Geological Circulars

Permanent URI for this collectionhttps://hdl.handle.net/2152/121888

Peer-reviewed geoscience research summaries, targeted on Bureau project areas in Texas and other locations, 1965–2003.

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Browsing Geological Circulars by Author "Dorfman, Myron"

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    Geothermal resources, Frio Formation, middle Texas Gulf Coast
    (University of Texas at Austin. Bureau of Economic Geology, 1975) Bebout, Don G.; Agagu, Olusegun Kokumo, 1948-; Dorfman, Myron
    Knowledge of the regional sand distribution and its relationship to formation temperature and pressure is a preliminary step in evaluating the geothermal resources of the Frio Formation. At depths generally greater than 7,000 feet, the sands and shales of the Frio Formation are overpressured and undercompacted. The insulating effect of these overpressured and undercompacted sediments results in the accumulation of subsurface heat and, thus, high temperature water. The local variations of depth to top of geopressure are related to the distribution of sand and shale lithologies and to the location of growth faults. For more information concerning origin of geopressure or high temperatures, see Jones (1970) and Dorfman and Kehle (1974). Bruce (1973) discusses the nature of growth faults in detail. The resource in the geopressured zone consists of high-temperature water with relatively low salinity and with dis solved methane gas. The objectives of this study were to determine regional sand distribution of the Frio Formation, identify depositional environments, and delineate the geopressured zone and its relationship to sand/shale distribution, growth faults, and fluid temperatures in the Middle Texas Gulf Coast. This study is essentially an extension of that completed earlier for South Texas (Bebout, Dorfman, and Agagu, 1975); all correlation and mapping units are the same as those represented in the South Texas report. The Energy Research and Development Administration, through the Lawrence Livermore Laboratory, supported this study of the geothermal resources of the Frio Formation in Middle Texas Gulf Coast.
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    Geothermal resources, Frio Formation, south Texas
    (University of Texas at Austin. Bureau of Economic Geology, 1975) Bebout, Don G.; Agagu, Olusegun Kokumo, 1948-; Dorfman, Myron
    A preliminary study of the Frio sand distribution and formation temperatures and pressures was undertaken in order to define prospective areas in which a more detailed reservoir analysis is necessary prior to the selection of a site for a geothermal well. As the result of prospective oil wells that penetrated the Tertiary sediments, a geopressured zone containing fluids with high temperatures is known to occur along the Texas Gulf Coast. Few oil or gas wells produce from this area, and the regional sand distribution within these zones is not well known. Limited data, however, indicate that the pore spaces within the sands in the geopressured zone are filled with water which has high temperatures and relatively low dissolved-solids content, and which is saturated with methane. These waters are believed to be an important source of thermal energy and methane gas. For more information concerning the origin of the geopressured zone, see Dorfman and Kehle (1974) and Jones (1970). The first step in appraising the Gulf Coast geothermal resources entails a detailed geologic study of the main sand trends; the Frio and Wilcox Formations appear to be the best prospects. This report will deal largely with the Frio. The Wilcox Formation has been studied by Fisher and McGowen (1967). Other parts of the Tertiary which have been studied in detail are the Queen City Formation (Claiborne), which was reported on by Guevara and Garcia (1972), and the Jackson, reported on by Fisher and others (1970). The United States Atomic Energy Commission, through the Lawrence Livermore Laboratory, and the Center for Energy Studies, The University of Texas at Austin, supported this preliminary study of the geothermal resource of the Frio sands in South Texas. The South Texas area (from just north of Corpus Christi and south to the Rio Grande) was selected because the geopressured zone is known to occur here at shallow depths (Jones, 1970), and because of the abundance of oil well records for the area. The study includes a sand-facies analysis and an integration of the facies data with existing information relative to temperatures and pressures.
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    Geothermal resources, Frio Formation, upper Texas Gulf Coast
    (University of Texas at Austin. Bureau of Economic Geology, 1976) Bebout, Don G.; Loucks, R. G.; Bosch, S. C.; Dorfman, Myron
    The objective of this study is to identify major sand trends, which, along with subsurface temperatures and pressures, aid in evaluating the potential of producing geothermal energy from the Frio Formation, Upper Texas Gulf Coast. During the Tertiary, huge quantities of terrigenous sediments were deposited as gulfward-thickening sedimentary wedges along the Texas Gulf Coast. The sand and shale making up these wedges were transported across a broad fluvial plain and deposited in deltaic complexes or were reworked by marine processes into strandplains and barrier islands. Growth faults developed contemporaneously at the site of maximum deposition as a result of rapid loading of large quantities of delfaic and strandplain sands onto previously deposited prodelta and shelf muds. These growth faults allowed the accumulation of extremely thick sections of sand and also caused the isolation of many of these sand bodies from porous updip sands; pressured reservoirs developed after further loading and compaction (Bruce, 1973; Jones, 1975). This study is investigating geopressured geothermal reservoirs in this setting. Limited data obtained from deep wells drilled for oil and gas indicate that many of these large sand reservoirs are filled with water which has high temperature, is relatively low in total dissolved solids, and is saturated with methane gas. To be suitable for electric power generation, the reservoir should have a volume greater than 3 cubic miles (which is equivalent to 300 feet of sand distributed areally more than 50 square miles), permeability greater than 20 millidarcies, and subsurface temperatures higher than 300°F. This report reviews the results of the Bureau of Economic Geology regional study of the Frio Formation in the Upper Texas Gulf Coast. It is a continuation of two similar studies of the Frio in the Lower and Middle Texas Gulf Coast (Bebout, Dorfman, and Agagu, 1975; Bebout, Agagu, and Dorfman, 1975). The objective of these reports is to outline areas (fairways) which appear the most prospective for producing geothermal energy and which therefore deserve further, more detailed study.
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    Potential geothermal resources of Texas
    (University of Texas at Austin. Bureau of Economic Geology, 1974) Dorfman, Myron; Kehle, Ralph O.
    Geothermal energy is rapidly becoming recognized, both in the United States and abroad, as a viable source of energy which can supplement fossil fuels for electric power generation. Exploration and development of geothermal reservoirs is intensifying in the western United States and Mexico, and will continue to expand as petroleum supplies diminish and costs increase. Although geothermal energy is commonly perceived as a new and exotic energy source, it is neither. Steam has been used for electric power generation since 1904 in Larderello, Italy, and geothermal waters have been used for space heating and agricultural purposes in other parts of the world since 1890. Geothermal power generation began in the United States in 1960 at the Geysers, California, and new fields are under development in the Salton trough of southern California. Herein we will attempt to answer some of the basic questions about geothermal energy: what it is, how deposits are formed, and where these deposits are located. Special emphasis is placed on the potential geothermal resources of the Texas Gulf Coast and Trans-Pecos Texas. This discussion should provide the reader with an appreciation for both the problems and advantages of this unfamiliar form of energy as well as the potential it holds for supplying Texas with a portion of its future energy needs.