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• 1. [Image] Formation Temperature Gauge Feasibility Study. Volume II, Interim Report

  	The present status of the formation temperature gauge feasibility study is reported. It also demonstrates the feasibility of the technique in the simplified situations examined to date both analytically ...
  	Citation × Citation Citation Abstract Copy Title: Formation Temperature Gauge Feasibility Study. Volume II, Interim Report Author: IRT Corporation Year: 1977 The present status of the formation temperature gauge feasibility study is reported. It also demonstrates the feasibility of the technique in the simplified situations examined to date both analytically and experimentally. The first section deals with the theory underlying the technique. The next three sections describe the temperature gauge, the simplified model calculations of the gauge response, and the preliminary experimental measurements performed to verify the results of the computational study. The final section describes the formation temperature test stand designed to demonstrate the feasibility of the technique in the geothermal well geometry. This test stand has been assembled and measurements of the gauge response will begin shortly. These are outlined at the end of this report Title: Formation Temperature Gauge Feasibility Study. Volume II, Interim Report Author: IRT Corporation Year: 1977 The present status of the formation temperature gauge feasibility study is reported. It also demonstrates the feasibility of the technique in the simplified situations examined to date both analytically and experimentally. The first section deals with the theory underlying the technique. The next three sections describe the temperature gauge, the simplified model calculations of the gauge response, and the preliminary experimental measurements performed to verify the results of the computational study. The final section describes the formation temperature test stand designed to demonstrate the feasibility of the technique in the geothermal well geometry. This test stand has been assembled and measurements of the gauge response will begin shortly. These are outlined at the end of this report Close

• 2. [Image] Potential of Low-Temperature Geothermal Resources in Northern California. Report No. TR13

  	Economically feasible uses for geothermal heat at temperatures too low for conventional electrical power generation at present are delineated. Several geothermal resource areas in northern California that ...
  	Citation × Citation Citation Abstract Copy Title: Potential of Low-Temperature Geothermal Resources in Northern California. Report No. TR13 Author: Hannah, J.L. Year: 1975 Economically feasible uses for geothermal heat at temperatures too low for conventional electrical power generation at present are delineated. Several geothermal resource areas in northern California that have development potential are described, and applications of the heat found in each area are suggested. Plates are included of the following field study areas: the east side of the Sierra-Cascade Range north of Bishop, and the northern Coast Range from San Francisco Bay to Clear Lake. The counties included in the study area are Mo doc, Lassen, Sierra, Plumas, Placer, Alpine, Mono, Mendocino, Lake, and Sonoma. (LBS) Title: Potential of Low-Temperature Geothermal Resources in Northern California. Report No. TR13 Author: Hannah, J.L. Year: 1975 Economically feasible uses for geothermal heat at temperatures too low for conventional electrical power generation at present are delineated. Several geothermal resource areas in northern California that have development potential are described, and applications of the heat found in each area are suggested. Plates are included of the following field study areas: the east side of the Sierra-Cascade Range north of Bishop, and the northern Coast Range from San Francisco Bay to Clear Lake. The counties included in the study area are Mo doc, Lassen, Sierra, Plumas, Placer, Alpine, Mono, Mendocino, Lake, and Sonoma. (LBS) Close

• 3. [Image] Assessment of low- to moderate-temperature geothermal resources of Nevada. Final report, April 1978-June 1979

