The results of a subsurface uranium favorability study of Tertiary rocks (late Eocene through Pliocene) in the Coastal Plain of South Texas are given. In ascending order, these rock units include the Yegua Formation, Jackson Group, Frio Clay, Catahoula Tuff, Oakville Sandstone, and Goliad Sand. The Vicksburg Group, Anahuac Formation, and Fleming Formation were not considered because they have unfavorable lithologies. The Yegua Formation, Jackson Group, Frio Clay, Catahoula Tuff, Oakville Sandstone, and Goliad Sand contain sandstones that may be favorable uranium hosts under certain environmental and structural conditions. All except the Yegua are known to contain ore-grade uranium deposits. Yegua and Jackson sandstones are found in strand plain-barrier bar systems that are aligned parallel to depositional and structural strike. These sands grade into shelf muds on the east, and lagoonal sediments updip toward the west. The lagoonal sediments in the Jackson are interrupted by dip-aligned fluvial systems. In both units, favorable areas are found in the lagoonal sands and in sands on the updip side of the strand-plain system. Favorable areas are also found along the margins of fluvial systems in the Jackson. The Frio and Catahoula consist of extensive alluvial-plain deposits. Favorable areas for uranium deposits are found …

Uranium deposits in the South Texas Uranium Region are classical roll-type deposits that formed at the margin of tongues of altered sandstone by the encroachment of oxidizing, uraniferous solutions into reduced aquifers containing pyrite and, in a few cases, carbonaceous plant material. Many of the uranium deposits in South Texas are dissimilar from the roll fronts of the Wyoming basins. The host sands for many of the deposits contain essentially no carbonaceous plant material, only abundant disseminated pyrite. Many of the deposits do not occur at the margin of altered (ferric oxide-bearing) sandstone tongues but rather occur entirely within reduced, pyurite-bearing sandstone. The abundance of pyrite within the sands probably reflects the introduction of H/sub 2/S up along faults from hydrocarbon accumulations at depth. Such introductions before ore formation prepared the sands for roll-front development, whereas post-ore introductions produced re-reduction of portions of the altered tongue, leaving the deposit suspended in reduced sandstone. Evidence from three deposits suggests that ore formation was not accompanied by the introduction of significant amounts of H/sub 2/S.

The purpose of this investigation is to determine the availability of ground-water resources of the Gulf Coast Region, Texas, with particular reference to the sources of water suitable for the development of geothermal energy utilization for generation of electric power. For this purpose the availability of water resources is important for heat rejection. The expected characteristics of the geopressured geothermal resource (lower temperatures) will result in low cycle efficiencies and hence large quantities of heat for rejection. Water resources will be very important, therefore, if evaporative cooling towers are to be used.

Stratigraphic, structure contour, and favorability maps are provided. (LK)

Rocks of the Wilcox and Claiborne Groups crop out in the Texas Gulf Coastal Plain and are represented by a series of sands and shales which reflect oscillation of the strandline. The Wilcox Group (lower Eocene), usually undifferentiated in Texas, consists of very fine sands and clays and abundant lignite. The Claiborne Group (middle Eocene) comprises, in ascending order, Carrizo Sand, Reklaw Formation (clay), Queen City Sand, Weches Formation (clay), Sparta Sand, Cook Mountain Formation (clay), and Yegua Formation (sand). Fluvial systems of the Wilcox and Claiborne Groups exist in east Texas and trend perpendicular to the present coastline. In central Texas, sand bodies are parallel to the present coastline and are strand-plain, barrier-bar systems. Since the time of deposition of the Queen City Sand, a significant fluvial sand buildup occurred in the area of the present Rio Grande embayment where the marine clays pinch out. Known occurrences of mineral matter in the Wilcox and Claiborne (up to the Yegua) are limited to lignite (particularly in the Wilcox), cannel coal in the upper Claiborne, and hydrocarbons throughout. No uranium mineralization is known, and no uranium is likely to be discovered in the Claiborne and Wilcox. Approximately 50 surface samples and …

