 10500 " a: 10600 0 10700 10800 KI NDE RHOOK z WOOOFORO Glouconite ~Anhydrite with thin beds F;.:;j ~ofred sandstone a: shale ...... .,. • Solt Oil production ~ ~Chert TD 111 PU BLIC SCHOO L LAN D I BLOCK A-7 p T O 5146 • • • BROWN FIELD .,,, ,.! • PUBLIC SCHOOL LAN D BLOCK A-8 201 I TD 21 J I p I 4975 IOI I p 11 4 19 p 11380 Cl z a.. ' p PUBLIC SCHOOL LAND BLOCK AX TD 6870p ll D 7838 495 494 456 4 55 4 18 4 11 N WASSON FIELD p TO 5079 31 I I I I I I c_c_ s_ D. a R_ G. N_G. R. R. co. I ,_.,1>-" 40 ~-.iO I 49 457 454 419 I 416493 ~ .\ BLOCK G TD 11205 I p _L ~ 0 ~ 30 ~ T D 11177 497 ~ 492 4 5 8 ~ D 11172 ~ x -'<­c,'­~~'?­-<)"a .\ .\ ~ .\ 498 ~ 491 .\ ~ .\ .\ 459 ~ ~ '1 I OLDEST HOR IZON l •\ ~ .\ .\ .\ .\ 0 I 0 .\ ~ I .\ .\ .\ .\ .\ oo\ /" . .\ .\ .\ .\ .\ .\ .\ .\ ;-\ ;. ;. ;. I 453 415 4201 .\ p TD 7412 0 .\ I ~ .\ 0 .\ 452 421 .\ p TO 8000 I I p TO 5224 4991 490 •\ .\ ~\ "' 460 "' .\ p TD 6320 451 EX PL AN ATION I UPPER CLEAR FORK it::? /. ;. .\ "' .\ I • Ori well 0 Drill ing we ll or location J I p TO 9668 p TO 6277 M I • ~Dis co very well p ;. Pr oduc ing from Upper Cl ear Fork .\ Producing from Lower Cl ear Fork •'< Depleted in Lower Cl ear Fork Dry hol e 5001 489 1 46"1 J 4501 ..1_ Pro ducing from Devonian Ip TO 8150 0 SC ALE 2 THOU S AMO FEET t-..) co t-..) ::0 c:: Ul Ul M L' L' '"Tj 1-1 M L' t:J 0 Q s· -..,] < Q rn RUSSELL FI ELD, Gaines County, Texas NATURE OF TRAPS Upper Clear Fork and Lower Clear Fork: The trap in each of these two reservoirs is due to a combination of anticlinal structure and updip decrease of porosity. Devonian: Anticlinal structure . THICKNESSES OF RESERVOIR ROCKS Feet Upper Clea r Fork Min. Max. Avg . From top to bottom ~ 230 150 Net productive 12 80 50 Lower Clear Fork From top to bottom 495 530 512 Net productive 165 177 17 l Devonian From top to bottom 65 467 100 Net productive 50 150 75 WATER PRODUCTION Upper Clear Fork: On or about January l. 1953, 4 of the 8 producing wells were producing water in r a tios varying from 25 to 90% of gross liquid . Lower Clear Fork: Water constitutes less than 5'1o of gross liquid produced. Devonian: On or about Ja nuary 1, 1953, 6 of the 16 pr o­ducing wells were producing water in r a tios varying from 10 to 60% of gross liquid. CONTINUITY OF RESERVOIR ROCKS Upper Clea r Fork and Lower Clear Fork: Each of these reservoir rocks can be correlated throughout the area covered by the accompanying map . However , the degree of porosity which occasions commercial production is very erratic , and , with few exceptions , is not continuous a t any one stratigraphic position throughout more than a few hun­dred acres . Although there are productive reservoirs at corresponding stratigraphic positions in several fields on the Central Basin platform , it i s not likely that conditions favorable for migration of r ese r voir fluids are continuous from either of these reservoirs to any reservoir in any other field . In the Lower Clear Fork on the east flank of the field , both the lateral and downward extent of the reser­voir is determined by a facies change from a porous dolo­mite to a dense limestone. Devonian: While this reservoir rock is continuous throughout the area of the a ccompanying map , the lithologic cha-racteristics change considerably within that area. The relative amounts of dolomite and limestone vary from well to well. Although there is considerable variation in porosity and permeability, it appears probable that there is sufficient continuity of porosity and permeability to permit migra tion of reservoir fluids throughout the area covered by the accompanying map . LITHOLOGY OF RESERVOIR ROCKS Upper Clear Fork: Dolomite; anhydritic, buff to tan, finely crystalline, with fair i ntercrystalline and solution porosity. Lower Clear Fork: Dolomite; s lightly anhydritic , buff to tan with some zones of gray and brown mottling, fine to medium crystalline, with fair intercrystalline and solution porosity. Thin spicular chert zones occur locally. Devonian: Interbedded limestone and dolomite con­taining small amounts of white chert; tan to white, fine to medium crystalline, with good vuggy and intercrystalline porosity, especially in the dolomite, which constitutes more than half of the reservoir rock. ACID TREATMENT Upper Clear Fork: Common practice is to wa sh r e ser­voir with 500 gallons of mud acid and then treat with 1 ,500 to 5 ,000 ga llons of regular acid. Ordinarily, 1,500 gallons is sufficient, but the quantity va ries in accordance wi th the response of each individua l well. Lower Clear Fork: Common practice is to wa sh reser­voi r with 500 gallons of mud acid and then treat with 10 ,000 to 20,000 gallons of regular acid. Ordinarily, 10,000 to 12 ,000 gallons is sufficient, but the quantity varies with the thickness of reservoir rock treated and in accordance wi th the response of each individual well. Devonian: Some wells are completed without acid treatment; others are treated with acid in quantities var ying with the response of ea ch individual well . Commonly, the treatment is with only 500 to l ,000 gallons of mud acid, but one well was treated with 12 ,000 gallons of regular acid . Ordinarily, the treatment is with 1,000 to 2 ,500 gallons of regula r acid . PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Year ly Cumulative Upper Clear F ork 1945 0 24 ,531 24,531 1946 1 25 ,514 50 ,045 1947 2 47 ,342 97 ,387 1948 2 2 52, 18 1 149 ,568 1949 3 2 63,852 213,420 1950 3 2 83, l 02 296 ,522 1951 3 2 87 ,285 383 ,807 1952 2 4 80 ,608 464,415 Lower Clear F ork 1943 l 39 ,425 39 ,425 1944 3 2 100 ,535 139.960 1945 2 8 225 ,290 365 ,250 1946 6 12 355 ,299 720,549 1947 9 20 438 ,772 1.159 ,321 1948 5 26 497 ,433 1 ,656 ,754 1949 3 32 394 ,048 2 ,050 ,802 1950 6 35 453,673 2,504,475 1951 4 41 595,1 75 3 ,099 ,650 1952 6 42 528 ,07 5 3 ,627 ,725 Devonia n 1948 0 4 ,386 4 ,386 1949 0 45 ,908 50 ,294 1950 2 64 ,304 114,598 1951 8 I 350 ,5 45 465,143 1952 13 3 798 ,388 1,263,531 GAS PRODUCTION : The only gas production has been incidental to oil production. The quantities produced have been minor and have been utilized in field operations. No analysis of the gas i s available. SAN BENITO FIELD Coke County. Texas J. R. KIENE Geologist, Sinclair Oil & Gas Co., Midland, Texas July 9, 1954 LOCATION The San Benito field is in north central Coke County 11 miles northwest of the town of Robert Lee, county seat. METHODS OF EXPLORATION LEADING TO DISCOVERY The location of the discovery well was based on studies of surface and subsurface geological data supplemented by magnetorri.eter data. MAP and STRATIGRAPlUC SECTION Because of geographic and geologic relationships, Arledge field and San Benito field are shown on the same map; presented in the foregoing paper on the Arledge field. The TYPICAL SECTION in the paper on the Arledge field applies also to this field. The stratigraphic position of the reservoir in the producing well in this field is the same as that of the reservoir in the Arledge field. The Ellenburger zone which produced for a short time is at the top of such Ellenburger as is present at this location. However, the top of the Ellenburger is an eroded surface and the exact position within the Ellenburger group is not known. DISCOVERIES Strawn: July 23, 1948; Alan Guiberson /11 J .Lassiter. During initial potential test, flowed through 17/64-inch choke at daily rate of 319 barrels of oil and 25 barrels of water . Ellenburger: Oct. 4, 1948; AlgordOilCo. /12 J.Lassiter. During initial potential test, pumped at daily rate of 176 barrels of oil and 53 barrels of water. ELEVATION OF SURFACE Ground Derrick floor Elev. at Strawn well, feet 2.TTIT 2,121 Elev. at Ellenburger well, ft. 2,133± 2 ,143 SURFACE FORMATIONS Undifferentiated formations of the Fredericksburg and Trinity groups are exposed on the hills and undifferentiated Tertiary beds occur in the valleys. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is 148 feet below the eroded top of the Ellenburger group. This penetration was in C . W. Sharp Ill B. D. Gartman, the dry hole about 1,300 feet west of the field discovery well. NATURE OF TRAPS Strawn and Ellenburger: The trap in each of the two reservoirs appears to be due to convex folding. There is a structural closure which amounts to at least as much as 17 feet at the top of the Strawn reservoir rock. LITHOLOGY OF RESERVOIR ROCKS Strawn: Limestone; dark brown, finely crystalline to dense, both intercrystalline and vug type porosity. Ellenburger: Dolomite; light gray, coarsely crystalline, intercrystalline type porosity. PRODUCTIVE AREAS Strawn 40 acres Ellenburger {depleted) 40 acres THICKNESSES OF RESERVOIR ROCKS Net productive Feet, approx. Strawn 25 Ellenburger {depleted) 50 CONTINUITY OF RESERVOIR ROCKS Strawn: The reservoir rock appears to be continuous throughout the area covered by the map presented in the foregoing paper on the Arledge field. Ellenburger: The continuity of the particular zone which was productive at the location of the abandoned well is not determinable from available data. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Strawn Ellenburger Elevation of top of oil, feet. -4,373 -4,675 Elevation of bottom of oil, ft. -4,398 -4,725 Relief 25 50 The above figures represent estimates of elevations as of respective discovery dates. CHARACTER OF OIL Strawn Ellenburger Gravity, A.P.I.@ 60° F. --w-45° Sulphur 0.2% 0.1% PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Yearly Cumulative Strawn: ms 0 11,198 11,198 1949 1 0 15 ,270 22 ,468 1950 0 3 ,933 26 ,40 l 1951 0 2,684 29 ,085 1952 0 4,364 33 ,449 1953 0 1,247 34,696 Ellenburger: 1948 0 1 2,200 2,200 1949 0 0 200 2,400 The only well which has produced from the Ellenburger, was completed on October 4, 1948 and was plugged and abandoned on January 27, 1949. SCURRY FIELD Scurry. Kent and Borden Counties. Texas PHILIP T. STAFFORD Geologist, U .S. Geological Survey, Austin, Texas March 1, 1954 LOCATION and INTRODUCTION The Scurry field is mainly in Scurry County covering an area about 32 miles long and generally 4 to 8 miles wide extending from near the southwest corner of Scurry County northeastward just west of the town of Snyder and extending 4 miles into Kent County. It includes 4 wells in Borden County, 2 ,185 in Scurry County and 153 in Kent County. Oil is produced from 38 distinct reservoirs at 13 stratigraphic positions The stratigraphic positions are shown on the accompanying TYPICAL SECTION; the areal extent of each reservoir is shown on one or more of the maps on the accompanying fold-in plate. The stratigraphic positions and the number of reservoirs at each position are indicated in the following tabulation. Stratigraphic Number of Located Prod. areas position reservoirs on map Total acres San Andres 2 II 920 San Angelo 2 IV 240 Clear Fork IV 1,880 "Wolfcamp" v 160 Cogdell 1 II 320 Fuller 3 II 800 "Cisco" 3 Ill 4,040 "Canyon" 6 I, II, Ill , IV, V 83,160 Strawn Zone A I 40 Strawn Zone B 5 I 1,160 Strawn Zone C 9 I 760 Strawn Zone D 1 I 240 Ellenburger 3 I 120 Scurry field 38 86,200 In the following presentation, where the entry applies to both of the two San Andres reservoirs, the heading is "San Andres (A, B)"; to the one Cogdell reservoir, "Cogdell (A)"; to the three Fuller reservoirs, "Fuller (A, B, C)", etc. The stratigraphic names in quotation marks are in common usage in the senses indicated on TYPICAL SECTION. Their usage here in quotation marks is not intended as an endorsement of such usages; it is merely the result of an effort to facilitate proper coordination of the information herein with corres­ponding and related information in other publications. FIELD NAMES The Scurry field includes 23 fields as now des­ignated by the Railroad Commission of Texas . Nine additional designations formerly used by the Com­mission are no longer used. The following tabulation lists those designations in the left column and, in the right column, indicates the corresponding stratigraphic positions and areas as designated in this paper. Now used by Comm. Designation herein: Cogdell "Canyon" (A) Cogdell (4900') Cogdell (A) Cogdell {Fuller Sand) Fuller (A, B) Cogdell {San Andres) San Andres (A, B) Cogdell {Strawn) Strawn Zone C (A) Cogdell, West (Strawn) Strawn Zone C (B, C) Dermott Ellenburger (A) Diamond 'M' Canyon "Canyon" (B) Diamond 'M' Clearfork Clear Fork (A) Diamond'M' San Andres San Angelo (A, B) Diamond 'M ' Wolfcamp "Wolfcamp" (A) Early {Strawn) Strawn Zone B (B, D) Fuller Fuller (C) Fuller, Southeast (7100' Strawn) "Canyon" (D) Fuller (Strawn 'B') Strawn Zone B (A) Kelly-Snyder "Canyon" {B) Kelly-Snyder (Caddo) Strawn Zone C (H, I) Kelly-Snyder (Cisco Sd.) "Cisco" (A, B, C) North Snyder {Strawn Zone 'A') Strawn Zone A (A) North Snyder (Strawn Zone 'B') Strawn Zone B (B, C, E) North Snyder Strawn Zone C (D, E, F, G) (Strawn Zone 'C') and Strawn Zone D {A) Schattel "Canyon" (F) Vernon Cox (Canyon Rf.) "Canyon" (C) No longer used by Comm . Brown (Cisco Sand) "Cisco" {A) Collins Strawn Zone B (B) Eiland (Ellenburger) Ellenburger (C) Kelly "Canyon" (B) North Snyder "Canyon" (B) North Snyder Ellenburger Ellenburger (B) North Snyder Strawn "Canyon" (E) * Publication authorized by Director, U. S. Strawn Zones B (B, C, E), Geological Survey. Stratigraphic nomenclature does C (D, E, G) and D (A) not necessarily conform to that of U.S. Geological Parks {Cisco Sand) "Cisco" (A) Survey. Sharon Ridge Canyon "Canyon" (B) SCURRY FIELD, Scurry, Kent and Borden Counties, Texas METHODS OF EXPLORATION LEADING TO DISCOVERY The location of the field discovery well was based on a seismograph survey and a study of the subsurface geological data. DISCOVERIES San Andres (A, B) : November 10, 1951; Chapman & McFarlin Producing Co. #33-A D.M.Cogdell San Angelo (A, B): December 14, 1950_; Robert W. McKissick #1 Hugh Birdwell Clear Fork (A): October 15, 1949; Hiawatha Oil & Gas Co. #7 L.M.Wilson "Wolfcamp" (A): October 14, 1952; Humble Oil & Refining Co. #4-B J .E.Sorrels Cogdell (A) : April 14, 1950; Chapman & McFarlin Producing Co. #6 D.M.Cogdell. Fuller (A, B, C): November 18, 1950; Chapman & McFarlin Producing Co. #25 D .M.Cogdell "Cisco" (A, B, C) : April 21, 1951; Standard Oil Co. of Texas #1-S G.E.Parks "Canyon" (A-F) and Field: July 16, 1948; Sun Oil Co. and Humble Oil & Refining Co . #1 Emil Schattel Strawn Zone A (A): May 15, 1953; Ralph A. JohnsQn and W .S.Johnson #1 V .H.Wade Strawn Zone B (A-E): April 14, 1949; Placid Oil Co. #1 W .W.Early Strawn Zone C (A-I): November 5, 1948; Magnolia Petroleum Co . #1 Winston Brothers Strawn Zone D {A): April 21, 1951; Cities Service Oil Co . #4 Poponoe "B" Ellenburger (A, B, C): April 27, 1949 ; Humble Oil & Refining Co. #1-B B .A.Moore SURF ACE FORMATIONS The Ogallala formation of the Tertiary system, the Fredericksburg and Trinity groups of the Creta­ceous system, the Dockum group of the Triassic system, and the Whitehorse group of the Permian system crop out within the area of the field . LITHOLOGY OF RESERVOIR ROCKS San Andres (A, B): Dolomite; light olive-gray, San Angelo (A, B) : Sandstone; light-gray, very-fine­to fine-grained; contains some interbedded shale and siltstone. Clear Fork (A): Dolomite; light olive-gray, scattered anhydrite aggregates, poor to good porosity. "Wolfcamp" (A): Limestone; light-to medium­gray, fine-grained, poor to fair porosity. Cogdell (A): Limestone; light-gray, fine-grained, vuggy. Fuller (A. B, C): Sandstone; fine-to medium-grained, angular to subangular, fair to good porosity and permeability; contains interbedded thin shales and siltstones. "Cisco" (A, B, C): Sandstone; fine-to medium­grained, subangular, loosely cemented, fair porosity; contains varying amounts of silty material and interbedded shales and siltstones . "Canyon" (A-F): Limestone; elastic, fine-to boulder -sized fragments; contains a small amount of lithographic limestone and shale; porosity is extremely variable, averaging l0.5o/o for productive rock. Strawn Zones A, B, C and D {all reservoirs): Lime­stone; elastic, fine-to medium-grained; porosity is extremely variable. Ellenburger (A, B, C): Dolomite; white to light brownish-gray, fine-grained; contains a small percentage of white chert; fair to poor porosity . RESERVOIR ENERGY "Canyon" (A-F) : The expansion of gas from solution is the primary type of reservoir energy in the "Canyon" reservoirs. No appreciable water drive or encroachment of water is evident. Reser­voir pressure has steadily declined from the initial 3,122 psi. to as low as 1,675 psi. in some places. The importance of pressure maintenance was recog­nized early in the development of the field. As early as December 1950, experimental water injection was begun. Gas injection on an experimental basis was started in June 1951. At present, a large-scale pressure maintenance program under a unitization agreement is being initiated for a large part of the "Canyon" producing area. Both gas injection and water injection are to be used in this program. Other reservoirs : Information is scanty con­cerning the reservoir energy in other reservoirs. Water drive appears to be the primary source of energy in most of the reservoirs other than "Canyon" (A-F) . SCURRY FIELD, Scurry, Kent and Borden Counties, Texas ELEVATION OF SURFACE At well locations (derrick floor): Highest, 2 ,622 feet; lowest, 2,124 feet. NATURE OF TRAPS San Andres (A, B) : Accumulation in each of the two reservoirs appears to be due to decrease in porosity updip to the east. San Angelo (A, B) : The factors which occasioned accumulation are not known. Since the degree of . porosity and permeability of the productive sand­stone is known to be irregular and since this sandstone generally yields water where penetrated within the area of the field, it is believed that the traps are due to updip decrease of porosity and permeability although the degree of inclination of the reservoir rock is evidently very low. Clear Fork (A), Cogdell (A) and Fuller (A, B, C}: The accumulation in each of these reservoirs is due to a convex fold . The structure of each reservoir rock is probably due mainly to differential compac­tion of lower beds deposited on and in the vicinity of a reef. "Wolfcamp" (A): The accumulation appears to be due mainly to updip decrease of porosity and permeability where the reservoir rock is warped into a gentle nose on a general westward dip . "Cisco" (A,B,C): The primary trap-forming factor is a convex fold, but variation in degree of porosity and permeability is a contributing factor, and probably the dominating factor as to "Cisco" (B) and "Cisco" (C) . "Canyon" (A-F) : The accumulation of oil in each of these reservoirs is due to a simple convex trap resulting from topography of highly porous reef limestone . The oil is trapped in buried topographic crests overlain and surrounded by relatively imper­vious shale . Strawn Zones A, B, C and D (All reservoirs}. The writer has not determined precisely the trap-forming factors for each of the 16 reservoirs in the Strawn series . However, it is evident that all accumulations are due to reef conditions . Generally, the accumu­lations appear to be in reservoirs with convex upper limits where the inclination of the reservoir rocks has resulted from deposition on a sloping surface and, to a lesser degree, from differential compaction of lower beds. Updip decrease in porosity and per­meability within complex reef may be the controlling factor for some reservoirs . Ellenburger (A, B, C): There is only a single well in each of the three reservoirs . Data are not available for determining the trap-forming factors. OLDEST HORIZON PENETRATED The oldest rock penetrated in the vicinity of the field is pre-Cambrian granite. The greatest pene­tration into the granite was in Humble Oil & Refining Company #14 LeRoy Spires, Jr., located in Sec . 719, Block 97, H . & 1. C . survey, which reached a total depth of 8,292 feet (-5,856 feet) after having pene­trated 36 feet of granite. One other hole in the immediate vicinity of the field and two holes within the field were drilled into the pre-Cambrian granite. A few holes in the southern part of the field were drilled deeper, but were in younger rocks at their total depths because of regional tilting and thickening southwestward. THICKNESSES OF RESERVOm ROCKS Feet Min. Max . Avg. San Andres (A, B) : Thickness of producing zone 19 38 28 Net productive thickness ? ? ? San Angelo (A, B): Thickness of producing zone 12 52 34 Net productive thickness ? ? ? Clear Fork (A) : Thickness of producing zone 45 190 110 Net productive thickness 10 60 20 "Wolfcamp" (A) : Thickness of producing zone 20 34 26 Net productive thickness ? ? ? Cogdell (A): Thickness of producing zone 23 46 39 Net productive thickness 5 19 12 Fuller (A, B. C): Thickness of producing zone 4 36 21 Net productive thickness 4 32 18 "Cisco" (A, B, C) : Thickness of producing zone 9 110 38 Net productive thickness 9 45 20 "Canyon" (A-F): Thickness of producing zone 5 770 350 Net productive thickness 5 635 180 Strawn Zone A (A): Thickness of producing zone 28 Net productive thickness 28 Strawn Zone B (A-E): Thickness of producing zone 15 86 48 Net productive thickness 6 50 20 Strawn Zone C (A-I): Thickness of producing zone 10 42 23 Net productive thickness 5 13 10 Strawn Zone D (A) : Thickness of producing zone 30 54 38 Net productive thickness 10 18 12 Ellenburger (A, B, C) : Thickness of producing zone 20 50 25 Net productive thickness ? ? ? SCURRY FIELD, Scurry, Kent and Borden Counties, Texas CONTINUITY OF RESERVOIR ROCKS San Andres (A, B) : The bed of dolomite whic h is productive in the two small areas indicated on Map II is probably continuous throughout the area of the field . However, the degrees of porosity and permeability are quite variable . San Angelo (A , B): The sandstone in the San Angelo formation appears to be continuous through­ out the area of the field. Generally, the degree of permeability is too low for commercial production of oil . Clear Fork (A): The dolomite in the Clear Fork group which is productive in an area of about 1,880 acres in the south part of the field is continuous throughout the area of the field . Generally it is not sufficiently porous and permeable to yield oil com­mercially. "Wolfcamp" (A) : The bedded limestone in the Wolfcamp series, part of which produces oil, is con­tinuous throughout the area of the field. Generally, the degree of porosity and permeability are not favorable for production of oil . Cogdell (A) : Although the limestone which is pro­ductive in 8 wells near the north end of the field has not been separately identified in the south part of the field, it appears likely that it is continuous through­out the northern three-fourths of the field . Where it has been identified, the degree of porosity appears adequate for free migration of reservoir fluids. Fuller (A, B, C) : The Fuller member has been recognized in only the northern part of the field. It is productive in three small areas covered by accompanying Map II but has been recognized only slightly further south than the southern border of that map . It appears to be continuous in the northern part of the field and to have a sufficient degree of porosity and permeability for free migration of reservoir fluids . "Cisco" (A, B, C): Although the three reservoirs indicated on Map III are at the same stratigraphic position, it is not known ·whether there is continuity of conditions favorable for m igration of reservoir fluids between the three areas. Throughout the area of the entire field , there is sandstone at or near this stratigraphic position, but, because of lenticularity, together with lateral variations in content of shale and siltstone, it is very difficult to correlate the individual sandstone beds . "Canyon" (A -F): The "Canyon" reef is con­tinuous throughout the field . It produces oil in all wells where it is above the water level except for a few wells on the margin of the field where such reef limestone as is above the water level is very dense. Strawn Zones A, B , C and D (all reservoirs) : The 16 reservoirs are all related to reef conditions. The continuity of each reservoir rock is dependent upon its particular reef relationships. Ellenburger (A, B, C): The productive rock in each of the three reservoirs is at the top of such portion of the Ellenburger dolomite as is present at the particular location . The top of the Ellenburger is a truncated surface throughout the area of the field . The exact position within the Ellenburger has not been determined for any one of the reservoirs and therefore the continuity of the reservoir rock cannot be determined . However, the Ellenburger dolomite has been demonstrated by many wells to be continuous throughout the area of the field . CH AR AC TER OF OIL G ravity, Min . A.P.I. @ 60 ° F. Max . Avg . Sulphur , 1o L ess than Color San .A n dres (A, B) 36 .2 San Angelo (A, B) 33 .2 Clear Fork (A) 28 .0 "Wolfcamp" (A) 42. 1 Cogdell (A) 41.5 Fuller (A, B, C) 40 .0 "Cisco" (A , B, C) 38.2 "Canyon" (A-F) 39 .4 Strawn Zone A (A) Strawn Zon e B (A-E) 37 .3 Strawn Z one C (A-I) 33 .5 Strawn Zone D (A) 38.6 E llenbu r g er (A , B, C) 36 0 39 0 39.0 34.0 43 .3 42 .7 45 .6 43 .7 45 .4 42 .4 45 .1 40 .6 46 .5 38 .0 35 9 31.0 42 .4 42 .1 42 .1 42 .3 43 .o 37 .2 38.0 40 .3 39 .5 41.2 1.00 0 .50 0 .25 0 .50 0 .40 0 .50 0 .30 Dark greenish-black Dark-to light-green Dark-green Green to g reeni sh-black Green to greenish-brown Green to greenish-brown Dark g reen to brownish-green For analyses see: U.S.Bureau of Mines Analyses of Crude Oils from some West Tex as fields, R .I. 4959 (March 1953). Items 49, 50, 51, 52, 53, 54, 56, 57, 58, 61, 62 , 63, 64, 65 and 66 . * A New Method of Determining Variations in Physical Properties of Oil in a Reservoir, with application to the Scurry Reef Field, Scurry County .. Texas, R .I. 5106 (February 1955). * Added by amendment. SCURRY FIELD, Scurry, Kent and Borden Counties, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES Elevation of oil (feet) R elief Top Bottom (feet) San Andres (A) 664 615 49 San Andres (B) 563 550 13 San Angelo (A) -97 -149 52 San Angelo (B) -95 -135 40 Clear Fork (A) -725 -950 225 "Wolfcamp" (A) -3 ,007 -3,152 145 Cogdell (A) -2 ,538 -2 ,604 66 Fuller (A) -2 ,641 -2 .670 29 Fuller (B) -2 ,658 -2 ,670 12 Fuller (C) -2 ,682 -2 ,755 73 "Cisco" (A) -3,615 -3 .900 285 "Cisco" (B) -3 ,680 -3 ,790 110 "Cisco" (C) -3 ,779 -3 ,861 82 "Canyon" (A) -3,792 -4 ,560 768 "Canyon" (B) -3 ,738 -4,540 802 "Canyon" (C) -4,660 -4,674 14 "Canyon" (D) -4 ,810 -4,820 10 "Canyon" (E) -4,769 -4,793 24 "Canyon" (F) -4,425 -4,501 76 Strawn Zone A (A) -4,672 -4,700 28 Strawn Zone B (A) -4,840 -4,855 15 Strawn Zone B (B) -4,890 -4,935 45 Strawn Zone B (C) -4,845 -4,955 110 Strawn Zone B (D) -5,128 -5,153 25 Strawn Zone B (E) -4,956 -5,011 55 Strawn Zone C (A) -4,917 -4,982 65 Strawn Zone C (B) -5 ,065 -5,088 23 Strawn Zone C (C) -5 ,091 -5,111 20 Strawn Zone C (D) -4,98 1 -5,01 9 38 Strawn Zone C (E) -5 ,094 -5 ,122 28 Strawn Zone C (F) -4,989 -5 ,000 11 Strawn Zone C (G) -5,070 -5 ,090 20 Strawn Zone C (H) -5 ,208 -5,240 32 Strawn Zone C (I) -5,215 -5 ,257 42 Strawn Zone D (A) -5 ,175 -5,301 126 Ellenburger (A) -5 ,580 -5 ,630 50 Ellenburger (B) -4 ,385 -5 ,405 20 Ellenburger (C) -5,713 -5,733 20 Bergenback, R. E., and Terriere, R. T. (1953) The petrography and petrology of the Scurry reef, Scurry County, Texas: Am. Assoc. Petrol. Geol. Bull., vol. 37, pp. 1014-1029. CHARACTER OF GAS SELECTED REFERENCES Anonymous (1951) Scurry conservation plans envisage billion barrel payoff: World Oil, vol. 133, No. 4, pp. 100-104 (September 1951). Cattell, R.A. (1953) Petroleum and natural gas re­search program Bureau of Mines, fiscal year 1952: U.S. Bureau of Mines, I.C. 7659, pp. 6-8. Clayton, Neal (1951) Geology and geophysics of the North Snyder area: Geophysics, vol. 16, pp. 1-13. Elliott, Wm.C., Jr. (1953) Chemical characteristics of waters from the Canyon, Strawn, and Wolfcamp formations in Scurry, Kent, Borden and Howard Counties, Texas: Petroleum Engineer, vol. 25, No. 6 (June 1953), pp. 8-77-89 . Heck, W.A., Yenne, K.A.. and Henbest, L.G. (1952) Pennsylvanian and Permian (?) contact in sub­surface Scurry reef, Scurry Co., Texas: Am.Assoc. Petrol. Geol. Bull., vol. 36, pp. 1465-1466. Heck, W.A., Yenne, K.A., and Henbest, L.G. (1952) Boundary of the Pennsylvanian and Permian (?) in the subsurface Scurry reef, Scurry County, Texas: Univ. of Texas, Bur. Econ. Geol., R.I. 13 ' 15 pp. , 5 figs., 1 pl. Horner, W.L. (1951) A petroleum engineering pro­gress report on the Scurry field: A. I. M. E., Jour. Petrol. Tech., April 1951, p. 17 et seq. Horner, W.L. (1951) Progress report on the reef pool of Scurry County, Texas: Texas Petrol. Research Comm. Bull. 11, Proceedings for Second Oil Recovery Conference, a symposium on carbonate reservoirs, pp. 112-117. Keplinger, C.H. and Wanenmacher, J.M. (1950) The new reef fields of Texas: World Oil, vol. 131, no.4. Myers, D.A., Stafford, P.T. and Burnside, R.J. (in press) Geology of the late Palezoic Horseshoe Atoll in western Texas: Univ. of Texas publ. Osborn, W .M. (1950) Scurry County stimulates search for reefs: World Oil, vol. 130, no. 5, pp. 40-47. Potter, G.C. (1952) D.M.Cogdell lease, Kent County, Texas: Abilene Geol. Soc., Geol. Contrib. 1952, pp. 12-13, 4 pl. Raman, N.D. (1952) Fuller sand pool, Scurry Courtty, Texas: Abilene Geol. Soc., Geol. Contrib. 1952, pp. 31-32. Rothrock, H. E., Bergenback, R . E., Myers, D.A., Stafford, P. T., and Terriere, R. T. (1953) Pre­liminary report on the geology of the Scurry reef in Scurry County, Texas: U.S. Geol. Survey, Oil and Gas lnves. Map OM 143. Smith, N.A.C., Smith, H.M. and McKinney, C.M. (1950) Characteristics of crude oils from the Scurry Co., Texas, area: U.S. Bureau of Mines, Petroleum Processing, vol. 5, July 1950, p. 730. Stafford, P.T. (in press) Geology of the late Palezoic Horseshoe Atoll in Scurry and southern Kent No gas analyses are available. The only gas Counties, Texas: U.S. Geol. Survey Prof. Paper. produced is gas which comes out of solution as the Van Siclen, D.C. (1950) Reef-type oil fields, Scurry oil is produced. No free gas has been found in any County, Texas : Abilene Geol. Soc., Geol. Contrib. of the reservoirs discovered to date. 1950, pp. 70-79, 6 pl. SCURRY FIELD, Scurry, Kent and Borden Counties, Texas ROCKS PENETRATED TYPICAL SECTION OF NOTE, This T YPICAL SECTION is based on a composite log. ll shows all stratigraphic units, including all reservoir rocks, although they are not all present at any one location. The nomenclature does not necessarily con­form with that of the U. S. Geological Survey. EXPLANATION Limestone ~Dolomite E===~=3 Shale ~ Sandstone Anhydrite Chert EZ2J m ~ :~;~~~ Granite .Oil product ion THE UNIVERSITY OF TEXAS, BUREAU OF ECONOMIC GEOLOGY, PUBLICATION 5716 S C URRY FIEL D, Scurry, Kent and Borden Counties, Texa s SCURRY FIELD, Scurry, Kent and Borden Counties, Texas (Attach SCURRY map) SCURRY FIELD, Scurry, Kent and Borden Counties, Texas WATER PRODUCTION and ACID TREATMENT ACID TREATMENT WATER 3 of wells '1o of wells Minimum Maximum Average tr eated treatment treatment treatment showing water at time of initial completion (a pproximate) _j[_allons) (gallons) (gallons) San Andres (A, B) 8 100 1 ,5 00 8 ,000 5 ,000 San Angelo (A, B) ........... . . .100. . .. 33. ..... ................ I ,000. ... 2 ,250 ............ ..... 1.675 Clear Fork (A) 75 95 2 ,500 20,000 10,500 "Wolfcamp" (A) 0 25 1,000 1 ,000 1,000 Cogdell (A) ... .. . . . 0 ........... . . 50 . . 250 ........... .. . 2 ,000. ... 950 Fuller (A, B, C) 20 0 0 0 0 " Cisco" (A, B, C) 0 10 20 6,300 1,100 "Canyon" (A -F) . . . . . . . . . 5 .... 90 ........... . .... 250 ............... 10,000 ...... ........... 1,000 Strawn Zone A (A) 0 0 0 0 0 Strawn Zone B (A -E) 10 50 500 5 ,500 2 ,500 Strawn Zone C (A -I). .35 67 ................. . . ...500.. . .. 2 ,000................. l ,000 Strawn Zon e D (A) 15 100 500 10 ,000 4, l 00 Ellenbu rger (A, B, C) 100 67 2 ,000 3 ,000 2 .500 TREATMENT by the Hydrofrac method has been applied to about 15'1o of all "Cisco" wells . Quantities used in such treatments ranged from l ,500 gallons to 6 ,000 gallons and averaged about 2 ,300 gallons . Nitroglycerin was used in the San Angelo discovery well and in about 10% of the wells completed in the reservior in the Clear Fork g roup . PRODUCTION HISTORY W E LLS P ROD UCING OIL PRODUCTION WELLS PRODUCING OIL PROD UCTION at end of year (barrels) at end of year (barrels) Tota l F low. Pump. Yearl..r__ Cumulative Total F low. -­ Pump.--­ Yearly C um u lative Field totals Fuller (A, B, C) 1948 4 3 24 ,530 24 ,530 1950 I 0 4 .060 4,060 1949 319 308 II 4,259.144 4 ,283 ,674 1951 16 15 1 159 ,714 16 3 ,774 1950 1,653 1,544 109 38 ,197 ,586 42 ,481 ,260 1952 19 13 6 367 ,163 530 .937 1951 2 ,026 J ,744 282 50,156,616 92 .637 ,876 1953 21 ? ? 360,470 891.407 1952 2 ,230 1.612 618 49 ,508 ,703 142 ,146,579 1953 2,322 ? ? 44,96 1 ,345 187 ,107 .924 "Cisco" (A, B, C) 1951 30 2 5 5 242 ,464 242 ,464 1952 101 13 88 1.613 ,068 1 ,855,532 San Andres (A , B) 195 3 I 0 l ? ? 1 ,286 ,591 3 ,142 ,123 195 1 0 I 880 88 0 1952 13 0 13 3 1,03 3 31.913 ''Canyon'' (A -F) 1953 22 ? 37 ,830 69 ,743 1948 4 3 1 24,530 24,530 1949 311 307 4 4,21 7 , 163 4 ,241,693 1950 J,616 I ,527 89 37 ,536 ,840 41,778 ,533 San Angelo (A, B) 1951 I ,910 I .695 215 48,557 ,200 90 ,335.73 3 1950 I 0 I ,052 I ,052 1952 2 ,0 I 0 I ,58 0 430 46 ,503 ,825 136 ,839 ,558 1951 I 0 2 ,038 3 ,090 1953 2 ,069 ? ? 42,192,138 179 ,03 1,696 1952 l 0 l ,449 4 ,539 1953 5 ? ? 4 ,374 8 ,913 Strawn Zones A, B, C and D (all reservoirs)* 1949 4 I 3 32,482 32,482 1950 22 17 5 551,203 583 ,685 Cl ear Fork (A) 195 1 32 9 23 J,026,019 1,609,704 1949 2 0 2 5 ,037 5 ,0 37 1952 41 4 37 8 17 ,3 42 2 ,427 ,046 1950 9 0 9 5 1 ,890 56.927 1953 43 ? ? 7 3 1 ,61 9 3 ,158 .665 195 1 33 0 33 100,225 157 ,l 52 1952 38 2 36 98 .430 2 55 ,582 Ellenburger (A, B, C) 1953 49 ? ? 99 .679 355,26 1 1949 2 0 2 4,462 4 ,462 1950 2 0 2 4 ,541 9 ,003 1951 0 2 ,640 11 ,643 ''Wolfcamp' '(A) 1952 0 l ,780 13 ,423 1952 l 0 9 ,305 9 ,305 1953 ? ? 1 ,429 14 ,852 195 3 4 ? ? 146, I 02 155,407 '~A few of the wells are dually completed in Strawn Zones Cogdell (A) Band C; each such well is coun ted as a sing l e well. 1950 2 0 2 48 ,000 48 ,000 1951 2 0 2 65,436 11 3 ,436 GAS PRODUCTION: The on ly g a s produc tion has been 1952 5 0 5 65,308 17 8,744 incidental to oil production. No estimat es of the qua ntities 1953 7 ? ? I 01,113 279.857 produced are available. SEMINOLE FIELD Gaines County, Texas E . R. DOUGLAS Geologist, The Atlantic Refining Company, Midland , Texas May 15, 1953 LOCATION The Seminole field extends from a location a mile south of the town of Seminole, county seat of Gaines County, northwestward a distance of 9 miles. It is on the northeast edge of the Central Basin platform. METHODS OF EXPLORATION LEADING TO DISCOVERY Studies of subsurface geological data and of the results of seismic and torsion balance surveys led to the discovery of the field . Before the commencement of the drilling operations which led directly to the discovery, it was widely known among operators that geophysical methods indicated the presence of a large anticline. Harry Adams Corporation and W. T. Walsh #1 S . J.Averitt, in the northeast corner of section 228, block G, Waxahachie Tap Railroad Co. survey, was commenced October 7 , 1935 and, before the end of the year, had encountered a large gas flow at depth of 4,885 feet. While contending with mechanical difficulties , the well gauged at the rate of 12 ,000 Mcf of gas per day after it had been drilled to its final total depth of 4,915 feet. It was abandoned early in 1936 after tools had been lost in the hole. It was at a location only 466 feet from where the field discovery well was later drilled . DISCOVERIES San Andres: January 8, 1937; Amerada Petroleum Corp. #1-A S . J . Averitt Clear Fork* : Amerada Petroleum Corp. #9 T . S. Riley ELEVATION OF SURFACE At well locations: Highest, 3 ,432 feet; lowest, 3 ,277 feet. SURF ACE FORMATION Undifferentiated sands and caliche of the Tertiary system. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon .penetrated is in the Wolfcamp series 2,512 feet below its top . This penetration was in Amerada Petroleum 9,312feet. Corp. #6 R. W. Robertson at its total depth of PRODUCTIVE AREAS San Andres Clear Fork Seminole field Acres 13 ,411 840 13 ,411 It is probable that future development will warrant Relief 262 Clear Fork: ---No free gas cap increasing the above estimate for Clear Fork . *The reservoir in the Clear Fork group has been designated by the Railroad Commission of Texas as the Seminole San Angelo field . NATURE OF TRAPS San Andres and Clear Fork: The trap in each of these two reservoirs is due to convex folding. THICKNESSES OF RESERVOIB ROCKS Feet San Andres§ : Max . Min. Avg. From top to bottom Gas cap 142 0 60 Oil 262 40 200 Net productive Gas cap 60 0 40 Oil 150 20 87 Clear Fork: From top to bottom 356 100 236 Net productive 150 50 80 LITHOLOGY OF RESERVOIR ROCKS San Andres: Dolomite; anhydritic, tan, granular to dense. Clear Fork: Dolomite; anhydritic, tan , dense to finely crystalline. CONTINUITY OF RESERVOIB ROCKS San Andres : The reservoir rock in the San Andres formation is continuous throughout the area of the field and probably far beyond the extent of the field. At about the same position in the San Andres formation there is dolomite of about the same characteristics throughout the area of the Central Basin platform and the Northern Shelf area of the Midland basin but whether the degrees of porosity and permeability are continuously sufficient for migration of reservoir fluids is not known. Secondary anhydrite commonly restricts porosity and permeability. Clear Fork : The degree of porosity and permeability is so variable that continuity of reservoir is difficult to determine . Dolomite of about the same characteristics is widespread in the region but actual continuity of the reser­voir beyond the presently productive wells cannot be determined. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Feet San Andres: Elevation of top of gas -l,557 Elevation of bottom of gas -1 .699 Relief 142 Elevation of top of oil -1,699 Elevation of bottom of oil -1 .961 Elevation of top of oil -2 ,865 Elevation of bottom of oil -3 ,221 Relief 356 §It appears that the author has confused relief of fluids with thickness of reservoir rock. See TYPICAL SECTION for approximate gross thickness. -Editor N --..-,i Ul I M I ~ ....... I I z 1861 I 0 L' M I I Q~ 'Tj ....... "'~ 196 -<.. ~o 1a1 M t <:;J<.:,,c, L' I •y o"l t:1 0 Q ...I I s· " "' ~ ~ "' ~ ~ GAMMA RAY RESISTIVITY .J GAMMA RAY RESISTIVITY .J 0 :! Q: ~ DEPTH AND S.P. 6 ~ ANO S.P. ELEVATION 6 :!: w U) 0: 0 z " " Q: • 0 • ~ RESERVOffi TEMPERATURE and PRESSURE and OIL SAMPLE DATA Character of oil Original bottom hole Original Bubble Volume Gravity Temp. Press. gas-oil ratio point factor A .P.J. ~~ (cf/bbl) ~(sur.: r es.) @ 60°F. Type Yates 87 1,940 200:1 to 5,000:1 1.4 est. 42.0 Sweet Deep Rock San Andres 93 I ,600 50:1 to 1.400:1 30.0 Sour North San Andres 93 J ,600 190:lto230:1 31.2 Sour Deep Rock Clear Fork 103 2 ,000 29: I 30.0 Sour Shafter Lake Clear Fork 108 2,210 528: I 1,310 1.342 41.4 Sour Wolfcamp 125 3 ,414 800: I 1,467 1.43 41.0 Sweet Pennsylvanian 127 2,825 233: I 38.4 Sweet East Pennsylvanian 129 4,625 982:1 39.0 Sweet Devonian 135 4,200 289: I.210 1.25 38 . l Sweet Ellenburge r 152 4,664 244: I 800± 1.24 42.5 Sweet For analyses of Devonian and Ellenburger samples see: U. S. Bureau of Mines Lab. ref. No. 5 1056 51055 Analyses of Crude Oils from Some West Texas Fields . R. I. 4959 (1953) Item 46 47 SHAFTER LAKE-DEEP ROCK FIELD Andrews County, Texas I TYPICAL SECTION OF ROCKS PENETRA TED [\IS~Y\?J SorwjsfoM t=:=:=::j Shole ~Dolomite Oolom1t1c ~Limestone .Anhydri tic sondstoM and shale dolomite ~Co1coreous~Limestone g Anhydrite dolomite ~Dolomitic +•+!+ Solt ~Chert limestone +• +. - • Oil productioo -i:t-Gos production SHAFTER LAKE-DEEP ROCK FIELD, Andrews County, Texas • • • • • . -;s;r;.-;-;w;-;r;.-;-;.•;-;•.• -;•.•;•."';,·~·.-;•.•.·~r;.·;-.·~.r.w;-;.-.•.•.•.•.•.•.•.•.•.•.•.•~~-·.•.•w•w•w•w•w•w•w•w•w•w•w•w•w*w*w'w•w•w•w*wl~~w Ww w w w w w \W W • W WWw w w w w w w w Ww w w W W w w Ww w w Ww w Ww WI : JI \\ \'Z. '2,\ : r.o • 445 ;r PRODUCTIVE AREAS MAP ~: SHAFTER LAKE-DEEP ROCK FIELD, Andrews County, Texas EXPLANATION Boundary of area shown on opposite poge Drilling well Producing from indicat ed reservoir F,{ Producing we1 1, abandoned in reservoir . indicated by underlined symbol Completed in Yoles between 4/10/53 ond 9/ 20/53 PROOUCTIVE AREA BOUNDARIES -+---+-~ Yates (Al ----Deep Rock Son Andres (Bl ----------North Son Andres (C) Deep Rock Clear Fork (0) ------Shafter Lake Cteor Fork (E) + + + + + + + + Wolfcomp (F) Pennsylvanian (G) East Pennsylvanian (H) Devonian (J) -x-x--Ellenburger (Kl SCALE •O THOUSAND rn:r SHAFTER LAKE-DEEP ROCK FIELD, Andrews County, Texas OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 335 feet below its top. This penetration was in Sinclair Oil & Gas Co. #154-8 University, Sec. 24, Biock 13, University Lands survey, at its total depth of 11,805 feet. Although Sinclair #154-12 (1,100 feet westward} drilled deeper (T.D. 11,945 feet), it drilled only 51 feet into Ellenburger. THICKNESSES OF RESERVOIR ROCKS Feet, approximate average Top to Net Bottom Productive y ·ates 34 20 Deep Rock San Andres 100 65 North San Andres 45 30 Deep Rock Clear Fork 95 50 Shafter Lake Clear Fork 110 75 Wolfcamp 60 30 Pennsylvanian 70 50 East Pennsylvanian 10 10 Devonian 380 120 Ellenburger 146 65 LITHOLOGY OF RESERVOIR ROCKS Yates: A hard, reddish gray to red, fine-grained sandstone with large frosted quartz grains alternat­ ing with some thin beds of anhydrite, shale and dolomite. Deep Rock San Andres and North San Andres: A hard, tan to white, fine crystalline dolomite. Deep Rock Clear Fork : A hard, dense, brownish gray, silty dolomite. Shafter Lake Clear Fork: A hard, buff to tan, finely crystalline, silty to sandy dolomite with slight traces of chert. Wolfcamp: A hard, black to light gray, medium crystalline, cherty limestone. Pennsylvanian and East Pennsylvanian: A hard, white, medium crystalline, chalky, fossiliferous limestone with some thin shale streaks. Devonian: A hard, light brown to white, medium crystalline, chalky limestone with some chert and traces of dolomite. Ellenburger: A hard, tan, medium to coarsely crystalline, fossiliferous, fractured dolomite with white chert. PRODUCTIVE AREAS Acres Yates (gas, 7 ,840; oil, 880+} IT;6oo Deep Rock San Andres 5 ,760 North San Andres 420 Deep Rock Clear Fork 80 Shafter Lake Clear Fork 140 Wolfcamp 2 ,930 Pennsylvanian 40 East Pennsylvanian 40 Devonian 2,840 Ellenburger .520 Shafter Lake -Deep Rock field 20,730 The Yates oil area has not been defined and therefore the above estimate includes only the area proven to date. Development now in progress will probably warrant increasing this estimate. CONTINUITY OF RESERVOIR ROCKS Yates: The reservoir rock is continuous throughout the area of the field; its porosity (nor­mally, about 20%} and permeability are continuous but decrease toward the edge of the field and are negligible in the bordering dry holes. The reservoir has a solution gas drive. San Andres: The reservoir rock is continuous throughout the area of the field; its porosity (nor­mally 15% to 20% in productive areas) is erratic and appears to be too low for migration of fluids except in the southern and eastern edges of the field. A solution gas drive provides the reservoir energy. Deep Rock Clear Fork and Shafter Lake Clear Fork: Each of these reservoir rocks is continuous throughout the area of the field. The porosity of each is very low. A solution gas drive provides the reservoir energy in each. Wolfcamp: The reservoir rock is continuous throughout the area of the field; its porosity (nor­mally, about 17.7 % ) and permeability (normally, about 48 md) are too low for migration of fluids except in the area of the large anticline in the western part of the field. A solution gas drive provides the reservoir energy. Pennsylvanian: The reservoir rock is continuous throughout the area of the field; its porosity is very low. Devonian: The reservoir rock is continuous throughout the area of the field; its effective porosity appears to be associated with a chalky facies. A solution gas drive provides the reservoir energy. Ellenburger: The reservoir rock and its effec­tive porosity and permeability (normally, about 213 md} are continuous throughout the area of the field and certainly for some miles beyond in all directions. Due to good secondary vuggy porosity and a high degree of fracturing, conditions are favorable for migration of fluids. There is a good water drive. SHAFTER LAKE-DEEP ROCK FIELD, Andrews County, Texas CHARACTER OF GAS Following are analyses of two representative samples of gas taken from two wells producing from the Yates reservoir, the only reservoir which originally contained free gas. Component Mol.% Mol.% Oxygen 0 ~ 00 0 .00 Carbon di oxide 0.10 0 .00 Nitrogen 17 . 15 18.55 Methane 67 .77 65.57 Ethane 8 .87 9 .11 P ropane 3.84 4.49 Iso-butane .47 .36 N-butane 1.07 1.01 Iso-pentane . 17 .26 N-pentane .28 .21 Hexanes .17 .23 Heptanes plus .11 .21 100.00 100.00 Calculated gross heating value @ 60° F. and 760 mm: 1,023 B.t.u. per cubic foot. COMPLETION TREATMENT Yates : The 48 gas wells were completed "natural". Of the 15 wells completed as oil wells, 4 were completed "natural", 4 with hydraulic fractur­ing, 4 with hydraulic fracturing and mud acid, 2 with acid and hydraulic fracturing and 1 with fracture-jel. Quantities used were as follows : hydraulic frac­turing, 1,500 to 5,000 gallons, normal, 1,500 gallons; mud acid, 250 to 500 gallons ; acid, 2,000 gallons; fracture-jel, 5,500 gallons. Deep Rock San Andres : 15 wells were com­pleted "natural"; 9 with acid treatment of 1,000 to 8,000 gallons, normal, 5,000 gallons ; 4 were shot with 420 to 1,500 quarts of nitroglycerin, normal, 500 to 600 quarts; 2 were shot with nitroglycerin, 480 and 680 quarts respectively, and treated with acid, 2,000 and 8, 000 gallons respectively. North San Andres: 3 wells were completed "natural", 1 with 5,000 gallons of acid. Deep Rock Glorieta: The two wells were each treated with 2,000 gallons of acid. Shafter Lake Clear Fork: 1 well completed "natural'', 2 with acid treatment, l with 9, 000 gallons and the other with 9,500 gallons. Wolfcamp: 2 wells completed "natural"; 47 with acid treatment of 500 to 5,000 gallons, normal, 1,500 to 2,000 gallons. Pennsylvanian: The one well was treated with 16,000 gallons of acid. East Pennsylvanian: The one well was treated with 250 gallons of acid. Devonian: 16 wells completed "natural"; 47 with acid treatment of 1,000 to 15,000 gallons, normal, 1,000 to 2,000 gallons; l with 500 gallons of mud acid. Ellenburger: l well completed "natural"; 9 with acid treatment of 500 to 10,000 gallons, normal, l , 000 to 3, 000 gallons. VARIATIONS IN THICKNESSES The Simpson group and the Mississippian and Pennsylvanian systems are thicker on the flanks of the anticline than they are over the axis. The Simpson thickens about 150 feet and Mississippian and Pennsylvanian combined thicken about 350 feet, The thickness of the Devonian remains fairly uniform. WATER PRODUCTION The quantity of water produced from each Yates, Deep Rock San Andres and North San Andres has been either none or negligible. The gross production of one of the two wells producing from Deep Rock Clear Fork is reported as currently about 60% water. The number of wells producing water at the end of each year and the quantities of water produced from the other reservoirs are indicated below. No . of Water No . of Water Year Wells (bbls) Wells (bbls) Shafter Lake Clear Fork Wolfcamp 1948 620 1949 2 6 ,590 5 24,655 1950 2 2 .976 6 18 ,811 1951 2 1,583 4 17,706 1952 2 2 ,17 3 4 11,754 Total 13 ,942 72 ,926 Pennsylvanian East P ennsylvanian 1950 199 1951 255 12,395 1952 368 9 ,080 Total 822 21,47 5 Devonian Ellenburger 1948 3 16,734 1949 10 182 ,184 3 8,457 1950 10 394,201 4 154,486 1951 11 477,771 3 744,962 1952 10 573,497 3 1,098,605 Total 1 ,644,387 2,006 ,51 0 PRESSURE MAINTENANCE Decline of pressure in the Devonian reservoir is being checked by injection of water through one well and gas through another well. Both operations were started in 1951, during which year 258,010 barrels of water and 11,366 Mcf of gas were injected. During 1952, 1,770,425 barrels of water and 321,397 Mcf of gas were injected. SHAFTER LAKE-DEEP ROCK FIELD , Andrews County, Texas Abandoned oil well Ori11ino well ff Dry hole • \:JI Discovery ~ Producinq from Yates A ; Abandoned in Yates SHAFTER LAKE-DEEP ROCK FIELD, Andrews County, Texas ~--1125-Contour on top of Son Andres group B . Producing from Deep Rock Son Andres ~ Producing from North Son Andres Producin9 from Deep Rock Clear Fork !. Producing well,obondoned in reservoir • indicated by underlined symbol SHAFTER LAKE-DEEP ROCK FIELD , Andrews County, Texas WEST A ELEVATION -+1000 -1000 -2000 -3000 -4000 -5000 -6000 -7000 -8000 -9000 EAST CROSS SECTION A-A' A' EL EVATION FEET +2000 +1000 -1000 -2000 -3000 -4000 -5000 -6000 -7000 -8000 THOUSAND FEET -9000 SHAFTER LAKE-DEEP ROCK FIELD, Andrews County, Texas NORTH SOU TH 8 CROSS SECTION 8-8' 8' ELEVATION EL EVAT ION FEET FEE T 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 +20 00 +2000 +1000 +1000 -1000 -1000 -2000 -2000 -3000 -3000 -4000 -4 000 -5000 -5000 -6000 -6000 -1000 -7000 -8000 -8000 -9000 -9000 D PRODUCTION WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION at end of year (barrels) (Md) Year Flow. Pump. Gas lift Yearly Cumulative Yearly Cumulative Field totals 1929-1938 687 ,609 1939 65 ,704 753,313 5,750 s ,7SO 1940 49 ,2 36 802 ,S49 14,185 19 ,935 1941 S2 ,056 854 ,605 16,168 36 ,103 1942 29 ,319 883 ,924 15 ,755 Sl ,8S8 1943 10 20 ,683 904,607 15,971 67 ,829 1944 II 32 ,034 936,641 28 ,546 96.375 194S 14 11 36 ,007 972,648 125 ,48 1 221 ,8S6 1946 19 II 41,181 1,013,829 855 ,595 1 ,077 ,451 1947 27 17 92,S 12 1,106,341 l ,S95,267 2,672,718 1948 94 21 1.880 ,972 2,9 87,313 3,316,318 5,989,036 1949 73 58 13 3,506,299 6.493,612 4,878,490 10 ,867 ,S26 I 9SO 65 78 8 2 .929 ,545 9,423,157 4,512,259 15,379,78S 19S 1 66 88 3,199.903 12,623,060 4,263,448 19,643,233 I9S2 75 108 2,929,263 15,552 ,323 4 ,483 ,009 24,126,242 I9S3• 3, l 08 ,2S6 18,660,579 s ,880 ,346 30 ,006 ,588 Yates 1939 s ,7SO s ,750 1940 14,18S 19 ,93S 1941 16 .168 36 ,103 1942 , 0 1S,7SS SI ,8S8 1943 0 IS,971 67 ,829 1944 28 ,S46 96.37S 194S 12 465 46S 12S ,481 22 I ,8S6 1946 17 3 ,263 3 ,728 8SS,S9S 1,077 ,451 1947 22 5,475 9 ,203 I ,S89 ,054 2 ,666 ,SOS 1948 33 399 9 ,602 2 ,494,770 S,161,27S 1949 38 1,974 11,576 3.478,295 8 ,6 39 ,S70 I 9SO 38 1,436 13,012 3 ,349 .697 11,989.267 I 9S I 42 1,264 14,276 3 ,041,079 15,030,346 I9S2 61 16 ,680 30,956 3,118,071 18,148,417 I9S3• 233,783 264 ,739 3,721,414 2 1,869.831 Deep Rock San Andres 1929-1938 687 ,609§ 1939 6S ,704 753,313 1940 49,236 802 ,S49 1941 S2 ,OS6 854,60S 1942 29 ,319 883.924 1943 I 0 20 ,683 904,607 1944 II 32 ,034 936 ,641 194S 11 3S ,S42 972,183 1946 II 37 ,918 1,010,101 1947 17 69 ,603 1.079 ,704 1948 16 9S ,979 l ,17S,6 83 1949 lS 78,266 1,253,949 1950 17 77 ,204 I ,331 ,153 1951 17 8S ,362 1.416,515 19S2 21 IOS,S72 I ,522 ,087 1953• IOS.92 1 1 ,628 ,008 * 1953 data added by amendment. § The only readily available record for years prior to 1939 reports totals for Deep Rock San Andres combined with Fuhrman and Fuhrman-Walker. The writer is unable to segregate the quantities. HISTORY GAS PRODUCTIONWELLS PRODUCING OIL PRODUCTION at end of year (barrels) (Md) Year Flow. Pump. Gas lift Yearly CU.mulative Yearly Cumulative North San Andres 6,387 6,387 774 774 19S2 2 32,810 39 ,197 5,S74 6,3481953• Deep Rock Clear Fork 891 8911948 0 9 .S92 10,48 31949 14,283 24,76619SO 16,4S5 41.221 1952 19Sl 18 ,7S8 S9 ,9 79 19S 3• IS,564 7S,S43 Shafter Lake Clear Fork Neg. Neg. 1949 21,390 2S,084 Neg. Neg. 19SO 17 ,195 42 ,279 I ,125 1.12s 1948 0 3,694 3,694 13,619 5S ,898 471 1 .S96 19S2 27 ,079 82 .977 s ,441 7 ,037 195 3• 47 ,960 130,937 13,963 21,000 19Sl Wolfcamp ~ 29 432,814 432,814 319,772 319,772 1949 8 610.980 1 ,043,794 438 ,069 7S7 ,841 1950 13 468 ,769 l,S l2 ,S63 33S,778 1,093,619 6S7 ,6S7 2,170,220 477,441 1 ,S7 I ,060 19Sl 21 1952 26 737 ,313 2 .907 ,S33 S20,0IS 2 ,09 I ,07 S 884,042 3,791,S7S I ,12 0 ,6S I 3 ,211,7261953• Pennsylvanian: 9 ,9S8 9 .9S8 2 ,41 S 2,41S19S O 6,016 IS.974 2 ,778 s, 19 3 19S l s ,104 21 ,078 437 s ,6 301952 1,342 22 ,420 S8 5 ,688I9S3•§ East Pennsylvanian 8.9S4 8 .954 9 ,l S9 9 ,159 I9Sl I 6 ,893 IS ,847 7 ,67 3 16 ,83219S2 2 ,439 18 ,286 3,000 19 ,832 1953* Devonian 17 ,434 17 ,434 6 ,213 6 ,213 1948 37 1 l,336,7S4 I ,3S4,188 498,832 sos ,04S 1949 13 33 2,1S6,644 3,Sl0,832 819,783 1,324,828 1950 10 42 l ,S74,968 s ,08S ,800 63S,739 I ,960,S67 ~ 1951 44 4 1,716,927 6,802,727 5S9 ,oos 2,519,S72 19S2 46 l ,495 ,859 8.298,S86 707 ,039 3 ,226 ,611 19S3• 1,360,8S1 9 ,6S9 ,437 907 ,302 4,133,913 Ellenburger 1948 10 ,441 10,441 2 .944 2 .944 1949 10 627 ,4S3 637 .894 142 ,343 I 4S ,287 1950 8 76S,732 1,403 ,626 187 .sos 332 ,792 l9Sl 69 3 ,649 2,097,275 173,S I 5 506 ,307 19S2 509 ,618 2,606,893 123,5S6 629 ,863 19S3• 423 ,S 44 3 ,0 30,437 108,384 738 ,247 * 1953 data added by amendment. §The one Pennsylvanian well was plugged back to Wolfcamp on April 12, 1953. (.V ....... CX> Ul :::r:: > "Tj ..., M ::0 r-' > 7': M I 0 M M 'U ::0 0 () 7': "Tj ...... M r-' 0 i> tn ~ ~ ..., ~ tn SHANNON FIELD Crockett County, Texaa J. D. HOLME Geologist, Sun Oil Company, Midland, Texas May 1. 1953 LOCATION and OTHER NAMES The Shannon field is in northwest Crockett County about 14 miles east of the town of Iraan, Pecos County. It is at the western dissected edge of the Edwards Plateau. Prior to 1947, the one well which had produced from the Grayburg reservoir was considered as in a separate field designated as the Live Oak field. In 1947, the Rail­road Commission changed its designation to "Shannon (Grayburg}" and reporting organizations generally followed the change. The Railroad Commission reports the produc­tion from the San Andres reservoir as from the ''Shannon (San Andres) field" . METHODS OF EXPLORATION LEADING TO DISCOVERY Mapping of surface rocks indicated structural condi­tions favorable for accumulation of oil and gas. Core drilling to the Yates formation by Moore Exploration Com­pany confirmed evidence afforded by surface exposures. DISCOVERIES Queen: September 1, 1944; Sohio Petroleum Co. #3-24 Margaret A. Shannon Estate. Drilled to total depth of 2,410 feet, from where sulphur water filled hole 600 feet in 8 hours. Plugged back to 1,983 feet and perforated casing with 80 holes from 1.960 to 1,970 feet. During potential test, production was at rate of 4 ,450 Mcf of gas per day . However, due to the lack of a market outlet, the well has been shut-in since its completion. Grayburg and Field: July 13, 1940; Moore Brothers and Olson Oil Co. #IA.C . Hoover. Pumped 53 barrels of oil per day after shot. San Andres: May 21, 1943; John I. Moore & P. D. Moore #1-12 Margaret A. Shannon Estate. Pumped 45 barrels of oil and 10.5 barrels of salt water per day after shot and treatment with acid. ELEVATION OF SURFACE At well locations: Highest, 2,747 feet; lowest, 2,366 feet . SURF ACE FORMATION All surface rocks within the area covered by the accompanying map are in the Edwards formation. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area covered by the accompanying map is in the Ellenburger group 650 feet below its top. This penetration was in John I. Moore #1-D A. C . Hoover, located in the northeast corner of Sec. 17, G.C . & S.F. R . R. Co . Block l; total depth, 8,440 feet. PRODUCTIVE AREAS NATURE OF TRAPS Queen, Grayburg and San Andres: It appears that updip decrease of porosity and permeability is the principal trap-forming factor in each of the reservoirs . The loca­tions of the commercial accumulations of oil and gas are in the vicinity of structural conditions favorable for structural traps, but it appears that porosity and permeability are so irregular that they determine the location of each accumulation. San Andres: As indicated on the accompanying map, there are several distinct areas where wells have been completed as commercial producers . Around and between these productive areas, many tests have yielded shows of oil and gas but not in sufficient quantity to warrant comple­tion as producers . In view of the irregularity of porosity and permeability, it is not known whether there is one single accumulation or several isolated accumulations. In any case, it is evident that irregularity in degree of porosity and permeability has been a dominant factor in forming the trap, or traps , in which the oil has accumulated. THICKNESSES OF RESERVOIR ROCKS Queen Grayburg San Andres From top to bottom, feet, avg.--2-0-80 66 LITHOLOGY OF RESERVOIR ROCKS Queen: Sandstone; red and gray, fine-to coarse­ grained, with numerous rounded frosted quartz grains . Grayburg : Dolomite; buff and brown, dense to finely crystalline, with very low porosity and permeability. This reservoir rock is partly in the Grayburg formatfon and partly in the San Andres formation . That portion in the Grayburg formation is only locally sufficiently porous to yield oil. It has been penetrated in all wells drilled in the area covered by the accompanying map and is productive in only three wells. San Andres: Dolomite; white and tan, finely crystalline, generally with very low porosity and permeability. Through­ out most of the area covered by the accompanying map, porosity and permeability are too low to yield oil and gas at rates sufficient for commercial production. CONTINUITY OF RESERVOIR ROCKS In no case can the productive reservoir in any well be proven to be continuously open for migration of fluids beyond the patterned area in which the well is represented on the accompanying map. However, it seems likely that the San Andres production is all from a single reservoir even though intercommunication has not been proven . CHARACTER OF OIL Grayburg San Andres Gravity , A.P .I.@ 60° F ., avg . 29° 25° Acres ACID TREATMENT Queen (gas) ~ Grayburg 120 More than half of all oil wells in the field were San Andres l ,800 acidized at the time of completion. Many were shot. Some Shannon field 1.925 were acidized and shot. SH ANN 0 N FIELD, Crockett County, Texas ;:f 2Z!t 8 9 SIMPSON FIELD 14 13 E. L. a R.R. R.R. CO. BLK. yz z~o1PP.,,, le. 9 10 iP :::. Zl 4$ EXPLANATION NOTE : All oil wells except the three in the Grayburg +400 -----Confour on top of San Andres formation productive area are producing from the San Andres reser­ voir. The single gas well was completed for production from +329 Elevation of top of Son Andres format ion the Queen reservoir, but has been shut in since the time of • Total depth of we ll its completion because of lack of market outlet. Plugged -bock depth of we lt *Gos well • Oil well P Ory hole • \::1J Discovery PRODUCTIVE AREAS SC ALE '0 Queen Son Andres Iii Gr oyburg THOUSAND FEET SH ANN 0 N FIELD, Crockett County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES T Y PICA L SE C TI 0 N OF ROCKS PENETRATED Queen (one well) Feet --"Thvation of top of gas 725 Elevation of bottom of gas 705 Relief 20 Grayburg Highest proven elevation of oil 461 Lowest proven elevation "of oil 376 Proven relief of oil column 85 San Andres Highest proven elevation of oil 431 Lowest proven elevation of oil 261 Apparent relief 170 Water has been found below oil in San Andres rocks as high as 344 feet and at various elevations down to the lowest proven elevation of oil. There probably never was a definite oil-water contact throughout the field . WATER PRODUCTION Grayburg : No water has been produced. San Andres: A few of the wells produced some water on initial poten­tial test . These wells now produce a very large percentage of water . Other wells which were water-free at time of potential test now produce some water. However, some wells still produce no water . There is no definite relationship between water production and elevation. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUC T ION at end of year (b arrels) Year Flowing Pumping Yearly Cumulative GraybUTg 1940 0 7xx 7xx 1941 0 1,612 2,4xx 1942 0 1,108 3,5xx 1943 0 558 4,0xx 1944 0 7xx 4 ,8xx 1945 0 955 5,7xx 1946 0 I 1,104 6,8xx 1947 0 3 1,727 8,6xx 1948 0 3 1,988 I0,6xx 1949 0 3 I ,201 l l ,8xx 1950 0 3 I ,1 44 12,9xx 1951 0 3 994 !3,9xx 1952 0 3 1,001 !4,9xx 1953* 0 3 938 15,8xx San Andres 1943 0 223 223 1944 0 4 401 624 1945 4 4 600 1,224 1946 4 4 0 1,224 1947 0 29 213,327 214,551 1948 0 37 272 ,081 486 .632 1949 0 34 198 ,5 47 685,179 19 50 2 38 207 .980 893,159 19 51 0 41 202 ,451 1,095,610 1952 0 42 170,200 1.265 ,810 1953* 0 40 163 ,220 I .429 ,030 RESERVOIRS z w ~ 0 . ~ 2: Cf) ~ LITHOLOGY z z ~ UJ ~ ; w . ­ w er o Cf> Cf) C> U. D£PTH ELEVATION o ~j 1300 1176 l.~.-:-J·:~.".C.~~-. 1400 1076 1500 976 1600 876 1700 776 1800 676 1900 076 GRAYBURG "' "' "' ~ um ~Dolomite Polyhol i te • (~==~ Red ~Solt •hole • Oil productiont=-=JGreen 'hole *Gos production *1953 data added by amendment. GAS PRODUCTION: The only gas production has been incidental to oil production. The quantities produced have been minor and have been utilized in field operations. The one gas well (Queen) has been shut-in since the time of its completion because of lack of a market outlet. SIMPSON FIELD Crockett County. Texas D. E . DAUGHERTY, H . J. McCOOL and J. A. BODJO Geologists, Sinclair Oil and Gas Company, Midland, Texas May 7, 1954 LOCATION The Simpson field is in west central Crockett County about 26 miles west and slightly north of the town of Ozona, county seat, and is about 2 miles south of the Shannon field and 4 miles east of the Olson field . MAP Because of geographic and geologic relationships, Hoover field and Simps on field are shown on the same map ; pre­sented in the foregoing paper on the Hoover field. METHOD OF EXPLORATION LEADING TO DISCOVERY The discovery well was located on the basis of studies of surface and subsurface geological data. DISCOVERIES Seven Rivers: October 25, 1947; C. W. Brown /11-D A .C .Hoover. Pumped 77 barrels of oil in 24 hours . Grayburg and Field: September 30, 1930; Magnolia Petroleum Co. 112 A.C.Hoover. At time of completion, the well produced by swabbing at rate of 22 barrels of oil per day. It produced a total 110 barrels of oil in ten days . It stood idle during several years and was sold to J .N.Simpson on October 1, 1937. Simpson revived ·production and then sold to Pitzer & West who drilled deeper in 1938 from the former total depth of 2 ,056 feet to the new total depth of 2 ,064 feet. Production, after shot, was at rate of 51 barrels per day by pumping . The well then produced 695 barrels of oil. It was plugged and abandoned in May 1938 , after having inspired drilling operations in the vicinity which resulted eventually in establishing commercial production. ELE.VATION OF SURFACE At well locations: Highest, 2,521 feet; lowest , 2,346 feet. SURFACE FORMATIONS Undifferentiated formations of the Fredericksburg and Washita groups of the Comanche series. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is in the Wolfcamp series 710 feet below the base of the Dean formation. This penetration was in Magnolia Petroleum Co. /11 A.C .Hoover, a dry hole about one mile northwest of the field. The accompanying TYPICAL SEC­TION is based on the log of that dry hole . NATURE OF TRAPS Seven Rivers: Updip lensing of reservoir on a structural nose . Grayburg: Updip termination of reservoir due to lensing. PRODUCTIVE AREAS Acres Seven Rivers 100 Grayburg 600 Simpson field 700 THICKNESSES OF RESERVOm ROCKS Seven Rivers : Feet, avg. From top to bottom 29 Net productive 20 Grayburg : From top to bottom 98 Net productive 25 UTHOLOGY OF RESERVOm ROCKS Seven Rivers: Grayish-green, slightly glauconitic, very loosely cemented sandstone. Grayburg : Tan to brown, finely-granular to crystalline dolomite with interbedded gray -green, medium -grained sandstone . CONTINUITY OF RESERVOm ROCKS Seven Rivers and Grayburg: The stratigraphic equivalent of each of the two reservoir rocks is continuous throughout the area covered by the accompanying map. However, due to small local lenses and irregularity of porosity and per­meability, it appears doubtful that conditions are favorable for migration of fluids in either reservoir rock for any considerable distance beyond the local productive areas. ELEVATION AND REUEF OF PRODUCTIVE ZONES Seven Rivers Grayburg Elevation of top of oil, feet 957 438 Elevation of bottom of oil, feet 928 340 Relief 29 98 CHARACTER OF OIL Seven Rivers and Grayburg: Gravity, A.P .I. @ 60° F .: Range, 24°-33 °; average, 27 .7° WATER PRODUCTION Very little water has been produced from either of the two reservoirs. SIM PS 0 N FIELD, Crockett County, Texas z ~ '; LITHOLOGY 0: "' 0 \L Ofl"TH ELE V ATION 2412 23t2 "' =>"' 0 :< 2212 "'" " z c c >-"' "' ~ 0" ,.. 2112 ·.:·:.·... .. . 1112 1712 t512 z c a: "' "'.. 1112 1012 ." EXPLANATION TYPICAL SECTION OF ~ 0 • f:HYJSandolano ~Dolomite § Sholo ~L;m.,tono e Oil product ion z 0 >­ ~ er: 0 u. z "' \U => 0 C> a: ~ >­ c a: C> "'.. => ~ c 0 c => C> "' "'a: 0 z Cl z c "' 0 a: c z 0 ~ "' " ~ (/) ~ (/) z c .. 0: " "' ~ a: \U (/) ~ 0 a: (,!) "' "'0: 0 :< "' '.:: :< ;< LITHOLOGY ~ DEPTH ELEVATION 0 17!50 1800 2100 2300 2 4 00 2600 2800 3200 3 300 3400 3500 3600 3700 3100 3150 ROCKS PENETRATED Total field WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Pumping Yearly Cumulative 1930­1938 l ,935 1939 1,000 2 .9 35 1940 0 0 2 .9 3'5 1941 1,793 4,728 1942 938 5 .666 1943 252 5 .918 1944 0 0 5 .918 1945 0 0 5 .9 18 1946 0 0 5,9 18 1947 3 3 .185 9 ,103 1948 5 9 ,723 18 ,826 1949 8 14,381 33 ,207 1950 5 10,722 43 .929 195 1 8 8,180 52,109 1952 7 7 ,920 60 ,029 1953 II 6 ,278 66 ,307 ""' "' "' >­ "' 0: ~ ~ z 0 c a: c "' z ~ .. ~ ~ z 0 >­ LITHOLOGY c "' a: ~ >­ a: a: .,"' c ~ "' z 0 z c 0 "' LITHOLOG Y E l [VAT IO ~ ·····,,., ====~ 5 100 0200 -=~­ -=-~ _-2688 -2788 -2888 5500 5600 5700 5800 -3088 -3388 6100 -3748. PRODUCTION HISTORY SMITH-SPRABERRY FIELD Dawson County. Texas W. D. GALLOWAY Geologist, Standard Oil Co. of Texas, Midland, Texas June 30, 1955 LOCATION The Smith-Spraberry field is in north central Dawson County about 13 miles northwest of Lamesa and 4 miles southwest of o·Donnell. METHODS OF EXPLORATION LEADING TO DISCOVERY Favorable structural conditions were first indi­cated by seismic exploration for the Standard Oil Company of Texas in 1950. The discovery well was drilled in late 1950 to test the Pennsylvanian. No oil was found in the Pennsylvanian and the well was plugged back and completed in the lower Spraberry. DISCOVERY Lower Spraberry: December l, 1950; Standard Oil Co. of Texas #1 M. V.A.Smith. ELEVATION OF SURFACE At well locations: Highest, 3, 085 ft. ; lowest, 3, 062 ft. SURFACE FORMATION Undifferentiated Tertiary. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest stratigraphic horizon penetrated with­in the vicinity of the field is 146 feet below the top of the Ellenburger dolomite. This penetration was at the total depth of 11, 376 feet in Standard Oil Co. of Texas #4 M. V. A. Smith #1. NATURE OF TRAP Lower Spraberry: Variation in degree of perme­ability appears to be the primary trap-forming factor. The convex form of the top of the reservoir rock• probably contributes locally to forming the trap. PRODUCTIVE AREA Lower Spraberry and Field: Irregularity of po­rosity and permeability precludes a close estimate of the productive area. In the writer's opinion, development to date indicates that the productive area is at least 400 acres in extent. WATER PRODUCTION Lower Spraberry: Production of water has been nearly negligible. THICKNESSES OF RESERVOm ROCK Lower Spraberry: Feet Min. Max. Avg. From top to bottom 22 36 30 Net productive 0 17 11 LITHOLOGY OF RESERVOm ROCK Lower Spraberry: Sandstone; gray to brown, uniformly very fine-grained, shaly and calcareous and with partings of various thicknesses of silt, shale and calcareous material. CONTINUITY OF RESERVOm ROCK Lower Spraberry: The reservoir is due to a local condition in the lower Spraberry member, which member is continuous throughout a large part of the Midland basin. The degree of porosity and permeability adequate for commercial production is a very local condition in the particular sandstone which is productive in this field. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Lower Spraberry: Feet Elevation of top of productive zone -4, 840 Elevation of bottom of productive zone -4,891 Relief of productive zone 51 Oil occupies interstitial space in the Lower Spraberry member both upward and downward from the elevations above stated, but the degree ofperme­ability is too low for commercial production beyond the above indicated elevations. The elevation of the oil-water contact has not been determined, but it is known to be above -4,895 feet. CHARACTER OF GAS Lower Spraberry: No analysis is available. The only gas production is incidental to oil production and the quantity of gas is very small. COMPLETION TREATMENT Lower Spraberry: In one well, the reservoir rock was hydraulically fractured by injection of 3,000 gallons of fluid and 1,5.00 pounds of sand with a maximum treating pressure of 2,650 psi. The other wells were shot with 110 to 170 quarts of nitroglycerin. PE RM IAN SYSTEM GUADAL UPE OC HOA !SERIES WHITE HORSE GROUP 0 ~ ~ ~ x "' ',.., (') "' -< > J> "" ~ ~ 0 "'J> IJ> ~:ti r­:u . :t> -l> -< -< 0 r­oO r-I> ,, 0 (') ~ ~~ "' -:::! -< < -< =< ~ ..c (') c: ""<~ ~ "' (J) I SYSTEM SERIES GROUP FO RMATION 0 ~ ~ ~ I> x "' "" J> 0 ;:: ;:: 0 : !: ~ ~ ..... ~ r< 0­ r--< 0 -< en " -< (') c: ~ >-I ...... < "" o< ..., ,.., "ti ::r: - 0 I en > "'d I:"" :::0 CJl :x:-. tr:I Oj 0 t'1 >-I :::0 - 0 :::0 z --< "Tj 0 ...... "'1 t'1 :JI t­0 tJ 0 !:Ill tJ CJl 0 ~ "ti g tr:I c.n SMITH-SPRABERRY FIELD, Dawson County, Texas TYPICAL SECTION OF ROCKS PENETRATED ELECTRIC a RADIOACTIVITY CURVES ,. en LITHOLOGY w .... '!! GAMMA RAY RESISTIVITY en a: AND S. P. ,.. w en z ...J ,.. -flfl20 c;­ en '-, ' z z / w '\Q_ ( -6720 <.. z 3 ' -&no n Base: M ixed paraffin a nd asphal t Viscosit y , S. U. : @ 130° F .. 36.8 sec.; @ 100° F., 40.6 sec .; @60°F. , 5 1.4 sec . PRODUCTION HISTORY WEL LS PRODUCING, OIL PRODUC TION at end of year (barre~l ) F lowi ng P um ping ~r Cum u la ti ve 1950 2 ,00 1 2 ,001 195 1 2 35 .297 37 ,298 19 52 . .0 ...5 ............ . . 7 3 ,900 .......I I 1,1 98 1953 60 ,802 I 7 2 ,000 1954 48 ,597 SOUTH BROWNFIELD FIELD Terry County, Texas MARSHALL L . MASON, JR . Geologist, Union Oil Company of California, Midland, Texas January 1, 1953 LOCATION The South Brownfield field is in southeast central Terry County, about 4i miles southeast of Brownfield,county seat. It is in Secs . 72 and 91, Block T, Dallas & Wichita Railroad Co . survey. It is the most northern of three fields in southern Terry County that produce from reefs of late Penn­sylvanian or early Permian age; the others are Wellman and Adair. METHOD OF EXPLORATION LEADING TO DISCOVERY This field was discovered as a result of a reflection seismograph survey conducted in the latter part of 1949 and ear1 y 19 5 0 for the Union Oil Company of California. On the basis of this survey, leases were acquired and the discovery well was commenced May 28, 1950, and drilled to a depth of 10,182 feet, where it was completed on August 14, 1950. DISCOVERY Pennsylvanian reef: August 14, 1950; Union Oil Company #1 Laura Cotton. Flowing potential, 1,812 barrels of oil per day. ELEVATION OF SURFACE At well locations : Highest, 3,271 ft.; lowest, 3,252 ft. SURF ACE FORMATION Tertiary sand OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is 440 feet below the top of the Strawn series. This penetration was in Union Oil Co. #3 Cristova Stitt, the most western well in the field, where total depth of 11,000 feet is indicated on the accompanying map. The oldest horizon penetrated in the vicinity of the field is 188 feet below the top of the Ellenburger group. This penetration was in Union Oil Co. #2 Laura Cotton, the dry hole offset north of the discovery well. NATURE OF TRAP Pennsylvanian reef: The accumulation of oil and gas is due to a simple convex trap resulting from Pennsylvanian reef topography. The reef is approximately one mile long and one-half mile wide, with steep slopes on the north and south flanks. Overlying and surrounding shales confine the oil to the crest of the reef. Drilling to date has not indi­cated that the trap is influenced by any structural factors. PRODUCTIVE AREA Pennsylvanian reef: 320 acres. There is a possibility that additional drilling might prove that a greater area is productive. How­ever, it now appears that additional drilling is not warranted. THICKNESSES OF RESERVOIR ROCK Pennsylvanian reef: Min. Max. Avg. Net productive, feet 40 170 90 LITHOLOGY OF RESERVOIR ROCK Pennsylvanian reef: White to light gray, fine to medium crystalline, highly fossiliferous, porous limestone containing secondary dolomite rhombs, calcite crystals and stylolites. The porosity is vuggy, cavernous and highly irregular. The degree of permeability is generally very high. The irreg­ularity of porosity causes great variation in the productivity of the reservoir . CONTINUITY OF RESERVOIR ROCK Pennsylvanian reef: The reservoir rock is a local reef of Cisco and Canyon age. Beyond the extent of the field but within the immediate region, generally there are no Pennsylvanian limestones above the Strawn series . Vertical and lateral gra­dation of limestone to shale restricts the reservoir to the reef mass. There are other isolated reser­voirs of this type and age in the northern Midland basin and on the Eastern platform. SOUTH BROWNFIELD FIELD, Terry County, Texas TYPICAL SECTION OF ROCKS PENETRATED ..J Q NOTE : This ELECTRIC CURV ES AND LITHOLOGY ELEVATIONDEPTH -7488 -7538 -7638 -7738 -7838 -7938 -8038 -8138 -8238 -8338 -8438 -8538 -8638 -8738 -8838 -8938 -9038 -9238 -9336 TYPICAL SECTION is based on a combination of the log of the discovery well and the log of the deepest test in the vicinity, the offset dry hole. • EXPLANATION ~Limestone fo~~~~WMJ Sonds1ooe F====~==3 Shole ~Calcareous • Cherfy dolomite ~shole Oil production ft~~ Sandy shale SOUTH BROWNFIELD FIELD, Terry County, Texas 98 91 72 / I I I ~A • -6841 TO t0,188 -68 90 TO I0,588 97 92 71 EXPLANATION ---7 000-Contour on top of reef limstone SCALE • Elevation of top of reef limstone -66•5 • Oil we lt THOUSAND FEET Ory hol e SOUTH NORTH CROSS SECTION A-A' Ehvotion Ftt l A ti Ettvotion 2 ­ -4500 -6750 -6750 ? -~-----­ -- T0 . 10,100 T. 0. 10,11 5 ~----· -----Oil-water contact -6875 ---------------~ T O. l0,309 -1000 -z -1000 z l .O.I0,588 w 0. HORIZONTAL SCALE ' VERTICAL SCALE SOUTH BROWNFIELD FIELD, Terry County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONE Pennsylvanian reef: F eet No free gas cap to date Elevation of top of oil -6,639 Elevation of bottom of oil -6,875 Maximum gross oil column 236 The above i:eported gross oil column should not be considered as actual oil column. The actual oil column varies from 40 feet to 170 feet due to the extremely variable porosity. RESERVOIR and OIL SAMPLE DATA Original reservoir pressure 4,285 psi Original reservoir temperature 154° F . Gravity of oil, A .P.I.@ 60° F. 41.2° Bubble point 1,675 psi Solution gas-oil ratio 725 cf/bbl Original volume factor, surface:reservoir 1.41 CHARACTER OF GAS Component Mol . 