Browsing by Author "Fisher, R. Stephen"

Now showing 1 - 20 of 20

Development and Application of the Nitrogen Isotope Tracer in Evaluating Hydrogeologic Controls on Abatement of Nonpoint Source Pollution From Livestock Confined Feeding Areas and Other Agricultural Operations
(1993) Fisher, R. Stephen
The U.S. Environmental Protection Agency (EPA) considers nonpoint source pollution to be the largest single category of contamination affecting the nation's waters. Agricultural nonpoint source pollution, which can be a significant component of this overall problem, requires further research to establish and implement best management practices. Improved land-management methods to control nonpoint source pollution must be based on an understanding of the geological and hydrological characteristics of soils, bedrock, and aquifers, as well as the social and economic impacts of recommended or regulated management practices. In particular, determining the source, mobility, and transport paths of contaminants to and within surface-water and groundwater systems is essential in developing prevention and remediation procedures and in formulating management policy for agriculture. In areas of multiple land use practices and nonpoint sources of contaminants, identifying contaminant sources and flow paths, and therefore establishing best management practices, can be exceedingly difficult. One such area is the Western Cross Timbers physiographic province of North-Central Texas, where land uses include crop agriculture, dairy farming, and tree growing. The Western Cross Timbers physiographic province includes Erath County and the drainage basin of the Upper North Bosque River. In 1989, the Texas State Soil and Water Conservation Board designated the Upper North Bosque River watershed as the watershed most severely affected by agricultural nonpoint source pollution (Texas Institute for Applied Environmental Research, 1992).
Floodplain Analyses and Drilling Reports for Camps Barkeley, Bowie, Mabry, Maxey, and Swift and Fort Wolters
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-
The Bureau of Economic Geology (BEG) is conducting hydrologic and hydrogeologic studies of Texas National Guard training facilities at Camps Barkeley, Bowie, Mabry, Maxey, and Swift and Fort Wolters. These investigations, in conjunction with aquatic and biological surveys conducted by the Texas Parks and Wildlife Department, will provide information needed by the Texas National Guard to plan training and preparedness activities such that environmental resources will be protected and enhanced without compromising national security readiness. This report presents interim results on floodplain analysis and drilling activities. Floodplain analysis results include 100-year rainfalls, 100-year flood hydrographs at camp and fort outlets, and maps of the 100-year floodplain at each training facility. Our drilling results include well schematics, well schedules, and location maps. Results are reported in 6 sections with each section discussing the drilling reports and floodplain mapping for an individual training facility. The methods section contains details about the procedures used to drill and complete the wells and map the floodplains.
Geologic, Geochemical and Geographic Controls on Norm in Produced Water From Texas Oil, Gas, and Geothermal Reservoirs
(1994) Fisher, R. Stephen
Water from Texas oil, gas, and geothermal wells contains natural radioactivity that ranges from several hundred to several thousand picocuries per liter (pCi/L). This natural radioactivity in produced fluids and the scale that forms in producing and processing equipment can lead to increased concerns for worker safety and additional costs for handling and disposing of water and scale. Naturally occurring radioactive materials (NORM) in oil and gas operations are mainly caused by concentrations of radium-226 (226Ra) and radium-228 (228Ra), daughter products of uranium-238 (238U) and thorium-232 (232Th), respectively, in barite scale. We examined (1) the geographic distribution of high NORM levels in oil-producing and gas-processing equipment, (2) geologic controls on uranium (U), thorium (Th), and radium (Ra) in sedimentary basins and reservoirs, (3) mineralogy of NORM scale, (4) chemical variability and potential to form barite scale in Texas formation waters, (5) Ra activity in Texas formation waters, and (6) geochemical controls on Ra isotopes in formation water and barite scale to explore natural controls on radioactivity. Our approach combined extensive compilations of published data, collection and analyses of new water samples and scale material, and geochemical modeling of scale precipitation and Ra incorporation in barite.
Ground Water Hydrochemistry in the Southeastern Hueco Bolson and Southwestern Diablo Plateau, Trans-Pecos Texas
(1990) Fisher, R. Stephen; Mullican, William F.