Results of a reconnaissance geochemical survey of the Beeville Quadrangle, Texas are reported. Field and laboratory data are presented for 373 groundwater and 364 stream sediment samples. Statistical and areal distributions of uranium and possible uranium-related variables are displayed. A generalized geologic map of the survey area is provided, and pertinent geologic factors which may be of significance in evaluating the potential for uranium mineralization are briefly discussed. The groundwater data indicate that the northwestern corner of the quadrangle is the most favorable for potential uranium mineralization. Favorability is indicated by high uranium concentrations; high arsenic, molybdenum, and vanadium concentrations; and proximity and similar geologic setting to the mines of the Karnes County mining district. Other areas that appear favorable are an area in Bee and Refugio Counties and the northeastern part of the quadrangle. Both areas have water chemistry similar to the Karnes County area, but the northeastern area does not have high concentrations of pathfinder elements. The stream sediment data indicate that the northeastern corner of the quadrangle is the most favorable for potential mineralization, but agricultural practices and mineralogy of the outcropping Beaumont Formation may indicate a false anomaly. The northwestern corner of the quadrangle is considered …

This report revises the original report that was published in 1980. Some of the topics covered in the earlier report were provisional and it is now practicable to reexamine them using new or revised geotechnical data and that obtained from SPR cavern operations, which involves 16 new caverns. Revised structure maps and sections show interpretative differences as compared with the 1980 report and more definition in the dome shape and caprock structural contours, especially a major southeast-northwest trending anomalous zone. The original interpretation was of westward tilt of the dome, this revision shows a tilt to the southeast, consistent with other gravity and seismic data. This interpretation refines the evaluation of additional cavern space, by adding more salt buffer and allowing several more caverns. Additional storage space is constrained on this nearly full dome because of low-lying peripheral wetlands, but 60 MMBBL or more of additional volume could be gained in six or more new caverns. Subsidence values at Bryan Mound are among the lowest in the SPR system, averaging about 11 mm/yr (0.4 in/yr), but measurement and interpretation issues persist, as observed values are about the same as survey measurement accuracy. Periodic flooding is a continuing threat because of …

Preliminary environmental data, including current land use, substrate lithology, soils, natural hazards, water resources, biological assemblages, meteorological data, and regulatory considerations have been collected and analyzed for approximately 150 km/sup 2/ of land: (1) near Chocolate Bayou, Brazoria County, Texas, where a geopressured-geothermal test well was drilled in 1978, and (2) near the rural community of Armstrong, Kenedy County, Texas, where future geopressured-geothermal test well development may occur. The study was designed to establish an environmental data base and to determine, within spatial constraints set by subsurface reservoir conditions, environmentally suitable sites for geopressured-geothermal wells.

Results of a reconnaissance geochemical survey of the Corpus Christi Quadrangle, Texas, are reported. Field and laboratory data are presented for 119 groundwater samples and 57 stream sediment samples. Also included is a brief discussion on the geology and hydrology of the quadrangle. Groundwater data indicate that uranium concentrations above the 85th percentile occur primarily in a trend in western Nueces County. With one exception, waters in the trend are produced from the Evangeline aquifer and have high values for selenium and strontium. Owing to urbanization, low topographic relief, and the presence of Recent-to-Pleistocene surface material, stream sediment data were found to be less than optimum for the determination of the potential for uranium mineralization, and variation in uranium concentrations between units may simply reflect lithologic differences.

In accordance with the requirements of 10 CFR Part 711, environmental assessments are being prepared for significant activities and individual projects of the Division of Geothermal Energy (DGE) of the Energy Research and Development Administration (ERDA). This environmental assessment of geopressure well testing addresses, on a regional basis, the expected activities, affected environments, and possible impacts in a broad sense. The specific part of the program addressed by this environmental assessment is geothermal well testing by the take-over of one or more unsuccessful oil wells before the drilling rig is removed and completion of drilling into the geopressured zone. Along the Texas and Louisiana Gulf Coast (Plate 1 and Overlay) water at high temperatures and high pressures is trapped within Gulf basin sediments. The water is confined within or below essentially impermeable shale sequences and carries most or all of the overburden pressure. Such zones are referred to as geopressured strata. These fluids and sediments are heated to abnormally high temperatures (up to 260 C) and may provide potential reservoirs for economical production of geothermal energy. The obvious need in resource development is to assess the resource. Ongoing studies to define large-sand-volume reservoirs will ultimately define optimum sites for drilling …

