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• 41. [Image] Hot-Dry-Rock Geothermal-Energy Development Program. Annual Report, Fiscal Year 1981

  	During fiscal year 1981, activities of the Hot Dry Rock Geothermal Energy Development Program were concentrated in four principal areas: (1) data collection to permit improved estimates of the hot dry ...
  	Citation × Citation Citation Abstract Copy Title: Hot-Dry-Rock Geothermal-Energy Development Program. Annual Report, Fiscal Year 1981 Author: Smith, M.C. (comp.) Year: 1981 During fiscal year 1981, activities of the Hot Dry Rock Geothermal Energy Development Program were concentrated in four principal areas: (1) data collection to permit improved estimates of the hot dry rock geothermal energy resource base of various regions of the United States and of the United States as a whole, combined with detailed investigations of several areas that appear particularly promising either for further energy extraction experiments or for future commercial development; (2) successful completion of a 9-month, continuous, closed-loop, recirculating flow test in the enlarged Phase I System at Fenton Hill, New Mexico - a pressurized-water heat-extraction loop developed in low-permeability granitic rock by hydraulic fracturing; (3) successful completion at a depth of 4084 m (13,933 ft) of well EE-3, the production well of a larger, deeper, and hotter, Phase II System at Fenton Hill. Well EE-3 was directionally drilled with control of both azimuth and inclination. Its inclined section is about 380 m (1250 ft) vertically above the injection well, EE-2, which was completed in FY80; and (4) supporting activities included new developments in downhole instrumentation and equipment, geochemical and geophysical studies, rock-mechanics and fluid-mechanics investigations, computer analyses and modeling, and overall system design. Under an International Energy Agency agreement, the New Energy Development Organization, representing the Government of Japan has joined Kernforschungsanlage-Juelich GmbH, representing the Federal Republic of Germany, and the US Department of Energy as an active participant in the Fenton Hill Hot Dry Rock Project Title: Hot-Dry-Rock Geothermal-Energy Development Program. Annual Report, Fiscal Year 1981 Author: Smith, M.C. (comp.) Year: 1981 During fiscal year 1981, activities of the Hot Dry Rock Geothermal Energy Development Program were concentrated in four principal areas: (1) data collection to permit improved estimates of the hot dry rock geothermal energy resource base of various regions of the United States and of the United States as a whole, combined with detailed investigations of several areas that appear particularly promising either for further energy extraction experiments or for future commercial development; (2) successful completion of a 9-month, continuous, closed-loop, recirculating flow test in the enlarged Phase I System at Fenton Hill, New Mexico - a pressurized-water heat-extraction loop developed in low-permeability granitic rock by hydraulic fracturing; (3) successful completion at a depth of 4084 m (13,933 ft) of well EE-3, the production well of a larger, deeper, and hotter, Phase II System at Fenton Hill. Well EE-3 was directionally drilled with control of both azimuth and inclination. Its inclined section is about 380 m (1250 ft) vertically above the injection well, EE-2, which was completed in FY80; and (4) supporting activities included new developments in downhole instrumentation and equipment, geochemical and geophysical studies, rock-mechanics and fluid-mechanics investigations, computer analyses and modeling, and overall system design. Under an International Energy Agency agreement, the New Energy Development Organization, representing the Government of Japan has joined Kernforschungsanlage-Juelich GmbH, representing the Federal Republic of Germany, and the US Department of Energy as an active participant in the Fenton Hill Hot Dry Rock Project Close

