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1

Geothermal systems  

NASA Technical Reports Server (NTRS)

Several tasks of JPL related to geothermal energy are discussed. The major task is the procurement and test and evaluation of a helical screw drive (wellhead unit). A general review of geothermal energy systems is given. The presentation focuses attention on geothermal reservoirs in California, with graphs and charts to support the discussion. Included are discussions on cost analysis, systems maintenance, and a comparison of geothermal and conventional heating and cooling systems.

Mohl, C.

1978-01-01

2

Calc-silicate mineralization in active geothermal systems  

SciTech Connect

The detailed study of calc-silicate mineral zones and coexisting phase relations in the Cerro Prieto geothermal system were used as examples for thermodynamic evaluation of phase relations among minerals of variable composition and to calculate the chemical characteristics of hydrothermal solutions compatible with the observed calc-silicate assemblages. In general there is a close correlation between calculated and observed fluid compositions. Calculated fugacities of O{sub 2} at about 320{degrees}C in the Cerro Prieto geothermal system are about five orders of magnitude less than that at the nearby Salton Sea geothermal system. This observation is consistent with the occurrence of Fe{sup 3+} rich epidotes in the latter system and the presence of prehnite at Cerro Prieto.

Bird, D.K.; Schiffman, P.; Elders, W.A.; Williams, A.E.; McDowell, S.D.

1983-01-01

3

Geothermal materials development activities  

SciTech Connect

This ongoing R&D program is a part of the Core Research Category of the Department of Energy/Geothermal Division initiative to accelerate the utilization of geothermal resources. High risk materials problems that if successfully solved will result in significant reductions in well drilling, fluid transport and energy conversion costs, are emphasized. The project has already developed several advanced materials systems that are being used by the geothermal industry and by Northeastern Electric, Gas and Steam Utilities. Specific topics currently being addressed include lightweight C0{sub 2}-resistant well cements, thermally conductive scale and corrosion resistant liner systems, chemical systems for lost circulation control, elastomer-metal bonding systems, and corrosion mitigation at the Geysers. Efforts to enhance the transfer of the technologies developed in these activities to other sectors of the economy are also underway.

Kukacka, L.E.

1993-06-01

4

Modeling the thermal evolution of an active geothermal system  

NASA Astrophysics Data System (ADS)

Temperature inversions at shallow to moderate depths have been observed commonly in boreholes drilled in geothermal areas. The inversions result from thermal disequilibria generated by steam and/or hydrothermal fluids invading shallow horizontal, or sub-horizontal fractures, or permeable horizons, from a deep vertical, or sub-vertical feeder-fracture. Subsurface distribution of temperatures in Momotombo geothermal area of Nicaragua, Central America, indicates that the anomaly is generated by steam and water, convecting in a narrow feeder-fracture-zone located at the western edge of the field. The north-trending zone of the feeder-fracture is bound on the west by the area of massive, impermeable andesitic rocks, and is capped by an impermeable, approximately 300 m. thick silica-cap, which seals if from the ground surface. The thermal fluids penetrate a system of horizontal, or sub-horizontal fractures, extending east of the feeder-fracture beneath the silica cap. The flow of thermal fluids eastward through the system of the horizontal, or sub-horizontal fractures is generating a plume-like geothermal anomaly, which is expressed by the temperature inversion zone pervasive in the boreholes to the east of the feeder-fracture. A time-dependant model for a semi-infinite half-space (z > 0) in contact with a hot, well stirred, isotropic fluid flowing through an aquifer overlain by a finite space of constant thickness is solved for the data collected from the Momotombo geothermal boreholes. Curve fitting between the simulated and observed temperature/depth profiles suggests that the thermo-tectonic events which caused the present-day Momotombo hydrothermal system occurred approximately 5,500 years ago, following development of vertical, or subvertical fractures along a N5E trending faultline. Hot fluids emerging from these fractures move eastward through a system of horizontal, or sub-horizontal fractures, with a velocity of 11 to 20 m/yr.

Eckstein, Y.; Maurath, G.; Ferry, R. A.

1985-12-01

5

Geothermal mineral extraction system  

Microsoft Academic Search

A system is described for recovering geothermal brines comprising in combination: a geothermal well having a first end adjacent the surface and a second end disposed within a wet geothermal aquifer containing hot saline geothermal brine; brine eductor means disposed at said second end comprising a venturi having a first inlet receiving a high velocity flow of dilute saline carrier

Meckler

1980-01-01

6

National Geothermal Data System  

NASA Astrophysics Data System (ADS)

The goal of the U.S. Department of Energy's National Geothermal Data System is to design, build, implement, deploy and populate a national, sustainable, distributed, interoperable network of data and service (application) providers. These providers will develop, collect, serve, and maintain geothermal-relevant data that operates as an integral component of NGDS. As a result the geothermal industry, the public, and policy makers will have access to consistent and reliable data, which in turn, reduces the amount of staff time devoted to finding, retrieving, integrating, and verifying information. With easier access to information, the high cost and risk of geothermal power projects (especially exploration drilling) is reduced. Five separate NGDS projects provide the data support, acquisition, and access to cyber infrastructure necessary to reduce cost and risk of the nation's geothermal energy strategy and US DOE program goals focused on the production and utilization of geothermal energy. The U.S DOE Office of Energy Efficiency and Renewable Energy Geothermal Technologies Program is developing the knowledge and data foundation necessary for discovery and development of large-scale energy production while the Buildings Technology Program is focused on other practical applications such as direct use and residential/commercial ground source heat pumps. The NGDS provides expanded reference and resource data for research and development activities (a subset of the US DOE goals) and includes data from across all fifty states and the nation's leading academic geothermal centers. Thus, the project incorporates not only high-temperature potential but also moderate and low-temperature locations incorporating US DOE's goal of adding more geothermal electricity to the grid. The program, through its development of data integration cyberinfrastructure, will help lead to innovative exploration technologies through increased data availability on geothermal energy capacity. Finally, the project will contribute new data from previously unexplored locations. NGDS is being built using the US Geoscience Information Network (US GIN) data integration framework to promote interoperability across the Earth sciences community and with other emerging data integration and networking efforts.

Anderson, A. F.; Cuyler, D.; Snyder, W. S.; Allison, M. L.; Blackwell, D. D.; Williams, C. F.

2011-12-01

7

Hydrothermal mineralogy and fluid inclusions chemistry to understand the roots of active geothermal systems  

NASA Astrophysics Data System (ADS)

An integrated study to link magmatic textures, magmatic mineral compositions, hydrothermal alteration zoning, hydrothermal mineral chemistry, and fluid inclusion compositions has been undertaken to link an intrusive complex and its degassing alteration halo with their surface equivalent in an active geothermal system. Ngatamariki geothermal system, New Zealand, presents a unique feature in the Taupo Volcanic Zone (TVZ). Drilling intercepted an intrusive complex with a high temperature alteration halo similarly to what is observed in magmatic-derived ore deposits. Thus it presents the perfect opportunity to study the magmatic-hydrothermal transition of the TVZ by characterizing the nature of the deep magmatic fluids link to the heat source of the world known geothermal fields. The record of magmatic-hydrothermal fluid-rock interactions preserved at Ngatamariki may be analogous of processes presently occurring at depth beneath TVZ geothermal systems. The intrusive complex consists of over 5 km3 of tonalite, diorite, basalt and aplitic dykes. Evidence of undercooling subsolidus magmatic textures such as myrmekite and skeletal overgrowth are commonly observed and often linked to volatile loss. The fluids released during the crystallization of the intrusive complex are interpreted to be at the origin of the surrounding high temperature alteration halo. Advanced argillic to potassic alteration and high temperature acidic assemblage is associated with high-temperature quartz veining at depth and vuggy silica at the paleo-surface. Major element compositions of the white micas associated with the high temperature halo show a transition from, muscovite to phengite, muscovitic illite away from the intrusion, with a transition to pyrophyllite and/ or topaz, and andalusite characteristic of more acidic conditions. Abundant high-density (up to 59 wt% NaCl eq and homogenization temperatures of 550 degree Celsius and above) coexist with low-density vapor fluid inclusions. This inferred heterogeneous entrapment represents the phase separation condition at the magmatic-hydrothermal conditions. Microthermometry measurements revealed the common presence of CO2, NaCl, KCl and CaCl2 species. Chemical compositions of the trapped fluids represent the closest equivalent of the magmatic fluids exsolving at depth feeding the deep roots of the geothermal fields. This study brings new constraints on the chemical conditions to model deep fluid-rock interactions in active geothermal systems.

Chambefort, I. S.; Dilles, J. H.; Heinrich, C.

2013-12-01

8

Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems  

PubMed Central

The composition of non-methane organic volatile compounds (VOCs) determined in 139 thermal gas discharges from 18 different geothermal and volcanic systems in Italy and Latin America, consists of C2C20 species pertaining to the alkanes, alkenes, aromatics and O-, S- and N-bearing classes of compounds. Thiophenes and mono-aromatics, especially the methylated species, are strongly enriched in fluids emissions related to hydrothermal systems. Addition of hydrogen sulphide to dienes and electrophilic methylation involving halogenated radicals may be invoked for the formation of these species. On the contrary, the formation of furans, with the only exception of C4H8O, seems to be favoured at oxidizing conditions and relatively high temperatures, although mechanisms similar to those hypothesized for the production of thiophenes can be suggested. Such thermodynamic features are typical of fluid reservoirs feeding high-temperature thermal discharges of volcanoes characterised by strong degassing activity, which are likely affected by conspicuous contribution from a magmatic source. The composition of heteroaromatics in fluids naturally discharged from active volcanoes and geothermal areas can then be considered largely dependent on the interplay between hydrothermal vs. magmatic contributions. This implies that they can be used as useful geochemical tools to be successfully applied in both volcanic monitoring and geothermal prospection. PMID:20480029

Tassi, Franco; Montegrossi, Giordano; Capecchiacci, Francesco; Vaselli, Orlando

2010-01-01

9

Cordon Caulle: an active volcanic-geothermal extensional system of Southern Andes of Chile  

NASA Astrophysics Data System (ADS)

Cordon Caulle (CC; 40.5 S) is an active volcanic-geothermal system of the Southern Volcanic Zone (SVZ; 37-44S). Morphologically, the CC system is a 6 km x 13 km volcanic plateau bordered by NW-trending structures, limited by Puyehue Volcano to the SE and by Caldera Nevada Caldera to the NW. While the SVZ is dominantly basaltic, CC is unique in that it has produced a wide compositional spectrum from basalt to rhyolite. The most recent volcanic activity of Puyehue-CC (last 70 ky) is dominantly silicic, including two historic fissure eruptions (1921-1922; 1960) and a recent central eruption from Puyehue Volcano (2011). Abnormally silicic volcanism was formerly attributed to a localized compression and long-term magma residence and differentiation, resulting from the NW orientation of underlying CC structures with respect to a NE-oriented ?1 (linked to regional strike-slip stress state). However, later studies, including examination of morpho-tectonic features; detailed structural analysis of the 1960 eruption (triggered by Mw 9.5 1960 Chilean Earthquake); InSAR deformation and gravity surveys, point to both historic and long-term extension at CC with ?hmax oriented NNW to NW. The pre-2011 (i.e. Puyehue Volcano eruption) geothermal features of CC included boiling hot springs and geysers (Caldera Nevada) and fumaroles (CC and Puyehue Volcano). Both water and gas chemistry surveys were undertaken to assess the source fluid composition and equilibrium temperature. The combination of water and gas geothermometers led to a conceptual model of a stratified geothermal reservoir, with shallow, low-chloride, steam-heated aquifers equilibrated at temperatures between 150-180C, overlying a deeper, possibly dominated reservoir with temperatures in excess of 280C. Gas chemistry also produced the highest He ratios of the SVZ, in agreement with a relatively pure, undiluted magmatic signature and heat source fueling the geothermal system. Other indicators such as N2/Ar ratios indicated two sources of gases: a geothermal source (i.e. associated with benign, neutral geothermal fluids) at the centre of the CC, and a more volcanic-magmatic (i.e. associated with acidic, oxidising fluids) source towards the SE (Puyehue Volcano), in agreement with the presence of an active volcanic system. The combination of silicic volcanism, extension and high-temperature geothermal activity of CC pose some resemblance to high-temperature geothermal systems of the Taupo Volcanic Zone, North Island, New Zealand. In this setting, recent studies show that rifting (i.e. extension) can be a magma-assisted process. In a similar fashion, I hypothesize that a deep (> 2 km), NW-elongate magma reservoir can account for the development of NW-trending structures at CC, and the existence of central volcanism at both ends of the CC.

Sepulveda, F.

2013-05-01

10

Geothermal mineral extraction system  

SciTech Connect

A system is described for recovering geothermal brines comprising in combination: a geothermal well having a first end adjacent the surface and a second end disposed within a wet geothermal aquifer containing hot saline geothermal brine; brine eductor means disposed at said second end comprising a venturi having a first inlet receiving a high velocity flow of dilute saline carrier solution, a nozzle inlet into which a flow of said geothermal brine is educted, mixing means receiving said flow of solution and flow of geothermal brine from sid inlets to form a recovery mixture having a saline content lower than that of said brine and an outlet communicating the mixture with the interior of said well; first conduit means within said well for delivering said high velocity flow of solution to said first inlet; and second means within said well for delivering said mixture from said outlet to the surface. A method of recovering geothermal brine from a geothermal aquifer comprising the steps of: establishing a high velocity flow of a carrier solution having a lower salt concentration than the brine from the surface into a geothermal well having a lower end disposed within the aquifer; flowing the solution through the well through a venturi having a nozzle communicating with the aquifer so that brine is educted from the aquifer into the solution to form a recovery mixture; and delivering the mixture through the well to the surface.

Meckler, M.

1980-07-08

11

Geothermal heat recovery system  

Microsoft Academic Search

A system for recovering heat from a geothermal well includes a quantity of heavy drilling mud filling the bottom of the geothermal well. A hollow heat absorber is disposed within the drilling mud in the well bottom. The heat absorber is supplied with a working fluid such as freon through a supply pipe extending from the top of the well,

W. F. Ash; F. R. Ash

1978-01-01

12

Isotopic constraints on ice age fluids in active geothermal systems: Reykjanes, Iceland  

Microsoft Academic Search

The Reykjanes geothermal system is located on the landward extension of the Mid-Atlantic Ridge in southwest Iceland, and provides an on-land proxy to high-temperature hydrothermal systems of oceanic spreading centers. Previous studies of elemental composition and salinity have shown that Reykjanes geothermal fluids are likely hydrothermally modified seawater. However, ?D values of these fluids are as low as ?23, which

Emily C. Pope; Dennis K. Bird; Stefn Arnrsson; Thrinn Fridriksson; Wilfred A. Elders; Gudmundur . Fridleifsson

2009-01-01

13

Geothermal activities in Central America  

Microsoft Academic Search

The Agency for International Development is funding a new program in energy and minerals for Central America. Geothermal energy is an important component. A country-wide geothermal assessment has started in Honduras, and other assessment activities are in progress or planned for Costa Rica, El Salvador, Guatemala, and Panama. Instrumentation for well logging has been provided to Costa Rica, and a

J. T. Whetten; R. J. Hanold

1985-01-01

14

Heat transfer in geothermal systems  

Microsoft Academic Search

Theoretical and experimental investigations of convective heat transfer in geothermal systems are reviewed. The governing equations for such heat transfer in geothermal systems are examined, along with heat transfer in hot-water, water-steam two-phase, and geopressured geothermal systems. Lumped-parameter analyses for predicting averaged reservoir characteristics during production are considered, heat transfer in other geothermal systems (e.g., dry hot rock and magma)

P. Cheng

1978-01-01

15

The Iceland Deep Drilling Project (IDDP): (II) Isotopic Constraints on Ice Age Hydrothermal Fluids in Active High-Temperature Geothermal Systems  

Microsoft Academic Search

The Krafla, Hengill and Reykjanes geothermal systems, located along the active rift-zone of Iceland, are three sites that will be drilled to 4-5 km depth by the Iceland Deep Drilling Project (IDDP). We use oxygen and hydrogen stable isotopes in hydrothermal minerals to characterize the source, composition and evolution of hydrothermal fluids in the IDDP geothermal systems. This research is

E. C. Pope; D. K. Bird; S. Arnrsson; T. Fridriksson; W. A. Elders; G. . Fridleifsson

2008-01-01

16

Geothermal instrumentation development activities at Sandia  

SciTech Connect

A major element of Sandia's Geothermal Technology Development Program is the effort directed toward development of instrumentation. This effort has two aspects, the development of high temperature components and prototype tools and the investigation of new concepts and capabilities. The focus of these activities is the acquisition of information to make geothermal drilling and resource development more efficient. Several projects of varying nature and scope make up the instrumentation development element, and this element will expand as the program emphasis on development of an advanced geothermal drilling system and the need for improved information grow. 13 refs.

Carson, C.C.

1985-03-01

17

Geothermal Systems for School.  

ERIC Educational Resources Information Center

Describes an award-winning school heating and cooling system in which two energy-efficient technologies, variable-flow pumping and geothermal heat pumps, were combined. The basic system schematic and annual energy use and cost savings statistics are provided. (GR)

Dinse, David H.

1998-01-01

18

Isotopic constraints on ice age fluids in active geothermal systems: Reykjanes, Iceland  

NASA Astrophysics Data System (ADS)

The Reykjanes geothermal system is located on the landward extension of the Mid-Atlantic Ridge in southwest Iceland, and provides an on-land proxy to high-temperature hydrothermal systems of oceanic spreading centers. Previous studies of elemental composition and salinity have shown that Reykjanes geothermal fluids are likely hydrothermally modified seawater. However, ?D values of these fluids are as low as -23, which is indicative of a meteoric water component. Here we constrain the origin of Reykjanes hydrothermal solutions by analysis of hydrogen and oxygen isotope compositions of hydrothermal epidote from geothermal drillholes at depths between 1 and 3 km. ?DEPIDOTE values from wells RN-8, -9, -10 and -17 collectively range from -60 to -78, and ?18OEPIDOTE in these wells are between -3.0 and 2.3. The ?D values of epidote generally increase along a NE trend through the geothermal field, whereas ?18O values generally decrease, suggesting a southwest to northeast migration of the geothermal upflow zone with time that is consistent with present-day temperatures and observed hydrothermal mineral zones. For comparative analysis, the meteoric-water dominated Nesjavellir and Krafla geothermal systems, which have a ?DFLUID of -79 and -89, respectively, show ?DEPIDOTE values of -115 and -125. In contrast, ?DEPIDOTE from the mixed meteoric-seawater Svartsengi geothermal system is -68; comparable to ?DEPIDOTE from well RN-10 at Reykjanes. Stable isotope compositions of geothermal fluids in isotopic equilibrium with the epidotes at Reykjanes are computed using published temperature dependent hydrogen and oxygen isotope fractionation curves for epidote-water, measured isotope composition of the epidotes and temperatures approximated from the boiling point curve with depth. Calculated ?D and ?18O of geothermal fluids are less than 0, suggesting that fluids of meteoric or glacial origin are a significant component of the geothermal solutions. Additionally, ?DFLUID values in equilibrium with geothermal epidote are lower than those of modern-day fluids, whereas calculated ?18OFLUID values are within range of the observed fluid isotope composition. We propose that modern ?DEPIDOTE and ?DFLUID values are the result of diffusional exchange between hydrous alteration minerals that precipitated from glacially-derived fluids early in the evolution of the Reykjanes system and modern seawater-derived geothermal fluids. A simplified model of isotope exchange in the Reykjanes geothermal system, in which the average starting ?DROCK value is -125 and the water to rock mass ratio is 0.25, predicts a ?DFLUID composition within 1 of average measured values. This model resolves the discrepancy between fluid salinity and isotope composition of Reykjanes geothermal fluids, explains the observed disequilibrium between modern fluids and hydrothermal epidote, and suggests that rock-fluid interaction is the dominant control over the evolution of fluid isotope composition in the hydrothermal system.

Pope, Emily C.; Bird, Dennis K.; Arnrsson, Stefn; Fridriksson, Thrinn; Elders, Wilfred A.; Fridleifsson, Gudmundur .

2009-08-01

19

Fluid inclusion gas compositions from an active magmatichydrothermal system: a case study of The Geysers geothermal field, USA  

Microsoft Academic Search

Hydrothermal alteration and the active vapor-dominated geothermal system at The Geysers, CA are related to a composite hypabyssal granitic pluton emplaced beneath the field 1.1 to 1.2 million years ago. Deep drill holes provide a complete transect across the thermal system and samples of the modern-day steam. The hydrothermal system was liquid-dominated prior to formation of the modern vapor-dominated regime

Joseph N Moore; David I Norman; B. Mack Kennedy

2001-01-01

20

Geothermal heating systems for greenhouses  

Microsoft Academic Search

Ways to utilize low-temperature geothermally heated water for a flow-through system are presented. The geothermal energy used for this system is the waste heat discharged from space heating 500,000 square feet of floor space at Oregon Institute of Technology with geothermal water pumped directly from the campus wells. The information collected and analyzed is from data developed from operating a

J. F. Silva; W. C. Johnson

1980-01-01

21

Selling Geothermal Systems The "Average" Contractor  

E-print Network

Selling Geothermal Systems #12;The "Average" Contractor · History of sales procedures · Manufacturer Driven Procedures · What makes geothermal technology any harder to sell? #12;"It's difficult to sell a geothermal system." · It should

22

National Geothermal Data System (NGDS)  

DOE Data Explorer

The National Geothermal Data System (NGDS) is a DOE-funded distributed network of databases and data sites. Much of the risk of geothermal energy development is associated with exploring for, confirming and characterizing the available geothermal resources. The overriding purpose of the NGDS is to help mitigate this up-front risk by serving as a central gateway for geothermal and relevant related data as well as a link to distributed data sources. Assessing and categorizing the nation's geothermal resources and consolidating all geothermal data through a publicly accessible data system will support research, stimulate public interest, promote market acceptance and investment, and, in turn, the growth of the geothermal industry. Major participants in the NGDS to date include universities, laboratories, the Arizona Geological Survey and Association of American State Geologists (Arizona Geological Survey, lead), the Geothermal Resources Council, and the U.S. Geological Survey. The Geothermal Energy Association is collaborating with the NGDS to insure that it meets the needs of the geothermal industry.

23

Geothermal heating systems for greenhouses  

SciTech Connect

Ways to utilize low-temperature geothermally heated water for a flow-through system are presented. The geothermal energy used for this system is the waste heat discharged from space heating 500,000 square feet of floor space at Oregon Institute of Technology with geothermal water pumped directly from the campus wells. The information collected and analyzed is from data developed from operating a greenhouse on the Oregon Institute of Technology campus from December 1979 to April 1980. Methods for calculating heating requirements of greenhouses using geothermal energy were developed from the analyses of the data obtained. (MHR)

Silva, J.F.; Johnson, W.C.