3 Nitrogen 9 .37 Oxygen 0 .94 Methane 49.61 Ethane 12 .50 Propane 18 .30 !so-butane 1.81 N-butane 5.00 Iso-pentane 1.11 N-pentane 0.45 Hexane 0 .91 Heptanes plus 0.0 WATER PRODUCTION NUMBER OF WELLS WATER PRODUCTION PRODUCING WATER (barrels) Year at end of year Yearly Cumulative 1950 None None None 1951 7 l ,985 1 .985 1952 7 l ,369 3 ,354 Since records for one well are not available, the above quantities were estimated on the basis of accurate records for six of the seven wells which produced water. One well in the eastern part of the field has produced no water to date . ACID TREATMENT Four of the eight wells in the field were com­pleted without acidization. Quantities used in the other wells ranged from 500 gallons to 12 ,000 gal­lons . Decision as to treatment of each well was based on nature of porosity of the reservoir rock at the particular location. RESERVOIR ENERGY Originally, the energizing force of the reservoir was water drive and oil expansion, but in the future it is expected that gas expansion plus water drive will be motivating a gents. There was no original gas cap , but reservoir studies indicate that declining pressures will eventually cause the gas to come out of solution and form a gas cap in the crest of the reef. PRODUCTION HISTORY WELLS PRODUCING at end of year Year Flowing Pumping OIL PRODUCTION (barrels) Yearly Cumulative GAS PRODUCTION (Mcf)* Yearly Cumulative 1950 3 0 51 .988 51 .988 33,532 33 ,532 1951 8 0 449 ,257 501,245 289,771 323 ,303 1952 0 8 310 ,878 812,123 200,516 523,819 *Gas production was estimated by taking the average gas-oil ratio and multiplying by the number of barrels of oil produced. SOUTH KEYSTONE FIELD Winkler County, Texas W. C. OSBORNE District Geologist, Union Oil & Gas Corp. of Louisiana, Midland, Texas December 19, 1956 LOCATION The South Keystone field is in east central Winkler County about 8 miles east of Kermit, county seat. It is about 3t miles southeast of the Keystone field and is on the same structural trend. The accompanying map overlaps slightly with the maps in the paper on the Keystone field presented earlier in this volume. METHOD OF EXPLORATION LEADING TO DISCOVERY As a result of reflection seismograph exploration, Gulf Oil Corporation discovered the anticlinal fold which later became productive. Gulf commenced the drilling of the dis­covery well on November 19, 1947. DISCOVERY "Tubb Zone": July 31, 1948; Gulf Oil Corp. #125-E (later, #125-T) Keystone Cattle Co. Completed in "Tubb Zone" from 6,400 feet to 6,600 feet with initial flowing potential of 162 barrels of oil per day through t-inch choke. The well was commenced as an Ellenburger test and was drilled 147 feetintoEllenburger atitstotal depth of 11,502 feet. Sulphur water was the only fluid found in Ellenburger. The well was plugged back to 6, 600 feet for production from "Tubb Zone" and its designation was changed from #125-E to #125-T. ELEVATION OF SURF ACE The elevation of the surface ranges from 2, 946 feet to 2,977 feet above sea level. TYPICAL SECTION OF ROCKS PENETRATED The TYPICAL SECTION in the accompanying paper on the Keystone field serves to report the character of rocks penetrated in the South Keystone field. Although the rocks here are of essentially the same character as those in the Keystone field, where nine stratigraphic units are productive, only the reservoir designated as "Tubb Zone" is productive here; that zone is not productive in the Keystone field. The reservoir which is productive in the South Keystone field is generally called "Tubb Zone" although it is now known to be stratigraphically lower than the widely recognized unit properly designated by the same name. The top of the res­ervoir rock in this field is about 250 feet below the base of the widely recognized Tubb zone. SURFACE FORMATION Quaternary sand, with only a sparse growth of mesquite and grasses, covers the surface. The sand is so loose that travel off of roads is extremely difficult. NATURE OF TRAP "Tubb Zone ": Anticlinal folding and variation in porosity and permeability. OLDEST STRATIGRAPIUC HORIZON PENETRATED The oldest horizon penetrated is in the Ellenburger group 147 feet below its top. This penetration was in the discovery well at its total depth of 11,502 feet. PRODUCTIVE AREA "Tubb Zone" and Field: 560 acres. THICKNESS OF RESERVOm ROCK "Tubb Zone": Min. Max. Avg. From top to bottom, feet 287 430 363 Available data do not afford an adequate basis for estimating net productive thickness. LITHOLOGY OF RESERVOm ROCK "Tubb Zone": The reservoir rock is comprisedof lime­stone and dolomite and a minor amount of silty sand. The ratio of limestone and dolomite to silty sand varies from well to well. Generally, limestone and dolomite constitute about 95% of the reservoir rock; everywhere, the amount of limestone and dolomite greatly exceeds the amount of silty sand. The limestone is tannish-brown, finely crystal­line. The dolomite is also tannish-brown and finely crystalline; slightly harder than the limestone. The silty sand is gray. The dolomite members are more porous than the limestone members and yield most of the oil production. The silty sand does not contribute materially to the produc­tive capacity. The better wells are those where the amount of dolomite exceeds the amount of limestone. CONTINUITY OF RESERVOIR ROCK "Tubb Zone": The reservoir rockis continuous through­out the area of the field, Its lithologic characteristics are so nearly the same as those of near-by rocks both higher and lower in the stratigraphic section that presently avail­able data do not afford a basis for correlation beyond the immediate vicinity of the productive wells. ELEVATION AND RELIEF OF PRODUCTIVE ZONE "Tubb Zone": Feet Elevation of top of gas -3,155 Elevation of bottom of gas -3,495 Relief 340 Elevation of top of oil -3,495 Elevation of bottom of oil -3,585 Relief 90 The above data represent conditions at time of dis­covery of the field. CHARACTER OF RESERVOm WATER "Tubb Zone": Average chloride content, 76, 300 parts per million. RESERVOffi TEMPERATURE and PRESSURE and OIL SAMPLE DATA "Tubb Zone ": Original reservoir pressure. psi. Original res ervoir temperature, °F. Gravity of oil, A. P. I. @ 60 • F. Sulphur in oil, % Bubble point, psi. Solution gas -oil ratio, cf/bbl. Volume factor, surface:reservoir CHARACTER OF GAS 2,863 102 38.5 0.48 2,844 1,050 I.525 "Tubb Zone " : No analysis of the gas is available. The sulphur content is probably so high that the gas is not suit­able for domestic utilization. Gas is produced only incidental to the production of oil and is flared. WATER PRODUCTION " Tubb Zone": Each well produces some water; no record is k ept of the quantities . Data are not available for making even approximate estimates of the amounts of water \.vhich have been produced. ACID TREATMENT " Tubb Zone": All wells hav e been treated wi th acid. The quantity of acid has ranged from 500gallons to 20,500 gallons. The normal treatment is with 2, 500 to 5, 500 gallons of acid. RESERVOm ENERGY "Tubb Zone": The energy which expels the oil from the reservoir rock is due to gas expansion as pressure declines. Most of the currently effective energy is due to gas coming out of solution in the oil. There is an ineffectual gas cap whose pressure is too low to contribute materially to pro­duction of oil, pa rticularly in view of the low permeability of the upper portion of the reservoir rock. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION a t end of year (barrels) Flowing Pumping Yearly Cumulative 1948 2 0 12, 865 12,865 1949 5 3 124, 879 1 37,744 1950 9 5 171, 339 309,083 1951 9 5 154,969 464, 052 1952 5 9 11 3, 761 577,813 1953 5 9 104, 900 682, 713 1954 5 9 95, 138 777,851 1955 5 9 84,930 862, 78 1 w w t--) U) 0 ~ >-j ::r: ~ M >-<:: U) >-j 0 z M '"Tj ........ M L' t1 ~ ff ?';"' -CD ""! 0 0 c ::s ...... "< >-j CD ~ rn SUSAN PEAK FIELD Tom Green County, Texas D.W . GRAHAM District Geologist, Plymouth Oil Company, Midland, Texas June 15, 1953 LOCATION and FIELD NAMES The Susan Peak field is in southeastern Torn Green County about ZO miles southeast of San Angelo. It derives its name from the topographic feature known as Susan Peak, which is a low, rounded Cretaceous limestone peak located near the geographic center of the field. The area which produces from the upper Strawn reservoir in the south half of sections 19 and ZO in the extreme south end of the field is treated as a separate field by the Railroad Commission of Texas and is designated as the South Susan Peak field. During a few months early in the development of the area along Lipan Creek in the northeast part of the field, that area was treated as a separate field and was known as the Lipan field. The separation was soon abandoned and the Lipan area has ever since been treated as constituting a part of the Susan Peak field . As development has progressed, it has become doubtful that the productive area of any one of the three reservoirs in the Lipan area overlaps the productive area of any one of the three reservoirs in the Susan Peak area. It is now recog­nized that there are two distinct productive areas constituting the Susan Peak field: namely, the Susan Peak area and the Lipan area. METHODS OF EXPLORATION LEADING TO DISCOVERY The lease block on which this field has been developed was originally taken on the basis of surface geological work, which showed a small northeast-southwest trending anticline centering near Susan Peak. Later, a reflection seismograph survey indicated an extension of this anticline northward beyond where surface exposures had provided data for mapping. The location for the discovery well was based largely on the results of the reflection seismograph survey. DISCOVERIES Susan Peak area: Canyon : May 31, 1949; Plymouth Oil Co. #3-A J. D. Robertson Upper Strawn: September 3, 1949; Plymouth Oil Co. #5-B J. W. Green Lower Strawn and Field: December 16, 1948; Plymouth Oil Co. Ill-A J. W. Green Lipan area: Canyon: No commercial production Upper Strawn: May 1. 1949; Wadley, Adams & Burns # l J. W. Green Lower Strawn: September 18, 1949; Wadley, Burns & Shanahan #3 J. W.Green (Later, Mystic Oil Co. #3 J. W. Green) ELEVATION OF SURFACE Surface elevations within the area of the field range from Z,053 feet to Z,359 feet above sea level. SURFACE FORMATION Undifferentiated Cretaceous limestone OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in pre-Cambrian igneous complex 340 feet below where igneous material was first encountered, and 10 feet below the top of solid, un­weathered, igneous rock. This penetration was in Plymouth Oil Co. #1-B J. W.Green, located in Sec. 193 and identified on an accompanying map by the label "OLDEST HORIZON". The accompanying TYPICAL SECTION is based on the log of this well. NATURE OF TRAPS Susan Peak area: The trap in each of the three reservoir rocks is due to convex folding along the apex of an anticline. Lipan area: The trap in each of the three reservoir rocks is due primarily to updip decrease of porosity and per­meability. There appear to be minor traps in small convex folds, but such traps constitute minor details within the major traps. PRODUCTIVE AREAS Acres Susan Peak Lipan Total Canyon no None no Upper Strawn zoo 80 Z80 Lower Strawn 1,880 160 Z,040 Susan Peak field Z,700 zoo Z,900 The productive areas of the Canyon and Upper Strawn reservoirs have not been fully defined in the Susan Peak area. The above figures represent best guesses on the basis of information now avail­able; they may be as much as 10% more or as much as 30% less than the actual productive areas. RESERVOIR TEMPERATURE AND PRESSURE At time of discovery, the temperature in the lower Strawn reservoir in the Susan Peak area was 139 • F . and the reservoir pr essure was l ,9Z 1 psi. Corresponding data for other reservoirs are not available. w w *"" en c:: en >o z ""d tT:I >­ (";; "Tj ...... tT:I L' t1 03 3 ~ ~ ~ a ~ ~ ~ 0 SCALE ~ Completed Oil -welt in Lower Strawn Abandoned oil wel I "' Gos well • \:]Discovery D Dry hole H SUSAN PEAK FIELD, Tom Green County, Texas TYPICAL ELECTRIC CURVES AND "' "' " >­ LITHOLOGY "' a: "'>­ "' OEPTH ELEVATION "' "' "' 20 100 ::> "' 0 "' " 19' 200 "' ~ a: " 300 "' 16• •OO 00 "' 700 1453 13' 800 900 12' 1000 Lt53 1100 10• 1200 a: " '" :> z 1300 a: 0 '" 140 0 7' 3 .,, 1500 1600 "3 1700 "3 1800 3'3 19 00 2'3 a_ :> 2000 1'3 " ~ -' 0 2100 ;t " SECTION OF ROCKS PENETRATED post-Ellenburger detrilol EXPLANATION Limeslone Shale 8 •D- ~Dolomite L19n1te E WeatheredSandstone igneous rock . Oil production Igneous rock 0 Gos producl1on CROSS SECT ION A-A' A' 8 ELEVATION -2100 -2200 -2400 -2500 -2600 -2100 Woler of low poros11y SUSAN PEAK FIELD, Tom Green County, Texas THICKNESSES OF RESERVOIR ROCKS Susan Peak area Lipan area From top to bottom: Feet Feet Gross: Min . Max. Min. Max. Canyon 20 73 60 ~ Upper Strawn 57 80 45 73 Lower Strawn 300 350 * * Exclusive of major shale partings: Canyon 20 56 52 76 Upper Strawn 30 70 26 55 Lower Strawn 300 350 * * *Complete thickness has not been penetrated. UTHOLOGY OF RESERVOIR ROCKS Canyon: The reservoir rock varies from a fairly clean white sand with only a little calcareous cement to a highly calcareous sandstone which might just as properly be classified as an arena­ceous limestone. Upper Strawn: The reservoir rock consists of two beds of limestone and an intervening bed of shale. The productive portion consists of the two beds of limestone, each of which is about 20 to 30 feet thick and is composed of dense, dark brown, calcareous, highly fractured limestone. Between the two beds of productive limestone is a bed of gray and green shale generally about 10 feet thick. The behavior of reservoir fluids proves that the two beds of lime­stone are parts of the same reservoir rock. The shale bed is probably not continuous throughout the area of the field; furthermore, it appears likely that the intercommunication is largely through frac­tures which extend across the intervening shale. Lower Strawn: In the extreme northern and southern ends of the field, the Lower Strawn reser­voir rock is a fairly uniform, massive, oolitic, coarsely granular, light brown to tan limestone. Throughout all the central portion of the field, the pay section in the Lower Strawn is divided into three distinct lithologic units. The upper unit is a relatively dense, highly fractured, dark brown, car­bonaceous limestone, varying in thickness from practically zero to 45 feet. The middle unit is a highly fractured black shale bed about 6 feet thick . The lower unit is a massive, coarsely granular, highly porous, light tan limestone of the same gen­eral character as is exhibited by the entire section in the northern and southern ends of the field. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Upper Strawn Susan Peak Lipan -2 ,509 No -2 ,650 free 141 gas -2 ,650 -2 ,540 -2 ,685+ -2 ,595 + 35+ 55+ ? ? Elevation of top of gas, feet Elevation of bottom of gas, fe et Relief, feet Elevation of top of oil, feet Elevation of bottom of oil, feet Relief. feet Elevation of top of water , feet Canyon Susan Peak Lipan -2 .182 -2,230 -2 ,244 -2 ,244 62 14 -2 ,244 No -2 ,320 oil 76 column -2 ,320 -2 ,244 CONTINUITY OF RESERVOIR ROCKS Each of the reservoir rocks in the Susan Peak area undoubtedly correlates with the reservoir rock in the corresponding stratigraphic unit in the Lipan area. Each appears to be continuous from one area to the other. However, between the two areas there is a narrow strip where porosity and permeability in each of the reservoir rocks are too low for free migration of reservoir fluids. The exact location of this belt of low porosity and permeability is not known for any one of the reservoir rocks. However, in each reservoir rock, it is evidently near the location of the boundary between the Susan Peak area and the Lipan area as that boundary is indi­cated on the accompanying maps. Canyon: The sandstone bed which is productive is not known to extend beyond the immediate vicinity of the field. Upper Strawn: The two limestone beds which are productive cannot be traced more than a few miles away from the Susan Peak field in any direction. Lower Strawn: This limestone, with greatly varying thicknesses, is widely distributed across the Eastern shelf of the Midland basin. Westward toward the Midland basin, this limestone inter­fingers with, and finally is completely replaced by a basin type shale and silty sandstone fades. CHARACTER OF GAS Following is an analysis of separator gas from the Lower Strawn reservoir in the Susan Peak area. No other analysis of gas is available. Component Mol. % G/ Mcf Methane 58.61 Ethane 15 .08 Propane 16 .05 !so-butane 1.90 N-butane 5 .11 Iso-pentane 0.68 N-pentane 0.80 Hexane 0 .30 Heptane plus 0 .17 Carbon dioxide 1.30 Specific gravity at 60 ° F. Heating value, B .t.u./cf Gasoline content, G/ Mcf 4.403 0 .620 0 .289 0 .123 1.607 0.248 0.082 .938 1,577 1.142 Lower Strawn Susan Peak Lipan No -2 ,603 fr ee -2 ,660 gas 57 -2 ,556 -2 ,660 -2 ,669 -2 ,669 113 9 -2 ,669 -2 .669 SUSAN PEAK FIELD, Tom Green County, Texas CHARACTER OF OIL Canyon Upper Strawn Lower Strawn Gravity, A.P.I.@ 60° F . 37.4°-39 .6° 32° -35° 39 ° Sulphur 0.15 ? 0 .35 An analysis of a sample from one of the Lower Strawn reservoirs indicated the bubble point was at 1 ,667 psi; solution gas-oil ratio, 620 cubic feet per barrel; volume factor, surface: reservoir, 1.4116. Corresponding data relative to oil in the other reservoirs are not available. For analyses see: U.S. Bureau of Mines Laboratory reference No. 51080 51081 51082 Analyses of Crude Oils from Some West Texas Fields . R.I. 4959 (1953) Item 81 80 79 PRODUCTION HISTORY Susan Peak area Lipan area WELLS PRODUCING OIL PRODUCTION WELLS PRODUCING OIL PRODUCTION at end of year (barrels) at end of year {barrels) Year Flowing Pumping Yearly Cumulative Flowing Pumping Yearly Cumulative Area totals 1948 l 0 1,206 1,206 0 0 0 0 1949 31 3 269 ,834 271,040 2 2 21,255 2 l ,255 1950, 50 7 l ,07 1,222 1,342,262 4 3 36,313 57 ,568 1951 55 10 1,634,724 2 ,976,986 3 40 ,058 97 ,626 1952 59* 10 1,354,399 4 ,331,385 3 35 ,049 132 ,675 Canyon 1949 0 6,398 6,398 0 0 0 0 1950 7 3 121,633 128,031 0 0 0 0 1951 7 6 141,960 269 ,991 0 0 0 0 1952 7 6 90,600 360 ,591 0 0 0 0 Upper Strawn 1949 0 2 ,412 2,412 l 2 3,140 3 ,140 1950 0 23,712 26,124 0 3 10 ,305 13 ,445 1951 2 41,145 67 ,269 0 11,380 24,825 1952 2 29 ,605 96,874 0 11,183 36 ,008 Lower Strawn 1948 0 1,206 1,206 0 0 0 0 1949 31 1 261 ,024 262,230 1 0 18,115 18,115 1950 43 3 925 ,877 1,188,107 4 0 26 ,008 44,123 1951 46 3 1,451,619 2,639,726 3 0 28 ,678 72,801 1952 50* 3 l,234,194 3,873,920 3 0 23 ,866 96 ,667 *Seven flowing wells were completed in Lower Strawn in 1952; 3 wells which had been producing from Lower Strawn were converted to ga !l injection wells . GAS PRODUCTION: No gas has ever b.een sold from this field . The wells completed in the Canyon and Upper Strawn reservoirs as gas wells are shut in for lack of a suitable market. All separator gas from the oil wells operated by Plymouth Oil Company is being injected into the Lower Strawn reservoir in the Susan Peak area by a cycling plant built by Plymouth Oil Company and placed in operation in April, 1952 . This plant has capacity to compress and inject 3 ,000 ,000 cubic feet of gas per day. SWEETIE PECK-WARSAN FIELD Midland and Upton Counties, Texas ROBERT R. HARBISON Geologist, Stanolind Oil & Gas Co., Midland, Texas January 1, 1955 LOCATION and FIELD NAMES The Sweetie Peck -Warsan field is mainly in southwest Midland County, with only the three southernmost wells in Upton County. It is about 20 miles southwest of the town of Midland, county seat of Midland County, anci about 15 miles southeast of the town of Odessa, county seat of Ector County. It is in the southwestern part of the Midland basin. The hyphenated name of the field results from the history of its development. Early wells were all in the south part of the field, and that area was designated as the Sweetie Peck field. In 1953, production in a Pennsylvanian reservoir was dis­covered in a well in the southwest corner of Sec. 38, Bl. 41, T. 3 S. The area including that well, and now including 7 wells in sections 38, 39, 46 and 47, became known first as the Warren Pennsylvanian field and then later as the War-San field. The 7 wells are now treated by the Railroad Commission as, 4 in the War-San Pennsylvanian field and 3 in the War-San Ellenburger field. In this paper, the area containing these 7 wells is combined with the area of the Sweetie Peck field and the combined area is treated as one field. METHODS OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph surveying and core dril­ling led to the discovery of the field. DISCOVERIES Wolfcamp: June 10, 1950; Norwood Drilling Co . #1-PW Josie Faye Peck. Bend: June 10, 1950; Norwood Drilling Co. #1-PW Josie Faye Peck. Devonian: June 22, 1950; General American Oil Co. #1-D Josie F. Peck. Fusselman: November 22, 1950; Benson & Montin, Inc. #1-E Josie Faye Peck. Ellenburger and Field: March 4, 1950; General American Oil Co. #1-E Josie F. Peck. ELEVATION OF SURFACE At well locations: Highest, 2,907 ft.; lowest, 2,888 ft. SURF ACE FORMATIONS Fredericksburg lime stone and overlying uncon­solidated Quaternary deposits constitute the surface rocks within the ar ea of the field. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 939 feet below the top of the Ellenburger group. This penetration was in Gulf Oil Corp. # 1 Josie Faye Peck at its total depth of 14,219 feet. This well is on the east limb of the anticlinal fold and is about a mile from the south end of the field, as indicated on accompanying maps. NATURE OF TRAPS Wolfcamp: The trap appears to be due primarily to convex folding and secondarily to variation in degree of porosity. Bend: Convex folding. ~ian: Convex folding and variation in degree of porosity. Fusselman: Convex folding and variation in degree of porosity. Ellenburger : Convex folding. PRODUCTIVE AREAS Acres Wolfcamp ---so Bend 7 ,580 Devonian 120 Fusselman 120 Ellenburger 5 ,000 Sweetie Peck -Warsan field 7 ,580 THICKNESSES OF RESERVOm ROCKS Feet, average Top to Net bottom productive Wolfcamp 30 ? Bend 70 ? Devonian 70 40 Fusselman ? 30 Ellenburger 282 ? LITHOLOGY OF RESERVOm ROCKS Wolfcamp: Limestone; tan to brown, fine-grained crystalline. Bend: Limestone; tan to light brown, chalky, fine-grained crystalline. Devonian: Limestone; brown, fine -grained crystalline; contains blue-gray chert. Fusselman: Limestone; white, fine-to medium­grained crystalline. Ellenburger : Dolomite; light brown, fine-to medium-grained crystalline. (/) ~ t'Tj t'Tj >-3 ,__. t'Tj '1J t'Tj 0 ~ I ~ ;:x:... ::0 (/) ;:x:... z 1-rj ........ t'Tj L' t::1 ~ 0.: § Q.. Q :::l Q.. c::: 'g_ 0 :::l g s:: :::l ....... (i)' _rll >-3 ~ Ul w w {() 340 SWEETIE PECK-W AHSAN FIELD, Midland and Upton Counties, Texas TYPICAL SECTION OF ROCKS PENETRATED EXPLANATION mAnhy dr ol t~Lom o.oooo t=======j Shole tnNI,.,,...,. ~'"'°''°"' ~."'" shole + + + ~Dolomite • Oil oroduc tion t-+ .,.+ So ll ++ t SWEETIE PECK-WARSAN FIELD, Midland and Upton Counties, Texas 341 TYPICAL SECTION OF ROCKS PENETRATED 342 SWEETIE PECK-W ARSAN FIELD, Midland and Upton Counties, Texas CONTINUITY OF RESERVOffi ROCKS Wolfcamp: The bed of limestone which is locally productive is c-ontinuous throughout the area of the field; however , the area where the degree of porosity is favorable for commercial production appears to be limited to the immediate vicinity of the two productive wells. Bend: This reservoir rock is continuous through­ out the area of the field. Devonian : The bed of limestone which is pro­ductive at the locations of two wells is continuous throughout the area of the field; however, the area where the degree of porosity is favorable for com­mer'cial production appears to be limited to the immediate vicinity of the two wells. Fusselman: The productive bed of limestone is continuous throughout the area of the field; however , its porosity is extremely irregular. Ellenburger : This reservoir rock is continuous throughout the area of the field . ELEVATION AND RELIEF OF PRODUCTIVE ZONES Known elevations of oil, feet Known relief, Highest Lowest _f_e_e_t__ Wolfcamp -6 ,938 -6 ,990 52 Be nd -7,378 -7,650 272 Devonian -9 ,382 -9 ,497 115 Fusselman -9 ,582 -9 ,682 l 00 Ellenburger -10,160 -10,442 282 The el evation of the oil-water contact is kn own in only the Ellenbu rger reservoir. It i s n ot known how far the oil extends downwar d beyond the above r e ported elevations. CHARACTER OF OIL Gravity, Sulphur, A.P.I.@ 60° F. '1o Wolfcamp 59 0.02 Bend 45 0.06 Devonian 48 0.05 Fusselman 51 0.04 Ellenburger 53 0.45 ACID TREATMENT Wolfcamp: One well was treated with 500 gallons and the other with 10,000 gallons of acid. Bend: Most of the Bend wells have been treated with acid; the quantities of acid have ranged from none to 4,000 gallons. Devonian: The first Devonian well was washed with 500 gallons of acid and the second was treated with 2,000 gallons of acid . Fusselman: Each of two of the three Fusselman wells was treated with 8 ,000 gallons of acid. Ellenburger: Most of the Ellenburger wells have been treated with acid; the quantities of acid have ranged from none to 22, 500 gallons. PRODUCTION HISTORY WEL LS P ROD UCING at end of year Flowing Pumping OIL PRODUCTION (barrels) Yearly Cumulative F i eld totals 1950 1951 1952 1953 1954 Wolfcamp 1950 1951 1952 1953 1954 Bend ---r95o 195 1 1952 1953 1954 Devonian 1950 1951 1952 1953 1954 Fusselman 1950 1951 1952 1953 1954 Ellenbu rger 1950 195 1 1952 1953 1954 19 34 34 36 36 2 2 2 9 21 23 24 19 2 l 2 6 9 7 8 12 0 510,819 3 1,665 ,297 6 937,869 8 855 ,429 8 978,126 0 10,308 0 16,355 0 5 ,071 0 7 ,386 0 5 ,004 0 19 1,004 0 744,608 0 237 ,224 0 130 ,066 0 2 18,404 0 2 1 .932 0 19 ,679 0 6 ,789 0 5 ,228 0 856 0 l ,740 0 21,683 0 13'140 22 ,000 32 ,488 0 285 ,835 3 862 ,972 6 675 ,645 7 690,749 7 72 1,374 510,819 2,176,116 3 ,113,985 3,969,414 4,947 ,540 10,308 26 ,663 31,7 34 39'120 44,124 191,004 935,612 1, 172,836 1 ,302 ,9 02 1 ,52 1,306 21,932 41,6 11 48 ,400 5 3 ,628 54 ,484 1,740 23 ,423 36,563 58 ,563 91,051 285,835 1,148,807 1,824,452 2,515,201 3,236 ,575 In the above tabulation, the Warsan area is treated as an extension to the previously discovered Sweetie Peck field. The number of wells and the quantities of oil produced represent totals for the combined area. The appropriate of the above figures for 1953 and 1954 include the following numbers of wells and quantities of oil which apply to the Warsan area, which area includes such part of the field as is in Block 41, Twp. 3 S. Warsan area totals 195 3 1 0 1 ,227 1,227 1954 8 0 30 1,838 303,065 Warsan Bend 19 5 3 1 0 l ,227 1,227 1954 4 0 144,694 145 ,92 1 Warsan Fusselman 1954 0 6 ,586 6 ,586 Warsan Ellenburger 1954 3 0 150,558 150 ,558 TAYLOR -LINK FIELD Pecos County, Texas ROBERT H. TAYLOR Geologist, Standard Oil Co. of Texas, Midland, Texas April 15, 1955 LOCATION and FIELD NAMES The Taylor-Link field is in eastern Pecos County about 30 miles east of Fort Stockton, county seat. It is one of a group of fields on the Central Basin platform near its southern end. Soon after completion in the San Andres forma­tion of Taylor-Link Oil Co. #1 University as the discovery well of the field, two gas wells were completed in the Grayburg formation about 4 miles southeastward. A few months previously (February 5, 1929), gas had been found in the San Andres formation at a location about a mile farther south­eastward. Although there was only little interest in the occurrence of gas, the immediate vicinity of these gas wells became known as the Taylor-Link gas field and also as the Bakersfield field. It was designated by these names until about the mid-forties when it became known as the Cardinal gas field. This name is used currently in the reporting of gas production from the one remaining gas well in the vicinity. METHODS OF EXPLORATION LEADING TO DISCOVERY Studies of surface and subsurface geological data led to the discovery of the field. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 410 feet below its top. This penetration was in Stanolind Oil & Gas Co. #9-B University at its total depth of 8,690 feet. This test was located in the north-central part of the field as indicated on the accompanying map. It was commenced in November of 1949 and abandoned as a dry hole on May 1, 1950. NATURE OF TRAPS Yates and Grayburg: Anticlinal folding is the primary trap-forming factor in each of these reservoirs; variation in degree of porosity and per­meability has contributed in a secondary manner to forming each of the traps. San Andres: The accumulation of hydrocarbons is due to a trap formed by anticlinal folding. There are important variations in degrees of porosity and permeability, but apparently nowhere are they determinative in forming a trap. DISCOVERIES Yates : GAS: Discovery of gas in the Yates reservoir followed soon after discovery of oil in San Andres reservoir, but, commercially, the gas was more of a handicap than it was an asset. Production of oil from San Andres was the primary objective in the vicinity of the San Andres discovery well, and many wells were drilled through gas-bearing Yates for completion as oil wells in San Andres. Many of the San Andres wells within a mile to the southwest­ward of the San Andres discovery well could have been completed as Yates gas wells if such completion had been commercially feasible. Yates : OIL: August 30, 1929; Shell Petrolewn Corp:-#1-C Bower-University (now, Sam Letwin #1-C Bower-University). Flowed initially at rate of 660 barrels of oil per hour from open hole at depth of 935 to 960 feet. This well ceased producing after it had produced only 16,941 barrels of oil and was then deepened to the San Andres reservoir where it was completed on December 9, 1929. Grayburg: GAS: Two wells were completed in the Grayburg formation as gas wells at about the same time but they occasioned only minor interest because it was doubtful whether they had discovered commercial production. Tower & McKanna, Inc. #1 University was completed on September 8, 1929, and Continental Oil .co. #1 University was completed on September 10, 1929. Grayburg: OIL: August 2, 1941; Milton Unger #1-A Shell-University (now, F.H. Walsh Investment Co. #1-A University). After being shot with 50 quarts of nitroglycerin, this well flowed at rate of 264 barrels of oil per day from depth between 1,445 and 1,470 feet; gas-oil ratio, 600: 1. San Andres: GAS: February 5, 1929; George H. Anderson and Tower & McKanna, Inc. #1 University. Drilled to depth of 1,998 feet and plugged back to produce gas from 1,960-1,963 feet; initial capacity, 7,000 Mcf per day; plugged and abandoned in 1948. Although this was the first well completed in what is_ now the area of the Taylor-Link field, it was of only minor importance in influencing activity in the area because of the fact that it was doubtful whether com­mercial production had been discovered. San Andres and Field: OIL: June 15, 1929; Taylor-Link Oil Co. #1 University (later, Lee Petroleum Corp. #1 University; plugged and aban­doned 9/19/41). Flowed at rate of 115 barrels of oil per dayfrom depth of 1,613 to 1,625 feet; total depth, 1,635 feet; plugged back to 1,626 feet. Since this well was the first to discover unquestionably com­mercial production and since it inspired an aggres­sive development campaign, it is generally recognized as the field discovery well. TAYLOR-LINK FIELD, Pecos County, Texas NEAR-BY NONCOMMERCIAL PROSPECT In the south-central part of the area covered by the accompanying map, two wells were completed as oil wells and one was completed as a gas well in an area which was widely recognized as the McKenzi e field although none of the wells produced sufficiently to return its cost. Buell & Hagen #1-B University, located in Sec. 36, Blk. 18, where its total depth of 1,372 feet is indicated on the accompanying map, was completed on July 1, 1929, with initial daily capacity of 15 barrels of oil and 1,000 Mcf of gas from a reservoir in the Tansill formation at depth of 1, 313 to 1,320 feet. The only definite record of production which we find indicates that the well produced 118 barrels of oil during December 1935 and 90 barrels of oil during each March and April of 1936. The well was acquired by Ajax Drilling Corporation in 1934 and was plugged and abandoned by that operator on May 11, 1936. An acid treatment report filed by Aji\X indicate s that the well was capable of producing about 5 barrels of oil per day prior to acid treatment and that after treat­ment with 1,000 gallons of acid on October 18, 1935, the well indicated a capacity of producing oil at rate of 250 barrels per day. Southern Crude Oil Purchasing Co. #1 T. N. Mc Kenzie, located in Sec. 10, Blk. 604, where its total depth of 2,315 feet is indicated on the accompanying map, was completed as a gas well on March 20, 1930, with initial daily capacity of 1,300 Mcf of gas; no oil. The hole was plugged back with cement to 1,550 feet for production from reservoir at top of Yates for­mation; depth, 1,494 to 1,505 feet. We find no record of production from this well. It was plugged and abandoned on October 17, 1931. Mac T. Anderson #1 T. N. McKenzie, located in Sec. l , Blk. 604, where its total depth of 1, 378 feet is indicated on the accompanying map, was completed on July 20, 1934, with initial daily capacity of 20 barrels of oil from a reservoir in the Tansill for­mation; depth, 1,338 to 1,353 feet. The well was shut in until October 10, 1935, at which time it was treated with 1,000 gallons of acid with the r e sult that it appeared to be capable of producing at rate of 4 32 barrels of oil per day. Its oil production in 1935 amounted to 1,000 barrels during October and 400 barrels during December; in 1936, 300 barrels during January, 100 barrels during each February and March, 110 barrels during April, 100 barrels during June and 39 barrels during July; total, 2, 149 barrels. Although it produced no additional oil, it was not plugged and abandoned until February 17, 1939. CONTINUITY OF RESERVOIR ROCKS Each of the reservoir rocks is continuous throughout the area of the field. However, porosity and permeability in the Yates and Grayburg r e ser­voirs are only locally adequate for commercial production. ELEVATION AND RELIEF OF PRODUCTIVE ZONES San Yates Grayburg Andres Elev. of top of. gas, ft. 1, 700 ? 975 Elev. of bottom of gas, ft. 1, 610 ? 945 Relief, feet 90 ? 30 Elev. of top of oil, ft. l, 610 l, 185 945 Elev. of bottom of oil, ft. 1,500 1,080 880 Relief, feet 11 0 105 65 The above figures represent estimated elevations as of respective discovery dates and apply to the field exclusive of that portion extending s outheast­ward into Sections 3, 4, 10 and 11 of Block 17, commonly designated as the Cardinal gas field. A structural saddle, along with variations in degrees of porosity and permeability, has occasioned dif­ferences in elevations of fluid contacts in the two areas. It appears that the oil-water contact in the Grayburg reservoir was at the same elevation on either side of the saddle, but that the original gas­oil contact was lower in the southeast segment than in the mai~ part of the field. Data relative to the Yates and San Andres reservoirs southwest of the· saddle are too meager to afford a basis for estimat­ing elevations of fluid contacts; no commercial oil has been found in either reservoir in this area; only showings of oil. CHARACTER OF OIL San Yates Grayburg Andres Gravity, A. P. I. @ 60°F. , 30° 32° 31° Sulphur ? ? 1. 32% F or analyses see: Railroad Commission Analyses of Texas Crude Oils (1940) pp. 34 and 64. U. S. Bureau of Mines Lab.ref. No.31165 Tabulated Analyses of Texas Crude Oils. R . I. 3252 (1 934) Grp. 2, Item 58 Tabulated Analyses of Texas Crude Oils. T . P. 607 (1 939) Grp. 2, Item 81 Analyses of Crude Oils from Some West Texas F ields. R . I. 3744 (1944) Page 34 TAYLOR-LINK FIELD, Pecos County, Texas ELEVATION OF SURFACE At well locations: Highest, 2, 752 ft.; lowest, 2,474 ft. SURFACE FORMATIONS Undifferentiated rocks of the Washita and Fredericksburg groups of the Comanche series. THICKNESSES . OF RESERVOIR ROCKS Feet Net productive Maximum Average Yates 10 8 Grayburg 30 15 San Andres 80 40 UTHOLOGY OF RESERVOIR ROCKS Yates: Thin beds of fine-grained sandstone interbedded with anhydrite. The sandstone is characterized by the presence of rounded frosted quartz grains. Porosity and permea­bility are quite variable and only locally ade­quate for commercial production. Extremely favorable porosity and permeability were manifested by a few wells with unusually high initial productive capacities; e.g., one well produced gas at the rate of 66,000 Mcf per day and one well produced oil at the rate of 2,000 barrels per day. The thickness of the reservoir rock is less over the apex of the anticline than on the flanks . Grayburg: Interbedded sandstones and sandy dolomite. The sandstones a re fine-grained. Porosity and permeability are quite variable; generally, too low for commercial production of oil except in a limited area mainly on the northeast flank of the anticline, as indicated by well symbols on the accompanying map. San Andres: Dolomite; buff colored; gener­ally, finely crystalline with favorable porosity. Although there are important variations in porosity, there is adequate continuity of porosity favorable for commercial production wherever the reservoir rock is higher than a few feet above the elevation of the oil-water contact (880 feet above sea level), with only minor excep­tions. WATER PRODUCTION Every well is producing some wate r. Defi­nite data relative to quantities of water are not available. ACID TREATMENT TYPICAL SECTION OF ROCKS PENETRATED 2~ "' ,.."' "' lU a:"' "' ~ 0a:"' z 0 >=.. 2 a: ~ DEPTH LITHOLOGY ELEVATIO N .J (5 "' :> 0 I 100 0 .. .... a: 0 z .. 2 00 ,.. .... 200 z a: .... 300 400 >OO 600 700 800 900 • z .. a: Q. .. 0 I 0 0 Q. => "' (/) 1000 1100 z 0 Cl).. "' ~ LITHOLOGY 0 z a: c .J ~ DEPTH fLEVATIO~ Q SEVEN RIVERS r-I--?­145 1 z .. -::E a: Q. "' Q. :.J .. 0 .. I.&.! "' a: 0 I "'.... x ~ > z 12:00 :> 0 1300 -1--? * 1400: :> Ill ,.. .. a: C) 1500 ' ' 1501 -1151 1001 ~~ 1600-~'------••1 1700 ... -­ "' a: 0 1800 z 1900 .. z .. "' 2000 ~/\!:> I '" ... ... 2 100 ... 22.00 ••1 . *The position of the Queen-Grayburg contact is questionable. It may be lower than above indicated . The reservoir rock herein indicated as in the Grayburg formation may be in the Queen formation. It is at about the same stratigraphic position as the principal reservoir in the White & Baker -Walker field . EXPLANATION Most of the wells in the field have been treated (b'.:FJJ{HJj Sandstone m Anhydrite t=======j Shale m Gypsum with acid subsequent to completion. Acidization was initiated in the San Andres wells in 1933 and Dolomitic * Gas production ~Dolomite • Oi I productionanhydrite proved to be very profitable. - w .i:::.. CJ) ~ ~ >-<: L' 0 :::0 I L' ........ z ~ 'Tj ........ M L' t1 '"Cl (1) () 0 en 0 0 c ::::1 "<­ ~ (1) >< Q en TAYLOR-LINK FIELD, Pecos County, Texas PRODUCTION HISTORY WELLS PRO DU GING OIL PRODUCTION at end of year (barrels} OIL Flow. Pump. Total GAS Yearly Cumulative Field totals 1929 ? ? 