• 42. [Image] Geothermal Reservoir Categorization and Stimulation Study

  	Analyses of the fraction of geothermal wells that are dry (dry-hole fraction) indicate that geothermal reservoirs can be fitted into four basic categories: (i) Quaternary to late Tertiary sediments (almost ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Reservoir Categorization and Stimulation Study Author: Overton, H.L. Year: 1977 Analyses of the fraction of geothermal wells that are dry (dry-hole fraction) indicate that geothermal reservoirs can be fitted into four basic categories: (i) Quaternary to late Tertiary sediments (almost no dry holes); (ii) Quaternary to late Tertiary extrusives (approximately 20 percent dry holes); (iii) Mesozoic or older metamorphic rocks (approximately 25-30 percent dry holes); and (iv) Precambrian or younger rocks (data limited to Roosevelt Springs where 33 percent of the wells were dry). Failure of geothermal wells to flow economically is due mainly to low-permeability formations in unfractured regions. Generally the permeability correlates inversely with the temperature-age product and directly with the original rock porosity and pore size. However, this correlation fails whenever high-stress fields provide vertical fracturing or faulting, and it is the high-stress/low-permeability category that is most amenable to artificial stimulation by hydraulic fracturing, propellant fracturing, or chemical explosive fracturing. Category (i) geothermal fields (e.g., Cerro Prieto, Mexico; Niland, CA; East Mesa, CA) are not recommended for artificial stimulation because these younger sediments almost always produce warm or hot water. Most geothermal fields fit into category (ii) (e.g., Wairakei, New Zealand; Matsukawa, Japan; Ahuachapan, El Salvador) and in the case of Mt. Home, ID, and Chandler, AZ, possess some potential for stimulation. The Geysers is a category (iii) field, and its highly stressed brittle rocks should make this site amenable to stimulation by explosive fracturing techniques. Roosevelt Springs, UT, Well 9-1 is in category (iv) and is a flow failure. It represents a prime candidate for stimulation by hydraulic fracturing because it has a measured temperature of 227/sup 0/C, is cased and available for experimentation, and is within 900 m of an excellent geothermal producing well Title: Geothermal Reservoir Categorization and Stimulation Study Author: Overton, H.L. Year: 1977 Analyses of the fraction of geothermal wells that are dry (dry-hole fraction) indicate that geothermal reservoirs can be fitted into four basic categories: (i) Quaternary to late Tertiary sediments (almost no dry holes); (ii) Quaternary to late Tertiary extrusives (approximately 20 percent dry holes); (iii) Mesozoic or older metamorphic rocks (approximately 25-30 percent dry holes); and (iv) Precambrian or younger rocks (data limited to Roosevelt Springs where 33 percent of the wells were dry). Failure of geothermal wells to flow economically is due mainly to low-permeability formations in unfractured regions. Generally the permeability correlates inversely with the temperature-age product and directly with the original rock porosity and pore size. However, this correlation fails whenever high-stress fields provide vertical fracturing or faulting, and it is the high-stress/low-permeability category that is most amenable to artificial stimulation by hydraulic fracturing, propellant fracturing, or chemical explosive fracturing. Category (i) geothermal fields (e.g., Cerro Prieto, Mexico; Niland, CA; East Mesa, CA) are not recommended for artificial stimulation because these younger sediments almost always produce warm or hot water. Most geothermal fields fit into category (ii) (e.g., Wairakei, New Zealand; Matsukawa, Japan; Ahuachapan, El Salvador) and in the case of Mt. Home, ID, and Chandler, AZ, possess some potential for stimulation. The Geysers is a category (iii) field, and its highly stressed brittle rocks should make this site amenable to stimulation by explosive fracturing techniques. Roosevelt Springs, UT, Well 9-1 is in category (iv) and is a flow failure. It represents a prime candidate for stimulation by hydraulic fracturing because it has a measured temperature of 227/sup 0/C, is cased and available for experimentation, and is within 900 m of an excellent geothermal producing well Close