1980-08-12

24

Induced Microseismic Activity in non Pressure Stimulated Geothermal System - an Example From Southern Germany  

NASA Astrophysics Data System (ADS)

In order to be efficient in selling heat and electric power, the most favorable locations for deep geothermal power plants are in close proximity to urbanized areas. This advantage bears the inherent danger of induced earthquakes especially during the stimulation and production phase of enhanced geothermal systems, which at least are partially felt in the near surroundings. Felt earthquakes, however, severely reduce the level of acceptance of residents close to the plant. The Bavarian Molasse basin is characterized by its highly permeable, deep groundwater bearing limestone layers. This high permeability permits the abdication of pressure stimulation of the geothermal reservoir and makes the close proximity to the densely populated area around Munich possible. In addition to this favorable production conditions, the Bavarian Molasse Basin is being considered as generally aseismic. In contrast to this obvious advantages five Ml > 2.0 events south of Munich which were felt by local residents attracted public attention. These events were located in the vicinity of a geothermal plant that took up production about half a year earlier. In the last two years a temporary network was set up that recorded more than 80 events with magnitudes mainly ranging from Ml -0.5 to 1.5. Events below magnitude 1.5 could not be detected and located prior to the production stage of the geothermal plant in the main network of the local earthquake service Erdbebendienst Bayern. Still, the exact mechanism leading to the seismicity remains unknown. Most likely the orientation of pre-existing faults, which are pierced by the open-hole part of wells with respect to present stress field and the volume of re-injected cold water play a key role in understanding the mechanisms leading to the observed seismicity. Within the framework of a project financed by the German federal ministry of Environment, further field experiments are conducted to address these open questions and test some working hypotheses. At two geothermal projects in comparable settings pre-production data is acquired in local seismometer networks to facilitate a comparison of possible microseismicity during production stages with natural background microseismicity.

Wassermann, J. M.; Megies, T.

2011-12-01

25

Earthquake Swarm Activity Beneath the Tokaanu-Waihi Geothermal System, Lake Taupo, New Zealand  

SciTech Connect

The hypocenters of 4 earthquake swarms (total of 54 events), recorded with a local network between 1986 April and 1987 January, occur within upper crustal rocks of the deeper Tokaanu-Waihi geothermal reservoir; all the events had a magnitude M{sub L} {le} 3.2. Most foci are aligned along two NW-trending basement fault structures along which young rhyodacitic extrusions can be found. The swarm activity has been interpreted in terms of injections into basement fractures of magma from deeper chambers (dyke injection swarm activity).

Hochstein, M.P.; Sherburn, S.; Tikku, J.

1995-01-01

26

Geothermal activities in Central America  

SciTech Connect

The Agency for International Development is funding a new program in energy and minerals for Central America. Geothermal energy is an important component. A country-wide geothermal assessment has started in Honduras, and other assessment activities are in progress or planned for Costa Rica, El Salvador, Guatemala, and Panama. Instrumentation for well logging has been provided to Costa Rica, and a self-contained logging truck will be made available for use throughout Central America. An important objective of this program is to involve the private sector in resource development. 4 refs., 3 figs.

Whetten, J.T.; Hanold, R.J.

1985-09-11

27

The role of active and ancient geothermal systems in evolution of Grant Canyon oil field, Railroad Valley, Nye County, Nevada  

SciTech Connect

Since discovery in 1983, the Grant Canyon field has been among the most prolific oil producers (on a per-well basis) in the US. Production through June 1990 was 12,935,630 bbl of oil, principally from two wells which in tandem have consistently yielded more than 6,000 bbl of oil per day. The field is hosted by highly porous Devonian dolomite breccia loosely cemented with hydrothermal quartz. Results of fluid-inclusion and petrographic research in progress at Grant Canyon suggest that paleogeothermal and perhaps currently circulating geothermal systems may have played a major role in oil-reservoir evolution. For example, as previously reported, the breccia-cementing quartz hosts primary aqueous, aqueous/oil, and oil fluid inclusions which were trapped at about 120C (average homogenization temperature) and document initial oil migration and entrapment as droplets or globules dispersed in dilute (< 2.2 wt.% equivalent NaCl) aqueous solutions. Additional evidence of geothermal connection is that the horst-block trap at Grant Canyon is top and side sealed by valley-fill clastic and volcanic rocks which are locally hydrothermally altered and calcite flooded. These secondary seals are enhanced by disseminated, solid asphaltic residues locally accounting for 23% (volume) of the rock. Current reservoir temperatures at Grant Canyon (120C) and the adjacent Bacon Flat field (171C) attest to vigorous contemporary geothermal activity. Based on results of the authors' Grant Canyon work to date, they suggest that active and paleohydrothermal systems could be viable petroleum exploration targets in otherwise favorable terrain elsewhere in the Basin and Range.

Hulen, J.B. (Univ. of Utah Research Inst., Salt Lake City (United States)); Bereskin, S.R. (Terra Tek, Inc., Salt Lake City, UT (United States)); Bortz, L.C.

1991-06-01

28

Geothermal reservoirs in hydrothermal convection systems  

SciTech Connect

Geothermal reservoirs commonly exist in hydrothermal convection systems involving fluid circulation downward in areas of recharge and upwards in areas of discharge. Because such reservoirs are not isolated from their surroundings, the nature of thermal and hydrologic connections with the rest of the system may have significant effects on the natural state of the reservoir and on its response to development. Conditions observed at numerous developed and undeveloped geothermal fields are discussed with respect to a basic model of the discharge portion of an active hydrothermal convection system. Effects of reservoir development on surficial discharge of thermal fluid are also delineated.

Sorey, M.L.

1982-01-01

29

Geothermal systems on the island of Java, Indonesia  

NASA Astrophysics Data System (ADS)

This paper presents an overview of all known geothermal systems on the island of Java by presenting physicochemical data for associated hot springs, cold springs and acid crater lakes. A total of 69 locations were sampled and classified based on their position in either a volcanic complex (volcano-hosted) or a fault zone (fault-hosted). In particular the potential of a magmatic heat source for fault-hosted geothermal systems was investigated. Volcano-hosted geothermal systems had higher HCO3- concentrations and higher Mg/Na ratios than fault-hosted geothermal systems. This geochemical difference is likely due to degassing and subsequent CO2-water reaction in the volcano-hosted systems, which is absent in the fault-hosted geothermal systems. The HCO3 vs. Cl and Mg/Na vs. SO4/Cl systematics indicated that fault-hosted geothermal systems located in the active Quaternary volcanic belt received shallow magmatic fluids, hence should be classified as volcano-hosted geothermal systems. The heat source of fault-hosted geothermal systems located in the old (Tertiary) volcanic belt was investigated by a combination of Li enrichment and calculated reservoir temperatures. There a shallow magmatic heat source was indicated only for the Cilayu and Cisolok geothermal systems. Thus, a deep seated magma was considered to be the heat source for the fault-hosted geothermal systems of Cikundul, Pakenjeng, Parangtritis and Pacitan. In ten of the volcano-hosted geothermal systems, 2H and 18O isotope enrichments were found, but not in any of the fault-hosted geothermal systems. Stable isotope enrichment due to evaporation was recognized in the Kawah Candradimuka and Kawah Sileri, Kawah Hujan and Candi Gedong Songo geothermal systems. A combination of intensive evaporation and magmatic gases input produced very heavy stable isotopes in the hot acid crater lakes of the Kawah Kamojang, Kawah Sikidang and Kawah Putih geothermal systems. The addition of substantial amounts of andesitic water to the geothermal fluid was observed in the Candi Songgoriti, Banyuasin and Pablengan geothermal systems. Contrary to established belief fault-hosted geothermal systems on Java could be considered a potential source for geothermal energy.

Purnomo, Budi Joko; Pichler, Thomas

2014-09-01

30

Investigating Geothermal Activity, Volcanic Systems, and Deep Tectonic Tremor on Akutan Island, Alaska, with Array Seismology  

NASA Astrophysics Data System (ADS)

In addition to hosting one of the most active volcanoes in the Aleutian Arc, Akutan Island, Alaska, is the site of a significant geothermal resource within Hot Springs Bay Valley (HSBV). We deployed 15 broadband (30 s to 50 Hz) seismometers in and around HSBV during July 2012 as part of an effort to establish a baseline for background seismic activity in HSBV prior to geothermal production on the island. The stations recorded data on-site and were retrieved in early September 2012. Additional targets for the array include the tracking of deep tectonic tremor known to occur within the Aleutian subduction zone and the characterization of volcano-tectonic (VT) and deep long period (DLP) earthquakes from Akutan Volcano. Because 13 of the stations in the array sit within an area roughly 1.5 km by 1.5 km, we plan to apply methods based on stacking and beamforming to analyze the waveforms of extended signals lacking clear phase arrivals (e.g., tremor). The average spacing of the seismometers, roughly 350 m, provides sensitivity to frequencies between 2-8 Hz. The stacking process also increases the signal-to-noise ratio of small amplitude signals propagating across the array (e.g., naturally occurring geothermal seismicity). As of August 2012, several episodes of tectonic tremor have been detected in the vicinity of Akutan Island during the array deployment based on recordings from nearby permanent stations operated by the Alaska Volcano Observatory (AVO). This is the first small-aperture array deployed in the Aleutian Islands and the results should serve as a guide for future array deployments along the Aleutian Arc as part of the upcoming EarthScope and GeoPRISMS push into Alaska. We demonstrate the power of array methods based on stacking at Akutan Volcano using a sequence of DLP earthquakes from June 11, 2012 that were recorded on the permanent AVO stations. We locate and characterize the lowest frequency portion of the signals at 0.5 Hz. At these low frequencies, the traditional "sparse" local network at Akutan effectively becomes a small-aperture array relative to the wavelength. We exploit the coherency among the stations and locate the DLPs by using a novel stacking method. The crux of the method involves scanning over all possible source locations and relative polarity combinations between the local stations to find the one that maximizes the stacked power at a well-defined region in the subsurface. As a result, the method is applicable even in the presence of mixed polarities. We discover that two of the stations at Akutan have DLP waveforms with opposite polarities compared to the other stations. Accounting for this polarity variation gives a DLP source location at 10 km depth, to the west-southwest of the Akutan summit caldera. These results give clear evidence for non-isotropic radiation patterns associated with DLPs and show the promise of array methods based on waveform stacking for providing future insights into the origin of volcanic as well as geothermal and tectonic seismicity.

Haney, M. M.; Prejean, S. G.; Ghosh, A.; Power, J. A.; Thurber, C. H.

2012-12-01

31

Arsenic geochemistry in geothermal systems  

Microsoft Academic Search

Arsenic is an important trace constituent in geothermal fluids, ranging in concentration from less than 0.1 to nearly 50 ppm. An evaluation of published fluid analyses from geothermal systems indicates that the As content of the reservoir fluids varies inversely with P\\/sub HS\\/ and directly with temperature. Aqueous As species occur in two oxidation states, As\\/sup III\\/ and As\\/sup V\\/.

J. M. Ballantyne; J. N. Moore

1988-01-01

32

Geothermal systems of the Cascade Range  

USGS Publications Warehouse

In the central and southern Cascade Range, plate convergence is oblique, and Quaternary volcanism produces mostly basalt and mafic andesite; large andesite-dacite composite volcanoes and silicic dome fields occur in restricted areas of long-lived igneous activity. To the north, plate convergence is normal, producing widely spaced centers in which mafic lavas are minor. Most Cascade volcanoes are short-lived and unlikely to be underlain at shallow levels by large magma bodies that could support high-temperature geothermal systems. Such systems are known, however, near Meager Mountain, at Newberry Volcano, and near Lassen Peak. Persistent fumaroles occur on several major composite volcanoes, but drilling to date has been insufficient to determine whether exploitable geothermal reservoirs occur at depth. Thermal springs away from the major volcanic centers are few and generally inconspicuous. However, significant geothermal systems along and west of the Cascade Range may well be masked by abundant cold ground water.

Muffler, L.J.; Bacon, Charles R.; Duffield, W.A.

1982-01-01

33

Lassen geothermal system  

SciTech Connect

The Lassen geothermal system consists of a central vapor-dominated reservoir underlain by hot water that discharges peripherally at lower elevations. The major thermal upflow at Bumpass Hell (elevation 2500 m) displays numerour superheated fumaroles, one of which in 1976 was 159/sup 0/C. Gas geothermometers from the fumarole areas and water geothermometers from boiling Cl-bearing waters at Morgan Hot Springs (elevation 1530 m; 8 km south of Bumpass Hell) and from 176/sup 0/C waters in a well 12 km southeast of Bumpass Hell both indicate 230 to 240/sup 0/C for the deep thermal water. With increasing distance from Bumpass Hell, gases are progressively depleted in H/sub 2/S relative to CO/sub 2/ and N/sub 2/, owing to oxidation of H/sub 2/S to pyrite, sulfur, and sulfates and to dilution with atmospheric N/sub 2/. H/sub 2/O/gas ratios and degree of superheat of fumaroles can be explained by mixing of steam of maximum enthalpy (2804 J g/sup -1/) with near-surface water and with the condensate layer overlying the vapor-dominated reservoir.

Muffler, L.J.P.; Nehring, N.L.; Truesdell, A.H.; Janik, C.J.; Clynne, M.A.; Thompson, J.M.

1982-01-01

34

Evolution of an active magmatic-geothermal system at The Geysers, California  

NASA Astrophysics Data System (ADS)

The Geysers geothermal system initially developed at 1.1 to 1.2 Ma in response to the intrusion of a hypabyssal granitic pluton exceeding 100 km2 in area. The geothermal system, which is developed in Mesozoic metagraywacke and the underlying granite, is currently vapor-dominated and produces only dry steam. Mineralogic, fluid inclusion and isotopic data demonstrate the current vapor-dominated regime evolved from a liquid-dominated system. Within 600 m of the pluton, the rocks were altered to a biotite hornfels that is cut by veins of tourmaline + biotite + actinolite + clinopyroxene + albitic plagioclase. Fluid inclusions trapped in the vein minerals record maximum homogenization temperatures near 380C and salinities up to 44 wt% NaCl equivalent. With increasing distance from the pluton, the veins are characterized by actinolite + epidote, epidote + chlorite, and finally calcite. Quartz and adularia are commonly observed in these veins. Fluid inclusions trapped at a distance of 1750 m from the intrusion record temperatures up to 305C and salinities of 5 wt% NaCl equivalent. Whole-rock oxygen isotope data indicates the metagraywacke and granitic reservoir rocks were isotopically exchanged with meteoric water during the liquid dominated phase of the system. The transition from liquid- to vapor-dominated conditions occurred at 0.25 to 0.28 Ma, based on 40Ar/39Ar spectrum dating of adularia. As the liquids boiled off, bladed calcite, chalcedony, quartz and adularia were deposited. Vapor-rich inclusions dominate the fluid inclusion populations of many samples. Low salinity liquid-rich fluid inclusions (0.0 - 0.4 wt% NaCl equivalent), interpreted to consist primarily of steam condensate, suggest that widespread boiling and vapor-dominated convection cells had formed in the upper part of the present-day reservoir by the time temperatures had dropped to approximately 250 - 265C. Subsequent inflow of relatively cool marginal meteoric waters resulted in the deposition of calcite and the formation of low permeability seals around the reservoir. The present vapor-dominated system at The Geysers consists of two distinct, hydraulically connected steam reservoirs. The upper, normal vapor-dominated reservoir is found throughout the field. Temperatures within this reservoir are isothermal and close to 240C. The lower high temperature reservoir occurs within the biotite hornfels in the northern half of the field. Measured temperatures follow a conductive gradient and range from about 240C to 400C. Pressures are vaporstatic in both reservoirs. The high temperature reservoir in the Northwest Geysers is the youngest part of the system. Here newly formed biotite hornfels is being heated by a recent magmatic intrusion interpreted to have been emplaced between 5,000 and 10,000 y bp. This portion of the deep Northwest reservoir is characterized by low permeabilities and the highest measured temperatures and 3He/4He ratios (~7-9.6Ra) encountered in the field. In contrast to other parts of the system, the biotite hornfels in the Northwest Geysers has not been isotopically exchanged with meteoric water.

Moore, J. N.; Walters, M.

2012-12-01

35

The nature of magmatism at Palinpinon geothermal field, Negros Island, Philippines: implications for geothermal activity and regional tectonics  

Microsoft Academic Search

The Palinpinon geothermal field, Negros Island, Philippines is a high-temperature, liquid-dominated geothermal system in an active island-arc volcanic setting. This paper presents a regional context for the Palinpinon geology, discusses the petrogenetic evolution of magmatism in the district and assesses the genetic relationships between intrusion and geothermal circulation. The oldest rock formation, the Lower Puhagan Volcanic Formation (Middle Miocene), is

Andrew J Rae; David R Cooke; David Phillips; Maribel Zaide-Delfin

2004-01-01

36

The Iceland Deep Drilling Project (IDDP): (II) Isotopic Constraints on Ice Age Hydrothermal Fluids in Active High-Temperature Geothermal Systems  

NASA Astrophysics Data System (ADS)

The Krafla, Hengill and Reykjanes geothermal systems, located along the active rift-zone of Iceland, are three sites that will be drilled to 4-5 km depth by the Iceland Deep Drilling Project (IDDP). We use oxygen and hydrogen stable isotopes in hydrothermal minerals to characterize the source, composition and evolution of hydrothermal fluids in the IDDP geothermal systems. This research is essential to effectively characterizing geochemical and hydrologic processes occurring at depth within these regions, especially in the high latitudes of Iceland, where periods of glaciation can have long lasting impacts on geothermal environments. Recent studies of the stable isotope composition of hydrothermal epidote in the Reykjanes geothermal system indicate a complex history of fluid source and fluid-rock interaction since at least the Pleistocene. The chlorine concentration of modern Reykjanes geothermal fluids indicate that they are hydrothermally modified seawater. However, measured hydrogen isotope values of these fluids are as low as -23. ?D values of hydrothermal epidote analyzed from four wells in Reykjanes range from -60 to - 78. These values are not in isotopic equilibrium with present day geothermal fluids, and retain an isotopic signature of a glacially-dominated fluid source early in the evolution of the geothermal system. If the Reykjanes system was initially sub-glacial, the depth of boiling in the basalt would have been more shallow due to the overburden of a thick insulating ice sheet. This may explain the presence of epidote and garnet mineralization at levels as shallow as 500 m in some wells. Additionally, estimates of the water-rock ratio and modal abundance of hydrous alteration minerals in the system suggest that there is enough relict (Ice Age) hydrogen in hydrothermally altered basalt to diffusionally exchange with modern geothermal fluids and lower the fluid hydrogen isotope composition by as much as 20. This study shows that hydrogen isotopes of geothermal waters cannot be used independently to trace the origin of these fluids. The age of the geothermal system and the extent of alteration through water-rock interaction are also critical in determining the fluid source and isotope composition. In previous studies of the Krafla geothermal system, fluids had an average ?D value of -89, which closely reflect isotope values of local precipitation. However, geothermal fluids of the Nesjavellir system (near Hengill) are ~ -79, 10-20 lower than local meteoric water. Structural and hydrologic interpretations of the region make it unlikely that this difference is due to fluid flow from the nearby Langjkull ice sheet. Preliminary analyses of hydrothermal epidote in these systems (~ -125 in Krafla and -115 in Nesjavellir) suggest that they are in isotopic equilibrium with the hydrothermal fluids. Further analyses of mineral-mineral and mineral-fluid fractionation will help determine the relative input of nearby and distal modern meteoric fluids as well as the potential for relict glacially-derived fluids as a source for the observed values in both systems.

Pope, E. C.; Bird, D. K.; Arnrsson, S.; Fridriksson, T.; Elders, W. A.; Fridleifsson, G. .

2008-12-01

37

Boise geothermal district heating system  

SciTech Connect

This document describes the Boise geothermal district heating project from preliminary feasibility studies completed in 1979 to a fully operational system by 1983. The report includes information about the two local governments that participated in the project - the City of Boise, Idaho and the Boise Warm Springs Water District. It also discusses the federal funding sources; the financial studies; the feasibility studies conducted; the general system planning and design; design of detailed system components; the legal issues involved in production; geological analysis of the resource area; distribution and disposal; the program to market system services; and the methods of retrofitting buildings to use geothermal hot water for space heating. Technically this report describes the Boise City district heating system based on 170/sup 0/F water, a 4000 gpm production system, a 41,000 foot pipeline system, and system economies. Comparable data are also provided for the Boise Warm Springs Water District. 62 figs., 31 tabs.

Hanson, P.J.

1985-10-01

38

Prediction of Scaling in Geothermal Systems  

Microsoft Academic Search

One of the main objectives of the DOE Geothermal Program is to improve the efficiency and reliability of geothermal operations so that this renewable form of energy can be integrated into the nation's energy system. Scale formation and other chemical problems associated with energy extraction from high temperature brines frequently inhibit the economical utilization of geothermal resources. In some cases,

John H. Weare; Nancy E. Moller

1989-01-01

39

NATIONAL GEOTHERMAL DATA SYSTEM (NGDS) GEOTHERMAL DATA DOMAIN: ASSESSMENT OF GEOTHERMAL COMMUNITY DATA NEEDS  

SciTech Connect

To satisfy the critical need for geothermal data to ad- vance geothermal energy as a viable renewable ener- gy contender, the U.S. Department of Energy is in- vesting in the development of the National Geother- mal Data System (NGDS). This paper outlines efforts among geothermal data providers nationwide to sup- ply cutting edge geo-informatics. NGDS geothermal data acquisition, delivery, and methodology are dis- cussed. In particular, this paper addresses the various types of data required to effectively assess geother- mal energy potential and why simple links to existing data are insufficient. To create a platform for ready access by all geothermal stakeholders, the NGDS in- cludes a work plan that addresses data assets and re- sources of interest to users, a survey of data provid- ers, data content models, and how data will be ex- changed and promoted, as well as lessons learned within the geothermal community.

Anderson, Arlene [United States Department of Energy; Blackwell, David [Southern Methodist University; Chickering, Cathy [Southern Methodist University; Boyd, Toni [Oregon Institute of Technology; Horne, Roland [Stanford University; MacKenzie, Matthew [Uberity Technology Corporation; Moore, Joseph [University of Utah; Nickull, Duane [Uberity Technology Corporation; Richard, Stephen [Arizona Geological survey; Shevenell, Lisa A. [University of Nevada, Reno

2013-01-01

40

Geothermal Data from the National Geothermal Data System (NGDS)  

DOE Data Explorer

The National Geothermal Data System (NGDS) is a distributed data system providing access to information resources related to geothermal energy from a network of data providers. Data are contributed by academic researchers, private industry, and state and federal agencies. Built on a scalable and open platform through the U.S. Geoscience Information Network (USGIN), NGDS respects data provenance while promoting shared resources.Since NGDS is built using a set of open protocols and standards, relying on the Open Geospatial Consortium (OGC) and International Organization for Standardization (ISO), members of the community may access the data in a variety of proprietary and open-source applications and software. In addition, developers can add functionality to the system by creating new applications based on the open protocols and standards of the NGDS. The NGDS, supported by the U.S. Department of Energys Geothermal Technology Program, is intended to provide access to all types of geothermal data to enable geothermal analysis and widespread public use in an effort to reduce the risk of geothermal energy development [copied from http://www.geothermaldata.org/page/about]. See the long list of data contributors at http://geothermaldata.org/page/data-types-and-contributors#data-contributors.

41

Enhanced Geothermal Systems in Switzerland  

E-print Network

The development of Enhanced Geothermal Systems (EGS) for the cogeneration of electricity and district heating is expected to be important in the future. The criteria to be accounted for in the energy conversion system design are the economic profitability, the thermodynamic efficiency in the usage of the resource, and the generated life-cycle environmental impacts, which are as well a key point for the public acceptance of geothermal energy. This paper presents a systematic methodology for the optimal design and configuration of geothermal systems considering environomic criteria. Process design and process integration techniques are used in combination with Life Cycle Assessment (LCA) and multiobjective optimization techniques, using a multi-period strategy to account for the seasonal variations in the district heating demand. It is illustrated by an application to the future EGS construction for cogeneration in the context of Switzerland. Different conversion cycles are considered: single and double flash systems, organic Rankine cycles (ORC), and Kalina cycles. The optimal configuration is determined at each construction depth for the EGS from 3000 down to 10000m and at each district heating network installed capacity from 0 to

Lda Gerber; Franois Marchal

42

Geothermal activity helps life survive glacial cycles.  