30 ? 558, l 02 558,102 1930 ... ? ..... ? ..... ? .... ? .. 1, 481, 576 2,039,678 19 31 ? ? 56 ? 505,056 2,544, 734 1932 2 54 56 ? 292,470 2,837,204 1933 ... 2 .... 45 ... 47 . ... ? .... 214,904 .... 3,052,108 1934 1 54 55 ? 3 78, 206 3,430,314 1935 0 55 55 ? 432, 540 3, 862, 854 1936 ... 0 54 ... 54 .... ? .... 433, 265 4,296,119 1937 1 62 63 ? 414,201 4, 710,320 1938 1 68 69 ? 465, 338 5, 175,658 1939 ... 2 82 84 .... 0 539,058 5, 714, 716 1940 0 94 94 0 616, 222 6,330,938 1941 6 102 108 0 700,117 7,031,055 1942 7 ... 114 ... 121 .... 0 601,431 7,632,486 1943 18 108 126 0 569, 561 8,202,047 1944 11 115 126 0 488, 591 8, 690, 638 1945 12 122 .. . 134 .... 0 429,063 9,119, 701 1946 13 131 144 457,295 9,576,996 1947 3 141 144 2 374,647 9,951,643 1948 ... 2 140 ... 142 .... 1 331, 654 ... 10,283,297 1949 2 141 143 2 280, 773 10, 564, 070 1950 2 138 140 2 269, 164 10,833,234 1951 6 ... 138 . . . 144 . . . . 2 244,520 11,077,754 1952 6 140 146 2 222,901 11, 300,655 1953 7 136 143 2 211, l 79 11,511 ,834 1954 ... 3 ... 134 ... 142 .... 2 202, 759 11,714,593 Ya tes 1931 ? ? ? ?* ? 347,369 1932 ? ? ? ?* 36,319 383, 688 1933 ... 1 .... 13 .... 14 .... ?* .... 33,833 .. .... 417,521 1934 0 8 8 O* 18, 270 435,79 1 1935 0 8 8 0'' 15, 000 450, 79 1 1936 .. . 0 ... . . 8 8 . . .. O* . . . . 15,000 . .. .. . 465, 79 1 1937 0 9 9 O* 27,500 493, 29 1 1938 0 9 9 O* 21,000 514,29 1 1939 ... 0 .. ... 8 .. .. 8 .. .. O* .. . . 19,590 .. . . . . 533,88 1 1940 0 9 9 O* 22, 760 556, 641 San Andres 1931 ? ? ? ?* ? 2, 173, 700 1932 ? ? ? ? t~ 274,348 2,448,048 1933 ... 1 .... 32 ... 33 .... ?* ... 186,145 .... 2,634, 193 1934 46 47 O* 361,644 2,995,837 1935 0 47 47 0'' 420,273 3,416,110 1936 ... 0 .... 48 48 .. .. O* ... 433,265 3, 849. 3 75 1937 53 54 l* 387, 335 4,236, 710 1938 1 59 60 l* 444, 338 4,681,048 1939 ... 0 . ... 81 ... 81 .... O* ... 519,468 5,200,516 1940 0 87 87 O* 604, 323 5,804,839 *Exclusive of the wells in the Cardinal area. Records of production by reser voirs are not a vailable except for the period prior to 1941 . The foregoing data relative to production from the Ya tes and San Andres reser­voirs have been transcribed from annual issues of Petroleum Development and Technology published by American Ins ti­tute of Mining and Metallurgical Engineers. They constitute the best available corresponding information pertaining to the only reservoirs which produced oil prior to 1941. Since the time of discovery of commercial oil in the Gra yburg reservoir, the reporting agencies have not reported pro­duction of each reservoir separately. The quantities of oil above reported under Field totals for the years prior to 1936 are in accordance with entries in annual issues of the Year Book published by National Oil Scouts Association. The quantities for 1936 et seq. are based on records of the Railroad Commission. The yearly totals for the Taylor-Link field as reported by the Commis­sion for 1940 et seq. have been adjusted by deduction of quantities produced on two leases (Helmerich & Payne, Inc. University "F" and William Wolf University "A") which are here considered to be in the White & Baker-Walker field in its northwestern end although treated by the Commission as in the Taylor-Link field. Complete data relative to those properties are presented in the accompanying paper on the White & Baker-Walker field. The above figures under Field totals representing number of wells producing at the end of each year have been compiled from three general sources. The entry for 1931 was transcribed from the corresponding Year Book, National Oil Scouts Association and all other entries for years prior to 1939 were transcribed from annual issues of Petroleum Development and Technology, American Institute of Mining and Metallurgical Engineers. The entries for 1939 et seq. have been transcribed from records of the Railroad Com­mission with appropriate adjustments applied to the figures for 1940 et seq. to correspond with the adjustments men­tioned in the next preceding paragraph. GAS PRODUCTION Available records pertaining to gas production are in­complete; adequate for little more than showing that gas production has been of only m inor importa nce. The first well completed in the field was a gas well. It was of doubt­ful commercial significance at the time of its completion. Although gas has probably been marketed in m inor quantity in almost every year since discovery, records of quantities are available for only recent years. While it is probable that in the early years most of the marketed gas was used for drilling operations, it is certain that some gas was ex ­ported for domestic utilization. The following, which wa s written early in 1932, is quoted from page 457 of Geology of Natural Gas, American Association of Petroleum Geologis ts: "Until recently, a combination 5-and 6-inch line 17 miles long transported this gas northeast to the town of McCamey. This gas is high in hydrogen sulphide which necessitates the use of flues when it is burned for domestic purposes, and it is now being replaced by 'sweet' gas from the Big Lake field. As a reserve, it is not important. " The following data, which have been transcribed from Ra ilroad Commission records, are believed to cover the tota l of gas marketed from gas wells during the indicated years : WELLS PRODUCING GAS P RODUCTION at end of year ( Mcf} Main field Cardinal Main field Cardinal Year area a r ea area area 1946 1 5, 660 1947 2 105,392 1948 . . . . . . . . . . . . . . . . . . . . . 127, 749 1949 181 119,019 1950 4,040 19,658 195 1 .... .. 1 .. .. . .... 6, 126 ........ 8,400 1952 1 7, 147 13, 527 1953 1 8,957 13,701 19 54 ...... 1 ......... 4,409 17,056 TENNYSON FIELD Coke County. Texas RICHARD A. LISMAN Geologist, Vincent & Welch, Inc., Midland, Texas June 27, 1955 LOCATION The Tennyson field (one well, now abandoned) is in the southeastern part of Coke County, 10 miles southeast of Robert Lee, county seat, and 4 miles northwest of the village of Tennyson. It is in Sec. l, H.E. & W. T. R.R. survey. METHOD OF EXPLORATION LEADING TO DISCOVERY Seismograph surveys led to the drilling of the discovery well. DISCOVERY Ellenburger: May 23, 1948; Seaboard Oil Co. and Southern Minerals Corp. #1 M.G.Reed. ELEVATION OF SURFACE Derrick floor at the one productive well: 1,914 feet. SURFACE FORMATION San Angelo formation of the El Reno group of the Guadalupe series. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the productive well is in the Ellenburger gr.oup 20 feet below its eroded top. The oldest horizon penetrated within the area covered by the accompanying map is in Cambrian sandstone 41 feet below its top. This penetration was in La Gloria Oil Corp. and Allen Dykes #1 M.G.Reed, located 2 3/4 miles southwest of the productive well and where the total depth of 6, 779 feet is indicated on the accompanying map. NATURE OF TRAP The trap appears to be due to updip decrease of porosity on a small anticlinal nose. PRODUCTIVE AREA Ellenburger and Field: 40 acres. THICKNESS OF RESERVOffi ROCK Ellenburger: 12 feet. LITHOLOGY OF RESERVOIR ROCK Ellenburger: Dolomite; gray to tan, crystalline, with scattered vuggy porosity. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Ellenburger: Feet Elevation of top of oil -4,268 Elevation of bottom of oil -4,280 Relief 12 CHARACTER OF OIL Ellenburger: Gravity, A. P. I. @ 60° F: 47°. WATER PRODUCTION Ellenburger: Tne liquid produced during the initial potential test was 59% water. Data concern­ing subsequent water production are not available. ACID TREATMENT Ellenburger: The productive well was treated with 175 gallons of acid. PRODUCTION HISTORY Ellenburger: The one well produced 20, 797 barrels of oil during 1948 and 9,633 barrels during 1949. The well was abandoned in May 1949 after having produced a total of 30,430 barrels of oil. TENNYSON FIELD, Coke County, Texas SECTION OF ROCKS PENETRATED Limestone ~Dolomite Sandstone ~ Shale ~ E=======j Red Sha le m Anhydri te ~Detri tus (s ha le, red shale, Oil product1anlimestone and chert) ~Unconformity ---~~~~~Probable unconformity TUCKER FIELD Crane County, Texas WILLIAM M. CAFFEY Development Geologist, Standard Oil Co. of Texas, Midland, Texas HERSHEL S. CARVER, Jr. District Geologist, Standard Oil Co. of Texas, Amarillo, Texas December 1, 1953 LOCATION The Tucker field is in southwest Crane County 2 miles north of the Pecos River and 6 miles north of the town of Imperial in Pecos County. It is on the Central Basin platform and in the midst of many fields near the southern end of the platform. METHODS OF EXPLORATION LEADING TO DISCOVERY Subsurface geology and geophysics, with more of the credit due to subsurface geology, prompted test-drilling. Geophysical exploration was difficult because of the unconformity at the base of the Permian. On October 18, 1945, Magnolia Petroleum Co. #1-B H. H. Tucker was completed at total depth of 5,817 feet in the Waddell sand. Although a drill stem test had indicated a commercial well, the completed well flowed only 19 barrels of oil per day and, after producing a short time at a declining rate, was soon abandoned without having been a commer­cial producer. DISCOVERIES Clear Fork: May 26, 1950; Jergins Oil Co. #2 M. D. Self & State. Initial production, 52 barrels of oil and 21 barrels of water per day through perfora­tions at 4,167 -4,173 feet. This is the only well which has produced from this reservoir. It was abandoned in 1952. McKee: January 15, 1952; George T. Abell #1 State-Brunson. Initial potential, 220 barrels of oil per day with gas-oil ratio of 550 :1; top of reservoir at depth of 5 ,482 feet . Waddell and Field: February 24, 1946; Standard Oil Co. of Texas/lTNellie M. Tucker. Initial poten­tial, 127 barrels of oil and 1,500 Mcf of gas per day through 1/ 4-inch choke ; gas-oil ratio, 11,000: 1 The writers wish to express their appreciation of the active assis tance of Jack L. Lawton, Division Petroleum Engineer, Standard Oil Co. of Texas, and of other fe llow engineers and to thank their employer for permission to publis h this paper. ELEVATION OF SURFACE The surface elevation averages about 2,450 feet above sea level. SURFACE FORMATION Quaternary caliche and sand with total thickness of about 50 feet generally. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is 205 feet below the top of the Ellenburger. This penetration was in the Waddell discovery well at its total depth of 6 ,303 feet. NATURE OF TRAPS Clear Fork: The trap is due to updip and lateral decrease in degree of porosity. McKee: The primary trap-forming factors are truncation of sloping reservoir rock and sealing by relatively impervious strata. Waddell: The trap is due to updip decrease in porosity. Shale content of the Waddell sand grad­ually increases eastward with the result that this reservoir rock is not sufficiently porous updip from the -3 ,300-foot contour to permit migration of oil. PRbDUCTIVE AREAS Acres Clear Fork (depleted} 10 McKee 80 Waddell 560 "Tucker field 650 The estimate for McKee includes only the area considered as proven by development to date . It is probable that future development will warrant increasing this estimate. Furthermore, there is some possibility of future development warranting an increase of the estimate for Waddell. TUCKER FIELD, Crane County, Texas THICKNESSES OF RESERVOIR ROCKS Gross from top to bottom Feet of productive rock Min. Max. Clear Fork 3 25 McKee 30 60 Waddell 20 45 CONTINUITY OF RESERVOIR ROCKS Clear F.ork: This reservoir rock is identifiable as a stratigraphic unit throughout the area of the field. However, at only one location has it been found sufficiently thick and with sufficient degree of porosity to occasion commercial production. It prQbably correlates with the Tubb sandstone, which is productive in several nearby fields. McKee: This reservoir rock is a blanket sand­stone which was deposited as a continuous bed over a large area including several nearby fields. It has been eroded from the crest of the structural high on which this field is located. Waddell: The Waddell sandstone was deposited as a blanket stratigraphic unit over a large portion of West Texas and Southeast New Mexico. It is characterized by local variation in degree of porosity and permeability and therefore is probably not con­tinuous for free migration of fluids over large areas. CHARACTER OF OIL Clear Fork: Gravity, A.P.I. @ 60 ° F. 37. McKee: Gravity, A.P.I. @ 60 ° F. 42. Waddell: Gravity, A.P.I. @ 60 ° F. 38.3. Sulphur, 0.414'7'o Color, Dark green Flash point, Below 60° F. Fire point, Below 60° F. Viscosity Saybolt seconds @ 60° F. 55.1 @100°F. 41.6 @130°F. 37 .1 Pour point, ASTM D97 10° F. Carbon residue, Dl89 2.25% Salt content, lb./1,000 bbls. 1.53 Yield: Distillation at atmospheric pressure ---:Wo E. P. gasoline, 31.0% 525 E. P. kerosene, 16.0% 675 E. P. gas oil, 20.0% Lube distillate 14.0% Residue 1-8.5% Source of sample: Standard Oil Co. of Texas #1 H. A. Reynolds LITHOLOGY OF RESERVOIR ROCKS Clear Fork: Brown to gray, fine to medium, crystalline dolomite with some traces of asphalt. McKee: Gray to brown, fine, quartz sand with a few large frosted grains. Much of the sand is cemented with lime or shale. Waddell: The reservoir rock consists of two sand members with a parting of limy, green shale approximately 10 feet thick. The top sand is com­posed of fine, rounded sand grains cemented by shale updip and varies in thickness from 3 to 10 feet. The lower sand is similar, with the grains slightly smaller and more compacted, and, like the upper sand, is cemented by shale updip. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Clear Fork: Feet No free gas cap Elevation of top of oil -1,704 Elevation of bottom of oil -1,722 Relief 18 The above elevations are those in the one well where this reservoir was productive. In other wells, shows of oil have been found at higher and lower elevations. Data are not available for concluding whether there is a fairly definite oil-water contact level in this reservoir rock, which generally lacks sufficient porosity for commercial production. McKee: Feet No free gas cap Highest known elevation of oil -3 ,026 Lowest known elevation of oil -3,079 Known relief 53 Waddell: Elevation of top of gas -3,249 Elevation of bottom of gas -3,327 Relief* 78 Elevation of top of oil -3,327 Elevation of bottom of oil -3 ,467 Relief 140 *The above indicated relief of 78 feet repre­sents the' original primary gas cap. This cap has been extended by expansion of gas with decrease of pressure and by gas coming out of solution as oil is produced. Because of the ex­pansion of the gas cap, operators have squeezed off upper perforations in some of the oil wells. There is no gas well recognized as producing from this reservoir. Humble Oil & Refining Co. #1 N.M. Tucker,which may be completed in this reservoir, has been shut in for lack of market for gas most of the time since its completion on January 14, 1946. This well has been treated by the Railroad Commission as in the Abell field. TUCKER FIELD , Crane County, Texas ., c..0- ~ q,.'l:-' v· °' .,... ~ "-· /' ~ +· (jo· ~ ~ ~­0 ~ ""' I e~ g <>" "> 'll' +· ~· q,V ~ \ \ II}~/I /JO -<-· ~~~\ \ \ \_ ''> Do ~ _,,,,~ "> • -1111 So -..!. '-...... !1111 ~ ~.. ~ p /,,,"' -1111 _!_ ~ N .f.. d •' '"' -.1.c"-"-"' ~\ 2 rz I I HUMBL E I # I N M TIJCKCR / vo· COUNTY f ~ ~-' ~~~'<, -'Co~ ~\I "-· G r.r,GO<, ;·-i··. ~ ~ "" 'll' (J' · A + q '~\-1. ~· -:3 c: 0 ~ M ::tJ '"Tj ,_. M L' t::I 0 a g 0 g ~ r Cll EXPLANATION -----3450----Contour on top of Waddel I member -J~n Elevation of top of Waddel I member nH Total depth • Oil well +Abandoned oil well ~ Gos well P Ory hole • ~Discovery le Completed in Clear Fork e\ Completec1 in Mc Kee ~ Completed in Waddell SCALE 10 THOUSAND FEET w c.n p w TUCKER FIELD, Crane County, Texas CHARACTER OF GAS Clear Fork: No analysis available McKee: No .analysis available Waddell: Podbielniak analysis: Component Mol. % G/Mcf Carbon dioxide Nil Methane 89. 34 Ethane 4.99 Propan e 3.12 0.856 !so-butane 0 .2 1 0.069 N-butane 1.13 0.355 Iso-pentane 0. 16 0.058 N-pentane 0.47 0.170 Hexane 0.37 0.152 Heptane plus 0 .21 0.097 Calculated yield: 26# R VP gasoline 0.760 18# RVP gasoline 0.576 Source of sample: Standard Oil Co. of Texas #1 H.A.R eynolds RESERVOIR ENERGY Clear Fork: Water drive. McKee: Insufficient history for positive deter­mination. Probably water drive. Waddell: In the early stages of development, the reservoir energy appeared to be solely of the solution gas type. Subsequent development proved that there was a primary gas cap. During the several years of productive history, the gas-oil ratio has increased considerably in a few of the higher wells; from 11,000: 1 to approximately 37,000:1 in the discovery well. The maximum recorded initial flowing reservoir pressure was 2 ,590 psi. and the calculated bubble point was 2,633 psi. The reservoir pressure is now around 2,100 to 2,300 psi. Apparently the primary gas cap has been effective in arresting the decline of reservoir pressure. There is no evidence of updip advance of the oil-water contact. WATER PRODUCTION Clear Fork: The water-oil ratio in the one productive well was initially 21: 52. The rate of oil production declined and the rate of water production increased, with the result that operation became unprofitable and the well was abandoned. McKee: Practically no water has been produced to date. Waddell: No water has been produced to date. ACID TREATMENT and HYDRAUUC FRACTURING McKee: The southern of the two producing wells was acidized with 1,000 gallons and fractured with 2 ,000 gallons. Waddell: The only well in which the Waddell reservoir was treated is the well in the north corner of Sec. 12, near the northeast corner of the area covered by the accompanying map. This well was acidized in two stages, fir st with 2 ,000 gallons and then with 1,500 gallons. At first, the treatment appeared to be successful, but the well was soon depleted and was abandoned. PRODUCTION HISTORY Year WELLS PRODUCING at end of year Flowing Pumping OIL PRODUCTION (barrels) Yearly Cumulative F ield tot als 1946 1947 0 0 2 ,726 28,900 2,726 31,626 1948 1949 4 7 0 0 106 ,549 223,809 138,175 361,984 1950 1951 9 8 3 2 150 ,428 97 ,742 512 ,412 610,154 1952 1953* 11 12 2 2 111,416 79'199 721,570 800 ,769 Clear Fork 1950 1951 1 0 1 1 5,765 3 ,811 5,765 9 ,576 1952 0 0 0 9 ,576 McKee 1952 1953* 2 2 0 0 15,722 7 ,164 15 ,722 22 ,886 Waddell 1946 1947 0 0 2,726 28 ,900 2,726 31,626 1948 1949 4 7 0 0 106 ,549 223,809 138,175 361,984 1950 1951 8 8 2 144,663 93,931 506 ,647 600 ,578 1952 1953* 9 9 2 2 95 .694 720,035 696,272 768,307 *195 3 data added by amendment. TUNSTILL FIELD Loving and Reeves Counties. Texas WILLIAM T. REID Geologist, Continental Oil Co., Midland, Texas August 17, 1953 LOCATION The Tunstill field occupies an area about 5 miles long partly in Loving County and partly in Reeves County. The south end of the field is about 4 miles northeast of the town of Orla in Reeves County and the north end of the field is about 5 miles south of the New Mexico -Texas boundary line. It is one of several similar fields in the central portion of the Delaware basin. METHODS OF EXPLORATION LEADING TO DISCOVERY Mapping of surface and subsurface geological data led to the discovery of the field. DISCOVERIES Bell Canyon: The first well completed as a productive well within the present area of the field was Pacific Mid-Continent Corp. #1 W. A. Tunstill, which was completed on October 12, 1938, as a gas well with potential capacity of 3 ,770 Mcf per day. After showi ngs of gas from the depth of 3 ,291 to 3,302 feet, there was an oil showing at 3 ,302 feet; 17 barrels of oil was produced during a 7-hour test. The well was continued to the total depth of 3 ,305 feet and completed as a gas well. It created very little interest and evidently was not recognized at the time as having discovered a commercial field. It was deepened in 1939 to a total depth of 3 ,5 56 feet and was plugged and abandoned in 1941. On October 27, 1947 ,Louis Crouch and Texzona Produc­tion Co. #1 Tunstill Brothers was completed and was currently recognized as a discovery well. Early in August of 1947, it had .unloaded its drilling mud at depth of 3 ,285 feet and again at 3 ,298 feet. It pro­duced oil and drilling fluid at the rate of 15 to 20 barrels hourly. Drilling was halted at depth of 3 ,308 feet to install control-head and tanks . With­out drilling deeper, the well was completed on October 27 as a flowing oil well with rated potential capacity of 71 barrels of oil per day. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the vicinity of the field is in the Cherry Canyon formation and is 1,397 feet below the top of the Delaware Mountain group. This penetration was in the dry hole near the west edge of the field and about i mile southwest of the Pecos River and near the southeast corner of section 4 where the total depth of 4,629 is indicated on the accompanying map. NATURE OF TRAP The oil accumulation is related to three factors, the predominant of which is a narrow terrace. Variation in degree of porosity and permeability is also an important trap -forming factor . Slight faulting is believed by the writer to contribute in a minor way to trapping of oil in certain parts of the field . PRODUCTIVE AREA Bell Canyon and Field: Development to date proves that an area of at least 4,240 acres is pro­ductive. Since drilling is still in progress, it seems likely that the productive area will be proven to be greater than it is now known to be. LITHOLOGY OF RESERVOIR ROCK Bell Canyon: Sandstone; calcareous , light to medium gray, fine-grained; interbedded with thin, black calcareous shale partings at various intervals . CONTINUITY OF RESERVOIR ROCK Bell Canyon: Throughout the Delaware basin there 1s a sandstone member at the stratigraphic position of this reservoir rock . The member appears to be continuous throughout this large area, but the degree of porosity and permeability varies considerably. However, it appears to be generally sufficiently porous to permit migration of reservoir fluids except locally where porosity and permea­bility are abnormally low. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Bell Canyon: Feet Free gas in negligible quantity only Elevation of top of oil -477 Elevation of bottom of oil -692 Relief 215 RESERVOIR ENERGY Bell Canyon: Production records indicate that the reservoir energy which expels the oil is due primarily to expansion of gas as it comes out of solution with decline of pressure. Although water is produced along with the oil, it does not appear that water is entering the general reservoir space at a sufficient rate to constitute a material water drive. The writer believes that the water which is being produced is water which is disseminated in the reservoir rock along with the oil. ELEVATION OF SURFACE At well locations: Highest, 3 ,062 feet Lowest, 2,751 feet SURFACE FORMATION Undifferentiated Quaternary sands and gravels. THICKNESS OF RESERVOIR ROCK Bell Canyon: Feet, average From top to bottom 60 Net productive 10 ..·.· ..·. I~ Ml hXK . ~ ~ r "' 3 0 ~ 0 0 " 0 , x "' r z • 0 !'.; . . z 0 ~ II " )> g> "' 0 0 c " n " 0 l 0 ," ~ ~ ~ 0 < " ;; CHARACTER OF OIL PRODUCTION HISTORY w (.Tl en Bell Canyon: WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION Gravity, A.P.I 36° ­43°; avg. 40° at end of year {barrels) {Mcf) Sulphur 0.15% Oil Gas Color Green Year Flowing Pumping Yearly Cumulative Yearly Cumulative Viscosity, Saybolt Universal @ 100 ° F. 35 sec. 1947 7 0 1 15 ,800 15,800 0­0 1948 4 1 4 1 478 ,680 494 ,480 28 ,079 28 ,079 For analysis see: 1949 80 4 1 777 ,604 1,272 ,084 15 ,57 5 43 ,654 U . S . Bureau of Mines L ab. ref-. No . 5 1064 1950 88 14 1 952 ,64 1 2 ,224 ,725 18 ,77 5 62 ,429 Analyses of Crude Oils F rom -­ Some West Texas Fields. R . I. 4959 {1953) Item 86 1951 1952 113 15 2 I.196,154 3 ,420 ,879 141 25 2 1,528 ,000 4 .948 ,879 45 ,261 20,988 107,690 128 ,678 >--3 c:: PERMIAN GUADALUPE OCHOA OELEWARE MTN. BELL CANYON CASTILE r.. .. . . "' 0 ~~ 0 0 0 0 0 "' 0 0 0 0 0 0 0 !.:..SHIFT SY DRAFTSMAN I I I . ~. . . : L • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ~~ . . . . . . . SYSTEM SERIES FORMATION 0 z 0 0... ::::0 CD ~ CD rn 0 0 c ~ ...... - CD rn >--3 ~ g . <>.. "' ;; "' ~ z "'c .... 0 "' z MEM BER . <>.. "' .."' "' ~ z "'c :;: 0 z OIL r ::; I 0 r 0 G> -< r ::; I 0 r 0 G> -< )> "' 0 0 )> (") -< < ::; -< (") c < "' (/) "' )> "' 0 0 )> (") -< < ::; -< (") c "' < (/) "' ..; -< "ti - n > l:"'4 tll trJ n ..; - z (/) >--3 ........ L' L' 1-rj ........ trj L' t1 b < s· lQ § SYSTEM SERIES GROUP FORMATION TUNS TILL FIELD, Loving and Reeves Counties, Texas EXPLANATION -­·420 -­Contour on top of Lamar member SC ALE *'Gos well Ji Dry lx>le 0 o Dr ill ing we ll ~Discovery THOUSAND f"EET . H 7o Total depth LOCATION The TXL field is in western Ector County about 20 miles west of Odessa, the county seat of Ector County. It is in the central portion of the Central Basin platform. METHOD OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph. DISCOVERIES San Andres : April 17, 1952; Phillips Petroleum Co. #TT-1 TXL. Upper Clear Fork: July 8, 1946; Phillips Petroleum Co . #E-1-A TXL. Tubb : December 2, 1950; ----Texas Gulf Producing Co. #1 Lola and Felix Woodard. Wolfcamp: January 20, 1947; American Republics Corp. #1 TXL. Oil was first produced from this reservoir by Shell Oil Co. & Arkansas Fuel Oil Co. #E-1 E.R. Thomas Estate, which was completed in this reservoir on February 9, 1946, with initial potential of 16.2 barrels of oil per day; abandoned in this reservoir and completed in Devonian in July 1946 after having produced only 970 barrels of Wolfcamp oil; later, plugged back to Upper Clear Fork. Devonian and Field: December 30, 1944; Shell Oil Co. & Cities Service Oil Co. #1 TXL. Fusselman South: December 20, 1946; Superior Oil Co. #7 J .E.Parker. Fusselman North: November 28, 1951; Shell Oil Co. #A-2 J .D.Slator, Jr. Waddell: May 23, 1953; Phillips Petroleum Co. #D-5 TXL . Ellenburger: May 15, 1945; Shell Oil Co. #1-A A.E .Thomas. Ellenburger Deep: February 7, 1946; The Texas Co. #D-1 G .C .Fraser. OLDEST ZONE PENETRATED Pre-Cambrian. TX L FIELD Ector County, Texas C . G . COOPER and B. J. FERRIS Geologists, Shell Oil Company, Midland, Texas June 30 , 1954 NATURE OF TRAPS San Andres : Not determined; possibly, variation in degree of porosity. Upper Clear Fork and Tubb: Anticlinal fold. Wolfcamp: Not determined. It appears that only locally is the reservoir rock sufficiently porous and permeable to permit migration of oil. Devonian: Updip termination of reservoir due to erosional truncation. Fusselman South and Fusselman North: Anti­clinal fold with subsidiary faulting. Waddell: Not determined; probably, anticlinal fold. Ellenburger : Anticlinal fold generally; in south part of field, reservoir is terminated by faulting. Ellenburger Deep: The trap is due primarily to an anticlinal fold on the downthrown side of a major fault. PRODUCTIVE AREAS San Andres Upper Clear Fork Tubb Wolfcamp Devonian Fusselman South Fusselman North {gas, Waddell Ellenburger Ellenburger Deep TXL field Acres --so 6,240 1,500 40 5,500 200 360; oil. 1,200} 1,560 40 5,900 160 16,440 THICKNESSES OF RESERVOIR ROCKS Average gross from top to bottom San Andres Upper Clear Fork Tubb Wolfcamp Devonian Fusselman South Fusselman North Waddell Ellenburger Ellenburger Deep Feet ---uJO 525 220 160 70 70 85 205 150 T X L FIELD, Ector County, Texas LITHOLOGY OF RESERVOIR ROCKS San Andres : Dolomitic limestone; tan to buff, fine-to medium-grained, porous. Upper Clear Fork: Dolomitic limestone; light gray, brown and buff, compact to finely saccharoidal, cherty, slightly anhydritic. Tubb: Dolomitic limestone; light brown, compact to finely saccharoidal, porous. Wolfcamp: Dolomitic limestone; light tan to brown, compact, fine"-grained. Devonian: The reservoir rock comprises an upper chert member and an underlying limestone member . The upper zone consists mainly of dense white to milky, porcel­laneous chert in which porosity appears to have been developed by sub-aerial weathering along cracks and joints resulting in the formation of stream bed crevices filled with elastic material, as well as through metasomatic change of the dense chert into a porous form called tripolite. This zone is highly permeable. It constitutes the main Devonian reservoir . The underlying limestone member is quite cherty and in places has been converted almost entirely into tripolite, which, although highly porous, is nevertheless only poorly permeable. Because of this difference in lithology, wells at the updip edge of the accumulation exhibit markedly different reservoir characteristics from those lower on structure. Fusselman South and Fusselman North: Glauconitic limestone; medium-to coarse-grained, compact, cherty. Waddell: Sandstone; tan, medium -grained, angular, with green shale partings. Ellenburger and Ellenburger Deep: Dolomite; brown to gray, medium-to coarse -grained, compact, rhombic, locally cherty. CORE OF DEVONIAN RESERVOIR ROCK :z: u z w z 0 From depth of 7 ,922 feet in Shell Oil Co. & Arkansas Fuel Oil Co. #8-B E .R .Thomas et al NE, SW, Sec.20, Blk.45, T. 1 S., T.&P.R.R. survey CONTINUITY OF RESERVOIR ROCKS As stratigraphic units, all reservoir rocks, with the exception of Devonian, show a fairly uniform development throughout the area of the field. Porosity and permeability, however, especially in the Permian reservoirs, exhibit variations which result in a wide range of productivities of wells. The Devonian reservoir is truncated to the extent that it is totally absent in a part of the field; its porosity decreases downdip. CHARACTER OF OIL Gravity, Sulphur A.P.I.@ 60° by wt. Color San Andres 37 .2. ? Dark green Upper Clear Fork 36.3. 0.62% Dark green Tubb 37 .2. 0.55% Dark green Devonian 40.7. 0.46% Dark green Fusselman South 38.5. 0.42% Dark green Fusselman North 37 .3. 0.52% Dark green Waddell 44.4. ? Dark green Ellenburger 44.5. 0. 15o/o Dark green For analyses see: U.S.Bureau of Mines Lab .ref.No. 46080 46081 46082 Analyses of Crude Oils from 283 Important Oil Fields of the U.S., R.I. 4289 (1948) Item 264 Analyses of Crude Oils from Some West Texas Fields, R.l. 4959 (1953) Item 87 88 ACID TREATMENT San Andres : Both wells were acidized at time of completion; one with 6,000 gallons and the other with 16,500 gallons of acid. Upper Clear Fork: All wells are treated with acid before final completion. The gross thickness of the reservoir is so great that the acid is injected by stages into separate, selected portions of the total thickness. Treatments range from 2 ,000 gallons to 30 ,000 gallons in from one to six stages. Tubb: Acid treatments ranging up to 13 ,000 gallons are given in from one to three stages. Wolfcamp: The sole Wolfcamp producer was treated with 13,000 gallons of acid in four stages. Devonian: The majority of the wells in the Devonian reservoir were completed by natural flow. In general. acid treatment was found necessary in wells located near the boundaries of the accumulation, either downdip where porosity grades to near zero or near the updip truncated edge where the presence of tripolite causes low perme­ability. Treatments ranged up to 27 ,500 gallons in four stages. Fusselman South: Acid treatment commonly is limited to a mud acid wash or a one-stage injection of about 500 gallons. Fusselman North: Most wells have been given a one­stage treatment with 500 gallons of acid. Waddell: The sole producer was first treated with 500 gallons of acid and then given a 5,000-gallon hydraulic frac­ture treatment. Ellenburger: Generally, wells completed in this reser­voir flowed naturally. The few wells which required treatment were, with one or two exceptions, given either mud acid wash treatments or injections of from 1,000 to 2, 000 gallons. Ellenburger Deep: The wells in this reservoir all flowed naturally except one; that one was given a 1,000­gallon acid treatment. SELECTED REFERENCE David, Max (1946) Devonian (?)producing zone, TXL pool , Ector County, Texas: Amer. Assoc. Petr. Geol., Bull. , vol. 30, pp. 118-119 . T X L FIELD, Ector County, Texas TYPICAL SECTION OF ROCKS PENETRATED SURFACE FORMATION: Lower Cretaceous limestone ELEVATION OF SURFACE: Highest, 3 ,361 feet; lowest. 3 ,058 feet z Q 0"' ELECTRIC CURVES "' I­> ANO :;; 0 ::> er "' "-" ~ _, "' LITHOLOGY ~ "' :i'. "'er OEPT H ELEVAT IO N 0 "' • DEPTH, ELEVATION AND RELIEF OF PRODUCTNE ZONES Fr ee gas .is present in only the north closure of the Fusselman North reservoir; there, the gas-oil contact was originally at -4,925 feet with maximum known gas column of 73 feet above th at elevation. Top of reser voir a t wells Eleva tion of oil Oil Depth (ft. below D .F .j Elevation (feet) (feet) Column Minimum Maximum Highest Lowest Top Bottom {feet) San Andres 4,260 4,290 -1,023 -1,058 Unknown Unknown Unknown Upper Clear Fork 5,302 5 ,692 -2 ,047 -2 ,441 -2 ,047 -2 ,790 743 Tubb. .. . ... .. .. .. 6,001. .6,280 . ...... -2,902. . -3'171 . ...... -2 .902 . . . . . -3 ,l 75 . . . 27 3 Wolfcamp 7 ,795 -4,742 -4 ,7 42 Unknown Unknown Devonian* 7 ,690 8,090 -4 ,433 -4 ,733 -4 ,43 3 -4 ,850 417 Fusselman South 8 ,300 8 ,5 23 -5 ,050 -5 ,266 -5 ,050 -5 ,380 330 Fu sselman North. 8 ,164 .. .8 ,493 ... -4,852. . -5' 153 .. . . -4 ,925 . -5'185 . .260 Ellenburger 9,25 0 -5 ,940 -5 ,940 -6,600§ 660 Ellenburger Deep 10,740 -7,475 -7,475 -7 ,6 7 5 200 Figures reporting eleva tion of oil and oil column in the several reservoirs represent conditions at respective discovery dates. * The difference of 300 feet in the elevations of the top of the Devonian does not represent the proven structural relief since a portion of the De vonian has been eroded off at the higher location. The elevation of the oil-water contact in the Ellenburger reservoir varied through a range of about 60 feet; from -6,540 feet to the extreme of -6 ,6 00 feet at the south ~Rock indicated, • Oil production ~silty extent of the Ellenburger pr oductive area . T X L FIELD, Ector County, Texas ELEVATION FEET -4300 -4500 -5000 -5500 -6000 -6500 T X L FIELD, Ector County, Texas C·~.z . 0 0 . 0 :; T Wo 0 . 0 . 4 0 . c o• 0. oc .c c• ' ,. . T F \ ~ EXPLA NA TIO N ., Olt •tll oil /I Orr hol e • '\.:] Dl•covtrr fJ. Ouol completion, produttive from indicGled rnervoln Oldnt renrwolr tuted, non-pr oductin t ·c . PRODUCTIVE RESERVOIRS Upper Clror Fork Fuur lrnon TX L FIELD, Ector County, Texas \ O•I Abondon1d oil /f Ory hol1 ProducliYt rrurvoir, obondonrd in rrurvoir lndlcoltd b)' underllntd $)'mbol 'J Ouol cornplrloon, produclfvr from indlcotrd ruervoin ? Cornplrltd in Wollcornp, ltmporGrily obondontd Otdru •Utrvo•r lnt r d, non -product1vt Ory hole , Son Andru not rtochcd PR ODUCTIV E R£ SERV01R S Son Andru Otvonion Upptr Cl r or fork Funtlrnon . Tubb . Elltnbur(j~ r ';' Woll com p - T X L FIELD , Ector County, Texas ----21so ---Contour on top of Upper Cleor Fork reservoir Oil well In pre-Permian reservoir + Abonooned oil well In pre-Ptrmi<1n reservo•r • \::11 Olscovery 1i Produc.1n9 from Son Andres, obondoned in Upoer Clear Fork (one welll I• Producin9 from Son Andres, dry in Upprr Cl ear Fork ton e well! Producin9 from Upper Clear Fork i~ Producing from Upper Clear Fork, abandoned in Tubb (Ol'll' welt) •1 Producin9 from Tubb Temporarily obondo11ed in Wolfcom p lone •1t lll Ji Ory in Permian resrrvoir O. Ory or obondoned In pre-Permion re1ervoir Tlli1 mop shows only 11o1ch wells o' pen etrated the contoured hori1on. T X L FIELD, Ector County, Texas ---ozo --Contour on Woodlo•d-Otvonion ----~•zo ---Con1ou1 on eroded Otvonion -•-•of:i/•-•-Contoc l 0 1 pre-Permian erosion surface '" -5io2 [levo• ion ol lop of Oevon ion 1011000 To101 depth Oil well In pre -Devonian restrvoir Abandoned oil "'I ll In pre·Devonlon reservoir fl Dry hole in pre-Devonian reservoir • Producinq from Oevonlon ; Abandoned in Devonian •riOuolF~:s:i~~l~~"F~~~~~~t~venol;o:b~n~voon:l;n(o~:d well) ff Dry in Devonian 0" Producin9 or obondoned ln posl·Dtvonion reurvoir o., Ory or obondoned in pre -Devonian re1ervolr This mop shows only such well• 01 penelroled the conloured horizon. l MOUSAllO f((T c T X L FIELD, Ector County, Texas ---scso --Contour on Top of Fusselman lormotion _ ,~o EltYOtlon of top of Funelmon tormo11on To un Tolot depth Oil we ll in pre-Funelmon rese rvoir Abandoned oil well in pre-F"uuelmon reservoi1 Or)' hole in pre -Fuuelmon r111r11oir • 'LJ] Discover)' ProduclnQ from Funelmot1 Abandoned in Funelmon ~o Prod1.1cino from Waddell co ,_,:) ><: L' '"Tj ...... rr:I L' Cl rr:I () 0 ...., ~ § ~ ,_,:) ~ Ul VERHALEN FIELD Rffves County, Texas EDWARD R . KENNEDY, Jr. Geologist, Argo Oil Corporation, Midland, Texas June 10, 1954 LOCATION The Verhalen field (one well, now abandoned) is in southeastern Reeves County, 23 miles south of Pecos and 13 miles northeast of Balmorhea. METHODS OF EXPLORATION LEADING TO DISCOVERY Gravity and magnetic surveying. DISCOVERY Wolfcamp: July 23 , 1947; Argo Oil Corporation #1 Dora Roberts. ELEVATION OF SURFACE The surface at the location of the one well is 2 ,870 feet above sea level. The depths indicated on the accompanying SECTION OF ROCKS PENETRATED were measured from derrick floor at the elevation of 2 ,880 feet. SURFACE FORMATION Undifferentiated rocks of the Comanche series. OLDEST STRATIGRAPI:UC HORIZON PENETRATED The oldest horizon penetrated in the one well in the field is about 500 feet below the top of the Canyon series, as indicated by the accompanying graphic section. NATURE OF TRAP Wolfcamp: Data for determining nature of trap are not available. PRODUCTIVE AREA Wolfcamp: Approximately 40 acres . TI:UCKNESS OF RESERVOm ROCK Wolfcamp: Thin beds of possible reservoir rock are scattered throughout 818 feet of section. The aggregate thickness of beds having appreciable shows of oil is approx­imately 90 feet. Completion of the productive well was effected from the entire 818-foot section, but drill-stem tests indicated that most of the oil came from a 30-foot section between the depths of 10,699 and 10,729 feet. LITHOLOGY OF RESERVOm ROCK Wolfcamp: The reservoir rock consists of (a) scattered thin layers of hard brownish-gray sandy limestone, (b) hard brownish-gray sandy limestone breccia, and (c) gray fine­grained sandstone interbedded with gray to black silty shale and dark-brown silty argillaceous limestone. Vertical fractures are scattered throughout this section and it is possible that they constitute a considerable portion of the reservoir. There appears to be no bed with a high degree of porosity. CONTINUITY OF RESERVOffi ROCK Wolfcamp: Data are not available for determining the continuity of the several thin beds which were productive in the one well. Good shows of oil and gas have been found at approximately the same stratigraphic positions at other wells in the Delaware basin, but whether the beds are continuous between such wells is not determinable. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Wolfcamp: Feet Elevation of top of oil -7,058 Elevation of bottom of oil -7 ,876 Relief 818 Scattered shows of oil were found throughout the above indicated section and the well was completed for production from the entire section. CHARACTER OF OIL Wolfcamp: Gravity, A.P.I.@ 60° F., 43.3. WATER PRODUCTION Wolfcamp: Water constituted about 10% of the initial gross production, which was at the daily rate of 71 barrels of oil and I 0 barrels of water. ACID TREATMENT Wolfcamp: The reservoir rock was treated with 7 ,000 gallons of acid. PRODUCTION HISTORY Wolfcamp: The one well flowed 2,722 barrels of oil during 1947 and 1.462 barrels during 1948; total, 4,184 barrels. The last reported production was in October 1948 . VERHALEN FIELD, Reeves County, Texas TYPICAL SECTION OF ROCKS PENETRATED TYPICAL SECTION OF ROCKS PENETRATED VERHALEN FIELD, Reeves County, Texas 371 ,. w w "' .... ii: w "' >­ "' "' ,.Q_ z " ,. u " a: "­ ...J Q_ w 0 3 0 u "' u z " z " >­ "' z z w Q_ z 0 >­ z " u [;~;%~fff@!J Sandstone ~Dolomite l:i£jjCo~~o;3~t~~e ~Umestone ~Sandy li mestone t======~ Sha le ~Co1coreous i limestone shale ~Sha y • Limestone sha le ~~~Sandy con9\omerote :1-..1-~: m Anhydri1e ... Solt .Oil production VON ROEDER FIELD Borden County. Texas WILLIAM B . ELLIS Geologist, Carlton Beal & Associates, Midland, Texas May 26, 1953 LOCATION and FIELD NAMES The Von Roeder field is in extreme southeast Borden County about 19 miles southwest of Snyder, county seat of Scurry County. It is in the southeast arc of the major Pennsylvanian reef trend in the northern portion of the Midland basin. There are two separate productive areas in the area herein treated as the Von Roeder field. The Railroad Commission of Texas designates the entire area as the Von Roeder field . Some operators differentiate by designating the northern productive area as the Von Roeder field and the southern pro­ductive area as the South Von Roeder field. With the exception of one well in the southern area producing from a local reservoir in the Clear Fork group, all production is from reef limestone, mainly of Cisco and Canyon age. Although the Cisco-Canyon reservoir in the northern area is at the same general stratigraphic position as the Cisco-Canyon reservoir in the southern area, the two reservoirs are separate and distinct. There are five dry holes between them and there is a 25-foot difference in elevation of water table, and, furthermore, there is an appreciable difference in reservoir pressure. In the absence of recognized names for the three reservoirs, the following para­graph headings , taken into consideration with the accompanying TYPICAL SECTION, should serve to facilitate an accurate understanding of the signifi­cant data pertaining to the field. METHODS OF EXPLORATION LEADING TO DISCOVERY Location of the discovery well was based on a reflection seismic survey in an area where sub­surface data indicated a major reef trend. DISCOVERIES Clear Fork: February 7, 1952; Magnolia Petroleum Co . #6 W . E . Murphy. This is the only well completed in this r eservoir. Cisco-Canyon North and Field: December 16, 1949; Amerada Petroleum Corp. #1 N. C. Von Roeder Cisco-Canyon South: July 17, 1950; P.R.Rutherford and Heep Oil Corp. #1 J.G . Davis ELEVATION OF SURFACE At well locations : Highest, 2 ,360 ft.; lowest, 2 ,220 ft. SURFACE FORMATIONS Recent alluvium and undifferentiated rocks of the Dockum group. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is 25 feet below the top of the Ellenburger group. This penetration was in the dry hole in the northwest corner of Sec. 70, the total depth of which is 1,565 feet below the top of the Cisco series at this location. NATURE OF TRAPS Clear Fork: The accumulation is due to updip decrease of porosity and permeability in a sloping reservoir rock. The inclination of the reservoir rock is probably due to slight initial slope at time of deposition on the flank of a reef and to differen­tial compaction of sediments below this reservoir rock. Cisco-Canyon: Each of the two main accumu­lations in the Von Roeder field is due to a convex upper limit of reef limestone which is covered by relatively impervious black shale and claystone. The form of each trap has been determined by reef growth. There appears to be no warping due to tectonic movements of rocks below the reef lim e­ stone. PRODUCTIVE AREAS Acres. Clear Fork 160* Cisco-Canyon North 1,160 Cisco-Canyon South 960 Von Roeder field 2,120 * It is probable that future development will warrant increasing the estimate for Clear Fork. THICKNESSES OF RESERVOIR ROCKS Feet Clear Fork: From top to bottom Net productive Cisco-Canyon North: From top to bottom 85 11 Net productive 39 5 Cisco-Canyon South: From top to bottom 157 10 Net productive 81 4 VON ROEDER FIELD, Borden County, Texas TYPICAL SECTION OF ROCKS PENETRATED @Reef limestone EXPLANATION E9 Dolomite ~Limestone ~Rock indicoled, ~Arg1lloceous [~{:?·~::] Sandstone [..: >:.\~/;j ::~:Yind1coted, ~ Oil produc tion ~Oolomihc sandstone W Water VON ROEDER FIELD, Borden County, Texas LITHOLOGY OF RESERVOIR ROCKS Clear Fork :. Dolomite; dark brown to buff , finely crystalline; minor streaks are siliceous, medium crystalline and contain anhydrite inclusions . Cisco-Canyon: Reef limestone; buff to gray , fine to medium crystalline with dominantly secon­dary vuggy porosity and containing minor lenses of black bituminous shale and claystone. CONTINUITY OF RESERVOIB ROCKS Clear Fork: The stratigraphic equivalent of the rock which produces in the Clear Fork discovery well has been penetrated at the location of every well and dry hole (except for two dry holes less than 1,000 feet deep) within the area covered by the accompanying map. There have been shows of oil at this stratigraphic position, particularly in wells in the vicinity of the discovery well, but in no other well has there been a showing sufficiently promising to warrant completion for production under the conditions then existing . The stratigraphic unit is continuous throughout the area of the field, but porosity and permeability adequate for commercial production have been found in the vicinity of the discovery well only. Cisco-Canyon: The two productive areas are on two distinct knobs on t°he same general reef. Water occupies the reef limestone interstices below -4 ,500 feet in the northern area and below -4 ,525 feet in the southern area, thus making two distinct productive areas. The same general reef is continuous north­eastward through Scurry County and southeast on an arc which crosses the southeast corner of Borden County, i.urns northward in Howard County and swings northwes t acros s the southwest corner of Borden County and into Dawson County. Within the a. ea of the accompanying map, at only 7 locations where the Ciscc--Canyon reef limestone has been penetrated above the respective water table have porosity and permeability been found too low for commercial production . ELEVATION AND RELIEF OF PRODUCTIVE ZONES Clear F ork Cisco-Canyon North South No free gas cap E levation of top of oElevation of bottom R elief, fe et il, ft . of oil, ft . -2 ,020 -2 ,070 50 4,420 4 ,500 80 -4,370 -4,525 155 CHARACTER OF GAS Clear Fork: No commercial gas; quantity insufficient for ga s-oil ratio test. Cisco-Canyon: Specific gravity , .98 Gasoline, 1 .26 gallons per Mcf H eating value , 1,555 B.t.u./cf CHARACTER OF OIL Clear F ork: Gravity, A.P.l.@ 60° F . 24.3 ° Cisco-Canyon: Gravity, A.P .l.@ 60° F . 41.7° Sulphur 0.26% Color Dark green Viscosity, Saybolt Universal@ 100° F . 45 sec. For analyses see: U . S. Bureau of Mines L ab. ref. No. 50035 Analyses of Crude Oils From Some West Texas Fields . R. I. 4959 (1953) Item 69 WATER PRODUCTION Clear Fork: Negligible. Cisco-Canyon: With exceptions due to minor water encroachment in edge wells, water production is negligible. ACID TREATMENT Clear Fork: The only well was treated with 2 ,000 gallons of acid. Cisco-Canyon: Many wells have been completed with:mt acid treatment; others have been treated with acid in quantities varying from 500 to 7 ,500 gallons. PRODUCTION HISTORY WELLS P R ODUCING OIL PRODUCTION at end of year {barrels) Year F lowing P umping Yearly Cum ulative Field totals 1949 0 1 ,182 1,182 1950 14 18 5 .948 187 ,1 30 195 1 36 2 l,238,858 1,425 ,988 1952 43 1,284,728 2,71 0 .7 16 - Clear Fork 1952 0 25,613 25 ,613 Cisc o-Canyon North 1949 1 0 1'182 l , 182 1950 11 1 151,524 152 ,706 1951 27 2 97 5 ,340 1,128,046 1952 25 4 808 ,446 1.936 ,492 Cisco-Canyon South 1950 3 0 34,424 34,424 263,5 18 297 ,942 1952 18 2 450 ,669 748,6 11 1951 9 0 GAS PRODUCTION: The only gas production has been incidental to oil production. The quantities produced have been minor. WAPLES -PLATTER FIELD Yoakum County. Texas C. G. COOPER and B . J . FERRIS Geologists, Shell Oil Co . , Midland, Texas January 1, 1953 LOCATION The Waples-Platter field is near the center of the southeast quarter of Yoakum County about 8 miles southeast of Plains, the county seat. It is bet-ween the Wasson and Ownby fields on the North Basin platform of the Northwestern Shelf area. Wasson , Waples-Platter and Ownby appear to constitute one continuously productive area and could logically be considered as one field . METHODS OF EXPLORATION LEADING TO DISCOVERY Reflection seismograph ;ind interpretation of subsurface data. DISCOVERY San Andres : June 3, 1939; Shell Oil Co. #1 Waples-Platter ELEVATION OF SURFACE Atwell locations : Highest,3 ,585 ft.; lowest,3,525 ft. SURFACE FORMATION Caliche and surface sand overlying Ogallala sand. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the San Andres group 640 feet below its top. NATURE OF TRAP Anticlinal fold PRODUCTIVE AREA San Andres and Field: 880 acres. THICKNESS OF RESERVOIR ROCK LITHOLOGY OF RESERVOIR ROCK San Andres: Dolomitic limestone; gray, tan and brown, compact to saccharoidal, fine-grained, cherty. The porosity and permeability are quite variable both vertically and horizontally. The extent of the portion of the San Andres formation constituting the reservoir rock is determined by the stratigraphic range of rock sufficiently porous to yield oil into the wells. Since the porosity is so variable, a large portion of the reservoir rock is not productive. CONTINUITY OF RESERVOIR ROCK San Andres : The lithologic unit considered as reservoir rock is continuous throughout the area of the field; the porosity within the unit is quite variable. Generally at the apex of the structural fold, the stratigraphically higher portion of the reservoir rock is sufficiently porous to yield oil, whereas downdip that portion is non-porous and impermeable; at lower structural positions, the porosity is lower in the section. ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Andres : Feet No free gas Elevation of highest known oil -1,670 (?) Elevation of bottom of oil -1,720 to 1,760 (?) Known relief 90 It appears that at the time of discovery of this field, the oil-water contact at the south end was at the elevation of -1,720 fe et and that the contact sloped regularly northward to -1 ,830 feet at the north end of the Ownby field . CHARACTER OF OIL San Andres : San Andres : From stratigraphic position of Gravity, A.P .I. @ 60 ° F . Average 29.9° highest production to stratigraphic position of Sulphur, by weight: 2 .26 o/o lowest production: Average, 65 feet. Color: Dark green WAPLES-PLATTER FIELD , Yoakum County, Texas OF TYPICAL SECTION ROCKS PENETRATED 432 433 434 4 437 436 435 489 492 4 84 485 486 490 491 JOHN H. GIBSON BLOCK D HORIZON 50 5 50 4 501 500 ff Ory hole • ~Discovery SCALE THOUSAND FE ET PRODUCTION HISTORY WELLS P RODUCING OIL PRODUCTION at end of year {barrels) Year F lowing Pumping WATER PRODUCTION San Andres: Most of the wells have pr oduced water either at completion or soon thereafter. At the end of 1952~ only 2 of the 13 wells were pro­ducing no water ; water constituted 23 to 64% of the gross production of the other 11 wells. An analysis of the water shows milligrams of constituents per liter of water as follows: cal­cium, 3 ,900; magnesium, 2, 190; sodium , 45, 150; bicarbonate, 573; carbonate. none; sulphate, 3,240; chloride, 80,180; total, 135,233. ACID TREATMENT San Andres: All wells were treated with acid at time of completion. Treatments, in either one or two stages, ranged from 500 gallons to 15 ,000 gallons. 1939 9 ,244 19 40 14,396 19 41 ................ 17 ,804 1942 22 ,318 1943 32,992 1944 . . 2 . ....... 12 54,210 1945 1 14 17 ,607 19 46 0 15 7 3 ,856 1947 0 .. .. 14 ... ...... 65 ,590 1948 14 64 ,007 1949 0 14 50,024 1950 ...... 0 ....... ..... . 14. .. 48 ,244 195 1 14 55,144 1952 13 5 1,070 1953• 13 48,790 •1953 data added by amendment. 9 ,244 23 ,640 41 ,444 63,762 96 ,754 .. 368 ,017 432,024 482 ,048 ..530,292 585 ,436 636,506 685 ,296 WASSON FIELD Yoakum and Gaines Counties, Texas W. T. SCHNEIDER Manager of Exploration, Mid-Continent Division, Honolulu Oil Corporation, Midland, Texas January 1, 1955 LOCATION The Wasson field occupies a triangular area mainly in southwestern Yoakum County with the southward corner extending into northwest Gaines County. The most western wells are about 4 miles from the Texas-New Mexico state boundary. From the standpoint of regional structure, the field is on the North Basin platform near its southern edge. HISTORY and FIELD NAMES For economic reasons (primarily, lack of pipe­line outlet), completion of the field discovery well was not followed immediately by further drilling activity. Development proceeded slowly, as indi­cated by numbers of wells reported in the following PRODUCTION HISTORY. Wells within the present area of the field but at considerable distances from the field discovery well were considered as dis­covering new fields. Drilling activity centered around each of several outlying wells. Each productive area was designated by a separate field name; the first was the Bennett field; the second, the Wasson field and the third, the Denver field. As development proceeded, and additional areas were designated as fields, and as it became evident that the productive areas-merge, the several field names lost their status as field names but were continued in use as sector names; For regulation purposes, on December l, 1939, the Railroad Commission con­solidated its rules and regulations applying to all sectors and designated the consolidated unit as the Wasson field. The names of Bennett, Denver, Roberts, Baumgart and Kendrick had temporary usage as field names and are used now to designate respective portions of the Wasson field. The name Wasson was applied to the second sector discovered and later was applied to the field as a whole. To avoid confusion, the sector originally designated as the Wasson field became identified as the South sector. As indicated on an accompanying map, the names Clawater and Dowdenare also used to designate sectors of the field. The boundaries between the sectors are indefinite. METHODS OF EXPLORATION LEADING TO DISCOVERY Studies of geological data afforded by previous drilling in the region and of data afforded by gravity and magnetic surveys led to the drilling of the field discovery well. Subsequent discovery wells and extension wells were located on the basis of sub­surface data afforded by drilling and by data afforded by gravity, magnetic and seismic surveys. DISCOVERIES San Andres and Field: April 15, 1936; Honolulu Oil Corp. & C.J.Davidson #1-678 L.P. Bennett (now Honolulu Oil Corp. & Cascade Petroleum Co. #1-678 L.P.Bennett). Clear Fork 66: December 24, 1940; A.G. Carter #>D A.L. Wasson (now, Shell Oil Co. #>D A.L. Wasson). Clear Fork 72: December 20, 1941; A.G. Carter #4-D A.L. Wasson (now, Shell Oil Co. #4-D A.L. Wasson). Clear Fork Bennett: September 3, 1954; Texas Pacific Coal & Oil Co. #55 Ruth Bennett Z-E Account. ELEVATION OF SURFACE As indicated by contours on an accompanying map, the surface slopes generally southeastward from an elevation of about 3, 700 feet above sea-level on the west to about 3,520 feet on the east side of the field. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest stratigraphic horizon penetrated is at the base of detrital sediments overlying granite. Within the productive area, the oldest stratigraphic horizon known to have been penetrated is in the Simp­son group about 280 feet below its top. This pene­tration was in the well designated as Well (A) in the following tabulation under VARIATIONS IN THICKNESSES. This well was drilled 5 feet into granite. Only two other wells have been drilled into pre-Permian rocks. Data afforded by the three wells are presented in the above cited tabulation. PRODUCTIVE AREAS Acres San Andres 59,925 Clear Fork 66 1,000 Clear Fork 72 480 Clear Fork Bennett 80 Wasson field 59,950 THICKNESSES OF RESERVOIR ROCKS Feet From top to bottom, gross: Min. Max. Avg. San Andres 5 450 186 Clear Fork 66 98 621 362 Clear Fork 72 242 367 323 Clear Fork Bennett 80 137 108 WASS 0 N FIELD , Yoakum and Gaines Counties, Texas SURFACE FORMATIONS Recent caliche and wind-blown sands. Where there is a soil mantle, it is thin. NATURE OF TRAPS General: The trapping of fluids in each of the Permian reservoirs is occasioned by a balance of closely related r egional, local, and temporal con­ditions that resulted in (1) a convex form of the upper extent of the reservoir rock, (2) local and regional variations in lithology and consequent porosity and permeability trapping, (3) volumetric ratio of fluids and permeable space, (4) geologic history. No single a gency (such as structural attitude or lithological variations) can be isolated as the sole controlling factor. The geologi c con­ditions cited are the result of (1) differential and regional subsidence of and around a pre-Permian uplift during the Permian period, (2) concurrent reef construction by chemical and organic processes around a subsiding pre-Permian high which not only kept abreast of the subsidence but slightly ex­ceeded it on the eastern side of the field, where the maximum subsidence took place. Hence the present convex profile of the porous rocks of the Clear Fork and the San Andres reservoirs is the result of a negative process of downwarping and a concurrent constructive process of reef building. Progressive variations in the lithology of the reef facies from east to west account for variations in (1) well per­formance, (2) fluid contact elevations, and (3) reser­voir thicknesses. The gross productive intervals of the Clear Fork reservoirs are much greater than that of the SanAndres reservoir; however, the lower orders of permeability and porosity have made the Clear Fork reservoirs, thus far, less productive than the San Andres reservoir. San Andres: The reservoir rock is thicker and has a higher degree of permeability in the eastern portion of the field where the maximum subsidence and the maximum reef development took place. The gas cap conforms to the highest structural position. Bottom waters do not conform to a sea-level datum, but are lower in the center and northern portions of the field. ' Along the eastern edge of the field the waters appear to occur along a stratigraphic position. Clear Fork 66 and Clear Fork 72: The accumu­lation in each of these reservoirs appears to be con­trolled by a structural nose that may be due to reefing and differential movement; however, also permeability and porosity are trap-forming factors in the reef-like mass of dolomite. Clear Fork Bennett: Insufficient data exist to determine the structural attitude of the reservoir rock. Rapid changes of permeability and porosity suggest a trap controlled by decrease of porosity and permeability to the we st. VARIATIONS IN THICKNESSES Isopach maps between Permian markers show thinning in the areas where an accompanying map indicates the top of the San Andres as structurally high. With the exception of the post-Triassic beds, each stratigraphic unit above m i d-San Andres shows some increment of thinning. The structural relief of the respective markers decreases from the lowest marker to the highest marker until, at the surface, the altitude of the beds shows only negligible devia­tion from the altitude due to regional tilt. However, the progressive westwardmigration of the structural axis, combined with the relatively strong eastward tilting, has, to a minor degree, masked the gradual upward thinning over the old structural axis. Although only three wells have been drilled into pre-Permian rocks, it is evident that there are great variations in intervals between Permian and pre-Permian markers, due inpartatleast to trunca­tion and off-lap of pre-Permian rocks. Variations in thicknesses are reflected in the following tabula­tion of data pertaining to the three wells which were drilled into pre-Permian rocks. In the following tabulation those wells are identified as Well (A), Well (B) and Well (C). Well (A) was drilled as Denver Producing & Refining Co. #>A C. A. Elliott and is now designated as Fikes & Murcheson #>A C. A. Elliott. It is located in Sec. 832, Blk. D, HORIZON is entered on an accompanying map. Well (B) is the Clear Fork 72 discovery well. Well (C) is Honolulu Oil Corp. #9 E. Hovencamp, which is the Clear Fork 72 well in Sec. 890, John H. Gibson survey, where OLDEST Blk. D, John H. Gibson survey. (A) (B) (C) Surface elevation, ft. 3, 618 3, 564 3, 572 Total depth, feet 11, 195 11, 108 11, 592 Elev. of total depth, ft. -7, 577 -7, 544 -8,020 Elevation of top, feet: San Andres -772 -766 -908 Glor i eta -2, 162 -2, 066 -2, 258 Clear F ork -2,632 -2, 746 -2, 948 Drinkard (Tubb) -3, 277 -3, 396 -3, 688 Abo -3,827 -3,846 -4, 278 Wolfcamp -4, 892 -5, 206 -5, 678 Pennsylvanian -5, 782 ? -7, 378 Mississippian -5,882 -6, 536 -7,968 Woodford -5,982 -6,936 Devonian -6,052 -6,986 Fusselman -6, 892 Montoya -7, 182 Simpson -7,292 Granite -7, 572 Interval, top to top, feet : (A) (B) (C) San Andres-Clear Fork l, 860 1,980 2, 040 Clear Fork-Wolfcamp 2, 260 2, 460 2, 730 Wolfcamp-Mississippian 990 l, 330 2, 290 WASSON FIELD, Yoakum and Gaines Counties, Texas LITHOLOGY OF RESERVOIR ROCKS San Andres: Dolomite; granular, with high de­gree of porosity. In general, the percentage of granularly porous dolomite diminishes westward to the gain of finely crystalline dolomite with a low de­gree of porosity. In the eastern part of the field, the reservoir rock contains thin lentils of dense dol­omite which occur in the manner of fores et beds, thus disclosing the incremental nature of the individual low stage reef units that combined to constitute the whole reef mass. These lentils disappear westward as they blend into tight finely crystalline dolomite. The reservoir rock is differentiated from overlying San Andres dolomite by the degree of porosity. However, it differs also in that it is of granular texture and contains minor amounts of chert and paper-thin partings of black shale. The porosity of the reservoir rock is of three types with pores averaging about O. 5 mm. in diameter and with diameters greater than 1 mm. very rare and with only very few larger than 2 mm. : (a) cavity-type with small irregularly shaped voids, (b) cast-type ·with pores showing fossil-cast outline and resulting from the removal of organic remains, and (c) inter­granular-type in which the interstices are among the dolomite granules of varying degrees of crystal­lization. The coarser pores of cavity and cast types are not consistently filled with oil. The intergranular type constitutes a large pa:rt of the pore space and, though finer than the other two, appears to yield the most oil -apparently because of greater permea­bility. The top of the reservoir rock (i. e. , the top of that portion of the San Andres dolomite which is sufficiently porous to yield oil and gas) is generally about 350 to 500 feet below the top of the San Andres formation. Clear Fork 66 and Clear Fork 72: Dolomite; fine-grained with low porosity and low permeability. Porosity and permeability in both reservoirs vary abruptly. Clear Fork Bennett: Dolomite; very similar to that of the other Clear Fork reservoirs. CHARACTER OF GAS ELEVATION AND RELIEF OF PRODUCTIVE ZONES San Andres Elevation of top of gas Elevation of bottom of gas Relief Elevation of top of oil Elevation of bottom of oil Relief Feet -1,000 -1, 316 to -1, 340 340 -1, 316 to -1, 550 -1, 428 to -1, 740 424 The oil-water contact is highest at the south end of the field and lowest at the northeast cor­ ner. Clear Fork 66 No free gas Elevation of top of oil Elevation of bottom of oil Relief Clear Fork 72 No free gas Elevation of top of oil Elevation of bottom of oil Relief Clear Fork Bennett No known gas cap Elevation of top of oil Elevation of bottom of oil Relief -2, 700 to -3, 043(?) -3, 117 to -3, 326( ?) 626 -3, 441 to -3, 936 -3, 796 to -4, 178 737 -4, 179 -4, 316 137 The above data represent conditions as of re­spective discovery dates. Removal of fluids has occasioned some minor adjustments of fluid eleva­tions, particularly the elevation of the gas-oil contact in the San Andres reservoir. The oil-water contacts in all reservoirs are now within a few feet of their positions at discovery dates. SELECTED REFERENCES Following is an analysis of a sample of typical casinghead Donnelly, A. S. (1941) High-pressure Yates gas from the San Andres reservoir: sand gas problem, Wasson field, Yoakum Component Mol. % Hydrogen sulphide Carbon dioxide Nitrogen Methane Ethane Propane !so-butane N-butane Iso-pentane & heavier 0.26 6.50 1. 01 58.22 16.81 11. 94 1. 26 2.86 1. 13 99.99 County, West Texas: Amer. Assoc. Calculated Petro. Geol., Bull., vol. 25, pp. · 1880­1897. Specific gravity Gasoline Gals. !so-butane N-butane Iso-pentane & heavier 35% butanes & 65% pentanes 0.8998 Schneider, W. T. (1943) Geology of Wasson I Mcf field, Yoakum and Gaines Counties, Tex­ as : Amer. Assoc. Petro. Geol., Bull. , 0.4104 vol. 27, pp. 478-523. 0.9051 Cattell, R. A. (1953) Sulfur compounds 0.4124 identified in Wasson, Texas, crude oil: U. S. Bureau of Mines, I. c. 7659, 0.6344 p. 35. WASS 0 N FIELD , Yoakum and Gaines Counties, Texas GENERALIZED COMPOSITE SECTION OF ROCKS PENETRATED z 0 ,. ;:: Q_ LITHOLOGY UJ ",. UJ "' "' ~ .... :J "' 0 '" 0: :J RESERVOIR 0: >­ UJ 0 ;;' u. DESIGNATION "' "' "' UJ _, z Sholts ond sondstonn , red, micoceous i u ,. u u; :J u "' " 0 Cl " .... '" ISOO -_-_:-_-_-_-_­ l--+-------1:-.-:::::::::::-.::--+---------------I -:;..:.;;:_;,:.-~·~:~:::;:: Sond•tonu,rtd ond i;iroy;shOIH,rtd w SrTA ROSA TECOVAS ? Shalt, red, compact l ==-=-~;~J}i.-..~~.~..•. ,-.--.•--. ,.. ,-~~••~;~,".~'".~-~.~~~~~-'-" DE,WEY LAKE ··:-·.:: : . .":.::~\ fros ltd quartz c;iroins RUSTLER 0 " 0: u 0 0 Cl " Solt; minor btds of anhydrite, _, potash ond elastics " "' TA 0 NSILL Solt; anhydr ite, dtnst ; shale, silty Y~TES Sondstont, rtd,frosted quartz groins UJ "' 0: 0 :J: UJ !:: :J: 31: "' 0: UJ > '"z UJ ~ "' Anhydrite; so11; sandstones ond sholu, red ~ .., :J 0 Sond1ton1, rtd; solt;dolom ift; anhydrite z !!,. 0:.., Q_ "'0: :J ~ " 0: "' ; ;;.·...·:.:::,:~.. :.: .... Anhydrite; dolomllt; sondstonH, rtdood oroy;bentonift .., Q_ :J_, " Cl Oo lo mllt, ton ond brown, fintly crystollint; " minor amounts of anhydrite :J "' .., "' 0: Cl " z z " "' Oolom lh, brown, portly c;1ronu lor, ~ 0: _, "' portly fintly cryatolline, porous to compact; trocH of chtrt ond shale EXPLANATION Solt Chert ~Limestone ~Dolomite ~Shale ~ Dolomite, portly crystollint, porfly c;1ronulor, nr~rNH ~Porous dolomite mAnhydrite ~ Sondstone ~ill Granite sligh1lyporous; trocesof1ond FL UID COLUMN SYMBOLS • Oil prod uction ~ Gos production ):( Noninf1ommoble gos W Woter WASSON FIELD, Yoakum and Gaines Counties, Texas NONINFLAMMABLE GAS ACID TREATMENT Throughout an area indicated on an accompany­ing map, the Yates formation yields noninflammable gas at pressures up to 2, 800 psi. During develop­ment operations, this gas was a serious hazard and added considerably to the cost of wells; it forced setting of additional casing, caused casing to collapse in many wells and caused complete loss of several holes. While the Yates gas in the indicated area is under high pressure and is noninflammable, small quantities of normal, but lean, inflammable gas occur in the Yates formation in the central and west parts of the field. Gas showings, at least, have been found in the Yates formation throughout the area o(the field. While some samples from the high­pres sure area show as much as 97% nitrogen, the following composition is more generally representa­tive: methane, 6. 5%; ethane, 0. 3%; propane, O. 2%; butane, 0.3%; pentane, 0.1 % ; nitrogen andinert gases, 92. 5%; spectroscope analysis indicates no helium. In a. small portion of the above mentioned area where the Yates formation yields high-pressure noninflammable gas, a member of the Queen formation also yields noninflammable gas at about the same high pressure. Since this gas occurs only locally and was found in only a relatively few wells, it is not indicated on the accompanying typical section. Since the above mentioned gas occurrences are not commercial, they are not given further treat­ment in this paper. Multi-stage acid treatments have been used on nearly all wells; generally, three-stage, but occasionally, two-stage. The common practice has been the use of pressure treatment with 1, 000, 2, 000 and 5, 000 gallons preceded by a wash treat­ment with about 700 gallons to clean the bore-hole wall. While the total quantity of acid has been nor­mally aboot 8, 700 gallons, more has been used in several wells, with the maximum known totaling 22, 000 gallons. Generally, treatment requires 6 to 14 qays. WATER PRODUCTION San Andres: On January 1, 1952, the gross production of each of 177 wells was more than 2% water. During test periods, the ratio of water to oil in the total production from the reservoir was 1 : 520 in 1938, 1 : 43 in 1944 and 1 : 53 late in 1951. Clear Fork 66: During test periods, the ratio of water to oil in the total production from the reser­voir has ranged from 1 : 321 to 1 : 20. During a t e st late in 1951, the ratio was 1 : 31. Clear Fork 72: Water production has been negligible to date. Clear Fork Bennett: Water production has been negligible to date. CHARACTER OF OIL San Clear Fork Andres 66 72 Bennett Gravity, A.P.I. @60°F. 34.6° 32.8° 35.2° 30. 7° Sulphur 1. 63% 1. 41% 0. 99% Sour Viscosity, S. U. @ 100° F., sec. 41 41 38 ? For analyses see: Railroad Commission of Texas Analyses of Texas Crude Oils (1940), pp. 34 and 64 Reference U. S. Bureau of Mines designation Tabulated Analyses of Texas Crude Oils. R. I. 3252 (1934) A Tabulated Analyses of Texas Crude Oils. T. P. 607 (1939) B Analyses of Crude Oils from Some West Texas Fields. R. I. 3744 (1944) Analyses of Crude Oils from 283 Important Oil Fields of the U. S. R. I. 4289 (1948) D Analyses of Crude Oils from Some West Texas Fields. R. I. 4949 (1953) E Reference designation Lab. ref. No. 31162 38146 38147 43143 43144 43145 48093 50070 A Group 2, Item 2 B Group 2, Item 43 2 c Page 39 . 40. 41 . D Item 268 E Item 93 94 ? 598 599 600 647 646 645 JOHN H. GIBSON BLOCK D 662 663 726 775 790 839 854 903 745 874 883 30 22 21 ----3620 ---­Contour showing elevation of surface Oil well, productive from Son Andres I• Oil well, productive from Cleor Fork 66 •t Oil well, productive from Clear Fork 72 !. Oil well1 productive from Clear Fork Bennett Abandoned oil well .P' Ory hole • ~Discovery Co. tn-'!1e1 345 " 20 ~~Ar~fg;_hperreess~~;e~ofn~~T1~~o~o~i1:ld;os ~Area of Son Andres gos cop IIDIEOOWCE~ Nome of development sector w N ~ ~ Cf) Cf) 0 z '"11 ....... M L' tJ .....::: 0 Q a ~ [ Q g1 S­ m ~ ::s ...... ~f r ~ ~ r.n r.n 0 z "Tj ........ M r-' 0 -< 0 Q ~ s [ Q ~ 5· -3 ~ ~ w 00 w PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at e nd of year (barrels) Year F lowing Art. lift Yearly Cumulative San~res l936 l 9 ,506 9 ,506 1937 26 3 14,024 323,530 l 9 38 20 l 2 .sol ,645 3,125, 17 5 l 939 707 22 5,934,151 9 ,059 ,326 l ,02 l. ........... 23. 10,976,744.. 20 ,036,070 l 941 1,253 58 13 ,0 13 ,979 33 ,050 ,049 1942 l.311 68 9 ,5 l l .962 42 ,562,011 1943 l .337 l l 3 12,386,5!6 54,948,527 1944 l ,366 143 23,725,909 78,674,436 1945. .... l,347 ......... . 192 .. .. 22,659,524. 101,333 ,960 1946 l,346 198 20,706.513 122,040,473 l 947 1,380 19 3 25,407 ,883 147 ,448,356 l 948 l ,377 21 l 28,165,780 175,614,136 l 949 l ,368 232 18,765,190 194,379,326 1950. 1.387 .247 .. .. 18 ,051,249 .. .. 212,430,575 l 95 l l ,370 275 21,633,959 234,064 ,534 1952 l ,376 302 l 9 ,438 ,608 253,503,142 l 953 1.392 306 18,421,128 271,924,270 1954 1,380 3 19 l 5 ,4 l 5 ,569 287 ,339 ,839 Clear F ork 66 1940 l ,849 l ,849 l 941 19 ,l73 21,022 1942 14,747 35 ,769 1943 19 ,Ol 3 54 ,782 l 944 63,263 l 18 ,045 245 ,46!. . 36 3 ,506 1946 14 423,823 787 ,329 l 947 14 512 ,459 l ,299.788 l 948 5 18 643 ,533 l ,943 ,32 l 1949 l 2 l 447 ,"359 2 ,390 ,680 !... . ... ..... 2 l 430,96!. .. 2,821 ,641 195 l 21 502 .507 3 ,324,148 1952 21 443 ,425 3,767,573 l 953 22 421.714 4 .189 ,287 1954 23 362 ,845 4,552,1 32 Clear F ork 72 l 94 l 1,077 l.077 l 942 33 ,819 34 ,896 l 943 14 .9 32 49 ,828 l 944 62 ,6 l I 11 2,439 180,232 ..... 292 ,67 I 1946 10 18 3 ,048 475,719 1947 5 129.927 605 ,646 1948 ·4 72,604 678 ,250 1949 0 37 ,290 715,540 l 950..... 752,014 1951 34,988 787 ,002 1952 31,973 818,975 l 953 29 ,473 848,448 1954 4 25,116 873 ,564 Clear Fork Bennett 1954 l 1.954 l l ,954 GAS PRODUCTION: Although in the San.Andres reservoir there was a gas cap which extended over an area of about 12,800 acres and which contained a large volume of free gas, there were only very few wells ever operated as gas wells. From time to time, there have been one, two or three wells operated temporarily as gas wells. The total quan­tity of gas produced by such wells has been relatively small. However, a very large quantity of gas has been produced incidental to the production of oil from the San Andres reservoir and minor amounts from the Clear Fork 66 and Clear Fork 72 reservoirs. The writer estimates that the total quantity of gas produced to January l, 1941, amounted to 35,500,000 Mcf and to January l, 1955, to 449,288, 727 Mcf. Practically all of this gas has been treated in one or the other of two gasoline plants (combined capacity, 142.,000 Mcf per day) located within the field. The liquid products have been exported mainly through two 6 -inch pipelines, only one of which is now operating. w 00 ,.j:>. ~ :x::o rn rn 0 z '"Tj :0A~:~: ::~.:::· : = ·lllfllllJQ[ll,UllJfllijl //~> ./. 7 ••1....... • •' ./ 7 M r' / Q .,o \ --·>(/~ . tJ ,· ~ 51: \\ 0--< ~ ~ ~. •/ /. / Q . \ '"'\ \ / ./ s ~ 'v'~\ • ' ::::s ·~ . 'b\ . \.. . . • . . Q ~ . \ . . . 0... \ • \ • .\ • ): 1· r f ·i 1 . . . . I. J . 52 • ) • : p·49 • I•\I•\. . I . /. I I. ~ I• ! ~' • \ \ I•• I ·/ . I s· I r I· ·' • • 1 m PUBLIC SCHOOL LANO • i· I• I~! ~ '.), \ \ I . , . 1· + .II . BLOCK AX /. • TO ~001 ~ ::::s ...... (i)" _UJ 41 '"""3 42 ~ -~ EXPLANATION ----2050 ----Contour on top of GJodeto formation • Oi1 well , productive from Son Andres fi I• Oil well, productive from Clear Fork 66 • I Oil well, productive from Clear Fork 72 I• Oil well, dry in Clear Fork 66 • I Oil well, dry in Clear Fork 72 +Abandoned oil well P Dry hole • ~Discovery B WATER VALLEY-CLARK FIELD Tom Green and Sterling Counties. Texas THOMAS H. COLE Consulting Geologist, Midland, Texas May 19, 1953 LOCATION The Water Valley-Clark field is about nine miles west of the town of Water Valley and is partly in Tom Green County and partly in Sterling County. In prior publications, this field has been treated generally as two fields, the Water Valley field in Torn Green County and the Clark field in Sterling County. METHOD OF EXPLORATION LEADING TO DISCOVERY Mapping of subsurface g eological data. DISCOVERIES San Andres: November 1, 1948; Placid Oil Co. #1 L. T. Clark. This well was drilled to total depth of 7, 738 feet (154 feet into Ellenburger) and was plugged back to produce from a zone in the San Andres formation, the top of which zone is at depth of 1, 035 feet. The initial daily potential was at the rate of 43 barrels of oil per day. San Angelo: February 3, 1950; Walker & Neill #1 George Weddell (now, Curtis Oil Co. #1 George Weddell). SURFACE FORMATION Undifferentiated Cretaceous limestone. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldesthorizonpenetratedis in the Ellenburger group 781 feet below its top. This penetration was in The Ohio Oil Co. #1 L. T. Clark, which is located near the apex of the structural high near the north end of the field, as indicated on the accompanying map. The discovery well is the only other well which was drilled to the Ellenburger within the area of the accompanying map. The author thanks Mr. Clyde M. Pederson and Mr. Alan Roberts of Cities Service Oil Company, Mr. J. Spencer Collins of Tennessee Production Co~pany and Mr. E. Russell Lloyd, Consultant, for their assistance in the preparation of this paper. ELEVATION OF SURFACE The elevation of surface ranges from 2,200 feet to 2, 400 feet above sea level. STRATIGRAPHIC POSITIONS OF RESERVOIR ROCKS This field is characterized by a series of thin zones which yield oil into the drill-holes. These zones are at various stratigraphic positions and most of them are evidently of only local extent. It appears probable that there are many separate and distinct reservoirs without intercommunication except through drill-holes. While the productive zones are mainly in the middle portion of the San Andres formation, their stratigraphic positions range from the top of the San Andres downward into the uppermost part of the Clear Fork group. At the north end of the field, there are a few wells producing from near the top of the San Andres; southward, the cor­relative section is nonproductive. Near the south end of the field, several wells produce from thin zones in the San Andres and thin zones in the San Angelo, and two wells produce also from the upper­most part of the Clear Fork, where the production is not sufficient that it alone would be commercial. NATURE OF TRAPS Since an anticline is the dominating structural feature in the area of the field, it appears likely that convex folding constitutes the primary trap­forrning factor, at least, as to several of the reservoirs. Updip and lateral lensing and decrease of porosity and permeability appear to have trapped the oil in several of the thin, local reservoirs. THICKNESSES OF RESERVOIR ROCKS The thicknesses of the several distinct reservoir rocks range from zero to about 20 feet. Except in the north part of the field (that part in Sterling County and known as the Clark field), the thickness of each productive zone is on the order of 5 feet or less. In Sterling County, four distinct reservoirs in the San Andres dolomite have been recognized and have thicknesses as follows : "980-foot", 15 feet; "l,010-foot (Clark zone)", 20 feet; "l,050-foot", 20 feet; and "l,080-foot", 15 feet. The number of zones and the total net thickness producing in individual wells is extremely variable. 386 WATER VALLEY-CLARK FIELD, Tom Green and Sterling Counties, Texas LITHOLOGY OF RESERVOIR ROCKS San Andres: Dolomite and sandstone. Most of the production is from dolomite at locations where the degree of porosity is above normal. Local lenses of sandstone, generally less than 5 feet thick, yield oil at locations where the degree of porosity is favorable. Such locations are limited to that portion of the field in Torn Green County. San Angelo: Sandstone. In the south part of the field, 2.3 wells are producing some oil from sandstone in the San Angelo formation . Clear Fork: Dolomite. Two wells are pro­ducing a minor quantity of oil from dolomite at the top of the Clear Fork group. CONTINUITY OF RESERVOIR ROCKS The stratigraphic zone (San Andres -Clear Fork) in which the several reservoirs occur is continuous throughout the area of the accompany­ing map and is of about the same general charac­ter throughout that area. The individual reser­voirs, however, are generally of only local extent. While it is evident that there is no long-distance continuity of zones where the degree of porosity and permeability are adequate for commercial production, it is not determinable whether there is continuity of porosity and permeability adequate for long-distance migration of fluids in geologic time. CHARACTER OF OIL Gravity, A.P .l.@ 60° F.: 2.8° -34° Sulphur : 1% -l.5o/o Base: Asphalt Color : Dark brown, dark green and black Gas content: Under saturated WATER PRODUCTION Most wells produce some water and at an essentially constant percentage of gross produc­tion. Generally, the percentage of water is directly related to str~ctural position, with water constituting as much as 50o/o of the gross produc­tion of some of the low wells. COMPLETION TREATMENT The reservoirs in nearly all wells were treated at time of completion either by acidiza­tion, by shooting with nitroglycerin or by hydrau­lic fracturing. The dolomite reservoirs have been acidized generally with 500 to 1,000 gallons of acid, but, in a few wells, the quantity was as high as 7,000 gallons. As to the sandstone reser­voirs, the general practice during the early history of the field was to shoot with 20 to 60 quarts of nitroglycerin. During recent comple­ TYPICAL SECTION OF ROCKS PENETRATED ,. LITHOLOGY .... "' ..J "' >­ DEPTH ELEVATION Q "' "' "' "' 0 :i:: "' :i:: 3' z "' ..J "' ,. ­ 0 "' 0 "' "' :::> z "' "' z "' 0 1Hni1i"!l r.11ifttiriJ.1iiJ.li .. "' ..J "' z :1 1;1 1 1:111i1~:~nWnN@ .. -: :··· .· -: ·.·;:.·.·.· ..z "' 1300 "" 0"' "' 0 "'u. z "' ~ ~ ..J ..J u 970 c ~Limestone Ill G•oy shole EXPLANATION ~Dolom ite Ill G,.en shote Sandstone E22] Red shale Iii tions, some operators have successfully used Oil production is at irregular hydraulic fracture treatments; quantity of fluid Anhydr ite positions within the above has ranged from 25 to 100 gallons . ind icofed stratigraphic ronoe. WATER VALLEY-CLARK FIELD, Tom Green and Sterling Counties, Texas 387 31 13 32 130 127 p' t410 H. 8 T. C. BLOCK RR . 6 129 CO. 128 PRODUCTIVE AREAS Acres San Andres only l ,040 San Andres and San Angelo 200 San Andres , San Angelo and Clear Fork 30 Water Valley -Clark field 1 ,27 0 PRODUCTION J:USTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Al1 Pumping Yearly Cumulative 1948 420 420 1949 13 ,109 13,529 1950 36 112 ,254 125,783 1951 68 165 ,396 291,179 1952 80 187 ,783 479,176 1953• 87 173 ,015 652 ,191 •1953 data added by amendme nt. 33 34 35 S. f' RR. co. ;. I• JI • 1306 g;I• 1fo • • /./.I• ~ I• ;. ;.~ /12 28 72 73 74 H. 8 T. C. 76 ( ,r{ 1398 75 RR. CO. BLOCK 5 67 70 69 68 66 E X PLANATION >­ f- z --+ 1380 Contour on top of Son Andres formolion >­ f­ ::J 0 Total depth z ::J (_) Oil well, producin9 from San Andres 0 (_) Oil well, producing from S on Andres and Son Angelo 57 Oil well, producing from Son Andres, San An9elo, and Clear Fork JI Dry hole z w (.'.) w a:: z (.'.) -' SCALE a:: ~h THOUSAND FEET (/) 0 f­52 48 WEBB RAY FIELD Upton County, Texas E . S. HUGHES Geologist, Gulf Oil Corporation, Fort Worth, Texas January 1, 1955 LOCATION The Webb Ray field is in southwest Upton County 2-! miles southeast of the McCamey fi e ld and st miles east-southeast of the town of McCamey. METHOD OF EXPLORATION LEADING TO DISCOVERY Mapping of subsurface geological data. DISCOVERY Grayburg: November 19, 1935; W.C.Ray #1 Cordova Union Oil Corp. The initial daily pumping capacity was at the rate of 334 barrels of fluid, 10% of which was water, from a total depth of 2,125 feet. MAP, LITHOLOGY and STRATIGRAPIUC SECTION Because of geographic and geologic relationships with the McCamey field, this field is shown on the map in the foregoing paper on that field. The TYPICAL SECTION and the description of the lithology of the Grayburg reservoir rock in the paper on the McCamey field apply also to this field. The stratigraphic position of the reservoir in this field is the same as that of the Grayburg reservoir in the McCamey field. ELEVATION OF SURFACE At well locations : Highest, 2,622 ft .; lowest,2,570 ft. SURFACE FORMATION Undifferentiated rocks of the Comanche series. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated in the Webb Ray field is in the Grayburg formation 216 feet below its top. This penetration was at the total depth of 2,176 feet in Cordova Union Oil Corp. #1 Cordova Union Oil Corp., located in the extreme southwes t part of the field where the total depth of 2,176 feet i s indi­cated on the accompanying map. NATURE OF TRAP Grayburg : The trap is due primarily to a small anticlinal fold with approximately 50 to 60 feet of closure. PRODUCTIVE AREA Grayburg and Field: Approximately 150 acres. THICKNESS OF RESERVOIR ROCK Grayburg: The gross thickness of the zone con­taining productive rock is on the order of 10 to 30 feet. Data are not available for estimating the portion of that zone which yields oil. CHARACTER OF OIL Grayburg: Gravity, A.P.I. @ 60° F., 26.5 ° WATER PRODUCTION Grayburg : At time of initial completion, sulphur water constitute d a large portion, generally 10% to 7 5 % , of the gross production of most of the wells . Detailed records of water production are not available. COMPLETION TREATMENT Grayburg : Most of the wells were treated with acid at time of completion; quantities used ranged from 1,000 gallons to 2 ,000 gallons. One well was shot with nitroglycerin. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels} Year Pumping Yearly Cumulative 1935 1 1,33 1 1,331 19 36 2 12,809 14, 140 1937 ....... . .. .. . 3 ............ . ...... 8,407 ........ 22,547 1938 4 8,277 30,824 1939 4 10,014 40,838 1940 ............. 4 ................... 8,785 ........ 49,623 1941 2 5,894 55,5 17 1942 2 3,972 59 ,489 1943 ............. 2 ...... ............. 2,791 ........ 62,280 1944 1 1,490 63 ,770 1945 1 l,727 65,497 1946 ............. 1 ............... .... 2,633 ........ 68,130 1947 2,810 70,940 1948 1 2,816 73,756 1949 ............. 1 . .................. 2,343 ........ 76,099 1950 2,422 78,521 1951 2,056 80,577 1952 ............. 1 ................... 1,695 ........ 82,272 1953 l ,856 84 ,1 28 1954 1 ,419 85 ,547 WENDLAND FIELD Coke County, Texas C . R. WINKLER, Jr. Geologist , American Republics Corporation, Midland , Texas December L 1953 LOCATION The Wendland field (one well) is in the J . A. Gutierrez survey in southeastern Coke County about 7 miles southeast of the town of Robert Lee, county seat. METHODS OF EXPLORATION LEADING TO DISCOVERY Surface geological mapping and magnetic surveying. DISCOVERY Ellenburger: May 21, 1948; Shamrock Oil & Gas Corp . #1 H . G. Wendland ELEVATION OF SURFACE At well location: 1,870 ft. (Derrick floor, 1,880 ft.) SURFACE FORMATION San Angelo formation of Double Mountain group . OLDEST STRATIGRAPHIC HORIZON PENETRATED 25 feet below top of Ellenburger group. NATURE OF TRAP Ellenburger : The well is on a north -south trending Ellenburger terrace. The oil accumulation is isolated in a small local anticlinal fold on the larger structure . The factors controlling accumu­ lation are those anticlinal fold . of a simple convex trap on an PRODUCTIVE AREA Ellenburger and Field: 40 acres . THICKNESS OF RESERVOIR ROCK Ellenburger: 20 feet, gross. LITHOLOGY OF RESERVOm ROCK Ellenburg er: crystalline gray Dolomite; varies from to medium crystalline tan; finely highly fractured. Small amounts of chert occur locally. Production is from fractures and a little inter­crystalline type porosity. CONTINUITY OF RESERVOm ROCK Ellenburger: While the Ellenburger dolomite in which the reservoir occurs is continuous over a very large area, the porous condition which occa­sions commercial production at this location is a local condition, not present at the offset well and probably not continuously present throughout more than 40 acres surrounding the producing well . ELEVA TION AND RELIEF OF PRODUCTIVE ZONE Ellenburger: Feet No free gas cap Elevation of top of oil -4,350 Elevation of oil-water contact -4,370 Oil column 20 CHARACTER OF OIL Ellenburger : Gravity, A .P .I. @ 60 ° F. 49 ° Sulphur 0.1% CHARACTER OF GAS Ellenburger : The only gas produced is the small quantity which comes out of solution as the oil is produced. No analysis is available. WATER PRODUCTION Ellenburger : A small amount of water is produced with the oil. During potential test, water production was at the rate of 2i barrels per day. ACID TREATMENT Ellenburger : The well was washed with 250 gallons of mud acid and then treated with 1,000 gallons of regular acid. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Pumping Yearly Cumulative 1948 1 2,627 2 ,627 1949 1 2 ,738 5 .365 1950 l 1,978 7,343 1951 1 1.795 9.138 1952 1 1.407 10,545 WENDLAND FIELD, Coke County, Texas SECTION OF ROCKS PENETRATED WEST ANTON FIELD Hockley County, Texas C. S . PRESTON and M. V. SMITH Geologists, Sunray Oil Corp. , Midland, Texas December 31, 1952 LOCATION The West Anton field is 6 miles west of the town of Anton and 15 miles northeast of the town of Levelland, the county seat of Hockley County. It is one of several fields on the North Basin platform. METHODS OF EXPLORATION LEADING TO DISCOVERY In March, 1944, Humble Oil & Refining Co . conducted a broad reconnaissance survey in the region which includes the present area of the field. On the basis of a detailed seismic survey begun in March, 1949, Humble Oil & Refining Co. made the location for the test which became the discovery well. DISCOVERY Leonard: October 31, 1950; Humble Oil & Refining Co., #1 J. J. Hobgood ELEVATION OF SURF ACE Atwell locations: Highest.3.470 ft.; lowest,3,461 ft. SURFACE FORMATION Undifferentiated Tertiary sands . OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest rocks penetrated within the area of the field were penetrated in the discovery well, the log of which afforded the basis for the accompanying TYPICAL SECTION OF ROCKS PENETRATED. The oldest sedimentary rock is about l,250 feet below the top of the Wolfcamp series and is at the base of such portion of the Wolfcamp series as is present. The Wolfcamp unconformably overlies pre-Cambrian rhyolite, which was penetrated 1, 129 feet. Itappears probable that the pre-Cambrian rhyolite constituted a topographic high at the beginning of Wolfcamp time and that sediments of early Wolfcamp age were not deposited here. Since the writers do not have positive proof that the rocks immediately overlying the pre-Cambrian rhyolite are actually of Wolfcamp age, it appears appropriate to recognize that other geologists have expressed the opinion that such rocks are of Ellen­burger age. Top of Ellenburger has been reported at depth of 8,885 feet and top of Mississippi lime­stone at depth of 8, 780 feet in the above mentioned Well. NATURE OF TRAP Leonard: Convex folding is definitely the pri­mary trap-forming factor. Fracturing of the reser­voir rock appears to have been a secondary factor in occasioning the accumulation of oil at its present location. PRODUCTIVE AREA Leonard and Field: About 320 acres proven by development to d~ THICKNESSES OF RESERVOIR ROCK Feet Leonard: Min. Max. Avg . From top to bottom, gross -3-50 """"24 LITHOLOGY OF RESERVOIR ROCK Leonard : Fractured, fine to medium crystalline, tan to brown dolomite with thin shale and limestone partings and with traces of sand. The fracturing is very erratic. The yielding of reservoir fluids is evidently determined by the fracturing. Some wells produce water along .with oil from elevations far above those from which other wells produce only oil. CONTINUITY OF RESERVOIR ROCK Leonard: The reservoir rock which is produc­tive in this field cannot yet be definitely correlated beyond the present extent of the field. The Leonard series, of which this reservoir rock is a member, contains productive reservoirs in many fields in the Permian basin, but data are not available for deter­mining whether the reservoir rock in this field is exactly correlative with reservoir rocks at about the same stratigraphic position in other fields. CHARACTER OF OIL Leonard: Range Wtd. avg. Gravity, A.P .I. @ 60 ° F . 24.2°-25.9° 25 .2 ° WEST ANTON FIELD , Hockley County, Texas TYPICAL SECTION OF ROCKS PENETRATED RADIOACTI VITY 8 ELECTR IC CURVES LITHOLOGY ~ ~ 2 ID GAMMA RAY RESISTIVITY _, "' fr ~ " 5 w w "' a."' " _, 0z g " " z "" "'"' GLORI ETA "'er 0 "­ ID '° !::" "' 0 ~ "er 0 0 0 ? ? ? 0 • " " "' " w a. RADIOACTI VITY 6 ELECTRIC CURVES LITHOLOGY ~ Vl Cl. 1-­ " GAMMA RAY RESISTIVITY ~ 5w ~ (f) (f) ~ DEPTH ? z " 5" a. a. " u " "­ _, 0 3' EXPLANATI ON Sondstone Anhydrite ~ •m Argilloceous Anhydritic ~ sondstone dolomite ~ ~ Limestone Shofe ~ ~ Argilloceous ~ Solt hm estone + ~ D+ Dolomite Rhyolite ~ • Oil production Ch ert O Show of oil D . WEST ANTON FIELD, Hockley County, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONE Feet Leohard: Highest Lowest Elevation of top of oil in wells -3 ,027 -3,195 Lowest elevation of oil in any water-free well since discovery -3,121 Elevation from which water is produced -3,100 -3,195 The free migration of oil in fractures has resulted in confusion relative to the elevation of the bottom of the oil in the reservoir at any given time. The available data do not afford a basis for conclusions more definite than can be deduced from the above figures. WATER PRODUCTION Leonard: Practically all wells are producing some water . Water constitutes as much as 90% of the gross fluid produced by some wells . The chloride content of the water is 53 ,000 parts per million. ACID TREATMENT Leonard: All but one of the wells have been treated with acid. The quantity used in treating each well has ranged from 4 ,500 gallons to 6 ,500 gallons. PRODUCTION HISTORY Leonard and Field total : WELLS PRODUCING at end of year Year Flowing Pumping 1950 0 1951 0 8 1952 0 8 OIL PRODUCTION (barrels) Yearly Cumulative 8,354 8,354 116 ,418 124,772 128,852 253 ,624 LE AGUE 693 L EAGUE 692 LAM B COUNTY F======i=i = [S::Z:=======:=::==i = t:===========t HOCKLEY COUNTY N E X PLANATION -2730-Contour on bo se of (),io>.nn1 me mber _ Elevation of bose of Drinkard member 2; 42 SCALE •Oil well f:f Dry hole 0 2 4 BY THOUSANDS H WEST SEMINOLE FIELD Gaines County. Texas CLYDE M. PEDERSON Geologist. Cities Service Oil Co., Midland, Texas October 24, 1952 LOCATION and DEFINITION The West Seminole field is in west central Gaines County, with the eastern boundary of present dev.elopment approximately 8 miles west of the town of Seminole. Regionally, the field is near the north­east edge of the Central Basin platform. The area of the field is defined to the north and to the south and. appears to be about defined to the east, but additional development will be necessary to define the northwest extent. METHODS OF EXPLORATION LEADING TO DISCOVERY Mapping of data afforded by shallow wells indicated a structural high. This mapping was followed and confirmed by extensive seismograph exploration. The discovery well, located on the basis of seismograph work, was originally planned as a 7,500-foot test of the Clear Fork group, but was stopped at the total depth of 5, 352 feet for com­pletion after finding the productive zone in the San Andres formation. The second well, the deepest in the field to date, was drilled beyond the productive zone in the San Andres formation for the purpose of testing the Clear Fork group and was drilled 1,230 feet into that group with negative results. DISCOVERY San Andres: June 29, 1948; Cities Service Oil Co. and Atlantic Refining Co. #1 J. H. Proctor. Drilled to total depth of 5 ,352 feet and plugged back to 5,198 feet. During initial potential test, the well flowed from open hole from 5,031 to 5,198 feet at the rate of 411 barrels of oil per day through 30/64-inch choke. ELEVATION OF SURFACE At well locations: Highest, 3,476 ft.; lowest, 3,400 ft. SURFACE FORMATION The only rocks exposed at the surface are sands, gravels and clays of the Ogallala formation . OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in the Clear Fork group l, 230 feet below its top. This penetration was in Cities Service Oil Co. and Atlantic Refining Co. #2 J. H. Proctor, which is the next well east of the discovery well and is located where the datum elevation is indicated as -1,334 feet on the accompanying map. The accompanying TYPICAL SECTION is based on the log of that well. · It was drilled to the total depth of 7,660 feet. . NATURE OF TRAP San Andres: Simple convex trap on a northwest­southeast trending anticline. PRODUCTIVE AREA San Andres and Field: Development to date proves approximately 3000 acres as productive. Since the northwest extent of the field has not yet been defined , the data are not yet available for a reliable estimate of the total productive area. THICKNESSES OF RESERVOm ROCK Feet San Andres: Min. Max. Avg. From top to bottom ---z;Q ~'180 Net productive: 25% to 50% of gross from top to bottom LITHOLOGY OF RESERVOm ROCK San Andres: Dolomite; medium crystalline, light brown and contains anhydrite inclusions. Throughout the field, except along the southwest flank, in that portion which is productive (25% to 50%) there is good, intercrystalline, solution type porosity which continues, but in less degree, out beyond the periphery of the field. The degree of porosity, as is characteristic of dolomite, is erratic and along the southwest flank approaches the lower limit for commercial production. WEST SEMINOLE FIELD, Gaines County, Texas TYPICAL SECTION OF ROCKS PENETRATED "' .., .... "'>­"' ~ ii:.., "' .. :;) 0 a: "' z 0 ~ " a; 0... a;.., CD "'.., " RAD IO ACT IVITY CU RVES LITHOLOGY GAMMA RAY NEUTRON DEPTH ELEVATION 0 z «"' <( -'"' 0 "' 0 0 0 0 "' ..J "' "' 2700 2800 2900 1000 752 652 »2 .,, TANS/LL " >­ 3200 2'2 3300 "' "' 3400 " > a; z 3500 -·· "' > 3600 a; 37 00 0 " " ;t 3800 -3 48 3900 z " "' 0.. .., 0. :;) "0 <( z .., :;) 0 • OOO 4100 4200 4 300 "'a: :;) CD >­<( 44 00 4 500 •'700 48 00 .., a: 0 4900 i:i z <( 5000 5100 5200 5 3 00 5400 EXPLANATION L?/?//iil Sandst on e D - Red shale ~Limestone ml Anliydr ite ~ Dolomite .. ..... Chert.. .. Oi l production * Gos production WEST SEMINOLE FIELD , Gaines County, Texas - CONTINUITY OF RESERVOIR ROCK San Andres: This reservoir rock is present throughout most of the Permian basin exclusive of that portion desig­nated as Delaware basin. It is a prolific producing zone in numerous fields on the Central Basin platform and in scattered fields in the Midland basin and on the Eastern platform. ELEVATION AND RELIEF OF PRODUCTIVE ZONE San Andres: Feet Elevation of top of gas -1.450 Elevation of bottom of gas -1 ,585 Relief 135 Elevation of top of oil -1,585 Elevation of bottom of oil -1 ,650 to -1,760* Relief 65 to 175 *The elevation of the oil-water contact was -1.760 feet, or lower, on the east end of the field; -1 ,750 on the highest part of the structure; -1,700 on the north, south and southwest flanks ; -1,650 on the west and northwest extremities of present development. The above figures represent conditions at the time of discovery of the field. CHARACTER OF OIL San Andres: Gravity, A.P .I.@ 60" F ., 30.5"to36.5" Sulphur , 1.18'1· Color , Dark green Odor, Sour WATER PRODUCTION San Andres : Only the lowermost edge wells have pro­duced water in appreciable quantity. ACID TREATMENT San Andres : Several of the wells which would not pro­duce their allowables without treatment were acidized with from 500 to 8 ,000 gallons of 15% acid . In practically all cases , the injection of acid resulted in substantially in­creased rates of production. PRODUCTION HISTORY San Andres and Field total: WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Yearly Cumulative 1948 4 20 ,685 20 ,685 1949 32 2 296,550 317 ,235 1950 41 5 736 ,738 1,053.973 1951 50 6 l,032,148 2,086,121 1952* 61 5 1,107 ,946 3,194,067 *1952 data added by amendment . WHEAT FIELD Loving County. Texas F. H. REITER* Geologist, Natural Gas Pipeline Co. of America, Amarillo, Texas July 7, 1952 LOCATION ELEVATION OF SURF ACE The Wheat field is located in southwest Loving At well locations: Highest, 2,790 ft .; lowest, 2,669 ft. County in Blocks 1 and 2 of the W. & N.W. R.R. Co. survey and Block 33 of the H.&T.C.R.R.Co. survey. It is near the geographic center of the OLDEST STRATIGRAPIDC HORIZON PENETRATED Delaware basin, but on the west limb about one thousand feet higher than the synclinal axis . The oldest stratigraphic horizon penetrated in the vicinity of the field is in the Bell Canyon forma­METHODS OF EXPLORATION LEADING TO DISCOVERY tion of the Delaware Mountain group 930 feet below its top. This penetration was at the total depth of The first exploration was by random drilling and 5 ,083 feet at a location near the west edge of the that was ~ollowed by interpretation of subsurface field . The location may be identified on the accom­data. After thefirst well had been located by merely panying map by the total depth figure . random drilling, Wallace Lee was consulted as to the locations for the second and third wells. SURFACE FORMATIONS DISCOVERY Recent caliche, alluvium and wind-blown sand. Bell Canyon: It was not until after completion of the third well that discovery of commercial production was proved. Although the first well, Toyah Bell Oil Co. #1 L . B. Russell (later, Ramsey NATURE OF TRAP and STRUCTURE Oil Co. #1 L.B. Russell) , which was spudded in June 1920, flowed several heads of oil, it was never com­General structure: The Wheat field is on the pleted as a producing well. Bec;,ause of bad casing west limb of the Delaware basin. The eastward dip and improper drilling , it was abiandoned in 1925. at this location is less than normal and is inter­The second well, Pecos Valley Petroleum Co. #1 rupted by minor irregularities, as shown on the J. J. Wheat (now Sinclair Prairie Oil Co. #1 A . S. accompanying map. The general structural con­Chapman or Wheat "B" ) was commenced in 1924 dition is essentially that of a terrace sloping gently and, from a sand at depth of 4,212 to 4,259 feet, it eastward with much steeper east dip both east and produced 150 barrels of 40° gravity oil in four flows west of the field. on September 1, 1925. On October 12, 1925, it was Trap in Bell Canyon reservoir : Available shot, but bridged 380 feet off bottom. At the close facts are inadequate for positive determination of of that year, it had not yet been completed, but it the factors which occasioned the accumulation of oil appears that it was completed in 1926 as a 10-barrel and gas . However, the facts appear to warrant the well. The third well , Lockhart & Co. #1 R . L . Allen conclusion that the accumulation is due either to an (now Sinclair Prairie Oil Co. #1 R . L . Allen), drilled open terrace or to updip decrease of permeability. in 1926, was also a small well until it was success­The writer is inclined to favor the former interpre­fully shot in November 1927. The second well was tation. Geological evidence indicates that the struc­then re-shot. The second and third wells having tural noses at the top of the Delaware Mountain group each shown capacity of about 100 barrels of oil per were low closed convex folds prior to the Tertiary day, commercial production was considered proved tilting of the entire Delaware basin. The fact that and interest in the ar ea was revived. the oil is still at the location of the original convex folds can be explained by either of two theories. PRODUCTIVE AREA One is that the oil is actually moving updip, but the rate of movement is so slow and the time since tilting Bell Canyon and Field: Approximately 4,600 so short that the oil has not escaped yet. The second acres . Further development is likely to increase theory is that the oil is still trapped at the location this estimate. of the original convex fold because the differential pressure between the oil reservoir and the water outside the reservoir is so slight that the water co­*Formerly with Standard Oil Co. of Texas, Mid­ hesion in the low permeability sand medium develops land, Texas. The writer thanks John Emery Adams greater pressure in this capillary system than the and Hugh N. Frenzel for their criticisms and the differential pressure between the oil and water due Standard Oil Co. of Texas for the use of its files . to gravity differences and prevents updip migration. WHEAT FIELD , Loving County, Texas z 0 TYPICAL SECTIONS OF ROCKS PENETRATED V> a: i= w CL w <1 "w ~ 0: (f) 0 a: " A B c w w >­ 0 " "' (f) (f) ELE VATION u. ELEVATION " "' "' 2500 w .J ~ (f) :::> "' 2000 0 0 I 5 00 <( <( 10 00 <( 0 I 0 z '00 <( " "' CL -5 00 -1 000 -­ LAMAR ~ <1 w ~ z z 0 CL :::> >­ :::> 0 .J " z <\lSandstone uw 0 <( _J "' :::> _J <( w ~Solt EaDolomite ~===i Shale"' <( "'_J 0 .!. "' 0 . 0 SC ALE THOUSAHO FEET H.8 TC. R.R. CO. BLOCK 33 -1 580 LOVING COUNTY WARD COUNTY WHEAT FIELD, Loving County, Texas THICKNESS OF RESERVOIR ROCK Bell Canyon: The reservoir is primarily in the upper 8 to 15 feet of a sandstone which has a total thickness of approximately 30 feet . This sandstone is overlain by about 30 feet of calcareous Lamar shale at the top of the Delaware Mountain group. In some wells, the lower 2 to 4 feet of this shale produces oil from vertical fractures which allow mi­gration of the oil upward from the sandstone. LITHOLOGY OF RESERVOIR ROCK Bell Canyon: The productive sandstone is dark gray, fine, soft and slightly calcareous, grading downward into a hard, light gray, tight sandstone. The shale above is hard, black, sandy and also slightly calcareous. The sha·le is intensely fractured and many of the fractures contain secondary calcite. CONTINUITY OF RESERVOIR ROCK Bell Canyon: The reservoir rock appears to be con­tinuous throughout a very large area. There is a sandstone at the same stratigraphic position throughout a large portion of the Delaware basin. The productive reservoir in the Mason field appears to be at the same stratigraphic position. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Bell Canyon: Feet Highest known elevation of oil -1,410 Lowest known elevation of oil -1,640 Known relief 230 CHARACTER OF OIL Bell Canyon: Gravity: A .P .I.@ 60° F., 38° Sulphur : 0 . 14% Base: Intermediate and paraffinic-intermediate. For analyses see: Railroad Commission of Texas Analyses of Texas Crude Oils (1940), pp. 34 and 65 . U.S. Bureau of Mines. Lab. ref. No. 26180 32207 Tabulated Analyses of Texas Crude Oils. R . I. 3252 (1934) Grp. 2, Item 65 66 Tabulated Analyses of Texas Crude Oils. T. P. 607 (1939) Grp. 2, Item 92 91 Analyses of Crude Oils from Some West Texas Fields R. I. 3744 (1944) page 43 CHARACTER OF GAS Bell Canyon: Only a small amount of gas was found. It appeared to be in solution in the oil. The greatest volume of gas produced by any one well was at a rate slightly in excess of 250 Mcf per day. The gas is sweet and contains small quantities of gasoline. WATER PRODUCTION Bell Canyon: Only a small amount of water was ever produced with the oil. Generally the water production has been at about the ratio of one barrel of water to one hun­dred barrels of oil. COMPLETION TREATMENT Bell Canyon: In process of completion, the wells have been shot generally with 75 to 300 quarts of nitroglycerin; average, 100 quarts. RESERVOIR ENERGY Bell Canyon: The trend of gas-oil ratios indicates a dissolved gas drive with the possibility that gravity drainage becomes effective during the later producing life. Although a small quantity of water has always been produced with the oil, there appears to be no effective water drive. There has never been a gas cap drive; there was no free gas at the time of discovery nor has gas coming out of solution accu­mulated in sufficient quantity to form a gas cap. SELECTED REFERENCES Adams, J. E. (1936) Oil pool of open reservoir type: Amer . Assoc . Petr . Geel., Bull., vol. 20, pp . 780-795 . Wilson, W. B. (1936) Discussion of above paper; ibid., pp . 795-796 . PRODUCTION HISTORY Bell Canyon and Field total: Year WE LLS PRODUCING at end of y ear F lowing P umping OIL P R ODUCTION (barrels) Yearly Cum ulative 1926 1927 1928 1929 1930 11,288 68 ,488 249 ,329 668,215 2,168 13 ,456 8 1.944 33 1,273 999 ,488 1931 1932 1933 1934 1935 57 64 69 7 l 5 5 4 4 l ,254,555 l ,125,965 926,746 802,144 695 ,727 2 ,254.043 3 ,380 ,008 4 ,306,754 5, l 08 ,898 5 ,804 ,625 1936 1937 1938 1939 1940 74 73 53 56 54 4 5 14 27 3 1 604,496 525 ,913 457 .636 403 ,009 394,676 6,409, 121 6.935 ,034 7 ,392 ,670 7 ,795,679 8, 199,355 1941 1942 1943 1944 1945 39 37 34 32 28 49 49 53 54 51 397 ,463 339 ,251 296,388 276,554 254 ,969 8 ,587,818 8 ,927 ,069 9.223,457 9 .500,01 1 9,754,980 1946 1947 1948 1949 1950 23 16 14 15 16 54 60 6 1 6 1 65 248,5 10 262,378 257 ,203 247 ,275 260 ,061 l 0 ,003 ,490 l 0 ,265 ,868 10,523,071 10,77 0,346 11,030 ,407 1951 1952* 20 19 80 92 3 18,895 440 ,834 11 ,349 ,302 11,790,136 *1952 data a dded by amendment. There had been a total of 128 productive wells com­pleted prior to July 1, 1952. WHEELER FIELD Ector and Winkler Counties, Texas R. E. LeBLOND Consulting Geologist, Midland, Texas May 10, 1956 LOCATION The Wheeler field is on the common line of Ector and Winkler counties about 30 miles west of Odessa, county seat of Ector County, and 20 miles east of Kermit, county seat of Winkler County. It is near the geographic center of the Central Basin platform, which is the dominant structural feature of the Permian basin. METHQD OF EXPLORATION LEADING TO DISCOVERY Credit for discovery of the field is due to re­flection seismograph work. Both Shell Oil Co. and Stanolind Oil & Gas Co. conducted seismic surveys in the area in 1940 and 1941. The bulk of the acreage was under lease to Shell and that company commenced drilling on July 22, 1942. When the well had reached a depth of 9,437 feet, Stanolind acquired a one-half interest in the well and block of leases and assumed operation of the well. The well was then drilled to 10,697 feet, where, on July 9, 1943, it was completed as the discovery well; it flowed at the rate of 1,370 barrels of oil per day from the Ellenburger dolomite. DISCOVERIES Devonian: April 2, 1945; Sun Oil Company #1 R. A. Wheeler Fusselman: December 5, 1945; Stanolind Oil & Gas Co. and Shell Oil Co. #1 Waddell Bros. & Co. Ellenburger and Field: July 9, 1943; Stanolind Oil & Gas Co. and Shell Oil Co. #1 W. D. Blue. ELEVATION OF SURFACE At well locations: Highest, 3, 165 ft.; lowest, 3,051 ft. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 262 feet below its top. This penetra­tion was in Phillips Petroleum Co. #G-1 T. & P. Lands Trust, located in the south corner of Sec. 11, Blk. 46, where the total depth of 10,677 feet is indicated on an accompanying map. SURFACE FORMATIONS Quaternary sand; mainly recent wind-blown sand. NATURE OF TRAPS and STRUCTURE The Wheeler structure is a bifurcated anticlinal fold. Its principal axis trends northwest-southeast in conformity with the general grain of the country. The oil in each of the three reservoirs is trapped along the crest of the fold. Although the anticline has two separate, nearly parallel, minor closures, the separate closures are not determinative except that the eastern one has occasioned accumulation of gas to form a local gas cap; oil extends downdip beyond the elevation of the minor closures. Some geologists believe that the Wheeler structure is faulted; there is certainly some evidence in favor of faulting. Steep dip along the northeast flank of the west segment of the anticline is suggestive of normal faulting with downthrow to the east, and a similar situation exists on the east flank of the east segment. None of the wells, however, has intersected a fault, and apparently any faults which may be present have not disturbed the continuity of any of the three reser­voirs. Until further drilling proves the presence of one or more faults, it is believed that the unfaulted version here presented is a more reasonable inter­pretation of the available data. PRODUCTIVE AREAS Acres Devonian 2, 760 Fusselman Not defined Ellenburger 2, 700 Wheeler field 2,800+ Development has defined fairly definitely the extent of the productive areas of the Devonian and Ellenburger reservoirs; the above figures represent reasonably close estimates as to these reservoirs. The Fusselman reservoir, however, is still in a preliminary stage of development with only 5 pro­ducing wells. Drill-stem tests and production tests in several wells drilled deeper throughout the field indicate that the porosity and permeability of the Fusselman reservoir rock are irregular. While it is a potentially good producer at several locations, it will not be productive throughout the area of the field. WHEELER FIELD, Ector and Winkler Counties, Texas LITHOLOGY OF RESERVOIR ROCKS Devonian: This reservoir rock, which consti­tutes the upper 150 to 200 feet of the Devonian system, consists principally of chert with minor amounts of siliceous limestone. It contains chert in amounts ranging from 60% to 100% and includes a thin medium-grained glauconitic sandstone oc­curring about 140 feet below the top of the Devonian. This sandstone, which is 10 to 15 feet thick, pro­duces oil in some wells; locally it is very hard and tightly cemented. The oil production is largely from the main chert body. The chert itself has a charac­teristic blue-white color and is intensely fractured. The limestone varies in texture from granular to coarsely crystalline and, in color, from tan to white. There are generally two zones of favorable porosity; however, at the locations of some wells, the two zones apparently merge and cannot be distinguished on electrical logs. The reservoir rock is intricately fractured, with vugs and cavities developed along fractures and bedding planes and especially at inter­sections of fractures and bedding planes. Very probably the two favorably porous zones represent exceptional development of cavernous or vuggy po­rosity. It appears likely that the entire reservoir is connected by means of vertical fracturing. The lower 250 feet of less cherty Devonian limestone contains too little oil to make it commercially pro­ductive; therefore it is not properly considered as a part of the reservoir rock. Fusselman: This reservoir rock is a coarsely crystalline limestone, generally white, but with a pinkish cast at some places. Minor amounts of piilky white chert occur throughout. The productive section seems to be confined largely to the upper 60 to 70 feet of the Fusselman formation. While generally the reservoir rock appears to be uniformly porous throughout, at the locations of a few wells, the upper 20 to 30 feet has higher than normal porosity. This zone with higher porosity is sepa­rated from the main body of reservoir rock by a thin, less porous zone. Probably fracturing and its attendant secondary vuggy or cavernous porosity accounts for little of the effective porosity of this reservoir rock. Intercrystalline porosity of the coarsely crystalline limestone constitutes most of the porosity. Permeability is quite irregular; at the locations of many wells, it is of a low order. Tests of the lower part of the Fusselman formation generally indicate the presence of little or no oil. Ellenburger: This reservoir rock varies from very-fine-grained gray to rather coarsely crystal­line, white-to-tan dolomite. It contains bands of darker colored dolomite at many places. Very minor amounts of chert occur, and there are occasional very thin partings of gray shale. Like that in the Devonian, the Ellenburger reservoir rock is highly fractured throughout and contains numer­ous vugs and cavities along fractures and bedding planes and especially at intersections of fractures and bedding planes. The reservoir cannot be sub­divided into zones on the basis of porosity. It is probably interconnected from top to bottom by verti­cal fractures. In small local areas, the upper 20 to 50 feet of Ellenburger is tight, p:robably because of cementation of the fractures. Productive rock occurs throughout the tested portion of the Ellen­burger group. The thickness of productive rock at any location is determined by the structural position; i.e., by the elevation of the top with re­spect to the elevation of the oil-water contact. Basis for descriptions: There has been only very little coring of any of the reservoir rocks. The above descriptions are based largely on cuttings. RESERVOIR ENERGY Devonian: Expulsion by gas expansion was evi­dent from the time of discovery, and it was evident that reservoir energy was due in part at least to gas coming out of solution. During the course of develop­ment of the field, it was found that a small gas cap existed on the crest of the dome in the eastern part of the field. After about three years of operations, there was a rather sharp increase in the amount of water production, particularly in the flank wells in the southern part of the field. At present, most of the wells produce some water. It is now evident that water drive also contributes to reservoir energy. Fusselman: With only five wells having been completed for production from this reservoir, very little is known about the reservoir energy. It is presumed that expulsion is due primarily to gas coming out of solution; however, it is quite possible that there is a gas cap although none has yet been detected. The existence of a gas cap is in harmony with certain evidence, particularly, fairly high gas­oil ratios in the production of two wells and the showing of gas and condensate during a drill-stem test of another well. Some water is being produced, but there is no conclusive evidence of an effective water drive. Ellenburger: This reservoir has an effective water drive. Water encroachment has been fairly uniform throughout the field. However, in spite of the fairly uniform encroachment, the elevation of the oil-water contact is now quite irregular, due mainly to irregularity of porosity and permeability and particularly to vertical fractures. As is charac­teristic of water-drive reservoirs, the bottom-hole pressure has declined only slightly from what it was at the time of discovery; i.e., 4,580 psi. There is no free gas cap in this reservoir. WHEELER FIELD , Ector and Winkler Counties, Texas THICKNESSES OF RESERVOffi ROCKS Top to bottom: Feet Min. Max. Avg. Devonian 30 290 205 Fusselman 60 90 70 Ellenburger 342 342. 