• 43. [Image] Drilling plan: Raft River Geothermal Exploratory Hole No. 3

  	The program, plans, and procedures to be used in drilling and completion of the Raft River Geothermal Exploratory Hole No. 3(RRGE-3) are described. RRGE-3 will be located in the Raft River valley of south ...
  	Citation × Citation Citation Abstract Copy Title: Drilling plan: Raft River Geothermal Exploratory Hole No. 3 Author: Industrial Applications Division , Nevada Operations Office Year: 1976 The program, plans, and procedures to be used in drilling and completion of the Raft River Geothermal Exploratory Hole No. 3(RRGE-3) are described. RRGE-3 will be located in the Raft River valley of south central Idaho, southeast of Burley, and approximately 16 miles south of Malta, Idaho. The third exploratory hole will be drilled to provide data to further investigate and evaluate the geothermal reservoir, as well as to optimize the location of possible future resource and/or injection wells, and to develop methods to reduce the cost of geothermal wells. Plans call for drilling to a total depth of approximately 6,000 ft., or to the depth at which it is either indicated from temperature and test flow data and from logs that an acceptable hot water resource is available or that the hole is accepted as a possible reinjection well. (LBS) Title: Drilling plan: Raft River Geothermal Exploratory Hole No. 3 Author: Industrial Applications Division , Nevada Operations Office Year: 1976 The program, plans, and procedures to be used in drilling and completion of the Raft River Geothermal Exploratory Hole No. 3(RRGE-3) are described. RRGE-3 will be located in the Raft River valley of south central Idaho, southeast of Burley, and approximately 16 miles south of Malta, Idaho. The third exploratory hole will be drilled to provide data to further investigate and evaluate the geothermal reservoir, as well as to optimize the location of possible future resource and/or injection wells, and to develop methods to reduce the cost of geothermal wells. Plans call for drilling to a total depth of approximately 6,000 ft., or to the depth at which it is either indicated from temperature and test flow data and from logs that an acceptable hot water resource is available or that the hole is accepted as a possible reinjection well. (LBS) Close

• 44. [Image] The Definition of Engineering Development and Research Problems Relating to the Use of Geothermal Fluids for Electric Power Generation and Nonelectric Heating

  	The use of geothermal fluids for electric power generation and nonelectric purposes causes problems not normally encountered when pure water is used for similar purposes. These problems must be identified ...
  	Citation × Citation Citation Abstract Copy Title: The Definition of Engineering Development and Research Problems Relating to the Use of Geothermal Fluids for Electric Power Generation and Nonelectric Heating Author: Apps, J.A. Year: 1977 The use of geothermal fluids for electric power generation and nonelectric purposes causes problems not normally encountered when pure water is used for similar purposes. These problems must be identified and means developed to overcome them before geothermal energy resources can become an important source of electric power or thermal energy in the United States. Research and development projects aimed at solving problems arising from the use of geothermal fluids from known sources in the United States are listed. Problem areas covered are: impact on engineering design caused by chemical, thermodynamic, and transport properties of geothermal fluids; scaling and sludge formation; gases, volatile brine constituents, condensate chemistry; environmental problems. The research projects identified are general in nature and are not site specific. (JGB) Title: The Definition of Engineering Development and Research Problems Relating to the Use of Geothermal Fluids for Electric Power Generation and Nonelectric Heating Author: Apps, J.A. Year: 1977 The use of geothermal fluids for electric power generation and nonelectric purposes causes problems not normally encountered when pure water is used for similar purposes. These problems must be identified and means developed to overcome them before geothermal energy resources can become an important source of electric power or thermal energy in the United States. Research and development projects aimed at solving problems arising from the use of geothermal fluids from known sources in the United States are listed. Problem areas covered are: impact on engineering design caused by chemical, thermodynamic, and transport properties of geothermal fluids; scaling and sludge formation; gases, volatile brine constituents, condensate chemistry; environmental problems. The research projects identified are general in nature and are not site specific. (JGB) Close

• 45. [Image] Delineation of an electrical resistivity anomaly, Malpais area, Beowawe KGRA, Eureka and Lander Counties, Nevada