The hydrochemical history of groundwater in the arid southeastern Hueco Bolson and southwestern Diablo Plateau was investigated by collecting soil-moisture samples from unsaturated siliciclastic bolson-fill sediments and groundwater samples from the Diablo Plateau aquifer, the Hueco Bolson silt and sand aquifer, and the Rio Grande alluvial aquifer. Major, minor, and trace solutes, stable isotopic compositions, and activities of tritium and carbon-14 were measured in groundwater samples; major solute concentrations were determined in soil-moisture samples. Soil samples were collected to determine the type and amount of material that could be readily dissolved by recharge water. Core samples of Cretaceous carbonate and bolson-fill material were analyzed to determine the mineralogy of sediment and aquifer matrix. The Hueco Bolson and Diablo Plateau aquifers contain mainly sodium-sulfate groundwater that derived solutes by calcite, dolomite, and gypsum dissolution, coupled with exchange of aqueous calcium and magnesium for sodium on clay minerals and other ion-exchange sites. Rio Grande groundwater is dominated by sodium and chloride derived from dissolution of salts precipitated in irrigated fields during times of high evaporation. All groundwaters are inferred to acquire major compositional characteristics early in the flow history, principally through reactions in the unsaturated zone. Ages estimated from tritium and carbon-14 activities show that Rio Grande groundwaters are youngest, reflecting the short flow paths from the river to sampled wells following irrigation and percolation. Young groundwater is also found in the Diablo Plateau aquifer at wells both on the plateau and near the toe of the plateau escarpment. These are inferred to be recharge waters that rapidly moved along fractures to the water table. Other groundwater samples from the Diablo Plateau and Hueco Bolson aquifers are as much as 28,000 years old. Carbon-14 ages and tritium activities do not vary uniformly along a flow path. However, the oldest waters are found in wells near the center of the bolson pediment, and the distribution of carbon-14 ages generally conforms to the salinity distribution, suggesting a systematic relation between residence time, chemical and isotopic composition of groundwater, and regional hydrologic properties of the aquifers.
Ground Water Hydrochemistry in the Southeastern Hueco Bolson,Trans-Pecos Texas
(1989) Fisher, R. Stephen; Mullican, William F.
The hydrochemical history of groundwater in the arid southeastern Hueco Bolson was investigated by collecting soil-moisture samples from unsaturated siliciclastic bolson-fill sediments and groundwater samples from the Diablo Plateau aquifer, the Hueco Bolson silt and sand aquifer, and the Rio Grande alluvial aquifer. Major, minor, and trace solutes, stable isotopic compositions, and activities of tritium and carbon-14 were measured in groundwater samples, while major solute concentrations were determined in soil-moisture samples. Soil samples were collected to determine the type and amount of material that could be readily dissolved by recharge water. Core samples of Cretaceous carbonate and bolson-fill material were analyzed to determine the mineralogy of sediment and aquifer matrix. The Hueco Belson and Diablo Plateau aquifers predominantly contain Na-SO4 groundwater, derived from solutes through carbonate and gypsum dissolution, coupled with the exchange of aqueous calcium and magnesium for sodium on clay minerals and other ion exchange sites. Rio Grande groundwater is dominated by sodium and chloride, derived from the dissolution of salts precipitated in irrigated fields during periods of high evaporation. Major compositional characteristics of all groundwater types appear to be acquired early in the flow history, primarily through reactions in the unsaturated zone. Ages estimated from tritium and carbon-14 activities indicate that Rio Grande groundwater is the youngest, reflecting short flow paths from land surface following irrigation, infiltration, and deep penetration from the river to sampled wells. Groundwater from the Diablo Plateau and Hueco Bolson aquifers ranges in age from a few hundred to nearly 29,000 years. Carbon-14 ages and tritium activities do not vary systematically along a flow path; however, the oldest waters are found in wells near the center of the bolson pediment. The irregular distribution of carbon-14 and tritium suggests that the Bolson and Diablo Plateau aquifers are internally complex, and flow velocities are not readily predictable solely based on the potentiometric gradient and estimates of regional porosity and permeability data.
Ground-Water and Surface-Water Hydrology of Camp Barkeley, Taylor County, Texas
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-; Boghici, Erika M.