  	The ultimate goal of the project was to produce a geothermal resource map of Nevada that provided detailed information on low- to moderate-temperature geothermal systems, and that also evaluated their ...
  	Citation × Citation Citation Abstract Copy Title: Assessment of low- to moderate-temperature geothermal resources of Nevada. Final report, April 1978-June 1979 Author: Trexler, D.T Year: 1979 The ultimate goal of the project was to produce a geothermal resource map of Nevada that provided detailed information on low- to moderate-temperature geothermal systems, and that also evaluated their potential for direct non-electric utilization. The investigation consisted of these six tasks: edit and verify existing USGS GEOTHERM file for springs and wells in Nevada; supplement GEOTHERM file with NBMG data; digitize the location of springs and wells on 1:250,000 scale maps of Nevada; update water chemistry by sampling areas devoid of data; field check springs and wells designated as hot or warm; and prepare a 1:500,000 scale map of Nevada that evaluates geothermal resource areas of potential for direct use. This report described the completed tasks, delineates problems encountered, and presents additional miscellaneous information that augments the investigation. The information shown on the accompanying map can be divided into two categories: spot data and regional assessment (or potential evaluation). Specific geochemical information, such as temperature, pH, and chemical species, is represented by approximately 300 circle and diamond-shaped symbols. Thirty-seven larger regions were evaluated for their potential for direct-use on the basis of a numerical technique, which is fully described in this report. An additional 15 sites were designated as areas that may provide a basis for investigations, but that lack sufficient data for a detailed potential evaluation at this time. ; NVO-01556-1 Title: Assessment of low- to moderate-temperature geothermal resources of Nevada. Final report, April 1978-June 1979 Author: Trexler, D.T Year: 1979 The ultimate goal of the project was to produce a geothermal resource map of Nevada that provided detailed information on low- to moderate-temperature geothermal systems, and that also evaluated their potential for direct non-electric utilization. The investigation consisted of these six tasks: edit and verify existing USGS GEOTHERM file for springs and wells in Nevada; supplement GEOTHERM file with NBMG data; digitize the location of springs and wells on 1:250,000 scale maps of Nevada; update water chemistry by sampling areas devoid of data; field check springs and wells designated as hot or warm; and prepare a 1:500,000 scale map of Nevada that evaluates geothermal resource areas of potential for direct use. This report described the completed tasks, delineates problems encountered, and presents additional miscellaneous information that augments the investigation. The information shown on the accompanying map can be divided into two categories: spot data and regional assessment (or potential evaluation). Specific geochemical information, such as temperature, pH, and chemical species, is represented by approximately 300 circle and diamond-shaped symbols. Thirty-seven larger regions were evaluated for their potential for direct-use on the basis of a numerical technique, which is fully described in this report. An additional 15 sites were designated as areas that may provide a basis for investigations, but that lack sufficient data for a detailed potential evaluation at this time. ; NVO-01556-1 Close

• 4. [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

• 5. [Image] Hot Dry Rock Geothermal Energy Development Project: Cablehead Assembly, Equipment Development Report

  	The development, design, and service history of a multiconductor cablehead capable of operation at 275/sup 0/C and 103 MPa (15,000 psi) are discussed. This high-temperature cablehead has been in service ...
  	Citation × Citation Citation Abstract Copy Title: Hot Dry Rock Geothermal Energy Development Project: Cablehead Assembly, Equipment Development Report Author: Archuleta, J.R. Year: 1978 The development, design, and service history of a multiconductor cablehead capable of operation at 275/sup 0/C and 103 MPa (15,000 psi) are discussed. This high-temperature cablehead has been in service for about 18 months; conclusions drawn from this test period are summarized Title: Hot Dry Rock Geothermal Energy Development Project: Cablehead Assembly, Equipment Development Report Author: Archuleta, J.R. Year: 1978 The development, design, and service history of a multiconductor cablehead capable of operation at 275/sup 0/C and 103 MPa (15,000 psi) are discussed. This high-temperature cablehead has been in service for about 18 months; conclusions drawn from this test period are summarized Close

