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• 1. [Image] Conceptual Design of Commercial 50 MWe(Net) Geothermal Power Plants at Heber and Niland, California. Final Report

  	The scope of work of this study includes conceptual designs, corresponding capital cost estimates and engineering and construction schedules for two 50 MWe (net) commercial-scale geothermal power plants. ...
  	Citation × Citation Citation Abstract Copy Title: Conceptual Design of Commercial 50 MWe(Net) Geothermal Power Plants at Heber and Niland, California. Final Report Author: Bechtel Corporation Year: 1976 The scope of work of this study includes conceptual designs, corresponding capital cost estimates and engineering and construction schedules for two 50 MWe (net) commercial-scale geothermal power plants. In order to develop and illustrate the concepts involved, the reservoir and site conditions of the geothermal field near Heber, California, which has moderate-temperature low-salinity brine, were used for one of the power plants. The conditions of the field near Niland, California (or the Salton Sea Geothermal Field), which has high-temperature high-salinity brine, were used for the other plant. Both fields are located in the Imperial Valley in Southern California. The two plants give perspective on plant design and capital costs for the range of hydrothermal resources that are of economic interest for electric power generation Title: Conceptual Design of Commercial 50 MWe(Net) Geothermal Power Plants at Heber and Niland, California. Final Report Author: Bechtel Corporation Year: 1976 The scope of work of this study includes conceptual designs, corresponding capital cost estimates and engineering and construction schedules for two 50 MWe (net) commercial-scale geothermal power plants. In order to develop and illustrate the concepts involved, the reservoir and site conditions of the geothermal field near Heber, California, which has moderate-temperature low-salinity brine, were used for one of the power plants. The conditions of the field near Niland, California (or the Salton Sea Geothermal Field), which has high-temperature high-salinity brine, were used for the other plant. Both fields are located in the Imperial Valley in Southern California. The two plants give perspective on plant design and capital costs for the range of hydrothermal resources that are of economic interest for electric power generation Close

• 2. [Image] Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California

  	A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent ...
  	Citation × Citation Citation Abstract Copy Title: Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent associated with the geothermal system at Coso. The boundaries of this low are generally well defined to the north and west but not as well to the south where an approximate southern limit has been determined. The bedrock resistivity low merges with an observed resistivity low over gravel fill east of Coso Hot Springs. A complex horizontal and vertical resistivity structure of the surveyed area has been defined which precludes the use of layered-earth or two-dimensional interpretive models for much of the surveyed area. In general the survey data indicate that a 10 to 20 ohm-meter zone extends from near surface to a depth greater than 750 meters within the geothermal system. This zone is bordered to the north and west by bedrock resistivities greater than 200 ohm-meters and to the south by bedrock resistivities greater than 50 ohm-meters. A combination of observed increases in: (1) fracture density (higher permeability), (2) alteration (high clay content), and (3) temperatures (higher dissolved solid content of ground water) within the bedrock low explain its presence Title: Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent associated with the geothermal system at Coso. The boundaries of this low are generally well defined to the north and west but not as well to the south where an approximate southern limit has been determined. The bedrock resistivity low merges with an observed resistivity low over gravel fill east of Coso Hot Springs. A complex horizontal and vertical resistivity structure of the surveyed area has been defined which precludes the use of layered-earth or two-dimensional interpretive models for much of the surveyed area. In general the survey data indicate that a 10 to 20 ohm-meter zone extends from near surface to a depth greater than 750 meters within the geothermal system. This zone is bordered to the north and west by bedrock resistivities greater than 200 ohm-meters and to the south by bedrock resistivities greater than 50 ohm-meters. A combination of observed increases in: (1) fracture density (higher permeability), (2) alteration (high clay content), and (3) temperatures (higher dissolved solid content of ground water) within the bedrock low explain its presence Close

• 3. [Image] Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

  	The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and ...
  	Citation × Citation Citation Abstract Copy Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustics logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustics logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Close