PubMed

Climate change has played a critical role in the evolution and structure of Earth's biodiversity. Geothermal activity, which can maintain ice-free terrain in glaciated regions, provides a tantalizing solution to the question of how diverse life can survive glaciations. No comprehensive assessment of this "geothermal glacial refugia" hypothesis has yet been undertaken, but Antarctica provides a unique setting for doing so. The continent has experienced repeated glaciations that most models indicate blanketed the continent in ice, yet many Antarctic species appear to have evolved in almost total isolation for millions of years, and hence must have persisted in situ throughout. How could terrestrial species have survived extreme glaciation events on the continent? Under a hypothesis of geothermal glacial refugia and subsequent recolonization of nongeothermal regions, we would expect to find greater contemporary diversity close to geothermal sites than in nongeothermal regions, and significant nestedness by distance of this diversity. We used spatial modeling approaches and the most comprehensive, validated terrestrial biodiversity dataset yet created for Antarctica to assess spatial patterns of diversity on the continent. Models clearly support our hypothesis, indicating that geothermally active regions have played a key role in structuring biodiversity patterns in Antarctica. These results provide critical insights into the evolutionary importance of geothermal refugia and the history of Antarctic species. PMID:24616489

Fraser, Ceridwen I; Terauds, Aleks; Smellie, John; Convey, Peter; Chown, Steven L

2014-04-15

43

Chelated Indium Activable Tracers for Geothermal Reservoirs  

E-print Network

SGP-TR-99 Chelated Indium Activable Tracers for Geothermal Reservoirs Constantinos V. Indium was se1ecti:d to be the most promising activable tracer. The thermal stability of indium tracer of the soluble indium concentration was made as a f'unction of time by neutron activation analysis. From the data

Stanford University

44

Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems  

NASA Astrophysics Data System (ADS)

Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1-2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.

Guo, Qinghai; Kirk Nordstrom, D.; Blaine McCleskey, R.

2014-11-01

45

Enhanced Geothermal Systems (EGS) R&D Program, Status Report: Foreign Research on Enhanced Geothermal Systems  

SciTech Connect

This report reviews enhanced geothermal systems (EGS) research outside the United States. The term ''enhanced geothermal systems'' refers to the use of advanced technology to extract heat energy from underground in areas with higher than average heat flow but where the natural permeability or fluid content is limited. EGS covers the spectrum of geothermal resources from low permeability hydrothermal to hot dry rock.

McLarty, Lynn; Entingh, Daniel

2000-09-29

46

Geopressured-geothermal well activities in Louisiana  

SciTech Connect

Since September 1978, microseismic networks have operated continuously around US Department of Energy (DOE) geopressured-geothermal well sites to monitor any microearthquake activity in the well vicinity. Microseismic monitoring is necessary before flow testing at a well site to establish the level of local background seismicity. Once flow testing has begun, well development may affect ground elevations and/or may activate growth faults, which are characteristic of the coastal region of southern Louisiana and southeastern Texas where these geopressured-geothermal wells are located. The microseismic networks are designed to detest small-scale local earthquakes indicative of such fault activation. Even after flow testing has ceased, monitoring continues to assess any microearthquake activity delayed by the time dependence of stress migration within the earth. Current monitoring shows no microseismicity in the geopressured-geothermal prospect areas before, during, or after flow testing.

John, C.J.

1992-10-01

47

GRC Transactions, Vol. 34, 2010 Geothermal, Engineered Geothermal Systems, EGS, induced  

E-print Network

GRC Transactions, Vol. 34, 2010 1213 Keywords Geothermal, Engineered Geothermal Systems, EGS in the geothermal, mining, petroleum and other industries must address. We present a brief review of the history of IIS, the importance of IIS to the growth of the geothermal energy industry, and suggest possible paths

Foulger, G. R.

48

Seismology and Enhanced Geothermal Systems Bruce R. Julian  

E-print Network

Seismology and Enhanced Geothermal Systems Bruce R. Julian Foulger Consulting, Palo Alto, CA 94306 in geothermal systems, and in Enhanced Geothermal Systems (EGS) experiments in particular, although many failure in both natural and exploited geothermal systems. Differential methods are poor for determining

Foulger, G. R.

49

Monitoring Biological Activity at Geothermal Power Plants  

Microsoft Academic Search

The economic impact of microbial growth in geothermal power plants has been estimated to be as high as $500,000 annually for a 100 MWe plant. Many methods are available to monitor biological activity at these facilities; however, very few plants have any on-line monitoring program in place. Metal coupon, selective culturing (MPN), total organic carbon (TOC), adenosine triphosphate (ATP), respirometry,

Peter A. Pryfogle

2005-01-01

50

Enhanced Geothermal Systems (EGS) R&D Program: US Geothermal Resources Review and Needs Assessment  

SciTech Connect

The purpose of this report is to lay the groundwork for an emerging process to assess U.S. geothermal resources that might be suitable for development as Enhanced Geothermal Systems (EGS). Interviews of leading geothermists indicate that doing that will be intertwined with updating assessments of U.S. higher-quality hydrothermal resources and reviewing methods for discovering ''hidden'' hydrothermal and EGS resources. The report reviews the history and status of assessment of high-temperature geothermal resources in the United States. Hydrothermal, Enhanced, and Hot Dry Rock resources are addressed. Geopressured geothermal resources are not. There are three main uses of geothermal resource assessments: (1) They inform industry and other interest parties of reasonable estimates of the amounts and likely locations of known and prospective geothermal resources. This provides a basis for private-sector decisions whether or not to enter the geothermal energy business at all, and for where to look for useful resources. (2) They inform government agencies (Federal, State, local) of the same kinds of information. This can inform strategic decisions, such as whether to continue to invest in creating and stimulating a geothermal industry--e.g., through research or financial incentives. And it informs certain agencies, e.g., Department of Interior, about what kinds of tactical operations might be required to support such activities as exploration and leasing. (3) They help the experts who are performing the assessment(s) to clarify their procedures and data, and in turn, provide the other two kinds of users with a more accurate interpretation of what the resulting estimates mean. The process of conducting this assessment brings a spotlight to bear on what has been accomplished in the domain of detecting and understanding reservoirs, in the period since the last major assessment was conducted.

Entingh, Dan; McLarty, Lynn

2000-11-30

51

The Socorro Geothermal System: A Low Temperature Geothermal Resource  

NASA Astrophysics Data System (ADS)

The State of New Mexico is endowed with relatively high background heat flow and permeable, fractured crystalline and sedimentary rocks. This combination has given rise to numerous low temperature geothermal systems throughout the state. In many instances, hot springs associated with these systems are located within gaps in regional confining units (a.k.a. hydrologic windows) caused either by fault block rotation or the emplacement of volcanic dikes. The Socorro Geothermal Area (SGA) is a prime example of this type of a forced convection geothermal system. The Socorro geothermal area (SGA) lies 2 miles to the west of the NM Tech Campus near the base of the Socorro Mountain Block and will be assessed for production by drilling a 1500ft test well in September 2009. Published shallow temperature gradient measurements in fractured, permeable (3000 Darcy) granites indicate peak heat flow values as high as 490 mW/m^2 but decreases to 25 mW/m^2 about 10 km to the west within the La Jencia Basin near the foothills of the Magdalena Mountains. Silica and Cation based geothermometers suggest that deep geothermal reservoir reaches temperatures of 80 to 112 deg. C. Carbon14 age dating of shallow groundwater within the discharge area are about 20,000 years old. Hydrothermal models we constructed indicates that Mountain front recharge penetrates to depths of 4.5 km below the La Jencia Basin sedimentary pile into fractured, crystalline rocks. Discharge occurs through a hydrologic window to the east within a breached playa deposit at the western edge of the Socorro Basin. The hydrologic window was caused by fault block rotation. Warm springs which produce several hundred gpm of 32 deg. C water at the surface several miles to the south of the proposed drilling area also attest to the presence of a significant hydrothermal system. This low temperature resource could potentially heat the Campus of NM Tech.

Person, M. A.; Owens, L. B.

2009-12-01

52

Sperry Low Temperature Geothermal Conversion System, Phase I and Phase II. Volume IV. Field activities. Final report  

SciTech Connect

This volume describes those activities which took place at the Sperry DOE Gravity Head plant site at the East Mesa Geothermal Reservoir near Holtville, California between February 1980, when site preparation was begun, and November 1982, when production well 87-6 was permanently abandoned. Construction activities were terminated in July 1981 following the liner collapse in well 87-6. Large amounts of program time manpower, materials, and funds had been diverted in a nine-month struggle to salvage the production well. Once these efforts proved futile, there was no rationale for continuing with the site work unless and until sufficient funding to duplicate well 87-6 was obtained. Activities reported here include: plant construction and pre-operational calibration and testing, drilling and completion of well 87-6, final repair effort on well 87-6, abandonment of well 87-6, and performance evaluation of well 87.6. (MHR)

Harvey, C.

1984-01-01

53

Neutron imaging for geothermal energy systems  

NASA Astrophysics Data System (ADS)

Geothermal systems extract heat energy from the interior of the earth using a working fluid, typically water. Three components are required for a commercially viable geothermal system: heat, fluid, and permeability. Current commercial electricity production using geothermal energy occurs where the three main components exist naturally. These are called hydrothermal systems. In the US, there is an estimated 30 GW of base load electrical power potential for hydrothermal sites. Next generation geothermal systems, named Enhanced Geothermal Systems (EGS), have an estimated potential of 4500 GW. EGSs lack in-situ fluid, permeability or both. As such, the heat exchange system must be developed or "engineered" within the rock. The envisioned method for producing permeability in the EGS reservoir is hydraulic fracturing, which is rarely practiced in the geothermal industry, and not well understood for the rocks typically present in geothermal reservoirs. High costs associated with trial and error learning in the field have led to an effort to characterize fluid flow and fracturing mechanisms in the laboratory to better understand how to design and manage EGS reservoirs. Neutron radiography has been investigated for potential use in this characterization. An environmental chamber has been developed that is suitable for reproduction of EGS pressures and temperatures and has been tested for both flow and precipitations studies with success for air/liquid interface imaging and 3D reconstruction of precipitation within the core.

Bingham, Philip; Polsky, Yarom; Anovitz, Lawrence

2013-03-01

54

Neutron imaging for geothermal energy systems  

SciTech Connect

Geothermal systems extract heat energy from the interior of the earth using a working fluid, typically water. Three components are required for a commercially viable geothermal system: heat, fluid, and permeability. Current commercial electricity production using geothermal energy occurs where the three main components exist naturally. These are called hydrothermal systems. In the US, there is an estimated 30 GW of base load electrical power potential for hydrothermal sites. Next generation geothermal systems, named Enhanced Geothermal Systems (EGS), have an estimated potential of 4500 GW. EGSs lack in-situ fluid, permeability or both. As such, the heat exchange system must be developed or engineered within the rock. The envisioned method for producing permeability in the EGS reservoir is hydraulic fracturing, which is rarely practiced in the geothermal industry, and not well understood for the rocks typically present in geothermal reservoirs. High costs associated with trial and error learning in the field have led to an effort to characterize fluid flow and fracturing mechanisms in the laboratory to better understand how to design and manage EGS reservoirs. Neutron radiography has been investigated for potential use in this characterization. An environmental chamber has been developed that is suitable for reproduction of EGS pressures and temperatures and has been tested for both flow and precipitations studies with success for air/liquid interface imaging and 3D reconstruction of precipitation within the core.

Bingham, Philip R [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Polsky, Yarom [ORNL

2013-01-01

55

Small geothermal electric systems for remote powering  

SciTech Connect

This report describes conditions and costs at which quite small (100 to 1,000 kilowatt) geothermal systems could be used for off-grid powering at remote locations. This is a first step in a larger process of determining locations and conditions at which markets for such systems could be developed. The results suggest that small geothermal systems offer substantial economic and environmental advantages for powering off-grid towns and villages. Geothermal power is most likely to be economic if the system size is 300 kW or greater, down to reservoir temperatures of 100{degree}C. For system sizes smaller than 300 kW, the economics can be favorable if the reservoir temperature is about 120{degree}C or above. Important markets include sites remote from grids in many developing and developed countries. Estimates of geothermal resources in many developing countries are shown.

Entingh, Daniel J.; Easwaran, Eyob.; McLarty, Lynn

1994-08-08

56

Utilization of geothermal energy in heating systems  

Microsoft Academic Search

This article describes exploitation of geothermal resources in the U.S.S.R. and their utilization in heating systems. The consumption of geothermal water in the national economy at present is as follows: agriculture 43%, municipal and domestic uses 23%, industry 19%, and electric power 8%. Over 300,000 inhabitants of the cities of Tbilisi, Makhachkala, Crozny, Kizlyar, Izberbash and other populated areas have

E SARNATSKI

1985-01-01

57

Chemistry and materials in geothermal systems  

SciTech Connect

The development of a geothermal fluid is traced, from its origin as meteoric water precipitating on the earth's surface, as it flows through the soils and rocks of geological formations, to the point where it returns to the surface as a hot spring, geyser, well, or other form. Water of magmatic origin is also included. The tendency of these hydrothermal fluids to form scale by precipitation of a portion of their dissolved solids is noted. A discussion is presented of types of information required for materials selection for energy systems utilizing geothermal fluids, including pH, temperature, the speciation of the particular geothermal fluid (especially its chloride, sulfide, and carbon dioxide content), and various types of corrosive attack on common materials. Specific examples of responses of materials to geothermal fluids are given. 8 refs.

Miller, R.L.

1980-01-01

58

National Geothermal Data System (NGDS) Geothermal Data: Community Requirements and Information Engineering  

SciTech Connect

To satisfy the critical need for geothermal data to advance geothermal energy as a viable renewable energy contender, the U.S. Department of Energy is investing in the development of the National Geothermal Data System (NGDS). This paper outlines efforts among geothermal data providers nationwide to supply cutting edge geo-informatics. NGDS geothermal data acquisition, delivery, and methodology are discussed. In particular, this paper addresses the various types of data required to effectively assess geothermal energy potential and why simple links to existing data are insufficient. To create a platform for ready access by all geothermal stakeholders, the NGDS includes a work plan that addresses data assets and resources of interest to users, a survey of data providers, data content models, and how data will be exchanged and promoted, as well as lessons learned within the geothermal community.

Anderson, Arlene [United States Department of Energy; Blackwell, David [Southern Methodist University; Chickering, Cathy [Southern Methodist University; Boyd, Toni [Oregon Institute of Technology; Horne, Roland [Stanford University; MacKenzie, Matthew [Uberity Technology Corporation; Moore, Joseph [University of Utah; Nickull, Duane [Uberity Technology Corporation; Richard, Stephen [Arizona Geological survey; Shevenell, Lisa A. [University of Nevada, Reno

2013-10-01

59

Geothermal materials development: FY 1990 accomplishments and current activities  

SciTech Connect

Advances in the development of hydrothermally stable materials, the commercial availabilities of which are considered essential for the attainment of the Geothermal Division's (GD) Hydrothermal Category Objectives, continue to be made. Fiscal year 1990 R D was focused on reducing well drilling and completion costs, energy conversion costs, and on mitigating corrosion in well casing. Activities on lost circulation control materials, CO{sub 2}-resistant lightweight cements and thermally conductive corrosion and scale-resistant linear systems have reached the final development stages. In addition, field tests to determine the feasibility for the use of polymer cement liners to mitigate HCl-induced corrosion at the Geysers were performed. Technology transfer efforts on high temperature elastomers for use in drilling tools such as drillpipe protectors and rotating head seals were continued under Geothermal Drilling Organization sponsorship. Recent accomplishments and ongoing work on each of these activities are described in the paper. 8 refs.

Kukacka, L.E.

1991-01-01

60

Exploration of geothermal systems using hyperspectral thermal infrared remote sensing  

NASA Astrophysics Data System (ADS)

Visible near infrared (VNIR), short-wave infrared (SWIR), and thermal infrared (TIR) remote sensing has long been used for geothermal exploration. Specific focus on the TIR region (8-12 ?m) has resulted in major-rock-forming mineral classes being identified and their areal percentages to be more easily mapped due in part to the linear mixing behavior of TIR emission. To understand the mineral compositional and thermal distribution of active geothermal surfaces systems, hyperspectral TIR data from the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) airborne sensor were acquired over the Salton Sea, CA geothermal fields by The Aerospace Corporation on March 26, 2009 and April 6, 2010. SEBASS collects 128 wavelength channels at ~ 1 m spatial resolution. Such high resolution data are rarely available for this type of scientific analysis and enabled the identification of rare mineral assemblages associated with the geothermally-active areas. One surface unit with a unique spectrum, believed to be a magnesium sulfate of unknown hydration state, was identified for the first time in the SEBASS data. The abundance and distribution of this mineral varied between 2009 and 2010 likely due to the precipitation conditions. Data obtained by the SEBASS sensor were also regressed to the 32 channel spectral resolution of the Mineral and Gas Identifier (MAGI) airborne sensor in order to test sensitivity limits. At this lower spectral resolution, all surface minerals were still effectively identified and therefore validated data at MAGI resolution are still very effective for accurate surface compositional mapping. A similar approach used at active geothermal areas in other semi-arid regions around the world has the potential to better characterize transient mineralogy, identify "indicators minerals", understand the influence of surface and ground water, and ultimately to locate new geothermal targets for future exploration. Furthermore, new Mineral and Gas Identification (MAGI) data serve as an excellent precursor for future spaceborne TIR data such as the system proposed for the Hyperspectral Infrared Imager (HyspIRI) instrument.

Reath, Kevin A.; Ramsey, Michael S.

2013-09-01

61

A new classification scheme for deep geothermal systems based on geologic controls  

NASA Astrophysics Data System (ADS)

A key element in the characterization, assessment and development of geothermal energy systems is the resource classification. Throughout the past 30 years many classifications and definitions were published mainly based on temperature and thermodynamic properties. In the past classification systems, temperature has been the essential measure of the quality of the resource and geothermal systems have been divided into three different temperature (or enthalpy) classes: low-temperature, moderate-temperature and high-temperature. There are, however, no uniform temperature ranges for these classes. It is still a key requirement of a geothermal classification that resource assessment provides logical and consistent frameworks simplified enough to communicate important aspects of geothermal energy potential to both non-experts and general public. One possible solution may be to avoid classifying geothermal resources by temperature and simply state the range of temperatures at the individual site. Due to technological development, in particular in EGS (Enhanced Geothermal Systems or Engineered Geothermal Systems; both terms are considered synonymously in this thesis) technology, currently there are more geothermal systems potentially economic than 30 years ago. An alternative possibility is to classify geothermal energy systems by their geologic setting. Understanding and characterizing the geologic controls on geothermal systems has been an ongoing focus on different scales from plate tectonics to local tectonics/structural geology. In fact, the geologic setting has a fundamental influence on the potential temperature, on the fluid composition, the reservoir characteristics and whether the system is a predominantly convective or conductive system. The key element in this new classification for geothermal systems is the recognition that a geothermal system is part of a geological system. The structural geological and plate tectonic setting has a fundamental influence on the characteristics of a geothermal system. The thermal regime and heat flow, hydrogeologic regime, fluid dynamics, fluid chemistry, faults and fractures, stress regime, and lithological sequence are controlled by the plate tectonic framework, hence critical for understanding the geothermal system. It is important to identify if the geothermal system is located at active plate boundaries or in intracontinental tectonically quiescent settings and thus how it relates to both active volcanism and active tectonics.

Moeck, I.

2012-04-01

62

A Geothermal GIS for Nevada: Defining Regional Controls and Favorable Exploration Terrains for Extensional Geothermal Systems  

USGS Publications Warehouse

Spatial analysis with a GIS was used to evaluate geothermal systems in Nevada using digital maps of geology, heat flow, young faults, young volcanism, depth to groundwater, groundwater geochemistry, earthquakes, and gravity. High-temperature (>160??C) extensional geothermal systems are preferentially associated with northeast-striking late Pleistocene and younger faults, caused by crustal extension, which in most of Nevada is currently oriented northwesterly (as measured by GPS). The distribution of sparse young (160??C) geothermal systems in Nevada are more likely to occur in areas where the groundwater table is shallow (<30m). Undiscovered geothermal systems may occur where groundwater levels are deeper and hot springs do not issue at the surface. A logistic regression exploration model was developed for geothermal systems, using young faults, young volcanics, positive gravity anomalies, and earthquakes to predict areas where deeper groundwater tables are most likely to conceal geothermal systems.

Coolbaugh, M.F.; Taranik, J.V.; Raines, G.L.; Shevenell, L.A.; Sawatzky, D.L.; Bedell, R.; Minor, T.B.

2002-01-01

63

2nd Quarterly technical progress report for geothermal system temperature-depth database  

SciTech Connect

At the Southern Methodist University Geothermal Laboratory in Dallas, Texas, the Earth`s surface and internal temperature are studied. With financial support from the U.S. Department of Energy, a data base containing geothermal temperature well information for the United States is being developed. During this calendar quarter, activity with this project has continued involving several different tasks: planning and development of the geothermal system thermal-well data base and temperature-depth data, development of the specifications for the data base, and completion of an initial inventory of the geothermal areas for which data are available.

Blackwell, D.D.

1997-07-30

64

Convective heat transport in geothermal systems  

SciTech Connect

Most geothermal systems under exploitation for direct use or electrical power production are of the hydrothermal type, where heat is transferred essentially by convection in the reservoir, conduction being secondary. In geothermal systems, buoyancy effects are generally important, but often the fluid and heat flow patterns are largely controlled by geologic features (e.g., faults, fractures, continuity of layers) and location of recharge and discharge zones. During exploitation, these flow patterns can drastically change in response to pressure and temperature declines, and changes in recharge/discharge patterns. Convective circulation models of several geothermal systems, before and after start of fluid production, are described, with emphasis on different characteristics of the systems and the effects of exploitation on their evolution. Convective heat transport in geothermal fields is discussed, taking into consideration (1) major geologic features; (2) temperature-dependent rock and fluid properties; (3) fracture- versus porous-medium characteristics; (4) single- versus two-phase reservoir systems; and (5) the presence of noncondensible gases.

Lippmann, M.J.; Bodvarsson, G.S.