342 Net Productive: The character of each reservoir rock is such that estimates of net productive thicknesses are of little accuracy or value. CONTINUITY OF RESERVOm ROCKS Devonian: The reservoir rock is continuous throughout the area of the field and probably through­out a much larger surrounding area. It is part of the widely distributed Devonian system, which is recognizable over much of the Central Basin plat­form andoutcropping in the mountainous areas many miles to the west and south. The producing zone in the Wheeler field is at the same stratigraphic posi­tion as one in the nearby TXL field and at essenti­ally the same stratigraphic position as productive Devonian in several other fields. Fusselman: The reservoir rock in the Fussel­man formation appears to be continuous throughout the area of the field. However, porosity and perm­eability are quite variable--too low for commercial production at some places and probably too low in small local areas to permit migration of reservoir fluids even in geologic time. Ellenburger: The reservoir rock in the Ellen­burger group is continuous throughout the area of the field and probably throughout a much larger surrounding area. The Ellenburger group is widely distributed and is generally productive where struc­tural conditions afford traps. It appears that a zone at the top of the Ellenburger is continuously favor­able for migration of reservoir fluids throughout an enormous area in West Texas. CHARACTER OF GAS No analysis of gas from any of the reservoirs is available to the writer. Although a substantial amount of gas is produced with the oil from each reservoir, no important gas reserve is known to exist. Until September 1948, all of the gas pro­duction was flared, there being no gas processing plant available to handle the gas being produced. During September 1948, the Shell Oil Company's TXL gasoline plant was put into operation, and part of the gas is now being processed at this plant. CHARACTER OF RESERVOm WATERS Devonian: Average chloride content, 39,235 parts per million (based on three samples). Fusselman: No information available. Ellenburger: Average chloride content, 94, 700 parts per million (based on five samples). COMPLETION TREATMENT Devonian: Some Devonian wells were completed "natural"; qthers were acidized. The treatment depended on the behavior of each individual well. In some wells, only a 500-gallon mud acid wash was necessary, but treatments of as much as 15,000 gallons have been used. Ordinarily 2,000 to 5,000 gallons is the maximum amount of acid required. Fusselman: One well was very heavily acid­ized; about 20, 000 gallons of acid was injected be­fore production was obtained. One was completed "natural" and another was treated with 1,000 gallons of acid. Ellenburger: Practically all Ellenburger com­pletions have been "natural". However, in a few wells a 500-gallon mud acid wash was used to clean the reservoir before starting production. In a few instances, treatments of 1,000 to 3,000 gallons have been used where the Ellenburger was unusually tight. FOOTNOTE TO PRODUCTION IDSTORY With reference to certain entries in the tabu­lation headed PRODUCTION HISTORY on a following page, the total number of wells producing in the field at the end of each year after 1944 was less than the sum of the figures representing the number of wells producing from the respective reservoirs; some wells produce from two reservoirs. Because of the many duel completions, available data are so confused that it is not practical to determine the net number of wells producing at the end of each year. The usual practice with dually completed wells is to discontinue operations in a res·ervoir whenever flowing stops; then, at a later date when the other reservoir ceases flowing, pumping is initiated to produce from either one or the other of the reser­voirs. Procedures of experimenting and switching from one reservoir to the other make it impractical to determine status at the end of each year. z 0 ...~II~" w a. CR O.S S SECTION A-A' ::> ~ ELEVATI ON 0 0: F EET 82 3 4 5 6 7 -4600 ~ ~ ~ z PERMIAN -4800 -5000 I ~ ::r: -5200 --f M M L' -5400 -f M ::xi -5600 -f 1-rj ,_, M L' -5800 --f tJ M -6000 -f () ...... 0 ., -6200 -I Q ::l Q... -64 00 -I ~ ....... ::l :>'i""' ........ -6600 -I CD ., 0 0 -6800 -I ~ ::l ...... ...... . yi -7000 i CD >-3 " 0 zlZ -"' '-' a. CD > ~ >< io en Q 0 -7200~ rn -7400 -7600 -78 00 I C> """ (J'1 ELEVATIOf -~i~~ -4800 -5000 -5200 -5400 -5600 -5800 -6000 -6200 -6400 -6600 -6800 -7000 -7200 -7400 -7600 -7800 WHEELER FIELD , Ector and Winkler Counties, Texas DEVONIAN MAP ~~ >­z f-­:::i z 0 :::i uo u ~ CO· ~· . I$. 1>.tJI'· N EXPLANATION ------5100-----Contour on top of Devonian syste m + --+ --+ --Boundary of Devonian productive area • Oil well Abandoned oil well Ji Dry hole • ~Discovery le Completed in Devonian e\ Completed in Fusselman * Produces gos from Fusselman Produces oos from Fusselman, formerly produced oil from some reservoir ..!.... Completed in Ellenburoer lf~filti.~~I Area of o field not treated in this paper SCALE THOUSAND FEET WHEELER FIELD, Ector and Winkler Counties, Texas ELLENBURGER MAP N E XPLANAT ION -----76001----Con tour on top of Ellenburger group Boundary of Ellenburger productive area -71H Elevation of top of Ellenburoer Qroup 10117 Total depth . • Oil well Abandoned oil well p Dry hole ·~Discovery ,4 Completed in Devonian •\ Completed in Fusselman * Produces oos from Fusselman • Area of a field not treated in this paper 0 SCALE THOUSAND FEET p 48 00 WHEELER FIELD, Ector and Winkler Counties, Texas ELEVATION AND RELIEF OF PRODUCTIVE ZONES Devonian Fuss elman Ellenburger Sub-sea elevation of top of gas, feet -5,092 Presence of Sub-sea elevation of bottom of gas, feet -5,240 free gas cap No free gas cap Gas column, feet 148 not established Sub-sea elevation of top of oil, feet -5, 240 -6,057§ -7,258 Sub-sea elevation of bottom of oil, feet -5,525 to -5,450* -6,286§ -7,600** Oil column, feet 210 to 285 229§ 342** All reservoirs: The above figures represent conditions as of respective discovery dates. * Devonian: The sub-sea elevation of the oil-water contact ranged from -5, 525 feet in north and central part of field to -5, 450 in extreme south part of field. § Fusselman: The oil column or gas-oil column may be as much as 100 feet greater than estimated from data now available. The exact extent and nature of the hydrocarbon column will not be known until after com­pletion of additional wells. ** Ellenburger: Water encroachment has materially changed the elevation of the oil-water contact. Due mainly to irregularity of porosity and permeability, and particularly to vertical fractures, the elevation of the oil-water contact is now so irregular that it is difficult to present a reasonably accurate understanding of the present condition. However, roughly, the oil-water. contact is now generally about 50 feet higher than it was at time of discovery of the field. RESERVOffi TEMPERATURE and PRESSURE and OIL SAMPLE DATA Devonian Fusselman Ellenburger Original reservoir pressure, psi. 3,636 4,580 Original reservoir temperature, •F. 122 146 Gravity of oil, A. P . I. @ 60°F. 38 31 45 Sulphur in oil, % 0.86 0.2 Bubble point, psi. 3,600 2,830 Solution gas -oil ratio, cf/bbl. l, 937 1, 360 Volume factor, surface:reservoir 1.505 1. 75 Devonian and Ellenburger data were determined from bottom hole samples. Corresponding data are not available for the Fusselman reservoir. WATER PRODUCTION Devonian F usselman Ellenburger No. of wells Water No. of wells Water No. of wells Water producing production producing production producing production water (barrels ) % water (barrels) % water (barrels ) % 1943 0 0 0.0 1944 0 0 o.o 1945 0 0 0.0 1 200 18.3 2 29,601 4.1 1946 0 0 0.0 1, 805 14.5 6 29,062 3.2 1947 2 4,070 0.4 2,410 1 7 .2 17 83,997 5.5 1948 7 13,310 0.7 2 3,073 4.5 23 228,35 1 10. l 1949 39 65,104 4.5 2 13,188 18.3 26 247, 308 13.5 1950 46 89,458 7.5 3 5,823 12.6 33 580,997 28.2 1951 51 110,265 11. 3 4 25, 300 43.4 38 1,025,411 38. l 1952 50 118,283 20.6 2 34, 228 53.4 35 875,515 40.3 1953 41 170,207 31.6 2 31,556 49.5 34 1, 752,970 61.2 1954 ? 145,134 33.2 ? 4, 711 13.1 ? 1,533,529 66.4 1955 ? ? ? ? ? ? ? ? ? WHEELER FIE t D , Ector and Winkler Counties, Texas PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION at end of year (barrels) (Mcf) Flowing Pumping Yearly Cumulative Yearly Cumulative Field totals 1943 1 0 40, 58 7 40,58 7 0 0 1944 ....... . 8 ....... . 0 ..••.... 305,193 . .... 345, 780 ....... . 425,439 . . . . . 425,439 1945 760,442 1,106,222 1,426, 149 1,851,588 * * 1946 1,297,504 2,403,726 1,747,121 3, 598, 709 * * "· ....... . 1947 .... ... . * ....... . ,,... 2,373,106 ..... 4, 776,8 32 ....... . 3,332,237 . . . . . 6,930,946 1948 4, 057, 058 8, 833, 890 5,523, 742 12,454,688 * 1949 3,026,658 11,860,548 4,600,697 17,055,385 * * 1950 ....... . '• ....... . 2,624,178 ..... "" ....... . "< 14,484, 726 ....... . 5, 743, 145 ... ; . 22, 798,530 1951 2,566,884 17,051,610 6,053,976 28,852,506 * 1952 l, 78 1,637 18,833,247 5,123,455 33,975,961 * 1953 ....... . ~' ....... . :::'.,: ....... . 1,513,624 . .... 20,346, 8 71 ....... . 4,632,531 ..... 38,608,492 1954 1,099, 145 21, 446,016 4,103,142 42,711,634 1955 949,572 22, 395, 588 ? ? Devonian 1945 3 0 68, 908 68,908 76,687 76,687 1946 12 0 398, 549 467,417 491,291 567,978 1947 ....... . 32 . . . . . . . . 1 .•...•.• 924,865 ..... 1,392,282 ....... . 1,319,013 ..... 1,886,991 1948 44 2 1,9 31, 969 3, 324,251 2, 743,968 4,630,959 1949 45 7 l, 377, 106 4,701,357 2,397,164 7,028,123 1950 ....... . 44........ 7 .•...... l, 101,573 . .. . . 5,802,930 ....... . 3,314,973 ..... 10,343,096 1951 43 7 866,307 6,669,237 3,621, 100 13,964, 196 1952 36 10 455, 177 7, 124,414 2,987,980 16,952,176 1953 ... .. .. . 26 . . . . . . . . 16 ....... . 367, 892 . . ... 7,492,306 ...... . . 2,696,622 ..... 19,648, 798 1954 22 18 292,511 7, 784,817 2,477,573 22,126,371 1955 24 16 277,017 8,061,834 ? ? Fusselman 1945 0 893 893 1,883 1,883 1946 0 1 10,650 11,543 2, 109 3,992 1947 ....... . 1 .... ... . 1 ....... . 11,572 . .. .. 23,115 ... .. .. . 503 ..... 4,495 1948 3 65, 549 88,664 129,206 133,701 1949 3 1 58, 869 147,533 85, 744 219,445 1950 ....... . 1 .. ..... . 2 . . ..... . 40,467 .. ... 188,000 ....... . 121,198 ..... 340, 643 1951 1 2 33,026 221,026 92,488 433,131 1952 1 2 29,855 250,881 86, 825 519,956 1953 ....... . 2 .•..•... 1 ....... . 32, 176 . . ... 283,057 .. . .... . 108,919 ..... 628,875 1954 2 1 31,371 314, 428 107, 752 736,627 1955 3 2 67,260 38 1,688 ? ? Ellenburger 1943 1 0 40,587 40,58 7 0 0 1944 ....... . 8 .. .. .. . . 0 .•.•... . 305, 193 ..... 345, 780 ....... . 425,439 425,439 1945 13 0 690,641 1,036,421 l, 347,5 79 l, 773,018 1946 21 0 888,345 1,924,766 1,253,721 3,026, 739 1947 ....... . 35 ....... . 0 .....•.. 1,436,669 ..... 3,361,435 ...... .. 2,012, 721 ..... 5,039,460 1948 37 2,059,540 5,420,975 2, 650, 568 7,690,028 1949 35 2 1,590,683 7,011,658 2,117,789 9,80 7, 81 7 1950 ....... . 35 ....... . 2 .•.•.... l, 482, 138 ....• 8,493, 796 .. . ... . . 2,306,974 ..... 12,114, 791 1951 38 0 1,667,551 10,1 6 1, 347 2,340,388 14, 551, 179 1952 26 9 1,296,605 11,457,952 2,048, 650 16,503,829 1953 .... ... . 21 ....... . 13 ....... . 1,113,556 .. ... 12,571,508 ....... . 1,826,990 ..... 18,330,819 1954 15 17 775, 263 13,346,771 1,517,817 19,848,636 1955 13 17 605,295 13,952,066 ? ? * See FOOTNOTE to PRODUCTION HISTORY entered on a preceding page. WHITE & BAKER -WALKER FIELD Pecos County. Texas JAMES P. MURPHY Geologist , Sinclair Oil & Gas Co., Midland, Texas May 7, 1954 LOCATION and FIELD NAMES The White & Baker -Walker field is in eastern Pecos County about 40 miles east of Fort Stockton, and is between the Taylor-Link field and the Yates field. It is on the Central Basin platform near the southern end of that platform. The area treated herein as the White & Baker­ Walker field includes areas treated by the Railroad Commission as the White & Baker field, as the Walker field and as a part of the Taylor-Link field. The dividing lines between the Commission areas are indicated on the accompanying map. The accompanying map covers an area extending beyond the area of the White & Baker-Walker field and includes, near the southwestern corner, a por­tion of the Taylor-Link field and, near the eastern margin, the one well which constituted the noncom­mercial Lowery &: Wilson (San Andres) field, which is treated briefly in the following paragraph. The Taylor-Link field is treated in another paper in this volume . NEAR-BY NONCOMMERCIAL PROSPECT The location of the well which prompted the designation of the Lowery & Wilson (San Andres) field is near the eastern margin of the area covered by the accompanying map. Helmerich&: Payne, Inc. # 1-F Lowery &: Wilson was completed on July 25, 1951, in the San Andres formation with an initial daily flowing potential of 59 barrels of 33.8° gravity oil. The productive reservoir was reported at the depth of 2 ,000-2,012 feet; the top of the San Andres formation, 1,990 feet; total depth, 2,019 feet. The well produced 1.194 barrels of oil during 1951 and 101 barrels of oil in 1952; a total of 1.295 barrels before abandonment in 1952. ELEVATION OF SURFACE At well locations : Highest, 3,112 ft . ; lowest,2,640 ft. SURFACE FORMATIONS Undifferentiated limestones of the Washita and Fredericksburg groups. METHODS OF EXPLORATION LEADING TO DISCOVERY Interpretation of surface and subsurface geolog­ical data led to the discovery of this field. DISCOVERIES Queen: January 12, 1935; Gulf Production Co. #3 White &: Baker . This well had produced 91 barrels of oil in December before its completion on January 12. Its capacity when completed was at rate of 52 barrels of oil per day. Before July 26, 1935, the daily rate of production had declined to 5 barrels of oil with water constituting 1% of gross liquid. The well was then shot with 180 quarts of nitroglycerin between the depths of l ,813 and 1 ,890 feet and production increased temporarily to 66 barrels of oil and 13 barrels of water per day. Operation soon became unprofitable and the well was plugged and abandoned on September 19, 1936. March 30, 1938; Cardinal Oil Co. #1-36 White &: Baker (later designated as Helmerich & Payne, Inc. #B-6 White&: Baker). Initially bailed at rate of 5 barrels of oil per day . After shot with nitro­glycerin from depth of 1,618 to 1,639 feet, the rate of production increased to 30 barrels of oil per day with consid.erable sulphur water which apparently came from near total depth of 1,802 feet and was later plugged off. March 28, 1940; R.L.Walker #1 White&: Baker (now Childress Royalty Co. #A-1 White &: Baker). Initial capacity was at rate of 20 barrels of oil per day after shot with nitroglycerin. San Andres: August 8, 1943; Cardinal Oil Co. #4-C White & Baker (later designated as Helmerich & Payne, Inc. #4-C White & Baker). This well produced gas from the Queen reservoir and oil from the San Andres reservoir. It is the only well completed in the San· Andres reservoir; it was abandoned in San Andres in 1946. Strawn: December 22, 1945; Helmerich & Payne, Inc. #8-C White &: Baker. This discovery was the result of a work-over of Humble Oil &: Refining Co. #1 White & Baker, which was abandoned July 19 34 as a dry hole after having been drilled to the total depth of 9,811 feet. This is the only well completed in the Strawn reservoir; it was abandoned in 1952. The accompanying TYPICAL SECTION is based on the log of this well. WHITE & BAKER-WALKER FIELD, Pecos County, Texas OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 548 feet below its top. This penetration was in Helmerich&Payne,Inc . #9-C White&Baker, the gas well located near the northwest corner of Sec. 44 where the total depth of 10,044 feet is indi­cated on the accompanying map. NATURE OF TRAPS Queen: Anticlinal folding appears to be the pri­mary trap-forming factor with variation in degree of porosity and permeability contributing as a secondary factor. San Andres and Strawn: Only one well has been productive in each of these reservoirs and both of these wells were located near the apex of a convex fold. While it appears that, as to each reservoir, convex folding is the primary factor, it is.probable that variation in degree of porosity and permeability has functioned as a secondary factor. PRODUCTIVE AREAS Acres Queen 5,200 San Andres 40 Strawn 40 Field 5 ,200 THICKNESSES OF RESERVOIR ROCKS Net productive: Feet Queen 5 to 35 San Andres 15± Strawn 48± UTHOLOGY OF RESERVOIR ROCKS Queen: Interbedded sandstones and shales. The sandstones are white to gray, fine -grained, with degrees of porosity and permeability quite variable and too low for commercial production in some parts of the general area of the field . SanAndres : Gray to tan, medium-to fine-grained dolomite and limestone. Strawn: White to gray-white and brown, finely­crystalline to dense, limestone. CONTINUITY OF RESERVOIR ROCKS Queen: The reservoir rock is continuous through­out the area of the field. However, locally in certain places, porosity and permeability are too low for commercial production. San Andres and Strawn: Available data do not afford a basis for determination of continuity of either of these reservoir rocks . ELEVATION AND RELIEF OF PRODUCTIVE ZONES Queen: Feet Highest known elevation of gas 1,540 Elev. of bottom of gas (gas -oil contact) 1,630 Known relief of gas column 90 Elevation of top of oil (gas-oil contact) 1,630 Elev. of bottom of oil (oil-water contact) l, 687 Relief of oil column 57 The above figures represent estimated elevations as of discovery date. Data are meager and unsatisfactory. San Andres and Strawn: Data are not available. CHARACTER OF OIL Queen San Andres Strawn Gravity, A.P.I.@ 60° F. ~2.­ 32.2° 37.9 ° Sulphur 1.4% ? ? For analyses see : Railroad Commission of Texas Analyses of Texas Crude Oils. (1940), pp. 34 and 65. U. S. Bureau of Mines Lab. ref. No. 38080 Tabulated Analyses of Texas Crude Oils. T.P. 607 (1939) Grp. 2, Item 93 CHARACTER OF GAS Queen: Specific gravity 0.642 Sulphur indication Sour WATER PRODUCTION Queen: Data relative to current water production are not readily available. It was a characteristic of the wells in this field that they produced very little water initially. COMPLETION TREATMENT Queen: Generally, each well was shot with 20 to 100 quarts of nitroglycerin at time of completion. SECONDARY RECOVERY Queen: A gas repressuring project was begun in August 1947 by Helmerich & Payne, Inc. As indicated on the accompanying map, gas is now being injected into the reservoir through two wells. SELECTED REFERENCE Carsey, J. Ben (1935) Unconformities in the Humble White & Baker deep test, Pecos County, Texas: Bureau Econ. Geology, Univ. Texas, Bull. 3501, pp. 127-12 9. .,, 58 1 51 1 53,(,1 52 Ji' ~+~ 13-~"•v:t200 20 15 '/1• ____ :~A -13 G. c. a s. F. R.R. Co. I I EX PLANATION BLK. 194 + 1s20 Contour on top of Yo Ies for motion ;.'////////////////////////////////////////////////////. Boundary for re9ulotory purposes 6 1 49 1 48 1 • Oil well , productive from Queen ; t ,abandoned in Queen ~ * Gos well, productive from Queen ; * , abandoned in Queen ::i:! &, lnjectin9 90s into Queen reservoir """""°4 T. C. R.R. Co. '"""3 BLK. 207 *1-Abandoned well ; formerly produced oil from Son Andres ; t"T1 90s from Queen (one well) ,r., I \ LLJ \ \ I · I\ ·'·,· I·:·~ "-. I'\.. ~+ Abandoned oil well, formerly productive from Strawn lone well) Qi SOI / Dry hole •Ho Total depth • \=:ti Discovery tJj 47 1 ::i::­ I I I I I 7': t C. R.R. Co. Ji M BLK. Z "" ::::0 I -::::! ,. <::; '" , ea~ s1 46 / 35 :rn;f 19 ..._., o.O ;1to&1 ti'' too u.f. .,>­,.\°' zon•l I ...:~\PAYNE, INC. r-4 HELMERICH 34 I 36 • 5 ~t+N ,,.roo 2 'fo0 • 1/\'Z./~ # f-F Lo w#r; 8 I 7': • ,;I Wiison •' I ,.../////, "'o M ::0 'Tj • ,{.,--ti ,........ e2 4~ 36 29 20 M r-4 +1560 t:1 • nu !l~O / • • +. 1600 • • £ . . i _,.,,/ I 'f•-+1580 • • • • • • • • • • 200p'4 " UNIVERSITY LANDS "" ''5i•o • • • ~~ '. •, ~· '"(j(() .t-1620 • • \. ~ so BLK. 17 / • -........:. ~ • • p' 0 Ji 0 U13 . --............_ • "'-. • '~"" 1110 0 ' '••o r1 ·1~· o~~·~~37~·,.,o 20 -·: 21 ~ 92 1 .... I . ( i i~<+ \\\::v OUEEN .... s:: 313013 121 I \ z".so , J... •.20~ 411-1\1 .!. p' ~ ~1 11to I "'"6' ~"' ... i600 / Ji oo 'o o\\~s ~ _,,----"" ~ '"""3 /s~0 "-..__ c,~~ ~~ _/ ----:... 1se~ ~ 21 + 22 1 I @ p' T. C. R.R. Co. UOI BLK. 179 G. c. a s. F. R.R. Co. BL~ 604 ,,, SCALE 0 2 3 4 5 6 7 8 9 10 I I T. c. R.R. co. BLK. 207 THOUSAND FEET 23 .......,. w WHITE & BAKER-WALKER FIELD, Pecos County, Texas PRODUCTION HISTORY Field totals: Because of the fact that so nearly all of the production WELLS PRODUCING OIL PRODUCTION has come from one reservoir (Queen) and because of space requirements, at end of year (barrels) it is left for the reader to add the figures for Queen, San Andres and Flowing Pumping Yearly Cumulative Strawn to determine field totals. Queen: The data for the Queen reservoir are reported below under Queen (b): four headings; viz: Queen total, wherein the figures represent totals for the three subdivisions; Queen (a), wherein the figures apply to that part 1940 5 I 11,987 11 ,987 of the field designated as the White & Baker field; Queen (b), whe rein the 1941 32 7 151.986 163,973 figures apply to that part of the field designated as the Walke r field; and, 1942 52 11 244,643 408 ,616 Queen (c), wherein the figures apply to the properties at the northwest end of the field which are treated by the Railroad Commission a s in the 1943 57 13 343 ,981 7 52 ,597 Taylor-Link field. 1944 57 17 399 ,511 l ,152,108 1945 58 23 404,095 1,556 ,203 WELLS PRODUCING OIL PRODUCTION GAS PRODUCTION 1946 54 28 362,781 1,918,984 at end of year (barrels) (Mcf) 1947 49 35 326,590 2,245,574 Oil Yearly Cumulative Yearly Cumulative 1948 47 39 283,447 2,529,021 Flowing Pumping Gas 1949 31 57 221.152 2,750,173 Queen total: 1950 20 75 241,105 2,991,278 1934 0 0 0 91 91 1951 26 75 221,513 3,212,791 1935 0 0 1,831 1,922 1936 0 0 1,123 3,045 1952 25 73 177,019 3,389 ,810 1937 0 0 0 0 3,045 1953 17 84 134,064 3,523,874 1938 2 0 0 4,771 7 ,816 1954 15 82 104,555 3 ,628 .429 1939 7 0 0 34,437 42 ,253 3,344 3,344 1940 18 l 73,304 115,557 21,858 25 ,202 Queen (c): 1941 50 8 2 223 ,465 339,022 42,019 67 ,221 1942 74 11 2 338,146 677 ,168 101,454 168,675 1940 I 0 1,847 1,847 1943 9 3 14 2 475,766 1,152,934 158,332 327,007 1941 0 I 975 2,822 1944 95 22 6 550 ,970 1,703,904 1,488,397 1,815,404 1942 2 0 8,718 11,540 1945 110 32 7 604,121 2,308,025 1,520,851 3,336,255 1943 7 0 13 ,840 25 ,380 1946 122 35 5 635 ,412 2,943,437 871,310 4,207 ,565 1944 6 4 18 ,809 44,189 1947 120 48 604,059 3 ,547,496 207,315 4,414,880 1945 4 6 13 ,097 57 ,286 1948 Ill 64 570,416 4,117 .912 262,654 4,677 ,534 1949 94 82 473,521 4,591,433 166 ,492 4,844,026 1946 4 6 12,185 69 ,471 1947 6 4 10 ,986 80 ,457 1950 68 115 465,047 5,056,480 220,154 5 ,064,180 1948 6 4 9 ,368 89 ,825 1951 71 119 410,621 5,467,101 193,473 5,257,653 1952 60 136 329,067 5,796,168 187,223 5 ,444,876 1949 6 4 8,523 98,348 1953 50 132 287 ,143 6,083,311 173,828 5,618,704 1950 3 7 9 ,305 l 07 ,653 1954 42 137 241,225 6,324,536 104,850 5,723,554 1951 3 5 8,587 116,240 1952 2 6 6,610 122 ,850 Queen (a): 1953 0 7 5 ,403 128 ,253 1934 1935 0 0 0 0 0 91 1,831 91 1,922 1954 0 7 4, 180 132,433 1936 0 1 0 l ,123 3,045 1937 0 0 0 0 3,045 San Andres: 1938 2 0 0 4,771 7 ,816 1939 7 0 0 34.437 42 ,253 3,344 3,344 1943 0 1,767 1,767 1940 12 0 1 59 ,470 101,723 21,858 25 ,202 1944 0 8,526 10,293 1941 1942 1943 18 20 29 0 0 l 2 2 2 70,504 84,785 117,945 172,227 257,012 374,957 42,019 101,454 158 ,332 67 ,221 168,675 327,007 1945 1946 l 0 0 0 3 ,903 2 ,838 14,196 17 ,034 1944 32 6 132 ,650 507 ,607 1,488 ,397 1,815 ,404 Strawn: 1945 48 3 7 186,929 694,536 1,520 ,851 3,336,255 1946 1947 1948 64 65 58 l 9 21 5 260 ,446 266 ,483 277 ,60 l 954.982 1,221,465 l .499 ,066 871,310 207,315 262 ,654 4,207 ,565 4,414,880 4,677 ,534 1945 1946 0 0 519 15 ,465 519 15,984 1949 57 21 243,846 1,742,912 166 .492 4,844,026 1947 0 5,885 21,869 1950 1951 46 42 33 39 214,637 180,521 1,957,549 2,138,070 220,154 193,473 5,064,180 5,257 ,653 1948 1949 0 0 3.492 3 ,322 25,361 28 ,683 1952 1953 1954 33 33 27 57 41 48 l l 145 ,438 147 ,676 132,490 2 ,283 ,508 2,431,184 2,563,674 187 ,223 173,828 104,850 5,444,876 5,618,704 5,723,554 1950 1951 1952 0 0 0 0 3 ,137 2 ,289 581 31,820 34, 109 34 ,690 WIL-JOHN FIELD Ward County, Texas EDWARD R. KENNEDY, Jr. Geologist, Argo Oil Corporation, Midland, Texas July 1, 1955 LOCATION and FIELD NAMES The Wil-John field is in south-central Ward County, 9 miles northeast of Barstow, st miles southwest of Pyote and about 3 miles northeast of the railroad siding of Quito. Prior to the drilling of the well now recognized as the discovery well, three wells had been completed (two as oil wells and one as a gas well) in the area herein treated as the area of the Wil-John field. Although none of these wells was a commercial well, they occasioned the application from time to time of the names Wilson field, Hayes field and Quito field. These three names have now been superseded by the name Wil-John field. The name Quito field is now used to designate a field discovered April 4, 1953, about 6 miles to the northwest and treated in another paper in this volume. METHOD OF EXPLORATION LEADING TO DISCOVERY Subsurface geology. ELEVATION OF SURFACE At well locations : Highest, 2, 740 ft. ; lowest, 2,670 ft. SURFACE FORMATION Undifferentiated Quaternary. OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Bell Canyon formation 547 feet below its top. This penetration was in Argo Oil Corp. #1 Pat Wilson, the discovery well. The accompanying TYPICAL SECTION is based on the log of this well. PRODUCTIVE AREA Bell Canyon: It is estimated that the two wells which are now producing are draining oil from an area of 80 acres. The surrounding area where oil and gas have been yielded in less than commercial quantities is much greater. DISCOVERY Bell Canyon: January 13, 1954; Argo Oil Corpo­ration #1 Pat Wilson et al. Initial potential, 27i barrels of oil per day through perforations at depth of 5,051-5,061 feet; gas-oil ratio, 2,974 : 1. Three wells had been completed (two as oil wells and one as a gas well) at earlier dates, but since none of them was a commercial well, it seems appropriate to recognize the above indicated well as the discovery well of the field. C.H. Mahres et al #1 Pat Wilson was completed September 14, 1937, after having been plugged back to 5,092 feet from the total depth of 5,094 feet. After a shot with 100 quarts of nitroglycerin, it produced oil at the rate of 132 barrels per day through tubing and was temporarily considered as the discovery well of a new field, called the Wilson field. In March 1938, the well was deepened to 5,120 feet. It was plugged and abandoned October 22, 1938, after pumping water at the rate of 10 barrels per da y. It produced 1,917 barrels of oil during 1937; available records do not indicate that any oil was marketed subsequently. Kenneth Slack et al #1 Bird S. Hayes was com­pleted July 20, 1940, as a gas well with capacity of 21,000 Mcf per day; pre ssure, 1,900 psi. This well was recognized as the discovery well of a field known both as the Hayes gas field and as the Quito field. It appears that gas marketed during 1941-1944 as from the Quito field was produced by this well; the quantities reported by the Railroad Commission were 181 , 141 Mcf during 1941 ; 202,421 Mcf during 1942; 256,545 Mcf during 1943 and 129, 169 Mcf during 1944. Available records do not indicate any other production, either earlier or later. This well proba­bly did not return its cost. At thetime ofits completion on October 22, 1941, Kenneth Slack et al #1 Pat Wilson indicated a daily potential of 24 barrels of 42 ° gravity oil and 150 Mcf of gas and was temporarily recognized as a discovery well, but before the end of the year it was abandoned as noncommercial. Available records do not indicate that any oil was marketed from this well. NATURE OF TRAP Bell Canyon: Complex permeability on the plunging axis of an anticline. ~ (/) ~ ~ "' "'w >­ tn WIL-JOHN FIELD, Ward County, Texas TYPICAL SECTION OF ROCKS PENETRATED ~ RADIOACTIVITY CURVES ~ ~ GAMMA RAY NEUTRON 00: Li.. DEPTH ELEVATION QU ATERNARY u in "' "' ii: I­ -----2350----Contour on lop of Bell Canyon formation • Oil well Abandoned oi l we ll *" Abandoned gos well Total depth p Dry hole SCALE 10 15 THOUSAND FEET TYPICAL DETAll. OF PRODUCTNE SECTION z 4 <( -o ,. :c 0:" ~ 671 "' "' 57 1 471 371 271 "" "' w~Z "-=> 0 => 0 .../,. >-z "' 0 w" "' 171 2500 "'0: .../ =>"' .../ "'3' w 2600 71 '.l"' w 0 -29 2735 2700 -64 WIL-JOHN FIELD, Ward County, Texas THICKNESSES OF RESERVOIR ROCK Bell Canyon: Feet From top to bottom 34 Net productive 24 The above figures apply to the two wells which are now producing. There are two productive sand­stones with about 10 feet of non-productive shale between them. In the discovery well, the lower sandstone, about 10 feet thick, is producing; the upper sandstone has not been perforated for produc­tion. In the other well, the upper sandstone, about 14 ·feet thick, is producing; the lower sandstone has not been perforated for production. LITHOLOGY OF RESERVOIR ROCK Bell Canyon: Sandstone; gray, fine-grained, friable, with porosity and permeability varying in a wide range and with shale interstratified as indi­cated on the accompanying graph under the heading TYPICAL DETAIL OF PRODUCTIVE SECTION. CONTINUITY OF RESERVOIR ROCK Bell Canyon: The r e servoir rock is continuous throughout the area of the accompanying map. While the general character is about the same throughout that area, the individual layers are generally of only local extent. Individual members cannot be correlated with certainty from well to well. B ecause of the lenticularity of the sandstone members and the variation in degrees of porosity and permeability, it is unlikely that there is sufficient freedom of migration of reservoir fluids to justify considering all of the productive lenses as part of one and the same reservoir. However, in geologic time, the reservoir fluids may have adjusted essentially in accordance with the interpretation that they were confined within a single container. WATER PRODUCTION Bell Canyon: Water constitutes a high percentage of the gross production of each of the two wells now producing. During initial potential test, water con­stituted, respectively, 85"/o and 50"/o of the gross production of the discovery well and of the other well. COMPLETION TREATMENT Bell Canyon: The reservoir rock in each of the two producing wells was subjected to hydraulic fracturing. The reservoir rock in each of the two abandoned oil wells was shot with 100 quarts of nitroglycerin. The abandoned gas well was completed without shooting or hydraulic fracturing. ELEVATION AND RELIEF OF PRODUCTIVE ZONE Bell Canyon: F eet, approx. Elevation of highest known gas -2,303 Elevation of gas-oil contact -2,358 Known relief 55 Elevation of gas -oil contact -2,358 Elevation of oil-water contact -2,390 Known relief 32 The above figures represent approximate condi­tions at time of first completion in the area. They do not have the normal significance of corresponding figures for other fields because it is doubtful whether there was ever continuous potential commercial production throughout the indicated interval. Dry holes and noncommercial wells demonstrate that porosity and permeability are too low for commer­cial production throughout a large portion of the area where trapping conditions appear favorable. Inter­fingering of sandstones which contain water, but no hydrocarbons, complicate the problem of estimating the elevation of the oil-water contact. No definite water table has yet been established. Oil was as low as -2,425 feet in C.H.Mahres et al #1 Pat Wilson. CHARACTER OF OIL Bell Canyon: Gravity, A. P . I. @ 60°F., 38.4°. PRODUCTION HISTORY Bell Canyon: WELLS PRODUCING OIL PRODUCTION at end of year (barrels) Year Flowing Pumping Yearly Cumulative 1937 0 0 1,919 1,919 1953 0 l, 120 3,039 1954 2 0 11,944 14,983 1955 to 7 / l 2 0 4,462 19,445 GAS PRODUCTION: The only reported gas produc­tion is that by Kenneth Slack et al #1 Bird S. Hayes mentioned above under DISCOVERY. WILSHIRE FIELD Upton County. Texas ROBERT R. HARBISON Geologist, Stanolind Oil & Gas Co., Midland, Texas February 12, 1953 LOCATION AND DEFINITION The Wilshire field is in west central Upton County 7i miles east of the Crane-Upton county line, and 6 miles east of the eastern extent of the McElroy field . It is in the southwestern part of the Midland basin and immediately east of the Central Basin platform. The field is composed of the Wilshire, the Wil­shire Pennsylvanian and the Wilshire Ellenburger pools. To date, the only well in the Wilshire pool is the Spraberry discovery well. The Wilshire Penn­sylvanian pool includes only one presently produc­tive well, the most northern well in the field; th~ discovery well was dually completed and was allowed to produce from the Pennsylvanian (Strawn) during only two months . The Wilshire Ellenburger pool includes 40 of the presently productive 42 wells in the field. METHODS OF EXPLORATION LEADING TO DISCOVERY Several reflection seismograph surveys of the region had been made several years prior to the discovery of the field . It appears likely, therefore, that reflection seismograph surveying was at least among the exploration methods· which led to the drilling of the discovery well. DISCOVERIES Spraberry : December 9, 1948; Wilshire Oil Co . #23-148 McElroy Ranch Strawn: April 24, 1951; Sinclair Oil & Gas Co. #1 McElroy Ranch This well was dually completed to produce fr om Strawn and Ellenburger. Beginning in May, 1951, it was allowed to produce from the two reservoirs, but after about two months, in accordance with an order of the Railroad Com­mission, production from Strawn was stopped and the well has not produced from Strawn since then . Sinclair Oil & Gas Co . #6 McElroy Ranch, 3 miles northward in Sec . 132, is the only other well which has produced from the Strawn reser­voir. It was completed February 20, 1952 . ELEVATION OF SURF ACE At well locations: Highest,2,854 ft.; lowest,2,749 ft. SURF ACE FORMATIONS Undifferentiated rocks of the Fredericksburg group are at the surface throughout the area of the field . OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the area of the field is in the Ellenburger group. NATURE OF TRAPS Spraberry: Unknown; probably either updip lensing or updip decrease of porosity . Strawn: Convex fold. Ellenburger : Convex fold . PRODUCTIVE AREAS Acres Spraberry 40 Strawri 80 Ellenburger 1640 Wilshire field 1720 It appears probable that future development will warrant increasing the above estimates . THICKNESSES OF RESERVOIR ROCKS Spraberry: The gross thickness from top to bottom in the only productive well is 205 feet. Strawn: The gross thickness from top to bottom in the one presently productive well is 65 feet . In the discovery well the gross thickness is about 40 feet and the net productive portions total about 25 feet. Ellenburger : April 24, 1951; Ellenburger: Average, 400 feet; maximum, 615 Sinclair Oil & Gas Co . #1 Mc Elroy Ranch feet. WILSHIRE FIELD, Upton County, Texas t; ._ ~ g ~ ~ e ..J '" z 0 ::> z "'" <) " 0 "' 0 ... z " TYPICAL RADIOACTIVITY 8 ELECTRIC CURVES LI THOLOGY GAMMA RAY RESISTIVITY DEPTH EL EVATION 2781 300 4-00 2381 500 2281 600 2181 700 2081 800 19 81 900 188 1 1000 t781 1100 1681 1200 1581 1300 148 DEWEY l-1400 1381 LAKE 1281 RU STL ER,, 1500 ~> 1081 981 0 J: 881 781 0 681 581 481 381 TANSILL z " ...... " >­ '" a. " 0 " ::> "'"' er ~ 0 > :c a:: z w > J:"' 3' ~ " z 0 2600 181 2700 81 2800 -19 2900 -119 3000 -219 3100 -319 3200 -419 3300 -519 3400 -619 3500 -719 3600 -819 3700 -919 3800 -1019 3900 -1119 4000 -1219 4100 -1319 4200 -1419 4300 -1519 4400 -1619 SECTION OF ROCKS PENETRATED ~ ~ >­ (/) ., ~ w rJJ " ::> ? 