• 6. [Image] Geology of the Colado Geothermal Area, Pershing County, Nevada

  	The Colado geothermal area in south-central Pershing County, Nevada is defined by hot water wells in alluvium just west of the West Humboldt Range. Geothermal gradient holes have encountered temperatures ...
  	Citation × Citation Citation Abstract Copy Title: Geology of the Colado Geothermal Area, Pershing County, Nevada Author: Sibbett, B.S. Year: 1980 The Colado geothermal area in south-central Pershing County, Nevada is defined by hot water wells in alluvium just west of the West Humboldt Range. Geothermal gradient holes have encountered temperatures up to 113.5/sup 0/C at a depth of 76 m (250 ft) with a gradient reversal in the alluvium below this depth. The West Humboldt Range consists mainly of Triassic to Jurassic slaty shale to quartzite of the Auld Lang Syne Group. Carbonate rocks of the Jurassic Lovelock Formation have been thrust over pelitic rocks on the south end of the area. Erosional remnants of Tertiary tuffs and sediments overlay the metasediments in the West Humboldt Range. The principal structures are high-angle faults striking north-northwest, northeast and north-south. The horst-to-graben transition along the range front consists of several step faults trending irregularly north. The structural pattern in the west edge of the range probably continues to the west under the Quaterary alluvium where the source of the hot water is located. Thermal waters probably rise along a major fault intersection in the Mesozoic rocks then spread out in an aquifer in the alluvium. Several thrust faults are exposed south of Coal Canyon, and a structural break in the Mesozoic rock exists under the canyon. Several low-angle faults are present north of Coal Canyon but their effect, if any, on the geothermal occurrence is not known; DOE/ID/12079-8; ESL-38 Title: Geology of the Colado Geothermal Area, Pershing County, Nevada Author: Sibbett, B.S. Year: 1980 The Colado geothermal area in south-central Pershing County, Nevada is defined by hot water wells in alluvium just west of the West Humboldt Range. Geothermal gradient holes have encountered temperatures up to 113.5/sup 0/C at a depth of 76 m (250 ft) with a gradient reversal in the alluvium below this depth. The West Humboldt Range consists mainly of Triassic to Jurassic slaty shale to quartzite of the Auld Lang Syne Group. Carbonate rocks of the Jurassic Lovelock Formation have been thrust over pelitic rocks on the south end of the area. Erosional remnants of Tertiary tuffs and sediments overlay the metasediments in the West Humboldt Range. The principal structures are high-angle faults striking north-northwest, northeast and north-south. The horst-to-graben transition along the range front consists of several step faults trending irregularly north. The structural pattern in the west edge of the range probably continues to the west under the Quaterary alluvium where the source of the hot water is located. Thermal waters probably rise along a major fault intersection in the Mesozoic rocks then spread out in an aquifer in the alluvium. Several thrust faults are exposed south of Coal Canyon, and a structural break in the Mesozoic rock exists under the canyon. Several low-angle faults are present north of Coal Canyon but their effect, if any, on the geothermal occurrence is not known; DOE/ID/12079-8; ESL-38 Close

• 7. [Image] Hot Dry Rock Geothermal Energy Development Program, Annual Report, Fiscal Year 1980

  	Investigation and flow testing of the enlarged Phase I heat-extraction system at Fenton Hill continued throughout FY80. Temperature drawdown observed at that time indicated an effective fracture of approximately ...
  	Citation × Citation Citation Abstract Copy Title: Hot Dry Rock Geothermal Energy Development Program, Annual Report, Fiscal Year 1980 Author: Cremer, G.M. (comp.) Year: 1981 Investigation and flow testing of the enlarged Phase I heat-extraction system at Fenton Hill continued throughout FY80. Temperature drawdown observed at that time indicated an effective fracture of approximately 40,000 to 60,000 m/sup 2/. In May 1980, hot dry rock (HDR) technology was used to produce electricity in an interface demonstration experiment at Fenton Hill. A 60-kVA binary-cycle electrical generator was installed in the Phase I surface system and heat from about 3 kg/s of geothermal fluid at 132/sup 0/C was used to boil Freon R-114, whose vapor drove a turboalternator. A Phase II system was designed and is now being constructed at Fenton Hill that should approach commercial requirements. Borehole EE-2, the injection well, was completed on May 12, 1980. It was drilled to a vertical depth of about 4500 m, where the rock temperature is approximately 320/sup 0/C. The production well, EE-3 had been drilled to a depth of 3044 m and drilling was continuing. Environmental monitoring of Fenton Hill site continued. Development of equipment, instruments, and materials for technical support at Fenton Hill continued during FY80. Several kinds of models were also developed to understand the behavior of the Phase I system and to develop a predictive capability for future systems. Data from extensive resource investigations were collected, analyzed, and assembled into a geothermal gradient map of the US, and studies were completed on five specific areas as possible locations for HDR Experimental Site 2 Title: Hot Dry Rock Geothermal Energy Development Program, Annual Report, Fiscal Year 1980 Author: Cremer, G.M. (comp.) Year: 1981 Investigation and flow testing of the enlarged Phase I heat-extraction system at Fenton Hill continued throughout FY80. Temperature drawdown observed at that time indicated an effective fracture of approximately 40,000 to 60,000 m/sup 2/. In May 1980, hot dry rock (HDR) technology was used to produce electricity in an interface demonstration experiment at Fenton Hill. A 60-kVA binary-cycle electrical generator was installed in the Phase I surface system and heat from about 3 kg/s of geothermal fluid at 132/sup 0/C was used to boil Freon R-114, whose vapor drove a turboalternator. A Phase II system was designed and is now being constructed at Fenton Hill that should approach commercial requirements. Borehole EE-2, the injection well, was completed on May 12, 1980. It was drilled to a vertical depth of about 4500 m, where the rock temperature is approximately 320/sup 0/C. The production well, EE-3 had been drilled to a depth of 3044 m and drilling was continuing. Environmental monitoring of Fenton Hill site continued. Development of equipment, instruments, and materials for technical support at Fenton Hill continued during FY80. Several kinds of models were also developed to understand the behavior of the Phase I system and to develop a predictive capability for future systems. Data from extensive resource investigations were collected, analyzed, and assembled into a geothermal gradient map of the US, and studies were completed on five specific areas as possible locations for HDR Experimental Site 2 Close