Separate abstracts were prepared for the eight chapters for ERA and one chapter for EAPA. Included in appendices are the reports of two subcontractors on the flashed steam and binary-fluid systems which are discussed at length in the chapters. (MHR)

None

The Underground Injection Control Regulations promulgated in 1980, under the Safe Drinking Water Act of 1974, require Area-of-Review (AOR) studies be conducted as part of the permitting process for newly drilled or converted Class II injection wells. Existing Class II injection wells operating at the time regulations became effective were excluded from the AOR requirement. The AOR is the area surrounding an injection well or wells defined by either the radial distance within which pressure in the injection zone may cause migration of the injection and/or formation fluid into an underground source of drinking water (USDW) or defined by a fixed radius of not less than one-fourth mile. In the method where injection pressure is used to define the AOR radial distance, the AOR is also known as the ''zone of endangering influence.''

Detailed geological, geophysical, and engineering studies conducted on the Frio Formation have delineated a geothermal test well site in the Austin Bayou Prospect which extends over an area of 60 square miles. A total of 800 to 900 feet of sandstone will occur between the depths of 13,500 and 16,500 feet. At leat 30 percent of the sand will have core permeabilities of 20 to 60 millidarcys. Temperature at the top of the sandstone section will be 300/sup 0/F. Water, produced at a rate of 20,000 to 40,000 barrels per day, will probably have to be disposed of by injection into shallower sandstone reservoirs. More than 10 billion barrels of water are in place in these sandstone reservoirs of the Austin Bayou Prospect; there should be approximately 400 billion cubic feet of methane in solution in this water. Only 10 percent of the water and methane (1 billion barrels of water and 40 billion cubic feet of methane) will be produced without reinjection of the waste water into the producing formation. Reservoir simulation studies indicate that 90 percent of the methane can be produced with reinjection. 106 figures.

This report describes techniques being used in the assessment of geopressured geothermal resources along the Texas Gulf Coast and defines geologic procedures for test- or industrial-site selection. These approaches have been proven in petroleum exploration and are applicable in geothermal exploration here in the Gulf basin and in other sedimentary basins.

This Environmental Assessment (EA) has been prepared to provide the environmental input into the Division of Geothermal Energy's decisions to expand the geothermal well testing activities to include sites in the Frio Formation of Texas and Louisiana. It is proposed that drilling rigs be leased before they are removed from sites in the formation where drilling for gas or oil exploration has been unsuccessful and that the rigs be used to complete the drilling into the geopressured zone for resource exploration. This EA addresses, on a regional basis, the expected activities, affected environment, and the possible impacts in a broad sense as they apply to the Gulf Coast well testing activity of the Geothermal Energy Geopressure Subprogram of the Department of Energy. Along the Texas and Louisiana Gulf Coast (Plate 1 and Overlay, Atlas) water at high temperatures and high pressures is trapped within Gulf basin sediments. The water is confined within or below essentially impermeable shale sequences and carries most or all of the overburden pressure. Such zones are referred to as geopressured strata. These fluids and sediments are heated to abnormally high temperatures (up to 260 C) and may provide potential reservoirs for economical production of geothermal energy. …

Information collected and analyzed for a preliminary environmental analysis of geopressured geothermal prospect areas in Colorado and DeWitt Counties, Texas is presented. Specific environmental concerns for each geopressured geothermal prospect area are identified and discussed. Approximately 218 km/sup 2/(85 mi/sup 2/) were studied in the vicinity of each prospect area to: (1) conduct an environmental analysis to identify more and less suited areas for geopressured test wells; and (2) provide an environmental data base for future development of geopressured geothermal energy resources. A series of maps and tables are included to illustrate environmental characteristics including: geology, water resources, soils, current land use, vegetation, wildlife, and meteorological characteristics, and additional relevant information on cultural resources, power- and pipelines, and regulatory agencies. A series of transparent overlays at the scale of the original mapping has also been produced for the purposes of identifying and ranking areas of potential conflict between geopressured geothermal development and environmental characteristics. The methodology for ranking suitability of areas within the two prospect areas is discussed in the appendix. (MHR)