1986-08-01

65

GEOTHERMAL ENERGY RESOURCE ASSESSMENT ON MILITARY LANDS  

Microsoft Academic Search

Innovative Technical Solutions, Inc. (ITSI) evaluated geothermal potential on selected military bases in the U.S. for the Department of Defense. Assessment activities included literature reviews, interviews with local specialists, geothermal field investigations at 3 installations, and development of conceptual geothermal occurrence models. Occurrence models integrate geothermal system characteristics with local structural\\/tectonic characteristics to identify potential geothermal targets. Spatial analyses of

R. Leong; U. Kansas

66

Induced seismicity associated with enhanced geothermal system  

SciTech Connect

Enhanced Geothermal Systems (EGS) offer the potential to significantly add to the world energy inventory. As with any development of new technology, some aspects of the technology has been accepted by the general public, but some have not yet been accepted and await further clarification before such acceptance is possible. One of the issues associated with EGS is the role of microseismicity during the creation of the underground reservoir and the subsequent extraction of the energy. The primary objectives of this white paper are to present an up-to-date review of the state of knowledge about induced seismicity during the creation and operation of enhanced geothermal systems, and to point out the gaps in knowledge that if addressed will allow an improved understanding of the mechanisms generating the events as well as serve as a basis to develop successful protocols for monitoring and addressing community issues associated with such induced seismicity. The information was collected though literature searches as well as convening three workshops to gather information from a wide audience. Although microseismicity has been associated with the development of production and injection operations in a variety of geothermal regions, there have been no or few adverse physical effects on the operations or on surrounding communities. Still, there is public concern over the possible amount and magnitude of the seismicity associated with current and future EGS operations. It is pointed out that microseismicity has been successfully dealt with in a variety of non-geothermal as well as geothermal environments. Several case histories are also presented to illustrate a variety of technical and public acceptance issues. It is concluded that EGS Induced seismicity need not pose any threat to the development of geothermal resources if community issues are properly handled. In fact, induced seismicity provides benefits because it can be used as a monitoring tool to understand the effectiveness of the EGS operations and shed light on the mechanics of the reservoir.

Majer, Ernest; Majer, Ernest L.; Baria, Roy; Stark, Mitch; Oates, Stephen; Bommer, Julian; Smith, Bill; Asanuma, Hiroshi

2006-09-26

67

Geothermal Resource Analysis and Structure of Basin and Range Systems, Especially Dixie Valley Geothermal Field, Nevada  

SciTech Connect

Publish new thermal and drill data from the Dizie Valley Geothermal Field that affect evaluation of Basin and Range Geothermal Resources in a very major and positive way. Completed new geophysical surveys of Dizie Valley including gravity and aeromagnetics and integrated the geophysical, seismic, geological and drilling data at Dizie Valley into local and regional geologic models. Developed natural state mass and energy transport fluid flow models of generic Basin and Range systems based on Dizie Valley data that help to understand the nature of large scale constraints on the location and characteristics of the geothermal systems. Documented a relation between natural heat loss for geothermal and electrical power production potential and determined heat flow for 27 different geothermal systems. Prepared data set for generation of a new geothermal map of North American including industry data totaling over 25,000 points in the US alone.

David Blackwell; Kenneth Wisian; Maria Richards; Mark Leidig; Richard Smith; Jason McKenna

2003-08-14

68

Natural radioactivity levels of geothermal waters and their influence on soil and agricultural activities.  

PubMed

All over the world geothermal sources are used for different purposes. The contents of these waters are important to understand positive/negative effects on human life. In this study, natural radioactivity concentrations of geothermal waters were investigated to evaluate the effect on soils and agricultural activities. Geothermal water samples were collected from the Seferihisar Geothermal Region, and the radon and radium concentrations of these waters were analysed using a collector chamber method. Also soil samples, which are irrigated with geothermal waters, were collected from the surroundings of geothermal areas, and natural radioactivity concentrations of collected samples (U, Th and K) were determined using an NaI(Tl) detector system. The activity concentrations of radon and radium were found to be 0.6-6.0 and 0.1-1.0 Bq l(-1), respectively. Generally, the obtained results are not higher compared with the geothermal waters of the world. The activity concentrations in soils were found to be in the range of 3.3-120.3 Bq kg(-1) for (226)Ra (eU), 0.3-108.5 Bq kg(-1) for (232)Th (eTh), 116.0-850.0 Bq kg(-1) for (40)K (% K). PMID:24026900

Murat Sa, Mslim; Aydemir, Sercan; Ihedef, Mutlu; Kumru, Mehmet N; Bolca, Mustafa; Ozen, Fulsen

2014-01-01

69

Structural controls on a geothermal system in the Tarutung Basin, north central Sumatra  

NASA Astrophysics Data System (ADS)

The Sumatra Fault System provides a unique geologic setting to evaluate the influence of structural controls on geothermal activity. Whereas most of the geothermal systems in Indonesia are controlled by volcanic activity, geothermal systems at the Sumatra Fault System might be controlled by faults and fractures. Exploration strategies for these geothermal systems need to be verified because the typical pattern of heat source and alteration clays are missing so that conventional exploration with magnetotelluric surveys might not provide sufficient data to delineate favorable settings for drilling. We present field geological, structural and geomorphological evidence combined with mapping of geothermal manifestations to allow constraints between fault dynamics and geothermal activity in the Tarutung Basin in north central Sumatra. Our results indicate that the fault pattern in the Tarutung Basin is generated by a compressional stress direction acting at a high angle to the right-lateral Sumatra Fault System. NW-SE striking normal faults possibly related to negative flower structures and NNW-SSE to NNE-SSW oriented dilative Riedel shears are preferential fluid pathways whereas ENE-WSW striking faults act as barriers in this system. The dominant of geothermal manifestations at the eastern part of the basin indicates local extension due to clockwise block rotation in the Sumatra Fault System. Our results support the effort to integrate detailed field geological surveys to refined exploration strategies even in tropical areas where outcrops are limited.

Nukman, Mochamad; Moeck, Inga

2013-09-01

70

Geothermal systems ancient and modern: a geochemical review  

NASA Astrophysics Data System (ADS)

Geothermal systems occur in a range of crustal settings. The emphasis of this review is on those occurring in regions of active or recently active volcanism, where magmatic heat at depths up to 8 km leads to convection of groundwater in the upper crust. Hot water (and steam) flows are controlled by the permeability of the crust and recent data have emphasised the dominance of secondary permeability, especially fractures. Drilling to depths of up to 3 km in these systems encounters near-neutral pH alkali chloride waters with temperatures up to about 350C and chloride contents generally in the range 500 to 15,000 mg kg -1 although much higher salinities are encountered in some systems such as in the Imperial Valley, California. Stable isotope studies indicate the predominance of a meteoric source in the majority of geothermal systems although seawater predominates in some regions, such as Reykjanes, Iceland. Mixing of waters from both sources also occurs in some systems and some magmatic fluid may also be present. The major element geochemistry of geothermal fluids is determined by a set of temperature-dependent mineral-fluid equilibria although chloride and rare gas contents appear to be independent variables reflecting the sources of these components (sedimentary or volcanic rocks, seawater, magmatic fluids, etc). Boiling in the upper portion of geothermal systems is accompanied by the transfer of acidic gases (CO 2 and H 2S) to the resultant steam which may penetrate the surface as fumarolic activity or become condensed into shallow groundwaters giving rise, with oxidation, to distinctive low pH sulphate bicarbonate water. Fluid inclusion, stable isotope and mineral alteration studies have led to the recognition in many Tertiary hydrothermal ore deposits of physical and chemical environments analogous to those encountered in the present-day systems. The vein-type gold-silver, Carlin-type gold and porphyry-type copper-molybdenum deposits of the western United States are particularly well studied examples. Sub-ocean floor equivalents of the terrestrial geothermal systems have been recognized in ocean floor spreading centres such as the East Pacific Rise and deep-sea submersible vehicles have allowed visual observation of sea floor hot springs actively depositing metal sulphides. These environments may parallel those of the Cyprus-type massive sulphide depositing systems, while sub-sea floor systems of the type responsible for Kuroko-type massive sulphide deposits may eventually be encountered in island are settings.

Henley, R. W.; Ellis, A. J.

1983-01-01

71

Utah State Prison Geothermal System  

SciTech Connect

A geothermal space heating project was recently completed at the Utah State Prison complex at Crystal Hot Springs located near Murray, Utah. The project was initiated in 1978 as a joint U.S. Department of Energy and State of Utah project. Geologic and geophysical investigations initiated in 1979 consist of surface geologic mapping and aeromagnetic and detailed gravity surveys. This exploration program along with several shallow thermal-gradient holes provided the structural details for a subsequent exploration drilling program. The exploration drilling program involved deepening an existing well (SF-1) to 500 ft (150 m) and drilling a new hole (USP/TH-1) to 1000 ft (300 m) to test the extent of the thermal anomaly. Well SF-1 intersected 175)2)F(79)2)C) temperatures in a low permeable quartzite, and well USP/TH-1 intersected highly fractured quartzite in the lower section of the well. A temperature reversal was noted in USP/TH-1 below 700 ft (213 m) with a maximum temperature of 175)2)F(79)2)C) occurring in the zone from 300 to 700 ft (90 to 215 m). Flow testing of USP/TH-1 indicated the well would flow at 1000 gpm with a sustained flow of 400 gpm at a 3.5 psi drawdown over the heating season. Testing also indicated interference with other nearby wells and thermal springs. Fluid production for space heating of the prison facilities took place during the winter of 1983-84. This production will give more data to refine the calculations of reservoir producibility and provide information on the economics of utilizing geothermal fluids for space heating.

Mink, L.R.

1984-07-01

72

Finite-element solutions for geothermal systems  

NASA Technical Reports Server (NTRS)

Vector potential and scalar potential are used to formulate the governing equations for a single-component and single-phase geothermal system. By assuming an initial temperature field, the fluid velocity can be determined which, in turn, is used to calculate the convective heat transfer. The energy equation is then solved by considering convected heat as a distributed source. Using the resulting temperature to compute new source terms, the final results are obtained by iterations of the procedure. Finite-element methods are proposed for modeling of realistic geothermal systems; the advantages of such methods are discussed. The developed methodology is then applied to a sample problem. Favorable agreement is obtained by comparisons with a previous study.

Chen, J. C.; Conel, J. E.

1977-01-01

73

Geothermal  

NSDL National Science Digital Library

What part does geothermal energy play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to heat within the Earth as an energy source. Here students read about the uses, benefits, and limitations of geothermal energy. Articles and information on places around the world that use geothermal energy and geothermal use by schools in Iowa are available from a sidebar. A link to a map of geothermal hotspots around the world is provided, along with a link to an ABC News article about geothermal power.

Iowa Public Television. Explore More Project

2004-01-01

74

A U Th calcite isochron age from an active geothermal field in New Zealand  

NASA Astrophysics Data System (ADS)

We report here the first U-Th disequilibrium age for a hydrothermal mineral from an active geothermal system in New Zealand. Vein calcite recovered from a depth of 389 m in Well Thm-1 at the Tauhara geothermal field has an age of 9944 ka BP. This age was determined using a leachate-leachate isochron technique on four silicate containing sub-samples of calcite from a single vein. Although the error on this isochron age is considerable, it is significantly younger than the earlier estimated age of 200 ka BP for the onset of activity at the Tauhara system and probably records the date of brecciation and veining, which may be associated with volcanic activity at the adjacent dacitic Tauhara Volcanic Complex. These results demonstrate that hydrothermal vein calcite can now be dated directly, and opens the way for more detailed studies of the evolution of the New Zealand geothermal systems.

Grimes, Stephen; Rickard, David; Hawkesworth, Chris; van Calsteren, Peter; Browne, Patrick

1998-05-01

75

Tracing Injection Fluids in Engineered Geothermal Systems  

NASA Astrophysics Data System (ADS)

The reinjection of produced fluids is crucial to the effective management of geothermal reservoirs, since it provides a mechanism for maintaining reservoir pressures while allowing for the disposal of a toxic byproduct. Tracers are essential to the proper location of injection wells since they are the only known tool for reliably characterizing the flow patterns of recirculated fluids. If injection wells are placed too close to production wells, then reinjected fluids do not have sufficient residence time to extract heat from the reservoir and premature thermal breakthrough results. If injection wells are placed too far away, then the reservoir risks unacceptable pressure loss. Several thermally stable compounds from a family of very detectable fluorescent organic compounds (the naphthalene sulfonates) were characterized and found to be effective for use as geothermal tracers. Through batch-autoclave reactions, their Arrhenius pseudo-first-order decay-rate constants were determined. An analytical method was developed that allows for the laboratory determination of concentrations in the low parts-per-trillion range. Field experiments in numerous geothermal reservoirs throughout the world have confirmed the laboratory findings. Whereas conservative tracers such as the naphthalene sulfonates are effective tools for indicating interwell flow patterns and for measuring reservoir pore volumes, 'reactive' tracers can be used to constrain fracture surface area, which is the effective area for heat extraction. This is especially important for engineered geothermal system (EGS) wells, since reactive tracers can be used to measure fracture surface area immediately after drilling and while the well stimulation equipment is still on site. The reactive properties of these tracers that can be exploited to constrain fracture surface area are reversible sorption, contrasting diffusivity, and thermal decay. Laboratory batch- and flow-reactor experiments in combination with numerical simulation studies have served to identify candidate compounds for use as reactive tracers. An emerging class of materials that show promise for use as geothermal and EGS tracers are colloidal nanocrystals (quantum dots). These are semiconductor particles that fluoresce as a function of particle size. Preliminary laboratory experimentation has demonstrated that these thermally stable, water-soluble particles can serve as conservative tracers for geothermal applications. Likewise, they show promise as potential reactive tracers, since their surfaces can be modified to be reversibly sorptive and their diameters are sufficiently large to allow for contrasts in diffusivity with solute tracers.

Rose, P. E.; Leecaster, K.; Mella, M.; Ayling, B.; Bartl, M. H.

2011-12-01

76

Geothermal Systems of the Yellowstone Caldera Field Trip Guide  

SciTech Connect

Geothermal studies are proceedings on two fronts in the West Yellowstone area. High-temperature resources for the generation of electricity are being sought in the Island Park area, and lower temperatures resources for direct applications, primarily space heating, are being explored for near the town of West Yellowstone. Potential electric geothermal development in the Island Park area has been the subject of widespread publicity over fears of damage to thermal features in Yellowstone Park. At the time of writing this guide, companies have applied for geothermal leases in the Island Park area, but these leases have not yet been granted by the US Forest Service. The Senate is now discussing a bill that would regulate geothermal development in Island Park; outcome of this debate will determine the course of action on the lease applications. The Island Park area was the site of two cycles of caldera activity, with major eruptions at 2.0 and 1.2 million years ago. The US Geological Survey estimates that 16,850 x 10{sup 18} joules of energy may remain in the system. Geothermal resources suitable for direct applications are being sought in the West Yellowstone vicinity by the Montana Bureau of Mines and Geology, under funding from the US Department of Energy. West Yellowstone has a mean annual temperature of 1-2 C. Research thus far suggests that basement rocks in the vicinity are at a depth of about 600 m and are probably similar to the rocks exposed north of Hebgen Lake, where Precambrian, Paleozoic and Mesozoic rocks have been mapped. A few sites with anomalously warm water have been identified near the town. Work is continuing on this project.

Foley, Duncan; Neilson, Dennis L.; Nichols, Clayton R.

1980-09-08

77

Conceptual design of a geothermal site development forecasting system  

SciTech Connect

A site development forecasting system has been designed in response to the need to monitor and forecast the development of specific geothermal resource sites for electrical power generation and direct heat applications. The system is comprised of customized software, a site development status data base, and a set of complex geothermal project development schedules. The system would use site-specific development status information obtained from the Geothermal Progress Monitor and other data derived from economic and market penetration studies to produce reports on the rates of geothermal energy development, federal agency manpower requirements to ensure these developments, and capital expenditures and technical/laborer manpower required to achieve these developments.

Neham, E.A.; Entingh, D.J.

1980-03-01

78

Temporary Cementitious Sealers in Enhanced Geothermal Systems  

SciTech Connect

Unlike conventional hydrothennal geothermal technology that utilizes hot water as the energy conversion resources tapped from natural hydrothermal reservoir located at {approx}10 km below the ground surface, Enhanced Geothermal System (EGS) must create a hydrothermal reservoir in a hot rock stratum at temperatures {ge}200 C, present in {approx}5 km deep underground by employing hydraulic fracturing. This is the process of initiating and propagating a fracture as well as opening pre-existing fractures in a rock layer. In this operation, a considerable attention is paid to the pre-existing fractures and pressure-generated ones made in the underground foundation during drilling and logging. These fractures in terms of lost circulation zones often cause the wastage of a substantial amount of the circulated water-based drilling fluid or mud. Thus, such lost circulation zones must be plugged by sealing materials, so that the drilling operation can resume and continue. Next, one important consideration is the fact that the sealers must be disintegrated by highly pressured water to reopen the plugged fractures and to promote the propagation of reopened fractures. In response to this need, the objective of this phase I project in FYs 2009-2011 was to develop temporary cementitious fracture sealing materials possessing self-degradable properties generating when {ge} 200 C-heated scalers came in contact with water. At BNL, we formulated two types of non-Portland cementitious systems using inexpensive industrial by-products with pozzolanic properties, such as granulated blast-furnace slag from the steel industries, and fly ashes from coal-combustion power plants. These byproducts were activated by sodium silicate to initiate their pozzolanic reactions, and to create a cemetitious structure. One developed system was sodium silicate alkali-activated slag/Class C fly ash (AASC); the other was sodium silicate alkali-activated slag/Class F fly ash (AASF) as the binder of temper-try sealers. Two specific additives without sodium silicate as alkaline additive were developed in this project: One additive was the sodium carboxymethyl cellulose (CMC) as self-degradation promoting additive; the other was the hard-burned magnesium oxide (MgO) made from calcinating at 1,000-1,500 C as an expansive additive. The AASC and AASF cementitious sealers made by incorporating an appropriate amount of these additives met the following six criteria: 1) One dry mix component product; 2) plastic viscosity, 20 to 70 cp at 300 rpm; 3) maintenance of pumpability for at least 1 hour at 85 C; 4) compressive strength >2000 psi; 5) self-degradable by injection with water at a certain pressure; and 6) expandable and swelling properties; {ge}0.5% of total volume of the sealer.

Sugama T.; Pyatina, T.; Butcher, T.; Brothers, L.; Bour, D.

2011-12-31

79

National Geothermal Data System: Transforming the Discovery, Access, and Analytics of Data for Geothermal Exploration  

SciTech Connect

Compendium of Papers from the 38th Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California February 11-13, 2013 The National Geothermal Data System (NGDS) is a distributed, interoperable network of data collected from state geological surveys across all fifty states and the nations leading academic geothermal centers. The system serves as a platform for sharing consistent, reliable, geothermal-relevant technical data with users of all types, while supplying tools relevant for their work. As aggregated data supports new scientific findings, this content-rich linked data ultimately broadens the pool of knowledge available to promote discovery and development of commercial-scale geothermal energy production. Most of the up-front risks associated with geothermal development stem from exploration and characterization of subsurface resources. Wider access to distributed data will, therefore, result in lower costs for geothermal development. NGDS is on track to become fully operational by 2014 and will provide a platform for custom applications for accessing geothermal relevant data in the U.S. and abroad. It is being built on the U.S. Geoscience Information Network (USGIN) data integration framework to promote interoperability across the Earth sciences community. The basic structure of the NGDS employs state-of-the art informatics to advance geothermal knowledge. The following four papers comprising this Open-File Report are a compendium of presentations, from the 38th Annual Workshop on Geothermal Reservoir Engineering, taking place February 11-13, 2013 at Stanford University, Stanford, California. NGDS Geothermal Data Domain: Assessment of Geothermal Community Data Needs, outlines the efforts of a set of nationwide data providers to supply data for the NGDS. In particular, data acquisition, delivery, and methodology are discussed. The paper addresses the various types of data and metadata required and why simple links to existing data are insufficient for promoting geothermal exploration. Authors of this paper are Arlene Anderson, US DOE Geothermal Technologies Office, David Blackwell, Southern Methodist University (SMU), Cathy Chickering (SMU), Toni Boyd, Oregon Institute of Technologys GeoHeat Center, Roland Horne, Stanford University, Matthew MacKenzie, Uberity, Joe Moore, University of Utah, Duane Nickull, Uberity, Stephen Richard, Arizona Geological Survey, and Lisa Shevenell, University of Nevada, Reno. NGDS User Centered Design: Meeting the Needs of the Geothermal Community, discusses the user- centered design approach taken in the development of a user interface solution for the NGDS. The development process is research based, highly collaborative, and incorporates state-of-the-art practices to ensure a quality user interface for the widest and greatest utility. Authors of this paper are Harold Blackman, Boise State University, Suzanne Boyd, Anthro-Tech, Kim Patten, Arizona Geological Survey, and Sam Zheng, Siemens Corporate Research. Fueling Innovation and Adoption by Sharing Data on the DOE Geothermal Data Repository Node on the National Geothermal Data System, describes the motivation behind the development of the Geothermal Data Repository (GDR) and its role in the NGDS. This includes the benefits of using the GDR to share geothermal data of all types and DOEs data submission process. Authors of this paper are Jon Weers, National Renewable Energy Laboratory and Arlene Anderson, US DOE Geothermal Technologies Office. Finally, Developing the NGDS Adoption of CKAN for Domestic & International Data Deployment, provides an overview of the Node-In-A-Box software package designed to provide data consumers with a highly functional interface to access the system, and to ease the burden on data providers who wish to publish data in the system. It is important to note that this software package constitutes a reference implementation and that the NGDS architecture is based on open standards, which means other server software can make resources available, a

Patten, Kim [Arizona Geological Survey

2013-05-01

80

Enthalpy restoration in geothermal energy processing system  

DOEpatents

A geothermal deep well energy extraction system is provided of the general type in which solute-bearing hot water is pumped to the earth's surface from a relatively low temperature geothermal source by transferring thermal energy from the hot water to a working fluid for driving a primary turbine-motor and a primary electrical generator at the earth's surface. The superheated expanded exhaust from the primary turbine motor is conducted to a bubble tank where it bubbles through a layer of sub-cooled working fluid that has been condensed. The superheat and latent heat from the expanded exhaust of the turbine transfers thermal energy to the sub-cooled condensate. The desuperheated exhaust is then conducted to the condenser where it is condensed and sub-cooled, whereupon it is conducted back to the bubble tank via a barometric storage tank. The novel condensing process of this invention makes it possible to exploit geothermal sources which might otherwise be non-exploitable.

Matthews, Hugh B. (Boylston, MA)

1983-01-01

81

GEOTHERM Data Set  

DOE Data Explorer

GEOTHERM is a comprehensive system of public databases and software used to store, locate, and evaluate information on the geology, geochemistry, and hydrology of geothermal systems. Three main databases address the general characteristics of geothermal wells and fields, and the chemical properties of geothermal fluids; the last database is currently the most active. System tasks are divided into four areas: (1) data acquisition and entry, involving data entry via word processors and magnetic tape; (2) quality assurance, including the criteria and standards handbook and front-end data-screening programs; (3) operation, involving database backups and information extraction; and (4) user assistance, preparation of such items as application programs, and a quarterly newsletter. The principal task of GEOTHERM is to provide information and research support for the conduct of national geothermal-resource assessments. The principal users of GEOTHERM are those involved with the Geothermal Research Program of the U.S. Geological Survey.

DeAngelo, Jacob

82

GEOTHERMAL ENVIRONMENTAL IMPACT ASSESSMENT: SUBSURFACE ENVIRONMENTAL ASSESSMENT FOR FOUR GEOTHERMAL SYSTEMS  

EPA Science Inventory

This is the second in a series of reports concerning the environmental assessments of effluent extraction, energy conversion, and waste disposal in geothermal systems. This study involves the subsurface environmental impact of the Imperial Valley and The Geysers, California; Klam...

83

Mantle helium and carbon isotopes in Separation Creek Geothermal Springs, Three Sisters area, Central Oregon: Evidence for renewed volcanic activity or a long term steady state system?  