0 t; RADIOACTIVITY 8 ELECTRIC CURVES "­ ~ LI THOLOGY ~ ~ GAMMA RAY RESISTIVITY a:: and SP0 Cl LI-DE PTH ELEVATION 0 4 4 00 OU E EN ·~~~: ANO ~-~-­ V'l SEVEN RIVERS .r--" a:: 0 ~ ~ I ; ~ ::; w z " ? ? 0 ? ? :c >­ '" 0 10,900 -'e 11 9 11,000 -8219 ll,100 TULIP CREEK i:j z ~ 11,600 ~ 0 l-+=+11,--11--'i;__-+~~ -700----..,:'"'I'~"" ­ 0 0 Q_ J: z OI L CREEK ~~+-+"J~O~S~---~-,."-~~~-.l'°--+--'--4. I N"-"I a: a: 12,100 0 '" "' a: a: 12, 200 '" ::> 3' "' 0 z 12 ,30 0 ..J "' 12,433 NOTE: This TYPICAL SECTION is based on the log of the Strawn and Ellenburger discover y we ll . The position of the Spraberry reservoir is indicated although commercial production was not found in the Spr aberry at this location . EXPL AN AT ION ES] Sandstone ~Dolomite filEE s hote r+7:'l ~Solt ~Limest one m Anhydr ite :tJ. Oi l pr odu ction Sh ow of gos f66i\l~Chert "' ;; z " ..J Q 0 S. BLOCK 42 TWP. 5 S. T. a P. RR Co. EXPLANATION ---7100 --Con1011r on lop of Slrown 1eries Oil we ll, produc in g from Sprob•rry Oil welt, producln9 from Sl rown • Oil well, producing from Ellenbu r oer • ~ 0 Drilling well Ory hole ff •-c::n Dlttower y Total depth12,; 89 ~ N A A' CROSS SECTION A -A' 0 ELEVATIO N I -0000 LEONARO N -6000 -7000 -8000 -9000 Co. -10,000 HORIZONTAL SCALE I •O ~ THOUSAND FEET ' -11,001 ,_. L' Ul Ji ::r: 3513 ,_. Co. ~ tT:I '"Tj ,_. tT:I L' t) c 'O ...... 0 ~ 0 0 c ~ ...... '"< ..., ~ 0 tll EXPLANATION ---10,100 --Conl our on top of Elhnburi;itr 9roup ~ 011 well, produclno from Spraberry 9 Oil well, produc in9 from Slrown Oil well , pro ducing lrom Ellenb11fQU 0 Drill ing we ll /f Ory hole . Tolol depth • \::n Olscoory 12,789 SCALE SCALE THOUSAND FEET THOUSAND FEET WILSHIRE FI ELD, Upton County, Texas UTHOLOGY OF RESERVOIR ROCKS Spraberry: Limestone; brown, medium crys­talline, oolitic . Strawn: Limestone; brown, medium crystalline, fossiliferous, with some milky, mottled, translucent chert. Ellenburger: Dolomite; brown, dark brown, gray and gray-white; very fine to coarsely crystal­line with some chert. Figures representing degree of porosity are not available. An examination of several micrologs indicates about 120 feet of net productive dolomite, but estimating net pay in Ellen­bur.ger on the basis of micrologs is most difficult. It is suspected that the reservoir rock is fractured and that an exact determination of net pay cannot be dedved from data afforded by our present methods of logging. CONTINUITY OF RESERVOIR ROCKS Spraberry: The reservoir rock is a member of a section which contains several such members. The particular member which is productive at the location of the only Spraberry well cannot be posi­tfvely correlated although there are similar rocks at about the same stratigraphic position in other wells. The particular lens of favorable porosity is cer­tainly not continuous beyond the immediate vicinity of the one well. Strawn: The reservoir rock is continuous throughout the area of the field but the degree of porosity and permeability of that rock are quite variable. Ellenburger: This reservoir rock is continuous throughout the area of the field and far beyond. There are minor variations in porosity and permea­bility. The degree of fracturing is a local feature. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Ellen-Spraberry Strawn burger Elev., top of oil, feet -5 ,001 -6 ,509 -9 ,135 Elev., bottom of oil, feet Unknown Unknown -9 ,150± Relief, feet Unknown Unknown 616± CHARACTER OF OIL Ellen­Spraberry Strawn burger Gravity, A.P.I. @ 60 ° F. 36.8 49.9 53.3 SELECTED REFERENCE Berry, 0. H., Jr. (1952) Wilshire Ellenburger field, Upton County, Texas: Amer. Inst. Min. & Met. Eng., Statistics of Oil and Gas Development and Production Covering 1951. pp. 442-444. ACID TREATMENT Spraberry: The reservoir rock in the one Spra­berry well was treated with l 0 ,000 gallons of acid prior to completion. Strawn: The Strawn reservoir rock in the Strawn dfscovery well was treated with 2 ,000 gallons of acid prior to completion. The reservoir rock in the presently productive Strawn well was treated with 15,000 gallons of acid. Ellenburger: Most of the Ellenburger wells have been completed without acid treatment. There have been no acid treatments subsequent to completion. PRODUCTION HISTORY WELLS PRODUCING OIL PRODUCTION a t end of year (barrels) Year Flowing Pumping Yearly Cumulative Field totals 1948 0 2 ,954 2 .954 1949 0 11 .696 14 ,650 1950 0 6 .929 21 ,579 1951 11 462 ,2 16 483 ,795 1952 41 3 ,887 ,071 4,370 ,866 Spraberry 1948 0 2 .954 2 .954 1949 0 11 .696 14 ,650 1950 0 6 .929 21 ,579 1951 0 4 ,3 52 25,931 1952 0 2 ,780 28 ,711 Strawn 195 1 0 2 ,359 2,359 1952 1 0 9 ,653 12 ,o 12 The 1951 production wa s from the discovery we ll and the 1952 production was from Sinclair Oil & Gas Co. #6 Mc Elroy Ranch. Ellenburg er 1951 11 0 455 ,505 455 ,505 1952 40 0 3,874 ,638 4,330,143 WORLD FIELD Crockett County. Texas MARIA SPENCER and WARREN MUERY Geologists, The Superior Oil Co., Midland , Texas March 24, 1954 LOCATION and OTHER NAMES The World field is in north central Crockett County, 3~ miles south of the Crockett-Reagan county boundary and 10 miles northwest of the Todd field . This field has been designated in some publica­ tions as the World-Powell field. During its early history it was commonly designated in current publications as the Powell field. METHOD OF EXPLORATION LEADING TO DISCOVERY Surface mapping on beds of lower Cretaceous age indicated a favorable structural feature , which led to the drilling of the discovery well. DISCOVERIES Grayburg : May 30 , 1925; World Oil Co. #1 L .P .Powell. Initial production, 50 barrels of oil per day. Total depth, 2,646 feet . Strawn: September 22, 1951; Continental Oil Co. #1-E L.P.Powell. Completed as a flowing oil well with a potential of 288 barrels of oil per day . Total depth, 8 ,288 feet; plugged back to 8,141 feet. This is the only well completed in this reservoir. It was plugged and abandoned on January 13, 1953, due to decline in reservoir pressure. ELEVATION OF SURFACE At well locations: Highest, 2 ,800±ft.; lowest, 2 ,600±ft. SURFACE FORMATION The rocks exposed at the surface are mainly limestones of the Washita group . OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated is in the Ellen­burger group 520 feet below its top . This penetration was in Continental Oil Co . #2-E L .P .Powell, the well about l ,250 feet north of the Strawn discovery well and where the total depth of 8,738 feet is indicated on the accompanying map. Four wells within the area of the accompanying map were drilled into the Ellenburger group . PRODUCTIVE AREAS Grayburg 4,500 acres Strawn (depleted) 40 acres NATURE OF TRAPS Grayburg : While anticlinal folding is the domi­nating trap-forming factor, the trap is due partly to lensing of porous zones in the reservoir rock on the east side of the field. Strawn: Since the accumulation at the only pro­ductive well is at the apex of an anticlinal fold, it appears that anticlinal folding is the dominating trap-forming factor; however, the possibility that the accumulation is due merely to convexity of the upper limit of reef limestone cannot be eliminated. THICKNESSES OF RESERVOIR ROCKS Grayburg : The sum of thicknesses of zones of productive rock ranges from 2 feet up to 65 feet. However, penetration of reservoir rock in the pro­ductive wells averages only about 10 feet due to precaution to avoid unnecessary production of water . Strawn : From top to bottom of productive rock in the single productive well is about 50 feet. LITHOLOGY OF RESERVOIR ROCKS Grayburg : Tan, saccharoidal, oolitic dolomite . The oolites are ellipsoidal and range in size from . 1 mm to 1.5 mm, averaging approximately .5 mm. The porosity is probably a result of the oolitic character of the dolomite. Individual zones of good porosity are discontinuous . Strawn: Coarsely crystalline, fossiliferous lime­stone. CONTINUITY OF RESERVOIR ROCKS Grayburg: The reservoir rock is continuous throughout the area covered by the accompanying map , but individual zones having favorable porosity are discontinuous; all zones grade into dense anhy­dritic dolomite on the east side of the field. Strawn: Probably continuous throughout the area of the accompanying map. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Grayburg Strawn No free gas cap in either .reservoir Elevation of top of oil. fe et 145 -5,331 Elevation of bottom of oil, feet 82 -5 ,381 World field 4,500 acres Relief, feet 63 WORLD FIELD, Crockett County, Texas CHARACTER OF OIL Grayburg Strawn Gravity, A .P .I.·@ 60 ° F. 27 ° to 32 ° 40 ° Sulphur 0.7% Grayburg : Generally, the quantity of gas in solution in the oil has not been quite enough to cause the wells to flow . However, a few wells have flo,wed their production temporarily . For analyses of Grayburg oil see : Railroad Commission of Texas Analyses of Texas Crude Oils (1940) pp. 32 and 61 U.S.Bureau of Mines Lab .ref.No . 27867 31164 Analyses of Crude Oils from the West Texas District. R.l. 2849 (1927) Page 16 Tabulated Analyses of Texas Crude Oils . R .I. 32 52 (1934) Group 2 Item 67 68 Tabulated Analyses of Texas Crude Oils. T .P. 607 (1939) Group 2 Item 94 95 Analyses of Crude Oils from Some West Texas Fields . R.l. 3744 (1944) Page 44 WATER PRODUCTION Grayburg : The percentage of water in gross production is extremely high and has been high continuously from the time of discovery. Because of the high water :oil ratio, there is a field rule forbidding the operation of a well whenever the water:oil ratio exceeds 20:1. At the present time, there is no apparent se.paration between the oil and water in the reservoir . There appears to be no definite oil-water contact , or , if there is, then its elevation is very irregular. Strawn: No record of water production. COMPLETION TREATMENT Grayburg: The early wells were completed "natural". Some of the later wells were shot. Prac­tically every well completed during the last fifteen years has been treated with 500 to 2,000 gallons of acid. Strawn: The single productive well was treated with 3,000 gallons of acid at time of completion. SELECTED REFERENCE Stratigraphic Problems Committee (1953) North­South Cross Section through Permian Basin of West Texas: We st Texas Geological Society Midland, Texas PRODUCTION HISTORY WELLS P RODUCING OIL PR ODUCTION a t end of year (barrels) Year F lowing Pumping Yearly Cumulative Graybur g : 1925 ....................... ..... ...... 3,320 ........... 3,320 1926 278,688 282,008 1927 549,483 83 1,491 1928 . .............................. 852 ,758 ..... l ,6 84,249 1929 684 ,7 90 2,369,039 1930 67 7 ,364 3 ,046 ,40 3 1931. ..... ....... . ... .. .. . ....... .. 511,51 3 . .... 3,557,916 1932 0 36 419,840 3,977 ,7 56 1933 0 35 322,687 4 ,300,443 1934.......... 0 .......... 41.. .... . 259,860 ..... 4,560,303 1935 0 37 312,854 4,873,157 1936 0 39 390 ,025 5,263,182 1937 .......... 0 .......... 40....... 424,119 ..... 5,687 ,301 1938 0 42 302 ,9 79 5 ,990 ,280 1939 0 46 3 4 7 '0 5 7 6 '3 3 7 '3 3 7 1940.......... 0 .......... 50....... 411 ,932...... 6,7 49,269 1941 0 65 5 10,754 7,260,023 1942 0 78 608,608 7,868,631 1943 ........ .. 0 ......... . 89....... 688,518 ..... 8,557 ,149 1944 0 90 717 ,284 9,274,433 1945 0 93 710,001 9,984,434 1946 .... ...... 0 ...... ... 101.. ..... 717,014.... 10,701,448 1947 0 117 862,770 11 ,564,218 1948 0 120 949,869 12,5 14,087 1949 .. .. ... ...0 ........ . l 3 6 . .... 1 ' l 1 1 '3 2 4 .. .. 1 3 '6 2 5 '41 l 1950 0 156 1,426,278 15,051,689 1951 0 178 1,414 ,572 16 ,466,26 1 1952..........0 ......... 182 ..... 1,506,896 .... 17,973,157 1953 0 195 1,498,277 19,471,434 Strawn: 1951 0 4 ,57 3 4 ,573 1952 0 4 ,340 8 ,91 3 1953 Abandoned 0 8 ,913 The figures representing yearly production for each year prior to 1934 have been transcribed from page 448 of TEXAS OIL AND GAS SINCF 1543 by C .A.Warner (Gulf Publishing Co .) and the fig ures for the years 1934-1937 are from the same source adjusted by deductions representing quantities pro­duced in the Todd field, also in Crockett County, as reported in annual issues of PETROLEUM DEVEL­OPMENT AND TECHNOLOG Y (A . I. M . E .). The figure for 1938 is that reported for the Wo rld field for that year in the c o rresponding volume of the A .I.M.E . series . The figur e s for 19 39 a nd s ubse ­ quent years have been transcribed from Annua l Reports of the Railr oad C ommission. z <{ - ,. er ~ N ~ B LOCK A EXPL ANATION -+225-Contour on top of Groyburg formation Groyburg Groyburg, Groyburg, grou p ~ 0 ::0 L" t:1 'Tj ........ M L" t:1 ~ () ~ CD ~ "~s. p o......._ TO 3206 "~~s ~ 1-~oo ::s ~ .-..,7s __ >--3 44 ~ QI ELECTRIC S. RADIOACTIVITY CURVES LITHOLOGY GAMMA RAY RESISTI VI T Y ~ ~ => :::t ~1~ 1~1~ ..J ~ ffi~~ ANO S. P. ~ 0 ::x:i t""' t:I '"Tj ...... M t""' t:I 0 a () :;.;" (t) - - 0 0 c :::1 -"<­>-j (t) >< Q Ul ,j:::.. N (Jl (f) IJ'l z 1~ "':;, ..J "' "' "' 0 "'" ~ :;, u.. DEPTH ELEVATION 0 .. 17 00 1057 •-'C -":::-:.. -<: <:::O, ..:::,..·­ 1800 ~ 9" -.:· ~ "' 1900 '" t­ "\:.__ H.ooo =~ '" "':..~~ .rs;..._ f .,, w l~~2100 ·~ ol I 2 2 00 '" ~ .,, 2300 ...,, ...;­ :c ii: "' z "' "' :;, 0 '""l 2500 ::E:.... '" ~{~ -.:::-­ ,., t... '>-;: a: -=-..­ ~ _.# >­ ...~= ex 2100 c._r ~ --='< -•> .-~~ z -143 ~ ~2900 :} ~­ ~ SCAl(:~CH•NG(liO "' ~i~!£'""" -243 "' ~3000 --.:::.:_=-( U' ~­ 30 50 ....... -Z9J EXPLANATION ~Dolomitic ~Limeston e . Chert limest on e ~ Ll Rock indicated,l\}{).j Sondsfone [~C~l~~~:~~nse sholy CJRock indicated, .Dolomitic ~Anhydrite anhydrite re d ~Anhydritic CJRock indicated, Solt salt Qreen []]Rock indic ated,~Gray calcareous ~Dolomite bl ock shale LJShale, 9roy unless • Oil production other color indicated TYPICAL SECTION OF ROCKS PENETRATED z 0 ;:: ~ "' "' ~ ii' a: "' 0 ~ ... "' ~ "' ~ a: :;, 0 ..J z "'"' ELECTRIC & RADIOACTIVITY CURVES LITHOLOGY 0 "' .. :;, 0 a: "' z 0 "' ..J z "' ~ GAMMA RAY ANO s. P. DEPTH 3050 ~~~ 3100 ·~ -;~~ e -~ 3200 < ~­ ~ ..,,..~ ~& HOO '<;=!_.._ --=--> :i_~ --.-._ 3• 00 ~ j~,.. 3'00 3600 ~--­? --),-~ _;:-. 3700 ;: .... -~ 3800 ;f ~ "!i 3900 ... ~~ ~:: ­ a: "' a: ..J"' "' "' a: ~ ~ a. ~ "' z "' u "' ... 0 ..J 0 "' ELECTRIC S. RADIOACTIVITY CURVES LITHOLO GY RESISTIVITY EL EVATION " "' -20 43 -2 I 43 -2243 -2 343 -244 3 -2543 -2643 -274 3 -28 4 3 -2943 -3043 -31 43 -JZ4J -JJ4J -34 43 -J54J ,..., -37 4 3 -3793 GAMMA RAY ANO s. P. DEP TH 4800 -=;­ ~ -,... 4900 -~-?~ < ~<:-­ 3w:.. 5000 ,;;, ::~---­ -~~~ .-..;• 5100 5200 ={ j ~ !!1300 54 00 5500 ?~ 5600 ~t: ..._"S­ 5700 s\ ~ 58 00 ::,~ _.. '900 -~~ ~ =~~­ •ooo -i~­ 6100 ~-=-­ 6200 6300 6400 ~ 6500 i~ ~ i 6550 YATES FIELD Pecos and Crockett Counties. Texas DAVID DONOGHUE and W. L. GUPTON, Jr. Consulting Geologists, Fort Worth, Texas January 10, 1956 LOCATION The Yates field is for the most part in Pecos County with the eastern tip extending across the Pecos River into Crockett County. It is on the southern end of the Central Basin platform. Physiographically, it is in the dissected northwestern portion of the Edwards plateau. INTRODUCTION The Yates field is notable for the extremely large poten­tial capacities of its wells, for the large return on capital invested, for low production costs and for the orderly and conservative manner in which it was developed and has been operated. Mid-Kansas Oil & Gas Co. and Transcontinental Oil Co. #30 I. G. Yates "A", although it was completed at the depth of only 1,070 feet, hadan initial capacity among the greatest, if not the greatest, of any well ever completed anywhere. Relative to this well, in their paper cited under SELECTED REFERENCES, Hennen and Metcalf say: "Official pro­ration test pf this well on September 23, 1929, gave it 8,528.4 barrels ofoil an hour, or a daily potential of 204,681 barrels -the largest actually gauged production ever found for any well. " At the time of completion on September 12, 1929, the well produced 4, 365 barrels in 34 minutes, or at the rate of 185,000 barrels per day. Relative to the second most prolific well in the field, in their paper cited below, Carpenter and Hill say: "The California Co. Reid well #3, completed January 1, 1935, had an initial production of 7,005 barrels per hour or at the rate of 168,120 barrels per day. The initial production of this well, the second largest in the field, is particularly noteworthy because when it was completed the field was 8 years old and had produced about 200,000, 000 barrels ofoil. " These two wells are in the east­central part of the field near the discovery well and are identified on the accompanying maps by entry of "A" and "B" respectively. Although the capacities of the wells were generally extremely high, and many of the:in were enormous, produc­tion was held to a conservative rate. Throughout its history, the field has been conservatively developed and operated, Organized curtailment ofproduction in Texas had its beginn­ing in the Yates field Octsiber l, 1927. The operators had ratified a voluntary plan ofproration in September, 1927 and continued to operate voluntarily under modifications of that plan until enforcement was assumed by the Railroad Com­mission on July l, 1928. (The Hendrick field, under an order effective May 5, 1928, was the first field prorated by authority of the Commission). Production from the Yates field is reported in four catagories: viz., (a) Toborg, (b) Yates Sand, (c) Yates Lime and (d) seepage oil or salvage oil. Toborg: The production in this catagory is commonly reported as from a separate and distinct field, with the name spelled variously as "Toborg", "Toburg", "Toberg", "Tobarg" and "Torburg". The correct spelling appears to be that of the name of the owner of the land on which the discov­ery well was drilled; that spelling appears to be "Toborg", In this paper, the Toborg production is treated as coming from a single distinct reservoir in the Yates field. However, it is recognized that there may be several distinct reservoirs INTRODUCTION (Continued) and that the oil in some of them probably migrated, due to leaky casing, from the Yates Lime reservoir subsequent to the discovery of the field. Such oil is, of course, more closely related to the oil in the fourth of the above listed catagories than it is to such oil as was in the Toborg reser­voir rock before development of the field. It appears likely that only a small percentage of the ultimate Toborg produc­tion was in the Toborg reservoir rocks when the Yates field was discovered. Prior to 1946, Toborg production was limited to a small area at the northwest edge of the Yates field. In the latter part of 1946, a drilling campaign was started, and now the Toborg productive area extends along the entire northeastern flank of the field. The total depths of the wells are mostly between 100 and 600 feet, with only a few slightly deeper and with many even shallower. Yates Sand: The Yates sandstone was recognized early as a distinct stratigraphic unit and was used as a strati­graphic marker, firstunderthe name of"Smith Sand", which name was preoccupied as the name for a stratigraphic unit, then under the name of "Yates Sand". Since the time when the formation was named in this field, it has been widely correlated throughout West Texas. Early in the development of the Yates field, substantial showings of oil were observed when this formation was penetrated, but production was de­ferred pending development of the more prolific Yates Lime. Since the time when producing operations were initiated in 1933, the production has been reported variously as from "Yates, Smith Sand", "Yates (Smith sand)", "Yates-Smith Sand", "Yates, sand", "Yates (sand)" and "Yates Sand". Yates Lime: The reservoir herein designated by this name is by far the most important reservoir in the field. Only a relatively small quantity of oil has been produced from the other reservoirs. As indicated on the accompanying GENERALIZED COMPOSITE SECTION, the reservoir rock consists of rocks of Queen, Grayburg and San Andres form­ations. An understanding of this reservoir requires thinking of it as composed of two parts: viz. , that part above the unconformity and that part below the unconformity. Thatpart above the unconformi tyis at the base of the Queen formation. That part of the Queen formation (the River Bed Sand) which constitutes a part of the reservoir rock is not present every­where in the field. There is no River Bed Sand throughout a considerable area at the structural apex, but, outward, except in the west-central part of the field, there is a varying amountof this member, with the maximum thickness around the periphery of the field -up to 120 feet at the northeast edge of the field. That part of the reservoir below the unconformity includes the main productive zone. The main productive zone, which is at the top of the Grayburg form­ation, has been called the "Brown Lime" and is a zone at the top of the "Big Lime" and has been correlated with the "Big Lake Lime", which is productive in the Big Lake field in Reagan County. The downward extent of the productive rock is not known, primarily because of a field rule that prohibited drilling more than 225 feet into the "Big Lime". In their paper cited below, Hennen and Metcalf say: "This excessive porosity seems to have been produced to a depth of several hundred feet into the limestone. No great de­e reas e has been noticed to a depth of 225 feet in the many wells that have been drilled to that depth. There is every indication that it will continue to the general water-table of YATES FIELD, Pecos and Crockett Counties, Texas INTRODUCTION (Continued) DISCOVERIES the field, which, in the central part of the pool, will permit a penetration of more than 375 feet of probable pay zone. " Seepage oil: Early in October of 1928, surface seepage of oil was observed along the Pecos River. Recovery was begun on October 12, 1928. Oil was recovered by skimming the water of Pecos River, by trenching, by digging pits and by drilling shallow wells. Recovery by these methods had amounted to 400,000 barrels up to July 1, 1929; thereafter the rate of recovery increased rapidly and then declined, as indicated by the figures presented in the following PRODUC­TION HISTORY, under Yates Lime: Seepage. Analyses of the oil corroberated the supposition that the occurrence was due to escape from the Yates Lime reservoir through im­perfect casing installations. A careful investigation resulted in remedial work; particularly cementing, at several wells; one well was plugged and abandoned. A gradual reduction in the amount of seepage oil indicated that the remedial work at the wells had been effective in curtailing the leak3ge. The seepage oil that is definitely recognized as such is now re­ported as production from Yates Lime reservoir. However, it is highly probable that a material portion of the Toborg production has escaped from the Yates Lime reservoir through leaky casing. The recovery of seepage oil has been from recent sands and gravels along the Pecos River and from rocks at various stratigraphic positions within the range of the Toborg reservoir as indicated on the accompany­ing GENERALIZED COMPOSITE SECTION. Since seepage oil is not regarded as occurring naturally in a separate and distinct reservoir, corresponding treatment is omitted under several of the following headings. METHODS OF EXPLORATION LEADING TO DISCOVERY Surface geological mapping in 1923 by members of its staff led Transcontinental Oil Company to acquire leasehold rights on several favorable blocks in this general region, including a solid block of 9,690 acres now largely within the area of this field. The surface geological conditions led Mid-Kansas Oil & Gas Company to enter into a deal with Transcontinental whereby it drilled a test well on each of three of the several blocks in consideration of a half-interest in the leasehold rights on all of them. Then the two operators drilled, on a fifty-fifty basis, the exploratory test which became the discovery well of the Yates field. SVRFACE FORMATIONS Rocks of Cretaceous age predominate, with merely a small area occupied by Triassic rocks and with a possibility that, within that small area, there is a very limited Perm­ian outcrop. The rugged topography occasions surface outcrop of much more section than common in the oil fields of West Texas. The oldest surface rocks are of Triassic age, or possibly late Permian, and above those are the younger stratigraphic units as indicated on the accompany­ing GENERALIZED COMPOSITE SECTION; however, the section within the field extends further upward and includes a total thickness of about 620 feet of undifferentiated Fred­ericksburg -Washita limestone. Toborg: No single Toborg well has all the attributes considered normal for discovery wells. The first completion as a commercially productive well followed after the pres­ence of oil in the Basement Sand had been demonstrated in several wells drilled deeper to the prolific Yates Lime reser­voir. Showings of oil, some apparently commercial, in the Basement Sand were observed in wells in Sections 39 and 40, Block 194, G. C. & S. F. survey. The observance of the showing was followed in due course by completion of wells in the Basement Sand in the southern end of Section 539, Arnold & Barrett survey and in Sections 39 and 40, Block 194, G. C. & S. F. survey. The first completion appears to have been in September of 1928, and this was followed rapidly by many others. By the end cif 1930 there were 40 of these shallow (350 to 600 feet) wells clustered at the northwest end of the Yates field. Yates Sand: Good showings of oil, apparently commer­cial, were observed in the Yates Sand during the process of drilling to the prolific Yates Lime reservoir. These show­ings were particularly promising in wells in the vicinity of the common corner of Sections 23, 24, 27 and 28, Block 194, G. C. & S. F. survey. It appears that the first com­pletion for production from this reservoir was in October of 1933 in the northeastern part of Section 24. The produc­tion was not very profitable and development progressed slowly, as indicated by entries in PRODUCTION HISTORY presented on a following page. Yates Lime and Field: October 26, 1926; Mid-Kansas Oil & Gas Co. and Tr-anscontinental Oil Co. #1 Ira G. Yates "A" (now, Ohio Oil Co. #1 Yates "A"). In their paper cited below under SELECTED REFERENCES, Hennen and Metcalf say: "It blew in unexpectedly in the top of the Big Lake lime at the shallow depth of 997 feet on October 28, 1926, with a large volume of gas and about 100 barrels of oil daily. Efforts were made immediately to mud off the oil and gas 'pay' until the well could be properly cased. It required several days to do this and it was accomplished only after a large quantity of mud had been blown out of the hole several times. The well was then deepened to 1,032 feet and completed on December 13, 1926, making 135 barrels per hour. Later (August 18, 1928) it was completed to its present depth of 1, 150 feet and its proration test at that time was 2, 950 barr!;!ls of oil per hour. Its proration test in the latter part of June, 1929, still gives it 2,999.31 barrels per hour, or 71,984 barrels daily. * * * The com­pletion of this remarkable well on such a large dome in the surface (Cretaceous) beds created great excitement in the oil fraternity, and development followed rapidly. By July 1, 1928, 207 wells had been completed in the pool with a daily potential production of 2, 575,047 barrels of oil, based on one-hour open-flow tests, and by July 1, 1929, a total of 306 producing wells had been completed with a daily potential production of 4,590,686 barrels, or a daily potential pro­duction per well of 12,439 barrels and 14,620 barrels for the respective dates. No such results have ever been duplicated in so many wells in any pool, regardless of depth to pay zones. " ELEVATION OF SURFACE The elevation of the surface ranges from about 2, 150 feet in the bed of the Pecos River up to about 3,000 feet at the high points on the mesas in the western portion of the field. A large part of the relief is in the almost vertical cliffs of the mesas. YATES FIELD , Pecos and Crockett Counties, Texas OLDEST STRATIGRAPHIC HORIZON PENETRATED The oldest horizon penetrated within the field is in the San Andres formation 292 feet below the top of the Gray­burg formation. During nearly the whole of the period of development there was a field rule prohibiting drilling more than 225 feet below the top of the "Big Lime" (i.e., top of Grayburg). Penetration in many wells is at or near that limit; in only a very few wells is that limit exceeded. The oldest horizon penetrated in the vicinity of the field is in the Ellenburger group 374 feet below its top. This penetration is in Standard Oil Co. of Texas #1 Douglas Oil Co. et al, a dry hole located near the southeast corner of Sec. 9. Block 194, where the total depth of 9,114 feet is indicated on the accompanying maps. VARIATIONS IN THICKNESSES In their paper cited under SELECTED REFERENCES, Hennen and Metcalf summarize certain important observa­tions as follows: •The Permian sediments encountered in the field represent a somewhat abbreviated section of those normally found in the Permian basin. Because of the struc­tural relief existing during the deposition of the upper Per­mian, these strata become much thinner toward the axis of the fold, and the upper part of the sediments is almost entirely missing in part of the field. " The degree of thinning over the axis decreases upward in the section. LITHOLOGY OF RESERVOIR ROCKS Toborg: In the original productive area iri Secs. 39 and 40, Blk. 194, G. C. & S. F. survey and Sec. 539, Arnold & Barrett survey, the Toborg reservoir rock is dolomite con­taining various amounts of coarse, well cemented sand and some free sulphur and with zones with porosity of the cavity or vug type. In the southeastern extension, production appears to come from several different zones, mainly zones in the Trinity sandstone where there is a high degree of porosity and permeability. Yates Sand: This reservoir rock is a shaly, calcareous sandstone containing thin layers of gypsum, dolomite and anhydrite. The productive portion consists of lenses of soft, saccharoidal sandstone totaling about 8 to 10 feet in thickness. Yates Lime: The Yates Lime reservoir occupies rocks in two distinct cata,gories: viz., those above the unconformity and those below the unconformity. Those above the uncon­formity are mainly basal sandstones in a series where anhy­drite is dominant. There is a minor amount of re-deposited dolomite and dolomitic lim-estone at the base of this series, and this re-worked material is locally productive. However, most of the production from above the unconformity is from sandstone lenses in the basal portion of the anhydrite series. The main productive rock of this reservoir, and of the Yates field, is the "Brown Lime", which is immediately below the unconformity and at the top of the Grayburg formation. This limestone is dolomitic, has vuggy to cavernous porosity and a very high degree of permeability. The degree of porosity is much greater on the steeply dipping eastern flank than elsewhere. While it has been observed that porosity and permeability decrease only slightly with deeper penetration in so far as the limited penetrations provide data, it appears probable that, in general, there is a decrease beyond the extent of the penetrations. NATURE OF TRAPS Toborg: Either updip decrease of porosity or updip lensing on a structural nose appears to be the principal trap­forming factor accounting for the accumulation in the area where Toborg production was initiated. As the productive area spread, it appears likely that Toborg production came to include some seepage oil which had not yet been trapped since its escape from the Yates Lime reservoir. Yates Sand: The accumulation in the Yates Sand appears to be due to updip and lateral variation in degree of porosity of the reservoir rock on a westward plunging structural nose. Yates Lime: Anticlinal folding is the primary trap­forming factor. Truncation of the reservoir rocks and sealing by overlying relatively impervious younger rocks is also important in forming the trap. Although some produc­tive lenses of the River Bed Sand member may be separated downdipwardfrom underlying Grayburg limestone, itappears that there is updip intercommunication and that there is merely on.e trap in which the enormous quantity of Yates Lime oil has accumulated. PRODUCTIVE AREAS Acres Toborg 4,520 Yates Sand 660 Yates Lime 20, 700 Yates field 22,430 THICKNESSES OF RESERVOIR ROCKS Toborg: In the area where Toborg production was initi­ated, there is a single productive sandstone, generally 5 to 15 feet thick. However, that sandstone has not been corre­lated except in a very limited area. It is probable that there are many separate and distinct sandstones now contributing to the Toborg production and that those sandstones are dis­tributed through a considerable stratigraphic range, as indicated on the accompanying GENERALIZED COMPOSITE SECTION. Available data do not warrant a guess as to total thickness. Yates Sand: In the area where the Yates Sand is produc­tive, the thickness from top to bottom is about 60 to 80 feet. The sum of the thicknesses of the portions which yield oil into the bore holes is about 8 to l 0 feet. Yates Lime: Data are not available for reporting appropriately on the thickness of the rock which yields the major production of the field. As indicated in the entry under this heading in the foregoing INTRODUCTION, a con­siderable portion of the contributing reservoir rock is below the extent of penetrations attained during development operations. The reservoir occupies rocks both above and below an unconformity, with considerable thickness between productive members at structurally low locations around the periphery of the field. The total net thickness of productive rock above the unconformity varies throughout the field from zero to 120 feet. That portion of the reservoir rock below the unconformity is certainly as much as 225 feet and probably does not exceed 400 feet in thickness. YATES FIELD, Pecos and Crockett Counties, Texas GENERALIZED COMPOSITE SECTIONCONTINUITY OF RESERVOIR ROCKS OF ROCKS PENETRATED Toborg: Except in the central part of the field where they have bee~~ved by erosion, the Trinity and Triassic zones which con­ ~ z LITHOLOGY :::; a:tain the locally productive lenses are continuous throughout the area .... (f) w a. w :::;of the field and far beyond the extent of the field. However, the indi­ .... :::; (f) a: 0 a: WITHIN FIELD DESIGNATION :::! ww a: >­ vidual productive lenses are only local. 0 (f) (f) ... :::; DEPTH ELEVATION Yates Sand: The stratigraphic equivalent of the reservoir rock is recognizable throughout a large portion of the field. However, in only a small area in the western part of the field is the degree of porosity and permeability adequate for commercial production. Yates Lime: That portion of the reservoir rock which is in the Queen formation consists of a series of members deposited around a sinking island. Even the higher members were not deposited over the apex of the anticline. The character of each productive member is different at different distances from the apex. That portion of the reservoir rock below the unconformity is continuous throughout the field and far beyond except that the uppermost portion of the Grayburg formation was truncated locally at the apex before post-erosional deposition was continuous over the entire area. ELEVATION AND RELIEF OF PRODUCTIVE ZONES Toborg: ----nata. are not readily available. Yates Sand: Data are not readily available. Yates Lime: Highest known elevation of oil Elevation of bottom of oil Relief Feet 1,476 Between 1,060 & 1,090 Between 386 & 416 In their paper cited under SELECTED REFERENCES, Hennen and Metcalf say, "the water-table maintains a practically uniform level" and report that the elevation of the water-table was between 1,060 and l,090 feet above sea-level. COMPLETION TREATMENT Toborg: No artificial completion treatments have been used. Yates Sand: No artificial completion treatments have been used. Yates Lime: Of the total of about 600 wells completed in the Yates Lime reservoir, 109 were acidized and about 60 were shot with nitro­glycerin. SECONDARY RECOVERY Water injection projects are in operation in the Toborg reservoir and in the Yates Sand reservoir. w z a. --' :::; ____ . _ .,.... ~ TANSIL L 25-200 ~-<~~~~·-·SEE NOTE ~--~..,. 1------~. , . .. . W. Yates ) I• ~ 6 00 ~ rnwnnrn.... l Sand 700 (f) a: w 0 > ,.., a: "' I 0 w 800 0 z ,.., (f) w a: > w 0 (f) :r w t oo .... :r 3': 0 0 1000 N 1500 z ' w 0 w 0 :::> 0 "'V'V"'iit :)( + ( Rl~;~D BED 0-120 1400 f a: . 1-;·. :::> (l) .."' ,_ Yates 1 .·..,.:·.·.:-:·. I I (f) 0 w 2 a: 0 c z a I 13 00 >-<:: :i::­ >-3 tTJ Ul >-rj ......... tTJ L' tJ ;oo 8 rn Q :::s 0... 0 a (') -~ (!) - 0 0 c :::s -(i)' rn >-3 ~ Q rn 54 62 I 5391 61 631 70 461 45 64 1 le. I .~. 1ti1 441 43 42 11!1 G.C. 8' S. F. R.R. Co. N I BLOCK 194 16 15,f.. 'it. ff UH CHARLES FIELP}·~,, ··::.f{,o, •'' oO 1tfo "I 14 ,:;, T. C. R.R. Co. BLOCK Z 12 " tt, 10{!' I n{{ 10 1fi. 1fo. 1f!1 fooo .f,o t., Z~I it{, ' ff )'47 r;lt 1f., •H­1!fr SCALE .f!n 10 It... 2 6 1 1f!1 29 " 27 2 8 T. C. R.R. Co . BLOCK 17 B G. C. ll< S. F. R.R. Co. BLOCK 194 THOUSAND FEET Jl1 577 RUNNELS CO UNT Y SCHOOL LAND I. ll< G. N. R.R. Co. BLOCK I PECOS COUNTY 68 E X PLANATION ---­+1350 ­--­Contour on top of Groyburg forrT'Olion CONTOUR INTERVAL 50 FEET • Oil ..... ell, producing from Yates Lime reservoir Abandoned oil well, formerly productive from Yotes Lime reservoir * Gos well, s hul in, completed in Yoles Lime reservoir Jf Dry hote 1 ~15 Total depth · ~Discovery ·---© ·--@--Mid-Konsos and Transcont inental Oil Go. #30 l.G.Yoles "A" (now, Ohio Oil Co. # 30 L G. Yates "A") California Co . # 3 Re id ( now, Standard Oil Co . ol Texas IF 3 Bob Reid) Area where wells ore productive from Toborg reservoi r Area where wells ore produc t ive from Yates Sand reservoir This mop shows only such wells os penetrated Yates Lime reservoir 741 73 'i f, 72 71 Co. P1 sn ~00 58 1. ll< G. N. R.R. Co. BLOCK I PECOS COUNTY . ~o 5 4 4 ff 15 55 Z~5 543 SS ,!.', T. C. R.R. Co. BLOCK 178 --< :i:::­ ...-j tr:! r:Jl ';j ........ tr:! L°' t:l ;oo () 0 Ul Q ::l 0.. 0 a ~