Ground-water and surface-water investigations were conducted on Camp Barkeley, Taylor County, Texas, to provide the Texas Army National Guard with information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted on Camps Bowie, Mabry, Maxey, and Swift, and Fort Wolters. Results of those studies are presented separately. Previous reports and public data files were examined to obtain background information on the camp and surrounding area. These data guided our more focused studies on the training facility. Ground-water studies included locating existing wells on and near the camp; installing new wells as needed for ground-water characterization; testing and sampling selected wells; determining ground-water levels, chemical compositions, and aquifer hydraulic properties; and developing a conceptual model of ground-water flow. Surface-water studies delineated watersheds and mapped floodplains. Alluvium along streams and the Antlers Formation are the principal aquifers in the Camp Barkeley area. Approximately 42 percent of all wells listed by the Texas Water Development Board (TWDB) in Taylor County produce from alluvium. Depths to water in existing wells vary both within and between formations, suggesting that the ground-water system is not well integrated. Groundwater compositions recorded in TWDB files show most samples to be fresh waters. A conceptual ground-water flow model resulting from this study indicates that local recharge most likely occurs through interconnected vertical fractures. Much of the water that infiltrates on topographically high parts of Camp Barkeley probably discharges at the edges of the mesas, with only minor discharge, if any, to deeper aquifers. The training facility resides in the Clear Fork River Basin. No significant permanent streams exist on the camp. Surface runoff flows to various first-order tributaries and creeks and ultimately to Lake Fort Phantom Hill, Clear Fork Brazos River, and the Brazos River. No significant 100-year floodplains exist on Camp Barkeley; however, severe rainfalls can produce heavy sheetflow and runoff that can quickly but temporarily fill arroyos and cause severe erosion.
Ground-Water and Surface-Water Hydrology of Camp Bowie, Brown County, Texas
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-; Boghici, Erika M.
Ground-water and surface-water investigations of Camp Bowie, Brown County, Texas, were conducted to provide the Texas Army National Guard information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Mabry, Maxey, and Swift, and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells on and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.
Ground-Water and Surface-Water Hydrology of Camp Mabry, Travis County, Texas
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-; Boghici, Erika M.
Ground-water and surface-water hydrologic investigations of Camp Mabry, Travis County, Texas, were conducted to provide the Texas Army National Guard information needed to plan and conduct training and preparedness activities while preserving environmental quality and resources. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Bowie, Maxey, and Swift and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells in and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.
Ground-Water and Surface-Water Hydrology of Camp Maxey, Lamar County, Texas
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-; Boghici, Erika M.
Ground-water and surface-water investigations of Camp Maxey, Lamar County, Texas, were conducted to provide the Texas Army National Guard information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Bowie, Mabry, and Swift, and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells in and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.
Ground-Water and Surface-Water Hydrology of Camp Swift, Bastrop County, Texas
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-; Boghici, Erika M.
Ground-water and surface-water investigations of Camp Maxey, Lamar County, Texas, were conducted to provide the Texas Army National Guard information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Bowie, Mabry, and Swift, and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells in and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.
Ground-Water and Surface-Water Hydrology of Fort Wolters, Parker and Palo Pinto Counties, Texas
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-; Boghici, Erika M.
Ground-water and surface-water investigations of Camp Maxey, Lamar County, Texas, were conducted to provide the Texas Army National Guard information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Bowie, Mabry, and Swift, and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells in and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.
Hydrologic and Hydrogeologic Survey of Camps Barkley, Bowie, Mabry, Maxey, and Swift and Fort Wolters
(1995) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-
The Bureau of Economic Geology (BEG) is conducting hydrologic and hydrogeologic studies of Texas National Guard training facilities at Camps Barkley, Bowie, Mabry, Maxey, and Swift and Fort Wolters. These investigations, in conjunction with aquatic and biological surveys conducted by the Texas Parks and Wildlife Department, will provide information needed by the Texas National Guard to plan training and preparedness activities such that environmental resources will be protected and enhanced without compromising national security readiness. This report presents data and analyses collected and performed by BEG researchers from October through December 1995. The activities presented in this report include results of the (1) hydrogeologic analysis, (2) surface-water analysis, and (3) well inventory on the camps and fort. The hydrogeologic analysis includes hydrostratigraphy, aquifer properties, ground-water chemistry, water levels, preliminary conceptual flow model, and drilling plans. Surface-water analysis includes description of principal streams and drainage basins, watershed delineation, and plots of flow duration and frequency. We present some results of our drilling program in the hydrogeologic analysis. Well reports will be presented in our February interim report and well tests and analyses in the final report. This report is divided into 6 sections with each section discussing the hydrologic and hydrogeologic assessment for an individual training facility.