SciTech Connect

Cold bubbling springs in the Separation Creek area, the locus of current uplift at South Sister volcano show strong mantle signatures in helium and carbon isotopes and CO{sub 2}/{sup 3}He. This suggests the presence of fresh basaltic magma in the volcanic plumbing system. Currently there is no evidence to link this system directly to the uplift, which started in 1998. To the contrary, all geochemical evidence suggests that there is a long-lived geothermal system in the Separation Creek area, which has not significantly changed since the early 1990s. There was no archived helium and carbon data, so a definite conclusion regarding the strong mantle signature observed in these tracers cannot yet be drawn. There is a distinct discrepancy between the yearly magma supply required to explain the current uplift (0.006 km{sup 3}/yr) and that required to explain the discharge of CO{sub 2} from the system (0.0005 km{sup 3}/yr). This discrepancy may imply that the chemical signal associated with the increase in magma supply has not reached the surface yet. With respect to this the small changes observed at upper Mesa Creek require further attention, due to the recent volcanic vent in that area it may be the location were the chemical signal related to the uplift can most quickly reach the surface. Occurrence of such strong mantle signals in cold/diffuse geothermal systems suggests that these systems should not be ignored during volcano monitoring or geothermal evaluation studies. Although the surface-expression of these springs in terms of heat is minimal, the chemistry carries important information concerning the size and nature of the underlying high-temperature system and any changes taking place in it.

van Soest, M.C.; Kennedy, B.M.; Evans, W.C.; Mariner, R.H.

2002-04-30

84

Choosing a Geothermal as an HVAC System.  

ERIC Educational Resources Information Center

Describes the process of selecting and installing geothermal water source heat pumps for new residence halls at Johnson Bible College in Knoxville, Tennessee, including choosing the type of geothermal design, contractors, and interior equipment, and cost and payback. (EV)

Lensenbigler, John D.

2002-01-01

85

Tracers for Characterizing Enhanced Geothermal Systems  

SciTech Connect

Information about the times of thermal breakthrough and subsequent rates of thermal drawdown in enhanced geothermal systems (EGS) is necessary for reservoir management, designing fracture stimulation and well drilling programs, and forecasting economic return. Thermal breakthrough in heterogeneous porous media can be estimated using conservative tracers and assumptions about heat transfer rates; however, tracers that undergo temperature-dependent changes can provide more detailed information about the thermal profile along the flow path through the reservoir. To be effectively applied, the thermal reaction rates of such temperature sensitive traces must be well characterized for the range of conditions that exist in geothermal systems. Reactive tracers proposed in the literature include benzoic and carboxylic acids (Adams) and organic esters and amides (Robinson et al.); however, the practical temperature range over which these tracers can be applied (100-275C) is somewhat limited. Further, for organic esters and amides, little is known about their sorption to the reservoir matrix and how such reactions impact data interpretation. Another approach involves tracers where the reference condition is internal to the tracer itself. Two examples are: 1) racemization of polymeric amino acids, and 2) mineral thermoluminescence. In these cases internal ratios of states are measured rather than extents of degradation and mass loss. Racemization of poly-L-lactic acid (for example) is temperature sensitive and therefore can be used as a temperature-recording tracer depending on the rates of racemization and stability of the amino acids. Heat-induced quenching of thermoluminescence of pre-irradiated LiF can also be used. To protect the tracers from alterations (extraneous reactions, dissolution) in geothermal environments we are encapsulating the tracers in core-shell colloidal structures that will subsequently be tested for their ability to be transported and to protect the tracers from incidental reactions. We review the criteria for practical reactive tracers, which serves as the basis for experimental testing and characterization and can be used to identify other potential candidate tracers. We will also discuss the information obtainable from individual tracers, which has implications for using multiple tracers to obtain information about the thermal history of a reservoir. We will provide an update on our progress for conducting proof-of-principle tests for reactive tracers in the Raft River geothermal system.

Karen Wright; George Redden; Carl D. Palmer; Harry Rollins; Mark Stone; Mason Harrup; Laurence C. Hull

2010-02-01

86

Roosevelt Hot Springs geothermal system, Utah - case study  

Microsoft Academic Search

The Roosevelt Hot Springs geothermal system has been undergoing intensive exploration since 1974 and has been used as a natural laboratory for the development and testing of geothermal exploration methods by research organizations. This paper summarizes the geological, geophysical, and geochemistry data which have been collected since 1974, and presents a retrospective strategy describing the most effective means of exploration

H. P. Ross; D. L. Nielson; J. N. Moore

1982-01-01

87

Enhanced Geothermal Systems (EGS) R&D Program: US Geothermal Resources Review and Needs Assessment  

Microsoft Academic Search

The purpose of this report is to lay the groundwork for an emerging process to assess U.S. geothermal resources that might be suitable for development as Enhanced Geothermal Systems (EGS). Interviews of leading geothermists indicate that doing that will be intertwined with updating assessments of U.S. higher-quality hydrothermal resources and reviewing methods for discovering ''hidden'' hydrothermal and EGS resources. The

Dan Entingh; Lynn McLarty

2000-01-01

88

Mapping temperature and radiant geothermal heat flux anomalies in the Yellowstone geothermal system using ASTER thermal infrared data  

USGS Publications Warehouse

The purpose of this work was to use satellite-based thermal infrared (TIR) remote sensing data to measure, map, and monitor geothermal activity within the Yellowstone geothermal area to help meet the missions of both the U.S. Geological Survey Yellowstone Volcano Observatory and the Yellowstone National Park Geology Program. Specifically, the goals were to: 1) address the challenges of remotely characterizing the spatially and temporally dynamic thermal features in Yellowstone by using nighttime TIR data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and 2) estimate the temperature, geothermal radiant emittance, and radiant geothermal heat flux (GHF) for Yellowstones thermal areas (both Park wide and for individual thermal areas). ASTER TIR data (90-m pixels) acquired at night during January and February, 2010, were used to estimate surface temperature, radiant emittance, and radiant GHF from all of Yellowstones thermal features, produce thermal anomaly maps, and update field-based maps of thermal areas. A background subtraction technique was used to isolate the geothermal component of TIR radiance from thermal radiance due to insolation. A lower limit for the Yellowstones total radiant GHF was established at ~2.0 GW, which is ~30-45% of the heat flux estimated through geochemical (Cl-flux) methods. Additionally, about 5 km2 was added to the geodatabase of mapped thermal areas. This work provides a framework for future satellite-based thermal monitoring at Yellowstone as well as exploration of other volcanic / geothermal systems on a global scale.

Vaughan, R. Greg; Lowenstern, Jacob B.; Keszthelyi, Laszlo P.; Jaworowski, Cheryl; Heasler, Henry

2012-01-01

89

Investigation of the Mount Tongariro, New Zealand, geothermal system through Self Potential mapping  

NASA Astrophysics Data System (ADS)

Mount Tongariro volcano is a composite of overlapping vents active since c. 275 ka with 6 main periods of cone building. The volcano hosts an active geothermal system thought to be vapour dominated with a capping condensate layer; active surface geothermal features are present at Ketetahi, Red Crater, Central Crater and Te Maari Craters. Mount Tongariro erupted twice at Upper Te Maari Crater in 2012 after 125 years of dormancy. The first eruption (August 6th) is thought to be triggered from uncapping of the geothermal system by a landslide caused by pore pressure changes due to dyke intrusion. In response to those eruptions I undertook a combined Self Potential (SP), soil CO2 and ground temperature survey to learn more about the geothermal system, its distribution and fluid flow patterns. Analysis of SP vs. topographic gradient delineated the Ketetahi and Red Crater geothermal surface features. I propose that low pH fluids, combined with hydrothermally altered and therefore electrically conductive ground are the dominate cause of subdued SP anomalies around these features. I interpret a large positive anomaly (+1100 mV) in Oturere Valley, which has no surface geothermal activity, to result from deepening of a ground water aquifer beneath a thick electrically resistive lava flow. Subsequent modelling of SP data to estimate both water table depth, and depth to a potential current source agree with the inferred thickness of the Oturere Valley lava flow, and imply that the lava flow is a poor aquifer. Therefore underlying material hosts the aquifer. Finally I interpret a large negative (-600 mV) SP anomaly on the NE flank of North Crater as a zone of down flowing meteoric fluids, situated outside of the geothermal system. The geothermal surface features with subdued SP anomalies resulting from low pH fluids and conductive hydrothermally altered ground, map zones of weakened rock. These zones may be prone to future flank collapse, especially in areas of steep topography. Such flank collapse could be initiated by volcanic activity, such as magma intruding into the geothermal system. This in turn would raise the pore pressure of the overlying rocks and promote their ability to fail, as likely observed in the August 2012 eruption. Thus, monitoring SP signals over time may indicate changes to the geothermal system ahead of an eruption or future flank collapse.

Miller, C. A.

2013-12-01

90

Investigation of Induced Seismicity from a Geothermal System, Neal Hot Springs, Eastern Oregon  

NASA Astrophysics Data System (ADS)

Newly acquired geophysical data from an eleven-seismometer network surrounding the Neal Hot Springs (NHS) Geothermal Power Plant in eastern Oregon was analyzed for induced seismicity and geothermal fluid flow. Major faults associated with the Oregon-Idaho Graben and the western Snake River Plain provides pathways for deep geothermal fluid flow for the NHS hot-water system. Our short-period seismic stations, can detect regional events not in published earthquake catalogs. These stations have been collecting seismic data from the initiation of the geothermal system's development through fluid injection tests this past summer. Background seismic values were acquired before plant production to measure natural geothermal fluid activity, but no natural fluid flow seismicity was identified. Two local events located less than 10 km to the northeast of NHS along with a catalogued, 2.8 M regional event 200 km away were identified in the data set, verifying the sensitivity and capability of the passive seismic network to capture events that were to occur at NHS. We monitored seismic activity from production and development with 4-8 hour durations for the past 15 months. We identify repeated signals at approximately 2 Hz that likely represent fluid injection or drilling cycles. However, induced earthquakes were not identified during production activities. The lack of microseismic events could be the result of the shallow depth of the geothermal resource, approximately 850 m below the earth surface. Future studies include a receiver function analysis to determine crustal boundaries beneath NHS, along with further monitoring of induced seismicity due to geothermal fluid flow as the geothermal power plant comes online.

Brenn, G. R.; Liberty, L. M.; Van Wijk, K.; Shaltry, D.; Colwell, C.

2012-12-01

91

Double-diffusive convection in geothermal systems: the salton sea, California, geothermal system as a likely candidate  

USGS Publications Warehouse

Much has been published about double-diffusive convection as a mechanism for explaining variations in composition and temperature within all-liquid natural systems. However, relatively little is known about the applicability of this phenomenon within the heterogeneous rocks of currently active geothermal systems where primary porosity may control fluid flow in some places and fractures may control it in others. The main appeal of double-diffusive convection within hydrothermal systems is-that it is a mechanism that may allow efficient transfer of heat mainly by convection, while at the same time maintaining vertical and lateral salinity gradients. The Salton Sea geothermal system exhibits the following reservoir characteristics: (1) decreasing salinity and temperature from bottom to top and center toward the sides, (2) a very high heat flow from the top of the system that seems to require a major component of convective transfer of heat within the chemically stratified main reservoir, and (3) a relatively uniform density of the reservoir fluid throughout the system at all combinations of subsurface temperature, pressure, and salinity. Double-diffusive convection can account for these characteristics very nicely whereas other previously suggested models appear to account either for the thermal structure or for the salinity variations, but not both. Hydrologists, reservoir engineers, and particularly geochemists should consider the possibility and consequences of double-diffusive convection when formulating models of hydrothermal processes, and of the response of reservoirs to testing and production. ?? 1990.

Fournier, R.O.

1990-01-01

92

Geology of the Rotorua geothermal system  

SciTech Connect

This paper discusses the Rotorua geothermal system located in the south part of Rotorua Caldera, which collapsed during and after the eruption of Mamaku Ignimbrite some 140 ka ago. Drillholes provide geological and hydrological information to 300 m depth. The Mamaku Ignimbrite aquifer has been drilled in the east and south of the field where it contains fluid at or near boiling point. The Ignimbrite drops from south to north across exposed and buried caldera collapse scarps. Rotorua City domes comprise a buried N-S ridge rising at either end to form north and south domes; both contain mostly sub-boiling water up to 190{degrees} C which flows laterally through the outer 40 m of permeably rhyolite as indicated by temperature data. The Fenton Park aquifer comprises sands and gravels in the shallow sedimentary sequence which contain hot water derived possibly from Whakarewarewa, the south dome or the Rotoatamaheke Fault.

Wood, C.P. (DSIR Geology and Geophysics, Rotorua (NZ))

1992-04-01

93

Isotope Transport and Exchange within the Coso Geothermal System  

NASA Astrophysics Data System (ADS)

We are investigating the plumbing of the Coso geothermal system and the nearby Coso Hot Springs using finite element models of single-phase, variable-density fluid flow, conductive-convective heat transfer, fluid-rock isotope exchange, and groundwater residence times. Using detailed seismic reflection data and geologic mapping, we constructed a regional cross-sectional model that extends laterally from the Sierra Nevada to Wildhorse Mesa, west of the Argus Range. The base of the model terminates at the brittle-ductile transition zone. A sensitivity study was conducted using the model to explore the interaction between local and mountain front recharge, the effects of spatial variations in heat flow, and the role of permeable faults in controlling fluid circulation patterns. The model is constrained by present day bore hole temperature surveys, fluid inclusion temperatures, fluid-rock isotopic alteration patterns, and hot spring activity. While the results are non-unique, the analysis permits us to bracket the likely ranges of permeabilities and heat flow conditions that are consistent with observed data. Our findings suggest that active faults and seismogenic zones in and around the Coso geothermal area have much higher permeability and reactive surface areas than far field crustal rocks such as those in the Sierra Nevada. The Coso Wash fault zone must extend down to brittle- ductile transition zone depths of about 4 km in order for modeled results to match the observed hot spring activity.

Person, M.; Cohen, D.; Sabin, A.; Unruhn, J.; Gable, C.; Zyvoloski, G.; Monastero, F.

2006-12-01

94

Mantle Helium and Carbon Isotopes in Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon: Evidence for Renewed Volcanic Activity or a Long Term Steady State System?  

USGS Publications Warehouse

Here we present the helium and carbon isotope results from the initial study of a fluid chemistry-monitoring program started in the summer of 2001 near the South Sister volcano in central Oregon. The Separation Creek area which is several miles due west of the volcano is the locus of strong crustal uplift currently occurring at a rate of 4-5 cm/yr (Wicks, et. al., 2001).Helium [RC/RA = 7.44 and 8.61 RA (RC/R A = (3He/4He)sample-. air corrected/(3He/4He)air))] and carbon (??13C = -11.59 to -9.03??? vs PDB) isotope data and CO2/3He (5 and 9 ?? 109) show that bubbling cold springs in the Separation Creek area near South Sister volcano carry a strong mantle signal, indicating the presence of fresh basaltic magma in the volcanic plumbing system. There is no evidence though, to directly relate this signal to the crustal uplift that is currently taking place in the area, which started in 1998. The geothermal system in the area is apparently much longer lived and shows no significant changes in chemistry compared to data from the early 1990s. Hot springs in the area, which are relatively far removed from the volcanic edifice, do not carry a strong mantle signal in helium isotope ratios (2.79 to 5.08 RA), unlike the cold springs, and also do not show any significant changes in helium isotope ratios compared to literature data for the same springs of over two decades ago. The cold springs of the Separation Creek area form a very diffuse but significant low temperature geothermal system, that should, due to its close vicinity to the center of up uplift, be more sensitive to changes in the deeper volcanic plumbing system than the far removed hot springs and therefore require much more study and consideration when dealing with volcano monitoring in the Cascade range or possibly with geothermal exploration in general.

Van Soest, M. C.; Kennedy, B.M.; Evans, William C.; Mariner, R.H.

2002-01-01

95

Regional and Local Controls on the Distribution of Geothermal Systems in the Great Basin, Western United States  

NASA Astrophysics Data System (ADS)

In the Great Basin (GB) of the western United States, geothermal systems with reservoir temperatures in excess of 150 C can be classified into two main categories (magmatic and amagmatic) according to the presence or absence of shallow magmatic heat sources. Magmatic systems are restricted to the margins of the GB where they are closely associated with Quaternary silicic volcanic rocks, whereas amagmatic systems occur over a large portion of the Great Basin interior and are not spatially associated with young silicic volcanism. A tabulation of temperature gradients for known geothermal systems in the world confirms research by others indicating that both magmatic and amagmatic systems occur within areas of high temperature gradients and high heat flow. However, high heat flow alone is not sufficient to explain the abundance of high-temperature geothermal activity in the GB interior. While the distribution of favorable host rocks likely plays a role, active crustal tectonics appears instrumental in explaining patterns of geothermal activity. At a detailed scale, Quaternary faults control the location of most geothermal systems in the GB. However, hundreds of Quaternary faults are distributed throughout the GB, and most do not host high-temperature geothermal resources. Spatial statistical analysis demonstrates that high-temperature geothermal systems (more than 150 C) are preferentially associated with NE-striking Quaternary faults, which in turn are oriented roughly perpendicular to the current direction of crustal extension in the western GB. Maps of active crustal extension rates in the GB, derived from Global Positioning System (GPS) velocity measurements and estimated slip rates on Quaternary faults, correlate well with the distribution of high-temperature geothermal systems and help explain why some faults with lower slip rates or unfavorable orientations don't host geothermal activity. Many geothermal systems in the GB occur in a broad transitional region between the transtensional Walker Lane and the more extensional interior of the GB. This pattern of geothermal activity is helping to clarify the tectonic evolution of the northwestern GB, where dextral strike-slip faulting along the Walker Lane is being transferred into a series of extensional structures in the Humboldt structural zone and the central Nevada seismic zone. On-going research at the University of Nevada, Reno is investigating the relationship between active crustal transtension, evolution of the Walker Lane, and the occurrence of high-temperature geothermal resources. One part of this investigation is the setup of a 60-station semi-permanent GPS network with 20km station spacing in western Nevada. Results from this network will be instrumental in further constraining the regional strain rate field.

Coolbaugh, M. F.; Blewitt, G.; Faulds, J. E.; Kreemer, C. W.

2005-12-01

96

Technical support for geopressured-geothermal well activities in Louisiana  

SciTech Connect

Continuous recording microearthquake monitoring networks have been established around US Department of Energy (DOE) geopressured-geothermal design wells in southwestern Louisiana and southeastern Texas since summer 1980 to assess the effects well development may have had on subsidence and growth-fault activation. This monitoring has shown several unusual characteristics of Gulf Coast seismic activity. The observed activity is classified into two dominant types, one with identifiable body phases (type 1) and the other with only surface-wave signatures (type 2). During this reporting period no type 1 or body-wave events were reported. A total of 230 type 2 or surface-wave events were recorded. Origins of the type 2 events are still not positively understood; however, little or no evidence is available to connect them with geopressured-geothermal well activity. We continue to suspect sonic booms from military aircraft or some other human-induced source. 37 refs., 16 figs., 6 tabs.

Not Available

1991-07-01

97

Geothermics 35 (2006) 368408 Tectonic and magmatic evolution of the active  

E-print Network

Geothermics 35 (2006) 368408 Tectonic and magmatic evolution of the active volcanic front in El Salvador: insight into the Berlin and Ahuachapan geothermal areas Samuele Agostinia,, Giacomo Cortia products, at least during the Plio-Quaternary. Detailed analyses within the geothermal fields of Berl

Doglioni, Carlo

2006-01-01

98

Heat pump assisted geothermal heating system for Felix Spa, Romania  

SciTech Connect

The paper presents a pre-feasibility type study of a proposed heat pump assisted geothermal heating system for an average hotel in Felix Spa, Romania. After a brief presentation of the geothermal reservoir, the paper gives the methodology and the results of the technical and economical calculations. The technical and economical viability of the proposed system is discussed in detail in the final part of the paper.

Rosca, Marcel; Maghiar, Teodor

1996-01-24

99

Magnetotelluric imaging of the Reporoa geothermal system in New Zealand  

NASA Astrophysics Data System (ADS)

The Reporoa geothermal area is located in a caldera on the eastern side of the Taupo Volcanic Zone in the North Island of New Zealand. For the last 40 years scientists have argued whether Reporoa is an independent geothermal system or just an outflow structure of the Waiotapu geothermal system to the north. Due to its location and possible connection to the Waiotapu geothermal system, which is a protected system and a big tourist attraction, the Reporoa system needs to be well characterised before commercial exploitation can be considered. Early DC resistivity surveys yielded information to depths of about 1 km, but were unable to resolve which, if either, of the two competing models was correct. In this project we electrically image much deeper structures beneath the Reporoa geothermal area in order to understand better this system. MT is a passive geophysical exploration tool that utilises naturally-occurring, time-varying electromagnetic (EM) fields recorded on the surface to determine spatial variations in subsurface electrical resistivity. Temperature, porosity and fluid content, as well as hydrothermal alteration processes, have significant effects on patterns of subsurface electrical resistivity. Therefore, MT is well suited to image the different parts of a geothermal system, and is accordingly the most utilized geophysical imaging technique in geothermal research. For this study close to 100 broadband Magnetotelluric (MT) measurements, acquired during several separate surveys over a 3 year period, were analysed and modelled. Station spacing varied from 500 m to 2 km forming a grid over the study area. The maximum depth of investigation for this study, which is a function of the subsurface resistivity and the maximum period of measurement (100 s), is of the order of several kilometres. This paper will describe the data acquired and models derived. Preliminary results from this study indicate both an outflow structure from Waiotapu at shallow depths and an independent geothermal upflow at depth.

Walter, Christina; Jones, Alan G.; Ryan, Graham A.

2013-04-01

100

Seismic Velocity Structures of Larderello Geothermal System, Italy: Preliminary Results  

NASA Astrophysics Data System (ADS)

The steam-dominated geothermal system of Larderello is located in Tuscany and is the largest Italian area of electricity generation from geothermal resources. Enel Green Power, the main company of the ENEL Group involved in the renewable resources development, has drilled several wells down to maximum depth of about 4.0 km below see level in order to exploit deep and hot steam reservoirs. The explored area is about 400 km2 with an installed running capacity of about 530 MW. Two steam-dominated reservoirs were found at different depth. The shallowest one at depth of about 1 km, with pressure between 0.2 and 1.5 MPa and temperatures ranging between 150C and 260C, is hosted in very permeable carbonate formations (limestone and anhydrite). The deepest reservoir is located in the metamorphic basement up to depth of 3-4 km b.s.l. and is characterized by pressure of about 7.0 MPa and temperature ranging between 300C and 350C. Water reinjection is operating in the shallow reservoir of the geothermal area with the aim of both sustaining and increasing reservoir pressures as well as steam production. A network of 26 seismic stations, three of which are three components, permanently records the seismic activity of the Larderello area. Data analysis showed that epicenters span over the whole exploited region even though clusters are visible in particular areas; hypocentral depths are mainly distributed up to 10 km. More detailed hypocenter re-localization might indicate linear features due to regional stress field regime and to the fluid propagation paths into the fracture systems that previously might have been obscured within the seismic clouds. However, precise hypocenter localization calls for high-resolution 3D-velocity model of subsurface structures that is lacking for this area. This study has been addressed to purse this goal and, as a consequence, images of the seismic velocity structures from earthquakes tomographic inversion have been computed. This area was chosen as a suitable test site since the availability of well data can provide a more constrained a priori velocity model. The analyzed data set consists of approximately 500 microearthquakes occurring from January 1994 through September 2000. The estimate duration magnitude ranges between 0-3. The good quality of recorded waveforms allowed us for high precision readings of P- and S- wave first arrivals. Results of a 3D velocity tomographic inversion contributed for a high-quality imaging of subsurface structures in term of Vp and Vp/Vs ratio that may be correlated to the main geological features of the geothermal system.

de Matteis, R.; Vanorio, T.; Ciulli, B.; Spinelli, E.; Fiordelisi, A.; Zollo, A.