  	A simple numerical model of previously released bipole-dipole resistivity data shows the margin of the graben to be anomalously conductive below the Malpais. The conductive area has been delineated with ...
  	Citation × Citation Citation Abstract Copy Title: Delineation of an electrical resistivity anomaly, Malpais area, Beowawe KGRA, Eureka and Lander Counties, Nevada Author: Smith, C. Year: 1980 A simple numerical model of previously released bipole-dipole resistivity data shows the margin of the graben to be anomalously conductive below the Malpais. The conductive area has been delineated with data from a dipole-dipole resistivity survey run in April 1980 for this study. Detailed numerical models of these data define a 1250 m wide body with resistivities less than 20 ohm-m that appear to connect The Geysers and the graben boundary. The minimum depth to the conductor is interpreted to be 375 m; its depth extent is undetermined. The electrical data do not resolve whether the anomaly below the Malpais may be the product of a defunct hydrothermal system or the signature of an active system. If thermal gradient data detect an enhanced heat flow anomaly in the same area, the Malpais may be a viable geothermal exploration target within the Beowawe KGRA; DOE/ID/12079-7 Title: Delineation of an electrical resistivity anomaly, Malpais area, Beowawe KGRA, Eureka and Lander Counties, Nevada Author: Smith, C. Year: 1980 A simple numerical model of previously released bipole-dipole resistivity data shows the margin of the graben to be anomalously conductive below the Malpais. The conductive area has been delineated with data from a dipole-dipole resistivity survey run in April 1980 for this study. Detailed numerical models of these data define a 1250 m wide body with resistivities less than 20 ohm-m that appear to connect The Geysers and the graben boundary. The minimum depth to the conductor is interpreted to be 375 m; its depth extent is undetermined. The electrical data do not resolve whether the anomaly below the Malpais may be the product of a defunct hydrothermal system or the signature of an active system. If thermal gradient data detect an enhanced heat flow anomaly in the same area, the Malpais may be a viable geothermal exploration target within the Beowawe KGRA; DOE/ID/12079-7 Close

• 46. [Image] Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems

  	A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in ...
  	Citation × Citation Citation Abstract Copy Title: Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems Author: Capuano, R.M. Year: 1978 A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in a hot-water geothermal system. Samples of -80 mesh soil were collected at 30.5 m intervals along traverses crossing known structures, surficial geothermal alteration, and exploration well sites, and were analyzed using a Gold Film Mercury Detector. Strong mercury anomalies occur at locations along known structures in close proximity to subsurface thermal activity; examples include areas over hot spring deposits and near a shallow producing well. In contrast, background mercury concentrations are present in nearby locations with little or no indication of subsurface thermal activity, such as areas around deep marginal producing wells and dry wells, and areas lacking hot spring deposits. These results indicate that mercury geochemical surveys can be useful for identifying and mapping structures controlling fluid flow in geothermal systems and for delineating areas overlying near-surface thermal activity. Soil mercury geochemistry thus provides information which may aid in the cost-effective selection of exploratory well sites Title: Initial Investigation of Soil Mercury Geochemistry as an Aid to Drill Site Selection in Geothermal Systems Author: Capuano, R.M. Year: 1978 A mercury-in-soil survey was conducted at the Roosevelt Hot Springs Known Geothermal Resource Area (KGRA), Utah, to evaluate mercury soil geochemistry as a method of selecting exploration well sites in a hot-water geothermal system. Samples of -80 mesh soil were collected at 30.5 m intervals along traverses crossing known structures, surficial geothermal alteration, and exploration well sites, and were analyzed using a Gold Film Mercury Detector. Strong mercury anomalies occur at locations along known structures in close proximity to subsurface thermal activity; examples include areas over hot spring deposits and near a shallow producing well. In contrast, background mercury concentrations are present in nearby locations with little or no indication of subsurface thermal activity, such as areas around deep marginal producing wells and dry wells, and areas lacking hot spring deposits. These results indicate that mercury geochemical surveys can be useful for identifying and mapping structures controlling fluid flow in geothermal systems and for delineating areas overlying near-surface thermal activity. Soil mercury geochemistry thus provides information which may aid in the cost-effective selection of exploratory well sites Close

• 47. [Image] Removal of Hydrogen Sulfide from Simulated Geothermal Brines by Reaction with Oxygen. Final Report, October 6, 1975-February 4, 1977