Hydrology of an Evaporite Aquitard Permian Evaporite
(1984) Kreitler, Charles W.; Fisher, R. Stephen; Senger, Rainer K.
Permian evaporite strata of the Palo Duro Basin, Texas Panhandle, are considered to have low permeabilities but are capable of some leakage. Cross-sectional and areal modeling of regional groundwater flow in the Palo Duro Basin indicates leakage from the Upper aquifer through the Evaporite aquitard that contributes approximately 30 percent of the water in the underlying Deep-Basin Brine aquifer. The regional estimate of permeability of the aquitard (~ 10^-4 md) is in general agreement with laboratory testing of salt permeability. Oxygen and hydrogen isotopic composition and the Cl/Br ratio of the deep-basin brines also suggest leakage through the aquitard. Isotopically non-equilibrated meteoric waters are found to depths of 8,000 ft. Leakage through the aquitard may occur as either matrix or fracture flow. According to petrographic and geochemical studies of the evaporite strata, halite dissolution and minor recrystallization occurred predominantly during Permian time. Post-Permian waters may have altered the top of the Evaporite aquitard. Fracturing is prevalent in the rock strata in the basin; the greatest density of fracturing occurs in areas with tectonic deformation. The potential for leakage may be greatest in these areas.
Hydrology of Camps Barkley, Bowie, Mabry, Maxey, Swift, and Wolters in Relation to Aquatic Biology
(1996) Fisher, R. Stephen; Mace, Robert E. (Robert Earl), 1967-; Kuharic, Conrad A.
The Bureau of Economic Geology (BEG) is conducting hydrogeologic studies of Texas National Guard training facilities at Camps Barkley, Bowie, Mabry, Maxie, and Swift, and Fort Wolters. These investigations, in conjunction with aquatic and biological surveys conducted by the Texas Parks and Wildlife Department, will provide information needed by the Texas National Guard to plan training and preparedness activities such that environmental resources will be protected and enhanced without compromising national security readiness. This report presents the data collected by BEG researchers and describes progress through August, 1995. Our activities have focused on (1) visiting each training site to meet the Facility Manager, review available records, and tour the grounds; (2) identifying existing data sources; obtaining, reviewing, and culling databases; merging data sets and formatting data for entry into a Geographic Information System (GIS); (3) organizing databases for use with the GIS software package ARC/INFO; (4) conducting perimeter well surveys for each training facility; (5) preparing watershed maps of each training facility; and (6) scheduling field activities for project completion.
Naturally occurring radioactive materials (NORM) in produced water and scale from Texas oil, gas, and geothermal wells: geographic, geologic, and geochemical controls
(University of Texas at Austin. Bureau of Economic Geology, 1995) Fisher, R. Stephen
Water produced from oil, gas, and geothermal reservoirs contains natural radioactivity that ranges from background levels to levels found in uranium mill tailings. Radioactivity in fluids and in the scale that forms in oil-producing and gas-processing equipment increases concerns for worker and public safety as well as costs of handling and disposing of naturally occurring radioactive materials (NORM), which include water, sludge, scale, and affected equipment. This study explored natural controls on such radioactivity to identify screening criteria by which high NORM activity can be anticipated on the basis of geologic or geochemical information. Such criteria can help State and Federal agencies target disposal regulations for situations likely to incur high radioactivity levels and can also prevent operators from making costly measurements if the likelihood of encountering elevated NORM activity is low. NORM in oil and gas operations is caused mainly by radium-226 (226Ra) and radium-228 (228Ra), daughter products of uranium-238 (238U) and thorium-232 (232Th) respectively, in barite scale. To explore natural controls on radioactivity, we considered the (1) geographic distribution of NORM in oil-producing and gas processing equipment, (2) geologic controls on uranium, thorium, and radium in sedimentary basins and reservoirs, (3) mineralogy of NORM scale, (4) potential of Texas formation waters to precipitate barite scale, (5) radium activity in Texas formation waters, and (6) geochemical controls on radium isotope activity in barite scale. Our approach combined compilations of published data, collection and analyses of new water and scale samples, and geochemical modeling of scale precipitation and radium incorporation in barite. We found that (1) elevated NORM levels (90th percentile in both major oil- and gas-producing regions of Texas) occur where volcanic rock fragments are abundant in sandstone reservoirs, (2) lithologic or mineralogic heterogeneities within reservoirs are a major control on NORM activities in produced water, (3) barite scale is the most likely NORM host in sludge and scale, (4) the potential for barite to precipitate from produced water increases with reservoir temperature, (5) high radium activity (> 200 pCi/L) occurs only if water salinity exceeds about 35,000 mg/L total dissolved solids, and (6) the radium activity of barite scale is predicted to vary significantly between major Texas basins. These results suggest that multivariate analysis of geologic and geochemical parameters may be useful in predicting NORM activity in produced water and scale in individual basins, plays, or reservoirs.