• 4. [Image] Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California

  	The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California Author: Howard, J. Year: 1978 The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production tests in the northern portion of the East Mesa KGRA, conversion tables, chemical analysis of fluids from East Mesa wells, and results of laboratory studies of scale samples taken from the vertical tube evaporator. (MHR) Title: Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California Author: Howard, J. Year: 1978 The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production tests in the northern portion of the East Mesa KGRA, conversion tables, chemical analysis of fluids from East Mesa wells, and results of laboratory studies of scale samples taken from the vertical tube evaporator. (MHR) Close

• 5. [Image] Heat Flow of Oregon

  	An extensive new heat flow and geothermal gradient data set for the State of Oregon is presented on a contour map of heat flow at a scale of 1:1,000,000 and is summarized in several figures and tables. ...
  	Citation × Citation Citation Abstract Copy Title: Heat Flow of Oregon Author: Blackwell, D.D. Year: 1978 An extensive new heat flow and geothermal gradient data set for the State of Oregon is presented on a contour map of heat flow at a scale of 1:1,000,000 and is summarized in several figures and tables. The 1:1,000,000 scale heat flow map is contoured at 20 mW/m/sup 2/ (0.5 HFU) intervals. Also presented are maps of heat flow and temperature at a depth of 1 km averaged for 1/sup 0/ x 1/sup 0/ intervals. Histograms and averages of geothermal gradient and heat flow for the State of Oregon and for the various physiographic provinces within Oregon are also included. The unweighted mean flow for Oregon is 81.3 +- 2.7 mW/m/sup 2/ (1.94 +- 0.06 HFU). The average unweighted geothermal gradient is 65.3 +- 2.5/sup 0/C/km. The average heat flow value weighted on the basis of geographic area is 68 +- 5 mW/m/sup 2/ (1.63 +- 0.12 HFU) and the average weighted geothermal gradient is 55.0 +- 5/sup 0/C/km Title: Heat Flow of Oregon Author: Blackwell, D.D. Year: 1978 An extensive new heat flow and geothermal gradient data set for the State of Oregon is presented on a contour map of heat flow at a scale of 1:1,000,000 and is summarized in several figures and tables. The 1:1,000,000 scale heat flow map is contoured at 20 mW/m/sup 2/ (0.5 HFU) intervals. Also presented are maps of heat flow and temperature at a depth of 1 km averaged for 1/sup 0/ x 1/sup 0/ intervals. Histograms and averages of geothermal gradient and heat flow for the State of Oregon and for the various physiographic provinces within Oregon are also included. The unweighted mean flow for Oregon is 81.3 +- 2.7 mW/m/sup 2/ (1.94 +- 0.06 HFU). The average unweighted geothermal gradient is 65.3 +- 2.5/sup 0/C/km. The average heat flow value weighted on the basis of geographic area is 68 +- 5 mW/m/sup 2/ (1.63 +- 0.12 HFU) and the average weighted geothermal gradient is 55.0 +- 5/sup 0/C/km Close

• 6. [Image] Linear Polarization Measurements at High Temperatures in Hypersaline Geothermal Brines

  	The Bureau of Mines conducted a series of in situ linear polarization measurements in high-temperature, high-pressure hypersaline geothermal brines at the Bureau of Mines Geothermal Test Facility in the ...
  	Citation × Citation Citation Abstract Copy Title: Linear Polarization Measurements at High Temperatures in Hypersaline Geothermal Brines Author: Cramer, S.D. Year: 1978 The Bureau of Mines conducted a series of in situ linear polarization measurements in high-temperature, high-pressure hypersaline geothermal brines at the Bureau of Mines Geothermal Test Facility in the Imperial Valley of California. The measurements represented an evaluation of the linear polarization technique for obtaining instantaneous corrosion rates of materials of construction in flowing hypersaline hydrothermal fluids that rapidly form scales on exposed surfaces. A special method was devised for use with the linear polarization technique that resulted in obtaining corrosion rates for 1020 carbon steel, 316 and 430 stainless steel, titanium, various nickel-based alloys, and aluminum 6061 under strong scale-forming conditions. The measurements also provided information on scale-deposition rates in various geothermal environments. Exploratory in situ potentiostatic polarization measurements were made in the flowing brines to qualitatively determine scale-deposition effects on the electrochemical measurements Title: Linear Polarization Measurements at High Temperatures in Hypersaline Geothermal Brines Author: Cramer, S.D. Year: 1978 The Bureau of Mines conducted a series of in situ linear polarization measurements in high-temperature, high-pressure hypersaline geothermal brines at the Bureau of Mines Geothermal Test Facility in the Imperial Valley of California. The measurements represented an evaluation of the linear polarization technique for obtaining instantaneous corrosion rates of materials of construction in flowing hypersaline hydrothermal fluids that rapidly form scales on exposed surfaces. A special method was devised for use with the linear polarization technique that resulted in obtaining corrosion rates for 1020 carbon steel, 316 and 430 stainless steel, titanium, various nickel-based alloys, and aluminum 6061 under strong scale-forming conditions. The measurements also provided information on scale-deposition rates in various geothermal environments. Exploratory in situ potentiostatic polarization measurements were made in the flowing brines to qualitatively determine scale-deposition effects on the electrochemical measurements Close