Regional sand distribution of the Frio Formation is determined; depositional environments are identified; and the geopressured zone and its relationship to sand/shale distribution, growth faults, and fluid temperatures in the Middle Texas Gulf Coast are delineated. (MHR)

Tertiary strata of the Texas Gulf Coast comprise a number of terrigenous depositional wedges, some of which thicken abruptly at their downdip ends as a result of contemporaneous movement of growth faults and underlying salt. The Frio Formation, one of these wedges, has been studied regionally by means of a grid of correlation cross sections aided by micropaleontological control. By means of these sections, the Frio was subdivided into six map units; maps of sandstone distribution within these units delineate principal elongate sandstone trends parallel to the Gulf Coast composed of deltaic, barrier-bar, and strandplain sandstones. These broad regional studies, followed by detailed local investigations, were pursued in order to delineate prospective areas for production of geopressured geothermal energy. A prospective area must meet the following minimum requirements; reservoir volume of 3 cubic miles, minimum permeability of 20 millidarcys (md), and fluid temperatures of 300/sup 0/F. Several geothermal fairways were identified as a result of this Frio study. In summary, detailed geological, geophysical, and engineering studies conducted on the Frio Formation have delineated a geothermal test well site in the Austin Bayou Prospect which extends over an area of 60 square miles. A total of 800 to 900 feet of …

Results are presented of a regional study to identify areas where the Wilcox Group contains significant thicknesses of sandstone with subsurface temperatures higher than 300/sup 0/F. Eight of these geothermal fairways were identified. Control for this study was based on wells chosen so as to provide stratigraphic dip sections spaced 15 to 20 miles apart along the entire Texas Gulf Coast. Electrical well logs from the eight fairways are shown. (MHR)

The Department of Energy (DOE) has initiated a program to evaluate the feasibility of developing the geothermal-geopressured energy resources of the Louisiana-Texas Gulf Coast. As part of this effort, DOE is contracting for the drilling of design wells to define the nature and extent of the geopressure resource. At each of several sites, one deep well (4000-6400 m) will be drilled and flow tested. One or more shallow wells will also be drilled to dispose of geopressured brines. Each site will require about 2 ha (5 acres) of land. Construction and initial flow testing will take approximately one year. If initial flow testing is successful, a continuous one-year duration flow test will take place at a rate of up to 6400 m{sup 3} (40,000 bbl) per day. Extensive tests will be conducted on the physical and chemical composition of the fluids, on their temperature and flow rate, on fluid disposal techniques, and on the reliability and performance of equipment. Each project will require a maximum of three years to complete drilling, testing, and site restoration.

Thirteen papers are included. Separate abstracts were prepared for each one. (MHR)

The Oil and Gas Field Code Master List 1997 is the sixteenth annual listing of all identified oil and gas fields in the US. It is updated with field information collected through October 1997. The purpose of this publication is to provide unique, standardized codes for identification of domestic fields. Use of these field codes fosters consistency of field identification by government and industry. As a result of their widespread adoption they have in effect become a national standard. The use of field names and codes listed in this publication is required on survey forms and other reports regarding field-specific data collected by EIA. There are 58,366 field records in this year`s FCML, 437 more than last year. The FCML includes: field records for each State and county in which a field resides; field records for each offshore area block in the Gulf of Mexico in which a field resides; field records for each alias field name (definition of alias is listed); fields crossing State boundaries that may be assigned different names by the respective State naming authorities. This report also contains an Invalid Field Record List of 4 records that have been removed from the FCML since last year`s …

The Department of Energy is developing an estimate of the hydropower development potential in this country. The Hydropower Evaluation Software (HES) is a computer model that was developed by the Idaho National Engineering Laboratory for this purpose. The HES measures the potential hydropower resources available in the United States, using uniform criteria for measurement. The software was developed and tested using hydropower information and data provided by the Southwestern Power Administration. It is a dBASE menu-driven software application that allows the personal computer user to assign environmental attributes to potential hydropower sites, calculate development suitability factors for each site based on the environmental attributes present, and generate reports based on these suitability factors. This report details the resource assessment results for the state of Texas.