Quantification of Flow Unit and Bounding Element Properties and Geometries, Ferron Sandstone, Utah: Implications for Heterogeneity in Gulf Coast Tertiary Deltaic Reservoirs
(1992) Fisher, R. Stephen; Tyler, N.; Barton, Mark D.
Outcrop mapping, field permeability measurements, petrographic analyses, petrophysical measurements, and pore-level modeling studies are being conducted on exposures of the Ferron Sandstone, east-central Utah, to develop a better understanding of the dimensions and internal arrangement of flow units, baffles, and barriers in sandstone gas reservoirs. The ultimate goals of this work are to establish methods for applying outcrop studies to reservoir characterization and to develop reservoir models that will guide infill drilling to maximize incremental gas reserve growth from fluvial-deltaic sandstone reservoirs. Activities during the second year of this 3-year project focused on data collection and preliminary interpretations. Mapping and field permeability measurements were initiated on the seaward-stepping Ferron unit 2 sandstone. These results will provide a comparison with data collected during the 1990 field season when landward-stepping sandstones of Ferron unit 3 were examined. Framework grain and cement mineralogy and the composition of intergranular material were quantified for selected samples from unit 3. Petrophysical measurements were completed on 24 specimens from units 2, 4, and 3. Sections of the pore-level modeling code were rewritten to improve accuracy and efficiency, and scenarios were developed to model the effects of grain size, cementation, and compaction on porosity, single-phase permeability, and formation factor. Preliminary results indicate that important differences exist in the internal geometry of landward- and seaward-stepping fluvial-deltaic sandstones. It was also found that closer-spaced permeability measurements improved the resolution of permeability structure. Petrographic studies documented differences in composition between fluvial, transgressive, delta-front, and distributary-channel sandstones; these differences in rock composition are reflected by differences in the mean permeability of these facies as measured on outcrop. Initial comparisons of pore-level model results with measured petrophysical properties are encouraging and suggest that refinements based on examination of the analyzed samples will lead to a close match between observed and modeled behavior.
Quantification of Flow Unit and Bounding Element Properties and Geometries, Ferron Sandstone, Utah: Implications for Heterogeneity in Gulf Coast Tertiary Deltaic Reservoirs
(1991) Tyler, N.; Fisher, R. Stephen; Barton, Mark D.
Outcrop exposures are being studied to quantify the internal permeability distribution of fluvial-deltaic sandstones, which results in reservoir compartments bounded by baffles or barriers to gas flow. This information will be used to develop reservoir models that can guide infill drilling to optimize incremental gas reserve growth from sandstone reservoirs. The objectives are being accomplished through integration of (1) outcrop characterization, (2) petrophysical measurements, and (3) pore-level modeling. Projected long-term benefits of the study are two-fold. First, increased understanding of internal architecture and improved methods for quantification of heterogeneity will facilitate development of strategies to minimize risk in the extended development of fluvial-dominated deltaic gas reservoirs. Second, targeting of incremental gas resources in mature reservoirs will lead to extended recovery of a low-cost, low-risk resource. Results of the first year of studies show that the architecture, geometry, and internal permeability distribution of fluvial-deltaic sandstones are generally predictable and that a four-order hierarchy of bounding surfaces exists. Initial tests have been completed, and reliable measurements of petrophysical properties of flow units, flow baffles, and flow barriers are being performed on outcrop samples. Development of a pore-level simulator has been essentially completed. Results, in general, indicate that the field approach is sound and that information gained on outcrop can be used to produce realistic reservoir models.
Quantifying Reservoir Heterogeneity Through Outcrop Characterization: 1. Architecture, Lithology, and Permeability Distribution of a Seaward-Stepping Fluvial-Deltaic Sequence, Ferron Sandstone (Cretaceous), Central Utah
(1993) Fisher, R. Stephen; Barton, Mark D.; Tyler, N.