• 8. [Image] Hot Dry Rock Geothermal Energy Development Program. Annual Report, Fiscal Year 1983

  	Emphasis was on hydraulic-fracturing experiments at depths around 3.5 km (11,473 ft) in the two inclined wells of the Phase II system at Fenton Hill, New Mexico; on improved facilities and techniques for ...
  	Citation × Citation Citation Abstract Copy Title: Hot Dry Rock Geothermal Energy Development Program. Annual Report, Fiscal Year 1983 Author: Smith, M.C. (comp.) Year: 1985 Emphasis was on hydraulic-fracturing experiments at depths around 3.5 km (11,473 ft) in the two inclined wells of the Phase II system at Fenton Hill, New Mexico; on improved facilities and techniques for mapping the source locations of acoustic signals generated by the fracturing events; on mathematical modeling of the fracture systems produced in these and earlier experiments; and on development of a family of slimline high-temperature downhole instruments that can be used within or through relatively small-diameter pressure tubing. Hydraulic fracturing at a vertical depth of approximately 3500 m (11,500 ft) in well EE-2, the deeper well, produced fractures that, in acoustic maps, appear to occupy a large, roughly ellipsoidal volume whose major axis is directed to the north of the other well, EE-3. Hydraulic fracturing from EE-3 at a similar depth produced another set of fractures that appear to be approximately parallel to and centered about 180 m (600 ft) east of the earlier set. Subsequent fluid injections reduced the distance between the two sets, but no hydraulic connection between them was established. Modeling the silica concentrations of fluid circulated through the earlier Phase I system indicates that this type of permeation also contributes significantly to heat extraction during system operation. The precision and accuracy of locating the sources of acoustic signals detected during hydraulic-fracturing operations have been increased by improvements in equipment, drilling of another deep hole for geophone emplacement, and additional station calibrations. Analysis of the signals has also been improved and broadened. Development of slimline downhole instruments has included a detonator tool, a geophone package, and final design of a high-temperature borehole acoustic televiewer. A crosswell acoustic transceiver has also been developed for investigating rock type and structure between wellbores. 32 refs., 35 figs. Title: Hot Dry Rock Geothermal Energy Development Program. Annual Report, Fiscal Year 1983 Author: Smith, M.C. (comp.) Year: 1985 Emphasis was on hydraulic-fracturing experiments at depths around 3.5 km (11,473 ft) in the two inclined wells of the Phase II system at Fenton Hill, New Mexico; on improved facilities and techniques for mapping the source locations of acoustic signals generated by the fracturing events; on mathematical modeling of the fracture systems produced in these and earlier experiments; and on development of a family of slimline high-temperature downhole instruments that can be used within or through relatively small-diameter pressure tubing. Hydraulic fracturing at a vertical depth of approximately 3500 m (11,500 ft) in well EE-2, the deeper well, produced fractures that, in acoustic maps, appear to occupy a large, roughly ellipsoidal volume whose major axis is directed to the north of the other well, EE-3. Hydraulic fracturing from EE-3 at a similar depth produced another set of fractures that appear to be approximately parallel to and centered about 180 m (600 ft) east of the earlier set. Subsequent fluid injections reduced the distance between the two sets, but no hydraulic connection between them was established. Modeling the silica concentrations of fluid circulated through the earlier Phase I system indicates that this type of permeation also contributes significantly to heat extraction during system operation. The precision and accuracy of locating the sources of acoustic signals detected during hydraulic-fracturing operations have been increased by improvements in equipment, drilling of another deep hole for geophone emplacement, and additional station calibrations. Analysis of the signals has also been improved and broadened. Development of slimline downhole instruments has included a detonator tool, a geophone package, and final design of a high-temperature borehole acoustic televiewer. A crosswell acoustic transceiver has also been developed for investigating rock type and structure between wellbores. 32 refs., 35 figs. Close