2002-12-01

101

Campi Flegrei Deep Drilling Project and geothermal activities in Campania Region (Southern Italy)  

NASA Astrophysics Data System (ADS)

The Campanian volcanic area has a huge geothermal potential (Carlino et al., 2012), similar to the Larderello-Radicondoli-Amiata region, in Tuscany (Italy), which has been the first site in the World exploited for electric production. Recently, the Campi Flegrei Deep Drilling Project (CFDDP), sponsored by ICDP and devoted to understand and mitigate the extreme volcanic risk in the area, has also risen new interest for geothermal exploration in several areas of Italy. Following the new Italian regulations which favour and incentivise innovative pilot power plants with zero emission, several geothermal projects have started in the Campania Region, characterized by strict cooperation among large to small industries, Universities and public Research Centers. INGV department of Naples (Osservatorio Vesuviano) has the technical/scientific leadership of such initiatives. Most of such projects are coordinated in the framework of the Regional District for Energy, in which a large part is represented by geothermal resource. Leading geothermal projects in the area include 'FORIO' pilot plant project, aimed to build two small (5 MWe each one) power plants in the Ischia island and two projects aimed to build pilot power plants in the Agnano-Fuorigrotta area in the city of Naples, at the easternmost part of Campi Flegrei caldera. One of the Campi Flegrei projects, 'SCARFOGLIO', is aimed to build a 5 MWe geothermal power plant in the Agnano area, whereas the 'START' project has the goal to build a tri-generation power plant in the Fuorigrotta area, fed mainly by geothermal source improved by solar termodynamic and bio-mass. Meanwhile such projects enter the field work operational phase, the pilot hole drilling of the CFDDP project, recently completed, represents an important experience for several operational aspects, which should contitute an example to be followed by the next geothermal activities in the area. It has been furthermore a source of valuable data for geothermal characterization of the Agnano-Fuorigrotta area, despite its mainly volcanological goals. In particular, the drilling site was equipped with dense and multidisciplinary continuous monitoring systems, an example to follow anyway to assure the minimum impact on such densely urbanised areas. Furthermore, innovative leak-off experiments mainly aimed to permeability and strength/stress measurements have been developed and tested. Such tests show permeability values before water injection between 10-14 and 10-15 m2 and, moreover, put in evidence a significant local increase of permeability obtained at the end of the injection experiment.

De Natale, Giuseppe; Troise, Claudia; Troiano, Antonio; Giulia Di Giuseppe, Maria; Mormone, Angela; Carlino, Stefano; Somma, Renato; Tramelli, Anna; Vertechi, Enrico; Sangianantoni, Agata; Piochi, Monica

2013-04-01

102

Enhanced Geothermal Systems (EGS) R&D Program  

SciTech Connect

The purpose of this workshop was to develop technical background facts necessary for planning continued research and development of Enhanced Geothermal Systems (EGS). EGS are geothermal reservoirs that require improvement of their permeability or fluid contents in order to achieve economic energy production. The initial focus of this R&D program is devising and testing means to extract additional economic energy from marginal volumes of hydrothermal reservoirs that are already producing commercial energy. By mid-1999, the evolution of the EGS R&D Program, begun in FY 1988 by the U.S. Department of Energy (DOE), reached the stage where considerable expertise had to be brought to bear on what technical goals should be pursued. The main purpose of this Workshop was to do that. The Workshop was sponsored by the Office of Geothermal Technologies of the Department of Energy. Its purpose and timing were endorsed by the EGS National Coordinating Committee, through which the EGS R&D Program receives guidance from members of the U.S. geothermal industry. Section 1.0 of this report documents the EGS R&D Program Review Session. There, managers and researchers described the goals and activities of the program. Recent experience with injection at The Geysers and analysis of downhole conditions at Dixie Valley highlighted this session. Section 2.0 contains a number of technical presentations that were invited or volunteered to illuminate important technical and economic facts and opportunities for research. The emphasis here was on fi.acture creation, detection, and analysis. Section 3.0 documents the initial general discussions of the participants. Important topics that emerged were: Specificity of defined projects, Optimizing cost effectiveness, Main technical areas to work on, Overlaps between EGS and Reservoir Technology R&D areas, Relationship of microseismic events to hydraulic fractures, and Defining criteria for prioritizing research thrusts. Sections 4.0 and 5.0 report the meat of the Workshop. Section 4.0 describes the nomination and clarification of technical thrusts, and Section 5.0 reports the results of prioritizing those thrusts via voting by the participants. Section 6.0 contains two discussions conducted after the work on research thrusts. The topics were ''Simulation'' and ''Stimulation''. A number of technical points that emerged here provide important guidance for both practical field work on EGS systems and for research.

Entingh, Daniel J.

1999-08-18

103

Changes in thermal activity in the Rotorua geothermal field  

SciTech Connect

During a period when geothermal fluid was being withdrawn for energy use at an increasing rate, the level of natural hydrothermal activity in the Rotorua geothermal field declined in an all-time low in the mid 1980s. total heatflow from a major hot-spring area fell by almost 50 percent, springs ceased their flow, and geysers displayed abnormal behavior consistent with a low aquifer pressure. since the enforced closure of bores within 1.5 km of Pohutu Geyser, sings of recovery, including a return to normal behavior of Pohutu and Waikorohihi Geysers, a resumption of activity at Kereru Geyser, and an increase in water flow from some springs are presented in this paper.

Cody, A.D. (DSIR Geology and Geophysics, P.O. Box 499, Rotorua (NZ)); Lumb, J.T. (DSIR Geology and Geophysics, P.O. Box 1320, Wellington (NZ))

1992-04-01

104

Investigation of a fossil geothermal system, Hamblin-Cleopatra Volcano, Clark County, Nevada. Final technical report  

SciTech Connect

The Hamblin-Cleopatra volcano, selected for study because erosion and fault displacement have exposed the entire volcanic succession, the intrusive core, a radial dike systems, and sedimentary and volcanic rocks that predate and postdate the volcano, was investigated to estimate the proportions of igneous materials forming lava flows, pyroclastic deposits, intrusive bodies, and reworked debris. Chemical changes in the magma throughout the active period of the volcano were documented. The geothermal system active within the pile after activity ceased was reconstructed. (ACR)

Barker, D.S.

1986-07-28

105

Geothermal direct applications hardware systems development and testing. 1979 summary report  

SciTech Connect

Activities performed during calendar year 1979 for the hardware system development and testing task are presented. The fluidized bed technology was applied to the drying of potato by-products and to the exchange of heat to air in the space heating experiment. Geothermal water was flashed to steam and also used as the prime energy source in the steam distillation of peppermint oil. Geothermal water temperatures as low as 112.8/sup 0/C were utilized to distill alcohol from sugar beet juice, and lower temperature water provided air conditioning through an absorption air conditioning system. These experiments are discussed.

Keller, J.G.

1980-03-01

106

Documentation of the status of international geothermal power plants and a list by country of selected geothermally active governmental and private sector entities  

SciTech Connect

This report includes the printouts from the International Geothermal Power Plant Data Base and the Geothermally Active Entity Data Base. Also included are the explanation of the abbreviations used in the power plant data base, maps of geothermal installations by country, and data base questionnaires and mailing lists.

Not Available

1992-10-01

107

Three dimensional images of geothermal systems: local earthquake P-wave velocity tomography at the Hengill and Krafla geothermal areas, Iceland, and The Geysers, California  

USGS Publications Warehouse

Local earthquake tomography - the use of earthquake signals to form a 3-dimensional structural image - is now a mature geophysical analysis method, particularly suited to the study of geothermal reservoirs, which are often seismically active and severely laterally inhomogeneous. Studies have been conducted of the Hengill (Iceland), Krafla (Iceland) and The Geysers (California) geothermal areas. All three systems are exploited for electricity and/or heat production, and all are highly seismically active. Tomographic studies of volumes a few km in dimension were conducted for each area using the method of Thurber (1983).

Julian, B.R.; Prisk, A.; Foulger, G.R.; Evans, J.R.

1993-01-01

108

A chlorite solid solution geothermometer the Los Azufres (Mexico) geothermal system  

Microsoft Academic Search

Chlorite constitutes a major hydrothermal alteration product of metamorphism of andesites, in the active geothermal system of Los Azufres (Mexico). Electron microprobe analyses performed on a set of crystals from each sample show wide variations in composition. Correlation coefficients among chemical constituents were calculated. It is shown that the tetrahedral charge is positively correlated with the octahedral vacancy and negatively

Michel Cathelineau; David Nieva

1985-01-01

109

The nature of magmatism at Palinpinon geothermal field, Negros Island, Philippines: implications for geothermal activity and regional tectonics  

NASA Astrophysics Data System (ADS)

The Palinpinon geothermal field, Negros Island, Philippines is a high-temperature, liquid-dominated geothermal system in an active island-arc volcanic setting. This paper presents a regional context for the Palinpinon geology, discusses the petrogenetic evolution of magmatism in the district and assesses the genetic relationships between intrusion and geothermal circulation. The oldest rock formation, the Lower Puhagan Volcanic Formation (Middle Miocene), is part of a volcanic sequence that is traceable throughout the Visayas region and is related to subduction of the Sulu Sea oceanic basin in a southeasterly direction beneath the Sulu arc. Late Miocene to Early Pliocene times mark a period of regional subsidence and marine sedimentation. A thick sequence of calcareous sediments (Okoy Formation) was deposited during this period. Magmatism in Early Pliocene to Recent times coincided with commencement of subduction at the Negros-Sulu Arc. This produced basaltic andesites and andesites belonging to the Southern Negros and Cuernos Volcanic Formations. During this time the Puhagan dikes and the Nasuji Pluton intruded Middle Miocene, Late Miocene and Early-Late Pliocene formations. Based on radiogenic ( 40Ar/ 39Ar) dating of hornblende, the Puhagan dikes are 4.1-4.2 Ma and the Nasuji Pluton 0.3-0.7 Ma. This age difference confirms these intrusions are not genetically related. The Early Pliocene age of the Puhagan dikes also confirms they are not the heat source for the current geothermal system and that a much younger intrusion is situated beyond drill depths. Igneous rock formations in southern Negros are the products of regional island-arc magmatism with medium K, calc-alkaline, basaltic to dacitic compositions. Their adakitic affinity implies that the melting of subducted oceanic basalt has influenced magmatism in this region. Considering the regional tectonic history the most likely scenarios for the generation of slab melts are: (1) during the Middle Miocene, by the melting of relatively young (<20 Ma) oceanic crust; (2) during Early Pliocene times, by the initiation of subduction along the Negros-Sulu Trench; and (3) during Late Pliocene times, by the melting of young (<10-20 Ma) oceanic crust. The adakitic composition of the magmas at Palinpinon has promoted the formation of a porphyry copper-style magmatic-hydrothermal system that is comparable to mineralised porphyry deposits elsewhere in the Philippines.

Rae, Andrew J.; Cooke, David R.; Phillips, David; Zaide-Delfin, Maribel

2004-01-01

110

Community Geothermal Technology Program: Bottom heating system using geothermal power for propagation. Final report, Phases 1 and 2  

Microsoft Academic Search

The objective is to develop and study a bottom-heating system in a greenhouse utilizing geothermal energy to aid germination and speed growth of palms. Source of heat was geothermal brine from HGP-A well. The project was successful; the heat made a dramatic difference with certain varieties, such as Areca catechu (betelnut) with 82% germination with heat, zero without. For other

1990-01-01

111

The Newcastle geothermal system, Iron County, Utah  

SciTech Connect

Geological, geophysical and geochemical studies contributed to conceptual hydrologic model of the blind'' (no surface expression), moderate-temperature (greater than 130{degree}C) Newcastle geothermal system, located in the Basin and Range-Colorado Plateau transition zone of southwestern Utah. Temperature gradient measurements define a thermal anomaly centered near the surface trace of the range-bounding Antelope Range fault with and elongate dissipative plume extending north into the adjacent Escalante Valley. Spontaneous potential and resistivity surveys sharply define the geometry of the dominant upflow zone (not yet explored), indicating that most of the thermal fluid issues form a short segment along the Antelope Range fault and discharges into a gently-dipping aquifer. Production wells show that this aquifer lies at a depth between 85 and 95 meter. Electrical surveys also show that some leakage of thermal fluid occurs over a 1.5 km (minimum) interval along the trace of the Antelope Range fault. Major element, oxygen and hydrogen isotopic analyses of water samples indicate that the thermal fluid is a mixture of meteoric water derived from recharge areas in the Pine Valley Mountains and cold, shallow groundwater. A northwest-southeast trending system of faults, encompassing a zone of increased fracture permeability, collects meteoric water from the recharge area, allows circulation to a depth of 3 to 5 kilometers, and intersects the northeast-striking Antelope Range fault. We postulate that mineral precipitates form a seal along the Antelope Range fault, preventing the discharge of thermal fluids into basin-fill sediments at depth, and allowing heated fluid to approach the surface. Eventually, continued mineral deposition could result in the development of hot springs at the ground surface.

Blackett, R.E.; Shubat, M.A.; Bishop, C.E. (Utah Geological and Mineral Survey, Salt Lake City, UT (USA)); Chapman, D.S.; Forster, C.B.; Schlinger, C.M. (Utah Univ., Salt Lake City, UT (USA). Dept. of Geology and Geophysics)

1990-03-01

112

Tectonic and Structural Controls of Geothermal Activity in the Great Basin Region, Western USA  

NASA Astrophysics Data System (ADS)

We are conducting a thorough inventory of structural settings of geothermal systems (>400 total) in the extensional to transtensional Great Basin region of the western USA. Most of the geothermal systems in this region are not related to upper crustal magmatism and thus regional tectonic and local structural controls are the most critical factors controlling the locations of the geothermal activity. A system of NW-striking dextral faults known as the Walker Lane accommodates ~20% of the North American-Pacific plate motion in the western Great Basin and is intimately linked to N- to NNE-striking normal fault systems throughout the region. Overall, geothermal systems are concentrated in areas with the highest strain rates within or proximal to the eastern and western margins of the Great Basin, with the high temperature systems clustering in transtensional areas of highest strain rate in the northwestern Great Basin. Enhanced extension in the northwestern Great Basin probably results from the northwestward termination of the Walker Lane and the concomitant transfer of dextral shear into west-northwest directed extension, thus producing a broad transtensional region. The capacity of geothermal power plants also correlates with strain rates, with the largest (hundreds of megawatts) along the Walker Lane or San Andreas fault system, where strain rates range from 10-100 nanostrain/yr to 1,000 nanostrain/yr, respectively. Lesser systems (tens of megawatts) reside in the Basin and Range (outside the Walker Lane), where local strain rates are typically < 10 nanostrain/yr. Of the 250+ geothermal fields catalogued, step-overs or relay ramps in normal fault zones serve as the most favorable setting, hosting ~32% of the systems. Such areas have multiple, overlapping fault strands, increased fracture density, and thus enhanced permeability. Other common settings include a) intersections between normal faults and strike-slip or oblique-slip faults (27%), where multiple minor faults connect major structures and fluids can flow readily through highly fractured, dilational quadrants, and b) normal fault terminations or tip-lines (22%), where horse-tailing generates closely-spaced faults and increased permeability. Other settings include accommodation zones (i.e., belts of intermeshing, oppositely dipping normal faults; 8%), major range-front faults (5-6%), and pull-aparts in strike-slip faults (4%). In addition, Quaternary faults lie within or near most systems. The relative scarcity of geothermal systems along displacement-maxima of major normal faults may be due to reduced permeability in thick zones of clay gouge and periodic release of stress in major earthquakes. Step-overs, terminations, intersections, and accommodation zones correspond to long-term, critically stressed areas, where fluid pathways are more likely to remain open in networks of closely-spaced, breccia-dominated fractures. These findings may help guide future exploration efforts, especially for blind geothermal systems, which probably comprise the bulk of the geothermal resources in the Great Basin.

Faulds, J. E.; Hinz, N.; Kreemer, C. W.

2012-12-01

113

Geomechanics of Hydraulic Stimulation in Geothermal Systems: Designing and Implementing a Successful Enhanced Geothermal System at Desert Peak, Nevada  

NASA Astrophysics Data System (ADS)

Creation of an Enhanced Geothermal System (EGS) in hot but low-permeability rocks involves hydraulic stimulation of fracture permeability to develop a complex heat exchange system with low hydraulic impedance. An integrated study of stress, fractures and rock mechanical properties was conducted to develop the geomechanical framework for a multi-stage EGS stimulation in Desert Peak well 27-15, located at the low-permeability margins of an active geothermal field. The stimulation targeted silicified tuffs and metamorphosed mudstones at depths of 0.9 to 1.8 km and temperatures ~180 to 210 C. Drilling-induced tensile fractures in image logs from well 27-15 show that the least horizontal principal stress (Shmin) is consistent with normal faulting on ESE- and WNW-dipping fractures mapped at the surface and seen in the image logs. A hydraulic fracturing stress measurement indicates that the magnitude of Shmin at ~0.93 km depth is 0.61 of the calculated vertical stress. Coulomb failure calculations using these stresses together with measurements of friction and permeability on core predict that dilatant shear failure should be induced on pre-existing conjugate normal faults once pore pressures are increased ~2.5 MPa or more above ambient values, generating a zone of enhanced permeability elongated in the direction toward active geothermal wells ~0.5 km to the SSW. Hydraulic stimulation of well 27-15 began in September 2010 by injecting water into the open-hole interval between the casing shoe at 0.9 km depth and a temporary cement plug at 1.1 km. Stimulation was monitored by combined surface and down-hole seismic monitoring, inter-well tracer testing and periodic pressure-temperature-flowmeter logging. An initial stage of low-pressure (shear) stimulation was conducted for ~100 days at a series of pressure steps Shmin and injection rates up to 2800 l/min, resulting in an additional 6-fold increase in injectivity. Numerous microearthquakes induced during this high-pressure stage along with tracer testing demonstrated growth of the stimulated volume and establishment of a strong hydrologic connection between well 27-15 and geothermal production wells to the SSW. After drilling out the cement plug and opening up the stimulation zone to the total depth of the well (1.8 km), additional stages of low- and high-pressure stimulation were carried out in early 2013. This full-hole stimulation was characterized by continued growth of the microseismic cloud in the NNE - SSW direction and strong tracer returns to the main geothermal field. A cumulative 175-fold injectivity gain was achieved in well 27-15 over the entire EGS project, which exceeded project goals. The Desert Peak geomechanical model predicted both the approximate initiation criteria and directional characteristics of the injection-induced shear and tensile failure and resulting permeability gains that led to success of this EGS project.

Hickman, S. H.; Davatzes, N. C.; Zemach, E.; Chabora, E.; Lutz, S.; Rose, P.; Majer, E. L.; Robertson-Tait, A.

2013-12-01

114

Standard Guide for Specifying Thermal Performance of Geothermal Power Systems  

E-print Network

1.1 This guide covers power plant performance terms and criteria for use in evaluation and comparison of geothermal energy conversion and power generation systems. The special nature of these geothermal systems makes performance criteria commonly used to evaluate conventional fossil fuel-fired systems of limited value. This guide identifies the limitations of the less useful criteria and defines an equitable basis for measuring the quality of differing thermal cycles and plant equipment for geothermal resources. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

American Society for Testing and Materials. Philadelphia

2000-01-01

115

Recommendations of the workshop on advanced geothermal drilling systems  

SciTech Connect

At the request of the U.S. Department of Energy, Office of Geothermal Technologies, Sandia National Laboratories convened a group of drilling experts in Berkeley, CA, on April 15-16, 1997, to discuss advanced geothermal drilling systems. The objective of the workshop was to develop one or more conceptual designs for an advanced geothermal drilling system that meets all of the criteria necessary to drill a model geothermal well. The drilling process was divided into ten essential functions. Each function was examined, and discussions were held on the conventional methods used to accomplish each function and the problems commonly encountered. Alternative methods of performing each function were then listed and evaluated by the group. Alternative methods considered feasible or at least worth further investigation were identified, while methods considered impractical or not potentially cost-saving were eliminated from further discussion. This report summarizes the recommendations of the workshop participants. For each of the ten functions, the conventional methods, common problems, and recommended alternative technologies and methods are listed. Each recommended alternative is discussed, and a description is given of the process by which this information will be used by the U.S. DOE to develop an advanced geothermal drilling research program.

Glowka, D.A.

1997-12-01

116

A market survey of geothermal wellhead power generation systems  

NASA Technical Reports Server (NTRS)

The market potential for a portable geothermal wellhead power conversion device is assessed. Major study objectives included identifying the most promising applications for such a system, the potential impediments confronting their industrialization, and the various government actions needed to overcome these impediments. The heart of the study was a series of structured interviews with key decision-making individual in the various disciplines of the geothermal community. In addition, some technical and economic analyses of a candidate system were performed to support the feasibility of the basic concept.

Leeds, M. W.

1978-01-01

117

Modeling and analysis of hybrid geothermal-solar thermal energy conversion systems  

E-print Network

Innovative solar-geothermal hybrid energy conversion systems were developed for low enthalpy geothermal resources augmented with solar energy. The goal is to find cost-effective hybrid power cycles that take advantage of ...

Greenhut, Andrew David

2010-01-01

118

Dual-temperature Kalina cycle for geothermal-solar hybrid power systems  

E-print Network

This thesis analyzes the thermodynamics of a power system coupling two renewable heat sources: low-temperature geothermal and a high-temperature solar. The process, referred to as a dual-temperature geothermal-solar Kalina ...

Boghossian, John G

2011-01-01

119

Progress Toward an Advanced Geothermal Deep-Drilling System  

SciTech Connect

A previously developed concept for an advanced geothermal drilling system (AGDS) has been extended toward a feasibility design stage. Hardware projects for two percussion, air and hydraulic, hammer drills are underway. Two drill string options and an unique nitrogen supply system are described.

Rowley, J.; Saito, S.; Long, R.

1995-01-01

120

Mathematical modeling of the behavior of geothermal systems under exploitation  

SciTech Connect

Analytical and numerical methods have been used in this investigation to model the behavior of geothermal systems under exploitation. The work is divided into three parts: (1) development of a numerical code, (2) theoretical studies of geothermal systems, and (3) field applications. A new single-phase three-dimensional simulator, capable of solving heat and mass flow problems in a saturated, heterogeneous porous or fractured medium has been developed. The simulator uses the integrated finite difference method for formulating the governing equations and an efficient sparse solver for the solution of the linearized equations. In the theoretical studies, various reservoir engineering problems have been examined. These include (a) well-test analysis, (b) exploitation strategies, (c) injection into fractured rocks, and (d) fault-charged geothermal reservoirs.

Bodvarsson, G.S.