• 7. [Image] Petrology of the Quaternary Volcanics of the Roosevelt KGRA, and Adjoining Area, Utah. Final Report, Volume 1

  	The Roosevelt KGRA (Known Geothermal Resource Area) located near Milford, Utah, is associated with a suite of quaternary silicic volcanics distributed for 15 km along the crest and western flank of the ...
  	Citation × Citation Citation Abstract Copy Title: Petrology of the Quaternary Volcanics of the Roosevelt KGRA, and Adjoining Area, Utah. Final Report, Volume 1 Author: Nash, W.P. Year: 1976 The Roosevelt KGRA (Known Geothermal Resource Area) located near Milford, Utah, is associated with a suite of quaternary silicic volcanics distributed for 15 km along the crest and western flank of the Mineral Mountains, a large tertiary granite batholith. The volcanics are high-silica rhyolites and occur as domes, flows and tuffs. Initial eruptions resulted in two flows of low viscosity, phenocryst-poor rhyolite. Later activity consisted of pyroclastic eruptions and the emplacement of at least 9 viscous domes. In addition to abundant glass the rhyolites contain alkali feldspar, plagioclase, biotite, iron-titanium oxides and small amounts of hornblende, allanite, apatite, zircon, sphene and topaz. Magmatic temperatures were about 700C and water fugacities ranged from 350 to 3450 bars. Based on water fugacity calculations it is concluded that there may have been one or more shallow magma chambers in the Mineral Range at depths of about 1.6 km. Title: Petrology of the Quaternary Volcanics of the Roosevelt KGRA, and Adjoining Area, Utah. Final Report, Volume 1 Author: Nash, W.P. Year: 1976 The Roosevelt KGRA (Known Geothermal Resource Area) located near Milford, Utah, is associated with a suite of quaternary silicic volcanics distributed for 15 km along the crest and western flank of the Mineral Mountains, a large tertiary granite batholith. The volcanics are high-silica rhyolites and occur as domes, flows and tuffs. Initial eruptions resulted in two flows of low viscosity, phenocryst-poor rhyolite. Later activity consisted of pyroclastic eruptions and the emplacement of at least 9 viscous domes. In addition to abundant glass the rhyolites contain alkali feldspar, plagioclase, biotite, iron-titanium oxides and small amounts of hornblende, allanite, apatite, zircon, sphene and topaz. Magmatic temperatures were about 700C and water fugacities ranged from 350 to 3450 bars. Based on water fugacity calculations it is concluded that there may have been one or more shallow magma chambers in the Mineral Range at depths of about 1.6 km. Close