• 9. [Image] Transient well testing in two-phase geothermal reservoirs

  	A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto ...
  	Citation × Citation Citation Abstract Copy Title: Transient well testing in two-phase geothermal reservoirs Author: Aydelotte, S.R. Year: 1980 A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto and the Hawaiian Geothermal project have been history matched. Using these well tests as a base, the influence of reservoir permeability, porosity, thickness, and heat capacity, along with flow rate and fracturing were studied. Single and two-phase transient well test equations were used to analyze these tests with poor results due to rapidly changing fluid properties and inability to calculate the flowing steam saturation in the reservoir. The injection of cold water into the reservoir does give good data from which formation properties can be calculated. Title: Transient well testing in two-phase geothermal reservoirs Author: Aydelotte, S.R. Year: 1980 A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto and the Hawaiian Geothermal project have been history matched. Using these well tests as a base, the influence of reservoir permeability, porosity, thickness, and heat capacity, along with flow rate and fracturing were studied. Single and two-phase transient well test equations were used to analyze these tests with poor results due to rapidly changing fluid properties and inability to calculate the flowing steam saturation in the reservoir. The injection of cold water into the reservoir does give good data from which formation properties can be calculated. Close

• 10. [Image] Planning, Drilling, Logging, and Testing of Energy Extraction Hole EE-1, Phases I and II

  	Energy Extraction Hole No. 1 (EE-1) is the second deep hole drilled into the Precambrian-age granitic rocks of the Jemez Mountains of north-central New Mexico. EE-1 was drilled to intersect a hydraulic ...
  	Citation × Citation Citation Abstract Copy Title: Planning, Drilling, Logging, and Testing of Energy Extraction Hole EE-1, Phases I and II Author: Pettitt, R.A. Year: 1977 Energy Extraction Hole No. 1 (EE-1) is the second deep hole drilled into the Precambrian-age granitic rocks of the Jemez Mountains of north-central New Mexico. EE-1 was drilled to intersect a hydraulic fracture extending outward from near the bottom of previously drilled hole GT-2, thus completing the underground circulation loop required for the hot dry rock geothermal energy extraction experiment. Directional drilling techniques were used to intersect the fracture zone. In addition, high-temperature instrumentation and equipment development, hydraulic fracturing experiments, pressure-flow testing of the fracture systems, and fracture mapping and borehole-ranging technique activities were conducted. The drilling, logging, and testing operations in EE-1 are described Title: Planning, Drilling, Logging, and Testing of Energy Extraction Hole EE-1, Phases I and II Author: Pettitt, R.A. Year: 1977 Energy Extraction Hole No. 1 (EE-1) is the second deep hole drilled into the Precambrian-age granitic rocks of the Jemez Mountains of north-central New Mexico. EE-1 was drilled to intersect a hydraulic fracture extending outward from near the bottom of previously drilled hole GT-2, thus completing the underground circulation loop required for the hot dry rock geothermal energy extraction experiment. Directional drilling techniques were used to intersect the fracture zone. In addition, high-temperature instrumentation and equipment development, hydraulic fracturing experiments, pressure-flow testing of the fracture systems, and fracture mapping and borehole-ranging technique activities were conducted. The drilling, logging, and testing operations in EE-1 are described Close