The internal architecture of natural gas reservoirs fundamentally controls production efficiency and the volume of gas unrecovered at abandonment. To better understand reservoir complexity, we investigated relations between sandstone architecture and permeability structure of landward-stepping (wave-modified) Ferron deltaic sandstones exposed in central Utah. Deltaic sandstones extend 4 mi along sediment-transport direction in the landward-stepping Ferron genetic sequence GS 5. Most sand was deposited in transgressive, delta-front, and distributary-channel facies. Distributary channels constitute the principal reservoir facies because mean permeability in distributary-channel sandstones is approximately twice that of delta-front and transgressive sandstones, and because distributary-channel sandstones are well developed. Channel architecture, bounding-surface character, and permeability distribution change systematically from landward to seaward position in the system. Near the landward limit, mean permeability is 300 md, mud occurs as clasts along channel-flank bounding surfaces, and permeability systematically decreases upward. Near the seaward extent of the system, mean permeability is 750 md, mud is segregated into discrete strata-bounding sand bodies, and vertical permeability trends are uniformly high. Statistical analysis shows that lithofacies are the fundamental sandstone architectural units. Similar lithofacies have similar permeability character, regardless of position in the facies tract. Variable preservation of lithofacies controls permeability distribution throughout the channel system. Semivariogram analysis shows that vertical and horizontal permeability correlation distances correspond to distances between bounding surfaces and to sand-body dimensions. Diagenetic overprint is minor, owing to low burial temperatures.
Quantifying Reservoir Heterogeneity Through Outcrop Characterization: 2. Architecture, Lithology, and Permeability Distribution of a Seaward-Stepping Fluvial-Deltaic Sequence, Ferron Sandstone (Cretaceous), Central Utah
(1993) Fisher, R. Stephen; Barton, Mark D.; Tyler, N.
The internal architecture of natural gas reservoirs fundamentally determines gas migration, production efficiency, and the volume of gas unrecovered at abandonment. To determine the style and scale of reservoir complexity in fluvially dominated (seaward-stepping) deltaic reservoirs, we investigated relations between sandstone architecture and permeability distribution in seaward-stepping deltaic Ferron genetic sequence (GS) 2 sandstone outcrops in central Utah. Distributary-channel, mouth-bar, and delta-front deposits are the volumetrically important sand repositories in the Ferron GS 2. Mouth-bar facies are laterally extensive and relatively simple sand bodies with moderate mean permeabilities. Distributary channels also have good permeability but are narrow, sinuous, and separated from mouth-bar sandstones by low-permeability bounding surfaces, making them difficult targets for development. Statistical analyses of permeability data show that lithofacies are the fundamental sandstone architectural elements. Therefore, lithofacies are the basic units that should be used to construct reservoir models. The variable preservation of lithofacies controls permeability throughout the system. Vertical and horizontal permeability correlation distances correspond to distances between bounding surfaces and to macroform dimensions. Estimates based on field-scale mapping show that 91 percent of the reservoir area could be contacted at 320-acre well spacing. Sandstone architecture and permeability relations of the Ferron GS 2 are similar to those in Lake Creek (Wilcox Group, Texas Gulf Coast) reservoirs. This outcrop-reservoir comparison confirms that outcrop data are transferable to reservoirs.
Regional and Isotopic Hydrogeochemistry: Deep-Basin Brine Aquifer Palo Duro Basin, Texas Panhandle
(1984) Fisher, R. Stephen
In the second half of 1983 and the first quarter of 1984, brines from the sub-salt, deep-basin aquifer were collected at the DOE-SWEC #1 J. Friemel well site in Deaf Smith County, Texas. Seven zones were sampled, bringing the total number of samples from permeable units below the Evaporite Aquitard in the Palo Duro Basin to seventeen. The locations of all DOE wells from which deep-basin brines have been collected are shown in Figure 1. The zones sampled are identified in Table 1, and the results of analyses for major and minor aqueous species and stable isotopes are presented in Table 2. This report presents the data for samples collected from the #1 J. Friemel well and provides a preliminary comparison of compositions of brines from the J. Friemel well with brines collected from the other DOE test wells. Results of a detailed study integrating all available hydrologic and geochemical data from the Palo Duro Basin will be the subject of a later report.