1982-01-01

121

Methanotrophic activity and diversity of methanotrophs in volcanic geothermal soils at Pantelleria (Italy)  

NASA Astrophysics Data System (ADS)

Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic or geothermal soils are not only a source of methane, but are also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria (Italy), Favara Grande, whose total methane emission was previously estimated at about 2.5 Mg a-1 (t a-1). Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values of up to 59.2 nmol g-1 soil d.w. h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile, the maximum methane consumption was measured in the top-soil layer, and values greater than 6.23 nmol g-1 h-1 were still detected up to a depth of 13 cm. The highest consumption rate was measured at 37 C, but a still detectable consumption at 80 C (> 1.25 nmol g-1 h-1) was recorded. The soil total DNA extracted from the three samples was probed by Polymerase Chain Reaction (PCR) using standard proteobacterial primers and newly designed verrucomicrobial primers, targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected at sites FAV2 and FAV3, but not at FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site (FAV2) pointed to a high diversity of gammaproteobacterial methanotrophs, distantly related to Methylocaldum-Metylococcus genera, and the presence of the newly discovered acido-thermophilic Verrucomicrobia methanotrophs. Alphaproteobacteria of the genus Methylocystis were isolated from enrichment cultures under a methane-containing atmosphere at 37 C. The isolates grow at a pH range of 3.5 to 8 and temperatures of 18-45 C, and consume 160 nmol of CH4 h-1 mL-1 of culture. Soils from Favara Grande showed the largest diversity of methanotrophic bacteria detected until now in a geothermal soil. While methanotrophic Verrucomicrobia are reported as dominating highly acidic geothermal sites, our results suggest that slightly acidic soils, in high-enthalpy geothermal systems, host a more diverse group of both culturable and uncultivated methanotrophs.

Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

2014-10-01

122

Methanotrophic activity and bacterial diversity in volcanic-geothermal soils at Pantelleria island (Italy)  

NASA Astrophysics Data System (ADS)

Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic/geothermal soils are source of methane, but also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria island (Italy), Favara Grande, whose total methane emission was previously estimated in about 2.5 t a-1. Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values up to 950 ng g-1 dry soil h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile and the maximum methane consumption was measured in the top-soil layer but values > 100 ng g-1 h-1 were maintained up to a depth of 15 cm. The highest consumption rate was measured at 37 C, but a still recognizable consumption at 80 C (> 20 ng g-1 h-1) was recorded. In order to estimate the bacterial diversity, total soil DNA was extracted from Favara Grande and analysed using a Temporal Temperature Gradient gel Electrophoresis (TTGE) analysis of the amplified bacterial 16S rRNA gene. The three soil samples were probed by PCR using standard proteobacterial primers and newly designed verrucomicrobial primers targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected in sites FAV2 and FAV3, but not in FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site FAV2 pointed out a high diversity of gammaproteobacterial methanotrophs distantly related to Methylococcus/Methylothermus genera and the presence of the newly discovered acido-thermophilic methanotrophs Verrucomicrobia. Alphaproteobacteria of the genus Methylocystis were isolated from enrichment cultures, under a methane containing atmosphere at 37 C. The isolates grow at pH 3.5-8 and temperatures of 18-45 C, and show a methane oxidation rate of ~ 450 ?mol mol-1 h-1. Soils from Favara Grande showed the largest diversity of methanotrophic bacteria until now detected in a geothermal soil. While methanotrophic Verrucomicrobia are reported to dominate highly acidic geothermal sites, our results suggest that slightly acidic soils, in high enthalpy geothermal systems, host a more diverse group of both culturable and uncultivated methanotrophs.

Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

2014-04-01

123

Recent Development of HFR Geothermal Reservoir System in Australia  

NASA Astrophysics Data System (ADS)

Since the 1970's, a number of research programmes have worked towards developing Hot Dry Rock technology (HDR) for geothermal energy which has been renamed as Hot Fractured Rock (HFR) in Australia. The HFR energy resource has the potential to supply base-load power with no greenhouse gas emissions. This paper will introduce the recent development of HFR geothermal reservoir system in Australia and focus on our related outcomes on numerical software development and field site operation as follows: (1). Geodynamics Limited is continuing to develop a world-class, high-grade geothermal energy resource contained in high temperature granites beneath the Cooper Basin in NE South Australia, which represents the largest known geothermal resource in the world and has the potential to supply 1000's MWe of low cost power to the national grid. The first deep well has reached a depth of over 4,400m, with temperatures exceeding 250C. Subsequent to drilling the well, a hydraulic stimulation programme resulted in the development of a large underground heat exchanger(reservoir). The encountered conditions of the hot granite are more favourable than expected. The economic feasibility of extracting heat from this reservoir will be established through a circulation test at 4,500m with the drilling of the production well. (2) Geothermal reservoir system as above involves the thermal, fluid and mechanical behaviour of geo-materials and natural seismic events, and potential geological perturbations to the geothermal reservoir. With the ARC Linkage grant, a 3D finite element based computational model and software for simulating a multi-scale highly coupled thermo-hydro-mechanical geo-mechanical system on the parallel supercomputer are being developed and preliminarily applied to analyze the Cooper Basin based on the available filed site data as above.

Xing, H.; Wyborn, D.; Xu, H.; Yin, C.; Mora, P.

2006-12-01

124

The importance of CO on freezing point measurements of fluid inclusions: evidence from active geothermal systems and implications for epithermal ore deposition  

Microsoft Academic Search

The authors show how the melting point of ice may be calculated for a fluid of known composites. Fluid inclusion ice-melting data from New Zealand geothermal fields correlate well with values calculated using the equation presented and the measured compositions of discharges from wells from which the inclusion samples were obtained. Loss of the dominant dissolved gas, CO during boiling

J. W. Hedenquist; R. W. Henley

1985-01-01

125

Reno Industrial Park geothermal district heating system  

Microsoft Academic Search

Ten miles south of Reno, on U.S. 395 near the junction of the road to historic Virginia City, is Steamboat Hot Springs, a popular stop for travelers since the mid-1800s. Legend has it that Mark Twain named the geothermal area because it looked and sounded like a chugging Mississippi River paddle-wheeler. It is said when he first saw the steam

Paul J. Lienau

1997-01-01

126

Direct utilization of geothermal heat in cascade application to aquaculture and greenhouse systems at Navarro College. Final report, March 1, 1979-September 30, 1984  

SciTech Connect

This final report documents the Navarro College geothermal use project, which is one of nineteen direct-use geothermal projects funded principally by DOE. The six-year project encompassed a broad range of technical, institutional, and economic activities including: resource and environmental assessment; well drilling and completion; system design, construction, and monitoring; economic analysis; and public awareness programs. Some of the project conclusions are that: (1) the 130/sup 0/F Central Texas geothermal resource can support additional geothermal development; (2) private sector economic incentives currently exist which encourage commercial development of this geothermal resource; (3) potential uses for this geothermal resource include water and space heating, aquacultural and agricultural heating uses, and fruit and vegetable dehydration; (4) high maintenance costs arising from the geofluids' scaling and corrosion characteristics can be avoided through proper analysis and design.

Smith, K.

1984-09-01

127

Applied Microearthquake Techniques for Geothermal Resource Development  

E-print Network

Applied Microearthquake Techniques for Geothermal Resource Development Gillian R. Foulger1 & Bruce@usgs.gov Geothermal areas are often associated with microearthquake activity [Foulger, 1982; Foulger and Long, 1984], and these earthquakes have often been used to learn more about both exploited and unexploited geothermal systems

Foulger, G. R.

128

Description and operation of Haakon School geothermal-heating system  

SciTech Connect

To encourage the development of hydrothermal energy, twenty-three demonstration projects were funded. The Haakon School project is one of twelve such projects. The geothermal direct-use heating system at the Haakon School complex in Philip, South Dakota is described and information gained during approximately three heating seasons of operation is presented.

Childs, F.W.; Kirol, L.D.; Sanders, R.D.; McLatchy, M.J.

1983-10-01

129

Lithium isotopes in island arc geothermal systems: Guadeloupe, Martinique (French West Indies) and experimental approach  

E-print Network

Lithium isotopes in island arc geothermal systems: Guadeloupe, Martinique (French West Indies'Orléans, Orléans, France (3) BRGM, Department of Geothermal Energy, Orléans, France Abstract We report Li isotopic measurements in seawater derived waters discharged from geothermal wells, thermal and submarine springs located

Boyer, Edmond

130

Numerical modeling of geothermal systems with applications to Krafla, Iceland and Olkaria, Kenya  

SciTech Connect

The use of numerical models for the evaluation of the generating potential of high temperature geothermal fields has increased rapidly in recent years. In the present paper a unified numerical approach to the modeling of geothermal systems is discussed and the results of recent modeling of the Krafla geothermal field in Iceland and the Olkaria, Kenya, are described. Emphasis is placed on describing the methodology using examples from the two geothermal fields.

Bodvarsson, G.S.

1987-08-01

131

COTHERM: Geophysical Modeling of High Enthalpy Geothermal Systems  

NASA Astrophysics Data System (ADS)

In recent years geothermal heating and electricity generation have become an attractive alternative energy resource, especially natural high enthalpy geothermal systems such as in Iceland. However, the financial risk of installing and operating geothermal power plants is still high and more needs to be known about the geothermal processes and state of the reservoir in the subsurface. A powerful tool for probing the underground system structure is provided by geophysical techniques, which are able to detect flow paths and fracture systems without drilling. It has been amply demonstrated that small-scale features can be well imaged at shallow depths, but only gross structures can be delineated for depths of several kilometers, where most high enthalpy systems are located. Therefore a major goal of our study is to improve geophysical mapping strategies by multi-method geophysical simulations and synthetic data inversions, to better resolve structures at greater depth, characterize the reservoir and monitor any changes within it. The investigation forms part of project COTHERM - COmbined hydrological, geochemical and geophysical modeling of geoTHERMal systems - in which a holistic and synergistic approach is being adopted to achieve multidisciplinary cooperation and mutual benefit. The geophysical simulations are being performed in combination with hydrothermal fluid flow modeling and chemical fluid rock interaction modeling, to provide realistic constraints on lithology, pressure, temperature and fluid conditions of the subsurface. Two sites in Iceland have been selected for the study, Krafla and Reykjanes. As a starting point for the geophysical modeling, we seek to establish petrophysical relations, connecting rock properties and reservoir conditions with geophysical parameters such as seismic wave speed, attenuation, electrical conductivity and magnetic susceptibility with a main focus on seismic properties. Therefore, we follow a comprehensive approach involving three components: (1) A literature study to find relevant, existing theoretical models, (2) laboratory determinations to confirm their validity for Icelandic rocks of interest and (3) a field campaign to obtain in-situ, shallow rock properties from seismic and resistivity tomography surveys over a fossilized and exhumed geothermal system. Theoretical models describing physical behavior for rocks with strong inhomogeneities, complex pore structure and complicated fluid-rock interaction mechanisms are often poorly constrained and require the knowledge about a wide range of parameters that are difficult to quantify. Therefore we calibrate the theoretical models by laboratory measurements on samples of rocks, forming magmatic geothermal reservoirs. Since the samples used in the laboratory are limited in size, and laboratory equipment operates at much higher frequency than the instruments used in the field, the results need to be up-scaled from the laboratory scale to field scale. This is not a simple process and entails many uncertainties.

Grab, Melchior; Maurer, Hansruedi; Greenhalgh, Stewart

2014-05-01

132

Description and operation of Haakon School geothermal heating system  

SciTech Connect

Haakon School is located in the city of Philip, near the Badlands National Park in the southwest quadrant of South Dakota. The town overlies the Madison Formation which is a large-area aquifer. The aquifer has a demonstrated capability to produce geothermal water. A system to tap this potential and heat the Haakon School District buildings in Philip has been in operation since November 1980. Five school buildings having a total area of 44,000 ft{sup 2} (4088 ft{sup 2}) are heated with 157{degrees}F (69{degrees}C) water. A single well provides water at a maximum artesian flow of 340 gpm (21.5 L/s), which more than meets the heat demand of the school buildings. Eight buildings in the Philip business district utilize geothermal fluid discharged from the school for space heating. During the 1980-81 heating season, these buildings obtained 75% to 90% of their heat from geothermal fluid. Peak heat delivery of the system is 5.5 million Btu/h (1.61. MJ/s), with an annual energy delivery of 9.5 billion Btu (10 TJ). The geothermal system has operated nearly problem free with the exception of the equipment to remove Radium-226 from the spent fluid. Barium chloride is added to the water to precipitate sulfates containing the radium. Accumulation of precipitates in piping has caused some operational problems.

Childs, F.W.; Kirol, L.D.; Sanders, R.D.; McLatchy, M.J.

1997-12-01

133

Life-cycle analysis results for geothermal systems in comparison to other power systems: Part II.  

SciTech Connect

A study has been conducted on the material demand and life-cycle energy and emissions performance of power-generating technologies in addition to those reported in Part I of this series. The additional technologies included concentrated solar power, integrated gasification combined cycle, and a fossil/renewable (termed hybrid) geothermal technology, more specifically, co-produced gas and electric power plants from geo-pressured gas and electric (GPGE) sites. For the latter, two cases were considered: gas and electricity export and electricity-only export. Also modeled were cement, steel and diesel fuel requirements for drilling geothermal wells as a function of well depth. The impact of the construction activities in the building of plants was also estimated. The results of this study are consistent with previously reported trends found in Part I of this series. Among all the technologies considered, fossil combustion-based power plants have the lowest material demand for their construction and composition. On the other hand, conventional fossil-based power technologies have the highest greenhouse gas (GHG) emissions, followed by the hybrid and then two of the renewable power systems, namely hydrothermal flash power and biomass-based combustion power. GHG emissions from U.S. geothermal flash plants were also discussed, estimates provided, and data needs identified. Of the GPGE scenarios modeled, the all-electric scenario had the highest GHG emissions. Similar trends were found for other combustion emissions.

Sullivan, J.L.; Clark, C.E.; Yuan, L.; Han, J.; Wang, M. (Energy Systems)

2012-02-08

134

Geothermal System Overview ASHRAE Headquarters Building  

E-print Network

center #12;Geothermal Loop · Vertical closed-loop ­ 12 bores at 400 feet deep with 1.25" HDPE ­ Boreholes;2010 Ground Loop Temperature 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Mar Apr May June July Aug Aept Oct Nov DecWh) Geo HP VRF #12;2011 Ground Loop Temperature 30 40 50 60 70 80 90 Jan Feb Mar Apr May June July Aug

Oak Ridge National Laboratory

135

Geothermal Energy Program overview  

SciTech Connect

The mission of the Geothermal Energy Program is to develop the science and technology necessary for tapping our nation's tremendous heat energy sources contained with the Earth. Geothermal energy is a domestic energy source that can produce clean, reliable, cost- effective heat and electricity for our nation's energy needs. Geothermal energy -- the heat of the Earth -- is one of our nation's most abundant energy resources. In fact, geothermal energy represents nearly 40% of the total US energy resource base and already provides an important contribution to our nation's energy needs. Geothermal energy systems can provide clean, reliable, cost-effective energy for our nation's industries, businesses, and homes in the form of heat and electricity. The US Department of Energy's (DOE) Geothermal Energy Program sponsors research aimed at developing the science and technology necessary for utilizing this resource more fully. Geothermal energy originates from the Earth's interior. The hottest fluids and rocks at accessible depths are associated with recent volcanic activity in the western states. In some places, heat comes to the surface as natural hot water or steam, which have been used since prehistoric times for cooking and bathing. Today, wells convey the heat from deep in the Earth to electric generators, factories, farms, and homes. The competitiveness of power generation with lower quality hydrothermal fluids, geopressured brines, hot dry rock, and magma ( the four types of geothermal energy) still depends on the technical advancements sought by DOE's Geothermal Energy Program.

Not Available

1991-12-01

136

Geothermal energy program overview  

NASA Astrophysics Data System (ADS)

The mission of the Geothermal Energy Program is to develop the science and technology necessary for tapping our nation's tremendous heat energy sources contained within the Earth. Geothermal energy is a domestic energy source that can produce clean, reliable, cost-effective heat and electricity for our nation's energy needs. Geothermal energy - the heat of the Earth - is one of our nation's most abundant energy resources. In fact, geothermal energy represents nearly 40 percent of the total U.S. energy resource base and already provides an important contribution to our nation's energy needs. Geothermal energy systems can provide clean, reliable, cost-effective energy for our nation's industries, businesses, and homes in the form of heat and electricity. The U.S. Department of Energy's (DOE) Geothermal Energy Program sponsors research aimed at developing the science and technology necessary for utilizing this resource more fully. Geothermal energy originates from the Earth's interior. The hottest fluids and rocks at accessible depths are associated with recent volcanic activity in the western states. In some places, heat comes to the surface as natural hot water or steam, which have been used since prehistoric times for cooking and bathing. Today, wells convey the heat from deep in the Earth to electric generators, factories, farms, and homes. The competitiveness of power generation with lower quality hydrothermal fluids, geopressured brines, hot dry rock, and magma (the four types of geothermal energy), still depends on the technical advancements sought by DOE's Geothermal Energy Program.

1991-12-01

137

COTHERM: Modelling fluid-rock interactions in Icelandic geothermal systems  

NASA Astrophysics Data System (ADS)

Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced geothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. We model the mineralogical and porosity evolution of Icelandic geothermal systems with 1D and 2D reactive transport models. These geothermal systems are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. The shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. We investigate two contrasting geothermal systems: Krafla, for which the water recharge consists of meteoritic water; and Reykjanes, for which the water recharge mainly consists of seawater. The initial rock composition is a fresh basalt. We use the GEM-Selektor geochemical modeling package [1] for calculation of kinetically controlled mineral equilibria between the rock and the ingression water. We consider basalt minerals dissolution kinetics according to Palandri & Kharaka [2]. Reactive surface areas are assumed to be geometric surface areas, and are corrected using a spherical-particle surface/mass relationship. For secondary minerals, we consider the partial equilibrium assuming that the primary mineral dissolution is slow, and the secondary mineral precipitation is fast. Comparison of our modeling results with the mineralogical assemblages observed in the field by Gudmundsson & Arnorsson [3] and by Icelandic partners of the COTHERM project suggests that the concept of partial equilibrium with instantaneous precipitation of secondary minerals is not sufficient to satisfactorily describe the experimental data. Considering kinetic controls also for secondary minerals appears as indispensable to properly describe the geothermal system evolution using a reactive transport modelling approach [4]. [1] Kulik D.A., Wagner T., Dmytrieva S.V., Kosakowski G., Hingerl F.F., Chudnenko K.V., Berner U., 2013. GEM-Selektor geochemical modeling package: revised algorithm and GEMS3K numerical kernel for coupled simulation codes. Computational Geosciences 17, 1-24. http://gems.web.psi.ch. [2] Palandri, J.L., Kharaka, Y.K., 2004. A compilation of rate parameters of water-mineral interaction kinetics for application to geochemical modelling. U.S.Geological Survey, Menlo Park, CA, pp. 1-64. [3] Gudmundsson B.T., Arnorsson S., 2005. Secondary mineral-fluid equilibria in the Krafla and Namafjall geothermal systems, Iceland. Applied Geochememistry 20, 1607-1625. [4] Kosakowski, G., & Watanabe, N., 2013. OpenGeoSys-Gem: A numerical tool for calculating geochemical and porosity changes in saturated and partially saturated media. Physics and Chemistry of the Earth, Parts A/B/C. doi:10.1016/j.pce.2013.11.008

Thien, Bruno; Kosakowski, Georg; Kulik, Dmitrii

2014-05-01

138

Community Geothermal Technology Program: Bottom heating system using geothermal power for propagation. Final report, Phases 1 and 2  

SciTech Connect

The objective is to develop and study a bottom-heating system in a greenhouse utilizing geothermal energy to aid germination and speed growth of palms. Source of heat was geothermal brine from HGP-A well. The project was successful; the heat made a dramatic difference with certain varieties, such as Areca catechu (betelnut) with 82% germination with heat, zero without. For other varieties, germination rates were much closer. Quality of seed is important. Tabs, figs.

Downing, J.C.

1990-01-01

139

Seal/lubricant systems for geothermal drilling equipment  

SciTech Connect

The development and testing of seals and lubricants for journal-type roller-cone rock bits for drilling into geothermal reservoirs at temperatures over 260/sup 0/C (500/sup 0/F) are described. The conditions experienced by seals and lubricants subjected to geothermal drilling are reviewed along with the basic design requirements for roller-cone bit seals and journal bearing lubricants. Two unique test facilities are described: a seal test machine which simulates pressures, temperatures, and mechanical eccentricities, and a lubricant tester capable of evaluating load-bearing ability at temperature and pressure. Three candidate elastomeric compounds demonstrated 288/sup 0/C (550/sup 0/F) capability and several others demonstrated 260/sup 0/C (500/sup 0/F) or greater capability. Successful elastomeric seal candidates were proprietary compounds based on EPDM, Kalrez, and/or Viton polymers. Three mechanical seals for reservoir temperatures over 288/sup 0/C (550/sup 0/F) are presented. Lubricant screening tests on more than 50 products are summarized, and several newly developed lubricants which meet both the compatibility and lubrication requirements are described. Several seal/lubricant systems are recommended for laboratory or field geothermal drilling tests in roller-cone drill bits. The future availability of drill bits for geothermal use is discussed, as well as the potential spinoffs of the program findings for nongeothermal roller-cone bits.

Hendrickson, R.R.; Winzenried, R.W.

1980-07-01

140

Multiparameter fiber optic sensing system for monitoring enhanced geothermal systems  

SciTech Connect

The goal of this project was to design, fabricate and test an optical fiber cable which supports multiple sensing modalities for measurements in the harsh environment of enhanced geothermal systems. To accomplish this task, optical fiber was tested at both high temperatures and strains for mechanical integrity, and in the presence of hydrogen for resistance to darkening. Both single mode (SM) and multimode (MM) commercially available optical fiber were identified and selected for the cable based on the results of these tests. The cable was designed and fabricated using a tube-within-tube construction containing two MM fibers and one SM fiber, and without supporting gel that is not suitable for high temperature environments. Commercial fiber optic sensing instruments using Raman DTS (distributed temperature sensing), Brillouin DTSS (distributed temperature and strain sensing), and Raleigh COTDR (coherent optical time domain reflectometry) were selected for field testing. A microelectromechanical systems (MEMS) pressure sensor was designed, fabricated, packaged, and calibrated for high pressure measurements at high temperatures and spliced to the cable. A fiber Bragg grating (FBG) temperature sensor was also spliced to the cable. A geothermal well was selected and its temperature and pressure were logged. The cable was then deployed in the well in two separate field tests and measurements were made on these different sensing modalities. Raman DTS measurements were found to be accurate to ???±5???°C, even with some residual hydrogen darkening. Brillouin DTSS measurements were in good agreement with the Raman results. The Rayleigh COTDR instrument was able to detect some acoustic signatures, but was generally disappointing. The FBG sensor was used to determine the effects of hydrogen darkening, but drift over time made it unreliable as a temperature or pressure sensor. The MEMS sensor was found to be highly stable and accurate to better than its 0.1% calibration.

William A. Challener

2014-12-04

141

Geothermal Energy.  

ERIC Educational Resources Information Center

Major activities, programs, and conferences in geothermal energy during 1982 are highlighted. These include first comprehensive national assessment of U.S. low-temperature geothermal resources (conducted by U.S. Geological Survey and Department of Energy), map production by U.S. Geological Survey, geothermal plant production, and others. (JN)

Bufe, Charles Glenn

1983-01-01

142

Evaluating Geothermal Potential in Germany by Numerical Reservoir Modeling of Engineered Geothermal Systems  

NASA Astrophysics Data System (ADS)

We model hypothetical Engineered Geothermal System (EGS) reservoirs by solving coupled partial differential equations governing fluid flow and heat transport. Building on EGS's strengths of inherent modularity and storage capability, it is possible to implement multiple wells in the reservoir to extend the rock volume accessible for circulating water in order to increase the heat yield. By varying parameters like flow rates and well-separations in the subsurface, this study looks at their long-term impacts on the reservoir development. This approach allows us to experiment with different placements of the engineered fractures and propose several EGS layouts for achieving optimized heat extraction. Considering the available crystalline area and accounting for the competing land uses, this study evaluates the overall EGS potential and compares it with those of other used renewables in Germany. There is enough area to support 13450 EGS plants, each with six reversed-triplets (18 wells) and an average electric power of 35.3MWe. When operated at full capacity, these systems can collectively supply 4155TWh of electric energy in one year which would be roughly six times the electric energy produced in Germany in the year 2011. Engineered Geothermal Systems make a compelling case for contributing towards national power production in a future powered by a sustainable, decentralized energy system.