• 8. [Image] Thermal Gradient and Heat Flow Drilling, Volume 5, Final Report

  	During the summer of 1975, the Department of Geology and Geophysics drilled nine drill thermal gradient/heat flow holes. Total footage drilled was 2125 feet. Seven holes were drilled with a Mayhew 1000 ...
  	Citation × Citation Citation Abstract Copy Title: Thermal Gradient and Heat Flow Drilling, Volume 5, Final Report Author: Whelan, J.A. Year: 1977 During the summer of 1975, the Department of Geology and Geophysics drilled nine drill thermal gradient/heat flow holes. Total footage drilled was 2125 feet. Seven holes were drilled with a Mayhew 1000 drill using various combinations of down the hole hammer drilling, rotary drilling, and NX diamond core drilling. Three of these were heat flow holes--one in the Mineral Range, one in the Tushar Range near Beaver, Utah, and one near Monroe, Utah. Two were alteration study holes in the Roosevelt KGRA and two were temperature gradient holes, in alluvium in the Roosevelt KGRA. The average depth of the holes drilled with the Mayhew 1000 drill was 247 feet. Holes ranged from 135 feet to 492 feet. Cost per foot averaged $18.53. Two holes were core drilled with a Joy 12, BX-size drill. One was to 75 feet, in perlite. This hole was abandoned. The other was to 323 feet in granite. These holes averaged $13.82 per foot. Permission to drill was obtained from BLM and drill sites were inspected with BLM personnel to avoid disturbing archeological sites. Sites were reseeded where disturbed. Holes were completed by setting capped one-inch black iron pipe, backfilling the hole with cuttings to 10 feet from surface and cementing to the surface Title: Thermal Gradient and Heat Flow Drilling, Volume 5, Final Report Author: Whelan, J.A. Year: 1977 During the summer of 1975, the Department of Geology and Geophysics drilled nine drill thermal gradient/heat flow holes. Total footage drilled was 2125 feet. Seven holes were drilled with a Mayhew 1000 drill using various combinations of down the hole hammer drilling, rotary drilling, and NX diamond core drilling. Three of these were heat flow holes--one in the Mineral Range, one in the Tushar Range near Beaver, Utah, and one near Monroe, Utah. Two were alteration study holes in the Roosevelt KGRA and two were temperature gradient holes, in alluvium in the Roosevelt KGRA. The average depth of the holes drilled with the Mayhew 1000 drill was 247 feet. Holes ranged from 135 feet to 492 feet. Cost per foot averaged $18.53. Two holes were core drilled with a Joy 12, BX-size drill. One was to 75 feet, in perlite. This hole was abandoned. The other was to 323 feet in granite. These holes averaged $13.82 per foot. Permission to drill was obtained from BLM and drill sites were inspected with BLM personnel to avoid disturbing archeological sites. Sites were reseeded where disturbed. Holes were completed by setting capped one-inch black iron pipe, backfilling the hole with cuttings to 10 feet from surface and cementing to the surface Close

• 9. [Image] Stratigraphy and Alteration, 15 Shallow Thermal Gradient Holes, Roosevelt Hot Springs KGRA and Vicinity, Millard and Beaver Counties, Utah