  	A process for controlling hydrogen sulfide emissions and corrosivity in geothermal systems has been evaluated on a small laboratory pilot plant scale and shown to be technically feasible. The hydrogen ...
  	Citation × Citation Citation Abstract Copy Title: Removal of Hydrogen Sulfide from Simulated Geothermal Brines by Reaction with Oxygen. Final Report, October 6, 1975-February 4, 1977 Author: Wilson, J.S. Year: 1977 A process for controlling hydrogen sulfide emissions and corrosivity in geothermal systems has been evaluated on a small laboratory pilot plant scale and shown to be technically feasible. The hydrogen sulfide was oxidized by oxygen injected directly into a 11.4-liter-(3-gallon)-per-minute flowing stream of simulated geothermal brine. The oxidation of the sulfide was complete at oxygen:sulfide mole ratios of 1.25:1 to 1.5:1, depending on temperature and total dissolved solids in the brine. The reaction products were free sulfur, sulfite and sulfate. The ratio of these was dependent upon the oxygen:sulfide mole ratios; but, generally, more than 80% of the sulfide was converted to sulfate, approximately 10% to free sulfur and less than 10% to sulfite Title: Removal of Hydrogen Sulfide from Simulated Geothermal Brines by Reaction with Oxygen. Final Report, October 6, 1975-February 4, 1977 Author: Wilson, J.S. Year: 1977 A process for controlling hydrogen sulfide emissions and corrosivity in geothermal systems has been evaluated on a small laboratory pilot plant scale and shown to be technically feasible. The hydrogen sulfide was oxidized by oxygen injected directly into a 11.4-liter-(3-gallon)-per-minute flowing stream of simulated geothermal brine. The oxidation of the sulfide was complete at oxygen:sulfide mole ratios of 1.25:1 to 1.5:1, depending on temperature and total dissolved solids in the brine. The reaction products were free sulfur, sulfite and sulfate. The ratio of these was dependent upon the oxygen:sulfide mole ratios; but, generally, more than 80% of the sulfide was converted to sulfate, approximately 10% to free sulfur and less than 10% to sulfite Close

• 48. [Image] Geothermal Progress Monitor: Report No. 17, December 1995

  	DOE is particularly concerned with reducing the costs of geothermal power generation, especially with the abundant moderate to low-temperature resources in the US. This concern is reflected in DOE`s support ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Progress Monitor: Report No. 17, December 1995 Author: Assistant Secretary for Energy and Efficiency and Renewable Energy, Geothermal Division Year: 1995 DOE is particularly concerned with reducing the costs of geothermal power generation, especially with the abundant moderate to low-temperature resources in the US. This concern is reflected in DOE`s support of a number of energy conversion projects. Projects which focus on the costs and performance of binary cycle technology include a commercial demonstration of supersaturated turbine expansions, which earlier Studies have indicated could increase the power produced per pound of fluid. Other binary cycle projects include evaluations of the performance of various working fluid mixtures and the development and testing of advanced heat rejection systems which are desperately needed in water-short geothermal areas. DOE is also investigating the applicability of flash steam technology to low-temperature resources, as an economic alternative to binary cycle systems. A low-cost, low-pressure steam turbine, selected for a grant, will be constructed to utilize fluid discharged from a flash steam plant in Nevada. Another project addresses the efficiency of high-temperature flash plants with a demonstration of the performance of the Biphase turbine which may increase the power output of such installations with no increase in fluid flow. Perhaps the most noteworthy feature of this issue of the GPM, the 17th since its inception in 1980, is the high degree of industry participation in federally-sponsored geothermal research and development. This report describes geothermal development activities Title: Geothermal Progress Monitor: Report No. 17, December 1995 Author: Assistant Secretary for Energy and Efficiency and Renewable Energy, Geothermal Division Year: 1995 DOE is particularly concerned with reducing the costs of geothermal power generation, especially with the abundant moderate to low-temperature resources in the US. This concern is reflected in DOE`s support of a number of energy conversion projects. Projects which focus on the costs and performance of binary cycle technology include a commercial demonstration of supersaturated turbine expansions, which earlier Studies have indicated could increase the power produced per pound of fluid. Other binary cycle projects include evaluations of the performance of various working fluid mixtures and the development and testing of advanced heat rejection systems which are desperately needed in water-short geothermal areas. DOE is also investigating the applicability of flash steam technology to low-temperature resources, as an economic alternative to binary cycle systems. A low-cost, low-pressure steam turbine, selected for a grant, will be constructed to utilize fluid discharged from a flash steam plant in Nevada. Another project addresses the efficiency of high-temperature flash plants with a demonstration of the performance of the Biphase turbine which may increase the power output of such installations with no increase in fluid flow. Perhaps the most noteworthy feature of this issue of the GPM, the 17th since its inception in 1980, is the high degree of industry participation in federally-sponsored geothermal research and development. This report describes geothermal development activities Close