  	Fifteen shallow thermal gradient drill holes were recently completed by Geothermal Power Corporation (GPCR) in the vicinity of the Roosevelt Hot Springs KGRA. Five holes penetrated Tertiary granitic rocks ...
  	Citation × Citation Citation Abstract Copy Title: Stratigraphy and Alteration, 15 Shallow Thermal Gradient Holes, Roosevelt Hot Springs KGRA and Vicinity, Millard and Beaver Counties, Utah Author: Hulen, J.B. Year: 1978 Fifteen shallow thermal gradient drill holes were recently completed by Geothermal Power Corporation (GPCR) in the vicinity of the Roosevelt Hot Springs KGRA. Five holes penetrated Tertiary granitic rocks and Precambrian gneiss east of the KGRA. Seven holes completed entirely in alluvium near the southwestern corner of the KGRA encountered a near-surface marker horizon of Pleistocene pumice and perlite. Maximum calculated alluvial sedimentation rates since initial deposition of this pumice and perlite range from 1 foot in 12,500 years to 1 foot in 2,300 years. Three holes east of the Mineral Mountains penetrated late Cenozoic basaltic andesite beneath a thin veneer of alluvium. All 15 GPCR drill holes appear to be peripheral to a central zone of anomalously high thermal gradient and low resisitivity delineated by previous investigations. GPCR-8 and -14, however, are characterized by high heat flow and relatively abundant manganese oxide mineralization, which may reflect a favorable hydrologic system controlling thermal fluid flow at depth. These holes thus seem most encouraging for discovery of a deeper high-temperature geothermal resource Title: Stratigraphy and Alteration, 15 Shallow Thermal Gradient Holes, Roosevelt Hot Springs KGRA and Vicinity, Millard and Beaver Counties, Utah Author: Hulen, J.B. Year: 1978 Fifteen shallow thermal gradient drill holes were recently completed by Geothermal Power Corporation (GPCR) in the vicinity of the Roosevelt Hot Springs KGRA. Five holes penetrated Tertiary granitic rocks and Precambrian gneiss east of the KGRA. Seven holes completed entirely in alluvium near the southwestern corner of the KGRA encountered a near-surface marker horizon of Pleistocene pumice and perlite. Maximum calculated alluvial sedimentation rates since initial deposition of this pumice and perlite range from 1 foot in 12,500 years to 1 foot in 2,300 years. Three holes east of the Mineral Mountains penetrated late Cenozoic basaltic andesite beneath a thin veneer of alluvium. All 15 GPCR drill holes appear to be peripheral to a central zone of anomalously high thermal gradient and low resisitivity delineated by previous investigations. GPCR-8 and -14, however, are characterized by high heat flow and relatively abundant manganese oxide mineralization, which may reflect a favorable hydrologic system controlling thermal fluid flow at depth. These holes thus seem most encouraging for discovery of a deeper high-temperature geothermal resource Close

• 10. [Image] C. D. Hopkins, et al. , No. 2. Geothermal Well-Of-Opportunity, Wayne County, Georgia. Operational Report

  	An oil and gas exploration well, located near Jesup in Wayne County, Georgia (lat. 31/sup 0/32' N, long. 81/sup 0/43' W), was deepened and used for geothermal temperature-gradient measurements. The well ...
  	Citation × Citation Citation Abstract Copy Title: C. D. Hopkins, et al. , No. 2. Geothermal Well-Of-Opportunity, Wayne County, Georgia. Operational Report Author: Lohse, A. Year: 1978 An oil and gas exploration well, located near Jesup in Wayne County, Georgia (lat. 31/sup 0/32' N, long. 81/sup 0/43' W), was deepened and used for geothermal temperature-gradient measurements. The well was drilled from 4,009 to 4,341 feet, then diamond cored to 4,371 feet, 28 feet of core being obtained for analysis. After logging by the U.S.G.S. District Groundwater Office in Atlanta, the well was terminated with 3/sup 1///sub 2/'' tubing to 4,386 feet. The bottom-hole temperature was determined to be 60/sup 0/C (140/sup 0/F) at 1,331 meters (4,365 feet). Over the interval 47 to 1,331 meters (154 to 4,365 feet) the least-squares temperature gradient was 29.3 +- 0.14 /sup 0/C/km (1.61 +- 0.25 /sup 0/F/100 ft) Title: C. D. Hopkins, et al. , No. 2. Geothermal Well-Of-Opportunity, Wayne County, Georgia. Operational Report Author: Lohse, A. Year: 1978 An oil and gas exploration well, located near Jesup in Wayne County, Georgia (lat. 31/sup 0/32' N, long. 81/sup 0/43' W), was deepened and used for geothermal temperature-gradient measurements. The well was drilled from 4,009 to 4,341 feet, then diamond cored to 4,371 feet, 28 feet of core being obtained for analysis. After logging by the U.S.G.S. District Groundwater Office in Atlanta, the well was terminated with 3/sup 1///sub 2/'' tubing to 4,386 feet. The bottom-hole temperature was determined to be 60/sup 0/C (140/sup 0/F) at 1,331 meters (4,365 feet). Over the interval 47 to 1,331 meters (154 to 4,365 feet) the least-squares temperature gradient was 29.3 +- 0.14 /sup 0/C/km (1.61 +- 0.25 /sup 0/F/100 ft) Close