• 49. [Image] Advanced Design and Economic Considerations for Commercial Geothermal Power Plants at Heber and Niland, California. Final Report

  	Two separate studies, involving advanced design and economic considerations for commercial geothermal power plants using liquid-dominated hydrothermal resources, are presented. In the first study, the ...
  	Citation × Citation Citation Abstract Copy Title: Advanced Design and Economic Considerations for Commercial Geothermal Power Plants at Heber and Niland, California. Final Report Author: Bechtel Corporation Year: 1977 Two separate studies, involving advanced design and economic considerations for commercial geothermal power plants using liquid-dominated hydrothermal resources, are presented. In the first study, the effects on design, capital cost, and bus bar electric energy production cost caused by an anticipated decline in available geothermal fluid temperature over the lifetime of power plants are described. A two-stage, flashed-steam energy conversion process was used for the conceptual design of the power plants, which operate from the moderate-temperature, low-salinity reservoir at Heber, California. Plants with net capacities of 50, 100, and 200 MWe (net) were investigated. The results show that it is important to include provision for geothermal fluid temperature decline in the design of power plants to prevent loss of electric energy production capability and to reduce bus bar electric energy costs. In the second study, the technical, economic, and environmental effects of adding regeneration to a 50 MWe (net) power plant employing the multistage-flash/binary process are described. Regeneration is potentially attractive because it recovers waste heat from the turbine exhaust and uses it in the power cycle. However, the pressure drop caused by the introduction of the regenerator decreases the turbine expansion and thus decreases system performance. An innovative approach was taken in the design of the regenerator, which minimized the expected performance degradation of the turbine. The result was that the performance, capital cost, and bus bar electric energy production cost are nearly the same for the processes with and without regeneration. On the other hand, the addition of regeneration has the environmental benefits of substantially reducing heat rejection to the atmosphere and cooling tower makeup and blowdown water requirements. It also increases the temperature of the brine returned to the field for reinjection Title: Advanced Design and Economic Considerations for Commercial Geothermal Power Plants at Heber and Niland, California. Final Report Author: Bechtel Corporation Year: 1977 Two separate studies, involving advanced design and economic considerations for commercial geothermal power plants using liquid-dominated hydrothermal resources, are presented. In the first study, the effects on design, capital cost, and bus bar electric energy production cost caused by an anticipated decline in available geothermal fluid temperature over the lifetime of power plants are described. A two-stage, flashed-steam energy conversion process was used for the conceptual design of the power plants, which operate from the moderate-temperature, low-salinity reservoir at Heber, California. Plants with net capacities of 50, 100, and 200 MWe (net) were investigated. The results show that it is important to include provision for geothermal fluid temperature decline in the design of power plants to prevent loss of electric energy production capability and to reduce bus bar electric energy costs. In the second study, the technical, economic, and environmental effects of adding regeneration to a 50 MWe (net) power plant employing the multistage-flash/binary process are described. Regeneration is potentially attractive because it recovers waste heat from the turbine exhaust and uses it in the power cycle. However, the pressure drop caused by the introduction of the regenerator decreases the turbine expansion and thus decreases system performance. An innovative approach was taken in the design of the regenerator, which minimized the expected performance degradation of the turbine. The result was that the performance, capital cost, and bus bar electric energy production cost are nearly the same for the processes with and without regeneration. On the other hand, the addition of regeneration has the environmental benefits of substantially reducing heat rejection to the atmosphere and cooling tower makeup and blowdown water requirements. It also increases the temperature of the brine returned to the field for reinjection Close