Jain, Charitra; Vogt, Christian; Clauser, Christoph

2014-05-01

143

Engineered Geothermal Systems Energy Return On Energy Investment  

SciTech Connect

Energy Return On Investment (EROI) is an important figure of merit for assessing the viability of energy alternatives. Too often comparisons of energy systems use ??efficiency? when EROI would be more appropriate. For geothermal electric power generation, EROI is determined by the electricity delivered to the consumer compared to the energy consumed to construct, operate, and decommission the facility. Critical factors in determining the EROI of Engineered Geothermal Systems (EGS) are examined in this work. These include the input energy embodied into the system. Embodied energy includes the energy contained in the materials, as well as, that consumed in each stage of manufacturing from mining the raw materials to assembling the finished system. Also critical are the system boundaries and value of the energy ?? heat is not as valuable as electrical energy. The EROI of an EGS depends upon a number of factors that are currently unknown, for example what will be typical EGS well productivity, as well as, reservoir depth, temperature, and temperature decline rate. Thus the approach developed is to consider these factors as parameters determining EROI as a function of number of wells needed. Since the energy needed to construct a geothermal well is a function of depth, results are provided as a function of well depth. Parametric determination of EGS EROI is calculated using existing information on EGS and US Department of Energy (DOE) targets and is compared to the ??minimum? EROI an energy production system should have to be an asset rather than a liability.

Mansure, A J

2012-12-10

144

GEOLOGIC SETTING OF THE CHENA HOT SPRINGS GEOTHERMAL SYSTEM, ALASKA  

Microsoft Academic Search

A belt of moderate-temperature geothermal activity runs east-west across central Alaska. Chena Hot Springs (CHS) is one of several Interior Alaskan hot springs in or near 55 Ma granites within Paleozoic metamorphic rocks. CHS is located within the CHS pluton, a composite body of quartz diorite, tonalite, granodiorite, and granite of both mid-Cretaceous and Early Tertiary ages. 40Ar\\/39Ar step heat

Amanda Kolker; Rainer Newberry; Jessica Larsen; Paul Layer; Patrick Stepp

2007-01-01

145

Environmental impacts of open loop geothermal system on groundwater  

NASA Astrophysics Data System (ADS)

Application of renewable energies such as sunlight, wind, rain, tides, waves and geothermal heat has gradually increased to reduce emission of CO2 which is supplied from combustion of fossil fuel. The geothermal energy of various renewable energies has benefit to be used to cooling and heating systems and has good energy efficiency compared with other renewable energies. However, open loop system of geothermal heat pump system has possibility that various environmental problems are induced because the system directly uses groundwater to exchange heat. This study was performed to collect data from many documents such as papers and reports and to summarize environmental impacts for application of open loop system. The environmental impacts are classified into change of hydrogeological factors such as water temperature, redox condition, EC, change of microbial species, well contamination and depletion of groundwater. The change of hydrogeological factors can induce new geological processes such as dissolution and precipitation of some minerals. For examples, increase of water temperature can change pH and Eh. These variations can change saturation index of some minerals. Therefore, dissolution and precipitation of some minerals such as quartz and carbonate species and compounds including Fe and Mn can induce a collapse and a clogging of well. The well contamination and depletion of groundwater can reduce available groundwater resources. These environmental impacts will be different in each region because hydrogeological properties and scale, operation period and kind of the system. Therefore, appropriate responses will be considered for each environmental impact. Also, sufficient study will be conducted to reduce the environmental impacts and to improve geothermal energy efficiency during the period that a open loop system is operated. This work was supported by the Energy Efficiency and Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No.20123040110010).

Kwon, Koo-Sang; Park, Youngyun; Yun, Sang Woong; Lee, Jin-Yong

2013-04-01

146

High Temperature Components of Magma-Related Geothermal Systems: An Experimental and Theoretical Approach  

SciTech Connect

This summarizes select components of a multi-faceted study of high temperature magmatic fluid behavior in shallow, silicic, volcano-plutonic geothermal systems. This work built on a foundation provided by DOE-supported advances made in our lab in understanding the physics and chemistry of the addition of HCI and other chlorides into the high temperature regions of geothermal systems. The emphasis of this project was to produce a model of the bolatile contributions from felsic magmatic systems to geothermal systems

Philip A. Candela; Philip M. Piccoli

2004-03-15

147

Geology of the Beowawe geothermal system, Eureka and Lander Counties, Nevada  

SciTech Connect

A geologic study is described undertaken to evaluate the nature of structural and stratigraphic controls within the Beowawe geothermal system, Eureka and Lander Counties, Nevada. This study includes geologic mapping at a scale of 1:24,000 and lithologic logs of deep Chevron wells. Two major normal fault systems control the configuration of the Beowawe geothermal system. Active hot springs and sinter deposits lie along the Malpais Fault zone at the base of the Malpais Rim. The Malpais Rim is one of several east-northeast-striking, fault-bounded cuestas in north central Nevada. A steeply inclined scarp slope faces northwest towards Whirlwind Valley. The general inclination of the volcanic rocks on the Malpais dip slope is 5/sup 0/ to 10/sup 0/ southeast.

Struhsacker, E.M.

1980-07-01

148

CO 2 emissions from geothermal power plants and natural geothermal activity in Iceland  

Microsoft Academic Search

The ratio of CO2 emissions from power plants to natural emissions is a measure of the environmental impact associated with geothermal power production. Emissions from Icelandic geothermal power plants amounted to 1.6108kgyear?1 in 2002. Two independent estimates of natural CO2 emissions range between 1108 and 2109kgyear?1. Thus, power plant emissions are significant compared to estimated total emissions (i.e., not less

Halldr rmannsson; Thrinn Fridriksson; Bjarni Reyr Kristjnsson

2005-01-01

149

Geothermal progress monitor report No. 6  

SciTech Connect

Geothermal Progress Monitor Report No. 6 presents a state-by-state summary of the status of geothermal leasing, exploration, and development in major physiographic regions where geothermal resource potential has been identified. Recent state-specific activities are reported at the end of each state status report, while recent activities of a more general nature are summarized briefly in Part II of the report. A list of recent publications of potential interest to the geothermal community and a directory of contributors to the geothermal progress monitoring system are also included.

Not Available

1982-06-01

150

Hydrocarbon anomaly in soil gas as near-surface expressions of upflows and outflows in geothermal systems  

SciTech Connect

A variety of hydrocarbons, C1 - C12, have been found in volcanic gases (fumarolic) and in geothermal waters and gases. The hydrocarbons are thought to have come from products of pyrolysis of kerogen in sedimentary rocks or they could be fed into the geothermal system by the recharging waters which may contain dissolved hydrocarbons or hydrocarbons extracted by the waters from the rocks. In the hot geothermal zone, 300+ C, many of these hydrocarbons are in their critical state. It is thought that they move upwards due to buoyancy and flux up with the upflowing geothermal fluids in the upflow zones together with the magmatic gases. Permeability which could be provided by faults, fissures, mini and micro fractures are thought to provide pathways for the upward flux. A sensitive technique (Petrex) utilizing passive integrative adsorption of the hydrocarbons in soil gas on activated charcoal followed by desorption and analysis of the hydrocarbons by direct introduction mass spectrometry allows mapping of the anomalous areas. Surveys for geothermal resources conducted in Japan and in Indonesia show that the hydrocarbon anomaly occur over known fields and over areas strongly suspected of geothermal potential. The hydrocarbons found and identified were n-paraffins (C7-C9) and aromatics (C7-C8). Detection of permeable, i.e. active or open faults, parts of older faults which have been reactivated, e.g. by younger intersecting faults, and the area surrounding these faulted and permeable region is possible. The mechanism leading to the appearance of the hydrocarbon in the soil gas over upflow zones of the geothermal reservoir is proposed. The paraffins seems to be better pathfinders for the location of upflows than the aromatics. However the aromatics may, under certain circumstances, give better indications of the direction of the outflow of the geothermal system. It is thought that an upflow zone can be defined when conditions exist where the recharging waters containing the hydrocarbons feed into the geothermal kitchen. The existence of open and active faults, fissures, mini and micro fractures allow sufficient permeability for the gases to flux up and express themselves at the surface as hydrocarbon anomaly in the soil gas. When any of the requirements is absent, i.e. in the absence of the recharging waters, hydrocarbons, temperature, or permeability, no anomaly can be expected. It assumes a dynamic convective system, i.e. recharging waters, upflow and outflow. The anomalies however can define to a certain extent, regions of geothermal upflow, buoyant transport of gases, and frequently down-gradient of cooling waters.

Ong, H.L.; Higashihara, M.; Klusman, R.W.; Voorhees, K.J.; Pudjianto, R.; Ong, J

1996-01-24

151

Thermally conductive cementitious grout for geothermal heat pump systems  

DOEpatents

A thermally conductive cement-sand grout for use with a geothermal heat pump system. The cement sand grout contains cement, silica sand, a superplasticizer, water and optionally bentonite. The present invention also includes a method of filling boreholes used for geothermal heat pump systems with the thermally conductive cement-sand grout. The cement-sand grout has improved thermal conductivity over neat cement and bentonite grouts, which allows shallower bore holes to be used to provide an equivalent heat transfer capacity. In addition, the cement-sand grouts of the present invention also provide improved bond strengths and decreased permeabilities. The cement-sand grouts can also contain blast furnace slag, fly ash, a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide and combinations thereof.

Allan, Marita (Old Field, NY)

2001-01-01

152

Proceedings of a Topical Meeting On Small Scale Geothermal Power Plants and Geothermal Power Plant Projects  

SciTech Connect

These proceedings describe the workshop of the Topical Meeting on Small Scale Geothermal Power Plants and Geothermal Power Plant Projects. The projects covered include binary power plants, rotary separator, screw expander power plants, modular wellhead power plants, inflow turbines, and the EPRI hybrid power system. Active projects versus geothermal power projects were described. In addition, a simple approach to estimating effects of fluid deliverability on geothermal power cost is described starting on page 119. (DJE-2005)

None

1986-02-12

153

Vertical arrays for fracture mapping in geothermal systems  

SciTech Connect

In collaboration with UNOCAL Geothermal Operations, Los Alamos National Laboratory assessed the feasibility of using vertical arrays of borehole seismic sensors for mapping of microseismicity in The Geysers geothermal field. Seismicity which arises from minute displacements along fracture or fault surfaces has been shown in studies of seismically active oil reservoirs to be useful in identifying fractures affected by and possibly contributing to production. Use of retrievable borehole seismic packages at The Geysers was found to reduce the threshold for detection of microearthquakes by an estimated 2--3 orders of magnitude in comparison to surface-based sensors. These studies led to the design, materials selection, fabrication, and installation of a permanent array of geophones intended for long term seismic monitoring and mapping of fractures in the vicinity of the array at The Geysers.

Albright, J.N. [Los Alamos National Lab., NM (United States); Rutledge, J.T.; Fairbanks, T.D. [Nambe Geophysics, Inc. (United States); Thomson, J.C. [Lithos Inc. (United States); Stevenson, M.A. [Petroleum Geo-Services (United States)

1998-12-01

154

Geothermal district heating system feasibility analysis, Thermopolis, Wyoming  

SciTech Connect

The purpose of this study is to determine the technical and economic feasibility of constructing and operating a district heating system to serve the residential, commercial, and public sectors in Thermopolis. The project geothermal resource assessment, based on reviews of existing information and data, indicated that substantial hot water resources likely exist in the Rose Dome region 10 miles northeast of Thermopolis, and with quantities capable of supporting the proposed geothermal uses. Preliminary engineering designs were developed to serve the space heating and hot water heating demands for buildings in the Thermopolis-East Thermopolis town service area. The heating district design is based on indirect geothermal heat supply and includes production wells, transmission lines, heat exchanger units, and the closed loop distribution and collection system necessary to serve the individual customers. Three options are presented for disposal of the cooled waters-reinjection, river disposal, and agricultural reuse. The preliminary engineering effort indicates the proposed system is technically feasible. The design is sized to serve 1545 residences, 190 businesses, and 24 public buildings. The peak design meets a demand of 128.2 million Btu at production rates of 6400 gpm.

Goering, S.W.; Garing, K.L.; Coury, G.; Mickley, M.C.

1982-04-26

155

Design details for an advanced geothermal deep-drilling system  

SciTech Connect

This is a progress report on a purpose-developed advanced geothermal deep-drilling system. Previous work has defined and reviewed a drilling system concept that provides the needed enhancement in performance with longer bit life and increased rate of penetration. The major drilling and related problems primarily associated with lost circulation are addressed by a dual-wall drillstring and reverse circulation. The high-temperature problems inherent in all successful geothermal drilling projects are also considered in the design of the system. The design details of several sub-components have subsequently been defined: air (nitrogen) and hydraulic (mud) percussion hammers, downhole indexing (rotation) of the percussion tools, steerable bottom hole assemblies (BHA), and initial, approximate pipe sizes for the two drillstring options being considered. Some structural and fluid flow analyses have been conducted. Review of these sub-components have been carried out. A recently developed, unique nitrogen supply unit has been selected to provide minimum corrosion of downhole equipment at the very high temperatures encountered in geothermal drilling.

Rowley, J. [Pajarito Enterprises, Los Alamos, NM (United States); Saito, Seiji [JMC Geothermal Div., Tokyo (Japan); Long, R. [Dept. of Energy, Las Vegas, NV (United States)

1996-09-01

156

Summary of geothermal drilling activities in the Western United States  

SciTech Connect

Geothermal drilling in the area which extends from the Geysers, north of San Francisco to the Imperial Valley in the south, then west to the Mojave Desert in California to Northern Nevada is emphasized. It is revealed that the Geysers' geothermal field, owned by Pacific Gas and Electric, is the largest geothermal field in the world, containing over 200 steam wells which average about 7,500 ft in depth and generate more than 900,000 kilowatts of electricity. PGandE operates the power plants while drilling companies provide the steam. Average steam production per well is 150,000 lbs per hr., with 13 wells needed to supply steam for a 110-MWe plant. From January 1970 to June 1979, 55% of all US geothermal wells were drilled in the Geyser, the only developed area of the 1970s. It is noted that the US Geological Survey has been encouraged by results of a pair of geothermal test wells.

Tanji, S.A.

1982-07-01

157

Enthalpy transients in fractured two-phase geothermal systems  

NASA Astrophysics Data System (ADS)

Numerical modeling techniques are used to study the changes in flowing enthalpy of fluids produced from a well completed in a fractured two-phase geothermal reservoir. Complex interactions between different fracture and porous matrix parameters control the enthalpy transients. The results show that the flowing enthalpy is most sensitive to the characteristics of the relative permeability curves, the magnitude of the matrix permeability and the effective fracture porosity. Other parameters such as the thermal conductivity and fracture spacing also significantly affect the flowing enthalpy. In spite of the complex phenomena associated with enthalpy transients in fractured two-phase systems, it is possible to infer useful information about the producing geothermal reservoirs from field data.

Lippmann, M. J.; Bodvarsson, G. S.; Gaulke, S. W.

1985-03-01

158

Beneficial effects of groundwater entry into liquid-dominated geothermal systems  

SciTech Connect

In all active liquid-dominated geothermal systems there is continuous circulation of mass and transfer of heat, otherwise they would slowly cool and fade away. In the natural state these systems are in dynamic equilibrium with the surrounding colder groundwater aquifers. The ascending geothermal fluids cool conductively, boil, or mix with groundwaters, and ultimately may discharge at the surface as fumaroles or hot springs. With the start of fluid production and the lowering of reservoir pressure, the natural equilibrium is disrupted and cooler groundwater tends to enter the reservoir. Improperly constructed or damaged wells, and wells located near the margins of the geothermal system, exhibit temperature reductions (and possibly scaling from mixing of chemically distinct fluids) as the cooler-water moves into the reservoir. These negative effects, especially in peripheral wells are, however, compensated by the maintenance of reservoir pressure and a reduction in reservoir boiling that might result in mineral precipitation in the formation pores and fractures. The positive effect of cold groundwater entry on the behavior of liquid-dominated system is illustrated by using simple reservoir models. The simulation results show that even though groundwater influx into the reservoir causes cooling of fluids produced from wells located near the cold-water recharge area, it also reduces pressure drawdown and boiling in the exploited zone, and sweeps the heat stored in the reservoir rocks toward production wells, thus increasing the productive life of the wells and field. 9 refs.

Lippmann, M.J. (Lawrence Berkeley Lab., CA (USA)); Truesdell, A.H. (Geological Survey, Menlo Park, CA (USA))

1990-04-01

159

Energy Return On Investment of Engineered Geothermal Systems Data  

DOE Data Explorer

EROI is a ratio of the energy delivered to the consumer to the energy consumed to build, operate, and decommission the facility. EROI is important in assessing the viability of energy alternatives. Currently EROI analyses of geothermal energy are either out-of-date, of uncertain methodology, or presented online with little supporting documentation. This data set is a collection of files documenting data used to calculate the Energy Return On Investment (EROI) of Engineered Geothermal Systems (EGS) and erratum to publications prior to the final report. Final report is available from the OSTI web site (http://www.osti.gov/geothermal/). Data in this collections includes the well designs used, input parameters for GETEM, a discussion of the energy needed to haul materials to the drill site, the baseline mud program, and a summary of the energy needed to drill each of the well designs. EROI is the ratio of the energy delivered to the customer to the energy consumed to construct, operate, and decommission the facility. Whereas efficiency is the ratio of the energy delivered to the customer to the energy extracted from the reservoir.

Mansure, Chip

160

I/S and C/S mixed layers, some indicators of recent physical-chemical changes in active geothermal systems: The case study of Chipilapa (El Salvador)  

SciTech Connect

I/S and C/S mixed layers from the geothermal field of Chipilapa (El Salvador) have been studied in details in order to reevaluate their potential use as indicator of the thermodynamic conditions in which they were formed. It is funded that overprinting of clay bearing alteration stages is common. For a given alteration stage, the spatial variation of I/S and C/S mixed layer ininerals is controlled by kinetics of mixed layer transformation and not only by temperature. Clay geo-thermometers cannot give reliable results because the present crystal-chemical states of the I/S and C/S mixed layers is not their initial state, it was aquired during the overall hydrothermal history which post dated the nucleation of smectitic clay material at high temperature. Occurrences of smectites or smectite-rich mixed layers at high temperature in reservoirs is a promising guide for reconstruct the zones in which boiling or mixing of non isotherinal fluids occurred very recently or still presently.

Beaufort, D.; Papapanagiotou, P.; patrier, P.; Fouillac, A.M.; Traineau, H.

1996-01-24

161

Thermal Infrared Remote Sensing of the Yellowstone Geothermal System  

NASA Astrophysics Data System (ADS)

The Yellowstone National Park (YNP) geothermal system is one of the largest in the world, with thousands of individual thermal features ranging in size from a few centimeters to tens of meters across, (e.g., fumaroles, geysers, mud pots and hot spring pools). Together, large concentrations of these thermal features make up dozens of distinct thermal areas, characterized by sparse vegetation, hydrothermally altered rocks, and usually either sinter, travertine, or acid sulfate alteration. The temperature of these thermal features generally ranges from ~30 to ~93 oC, which is the boiling temperature of water at the elevation of Yellowstone. In-situ temperature measurements of various thermal features are sparse in both space and time, but they show a dynamic time-temperature relationship. For example, as geysers erupt and send pulses of warm water down slope, the warm water cools rapidly and is then followed by another pulse of warm water, on time scales of minutes. The total heat flux from the Parks thermal features has been indirectly estimated from chemical analysis of Cl- flux in water flowing from Yellowstones rivers. We are working to provide a more direct measurement, as well as estimates of time variability, of the total heat flux using satellite multispectral thermal infrared (TIR) remote sensing data. Over the last 10 years, NASAs orbiting ASTER and MODIS instruments have acquired hundreds and thousands of multispectral TIR images, respectively, over the YNP area. Compared with some volcanoes, Yellowstone is a relatively low-temperature geothermal system, with low thermal contrast to the non-geothermal surrounding areas; therefore we are refining existing techniques to extract surface temperature and thermal flux information. This task is complicated by issues such as, during the day, solar heated surfaces may be warmer than nearby geothermal features; and there is some topographic (elevation) influence on surface temperatures, even at night. Still we have been able to obtain temperature and heat flux values from small scale geothermal features with ASTER and some larger scale thermal areas with MODIS. The latest results of this study will be presented; including MODIS time-series data and examples of using higher spatial resolution ASTER data for identifying hot spots.

Vaughan, R. G.; Keszthelyi, L. P.; Heasler, H.; Jaworowski, C.; Lowenstern, J. B.; Schneider, D. J.

2009-12-01

162

Summary of geothermal exploration activity in the State of Washington from 1978 to 1983. Final report  

SciTech Connect

Project activity is summarized with references to the publications produced. Project findings are reported as they relate to specific geothermal resource target areas. Some major projects of the goethermal exploration program are: thermal and mineral spring chemistry, heat flow drilling, temperature gradient measurements, Cascade Range regional gravity, geohydrology study of the Yakima area, low temperature geothermal resources, geology, geochemistry of Cascade Mountains volcanic rocks, and soil mercury studies. (MHR)

Korosec, M.A.

1984-01-01

163

Process Control System of the Mutnovskaya Geothermal Power Plant  

SciTech Connect

The experience of creating software and algorithms for automatic process control at the Mutnovskaya geothermal power plant (GTPP) on the basis of the Teleperm ME automation system is presented. The heat cycle and special features of the heat flow diagram of the power plant are briefly described. The engineering solutions used, the structure of the system, and the principles of process control at the Mutnovskaya GTPP are considered. Special attention is devoted to the turbine regulator that consists of several regulating units because of the great number of problems solved by control valves; each regulating unit solves control problems depending on the mode of operation of the power generating set.

Idzon, O. M.; Ivanov, V. V.; Ilyushin, V. V.; Nikol'skii, A. I. [Interavtomatika Company, VO Tekhnopromeksport Federal State Unitary Enterprise, Nauka Company (Russian Federation)

2004-01-15

164

Design procedure for a greenhouse space heating system utilizing geothermal warm water  

Microsoft Academic Search

Tal, A., Segal, I., Regev, R., Steinfeld, A., Cohen, S. and Zer, I., 1987. Design procedure for a greenhouse space heating system utilizing geothermal warm water. Energy Agric., 6: 27-34. Utilization of warm geothermal water (40 -60 C) supplied from deep wells for heating of win- ter crops is being pursued in the Arava region of Israel. Systems

A. TAL; I. SEGAL; R. REGEV; A. STEINFELD; S. COHEN; I ZER

1987-01-01

165

Parametric Analysis of the Factors Controlling the Costs of Sedimentary Geothermal Systems - Preliminary Results (Poster)  

SciTech Connect

Parametric analysis of the factors controlling the costs of sedimentary geothermal systems was carried out using a modified version of the Geothermal Electricity Technology Evaluation Model (GETEM). The sedimentary system modeled assumed production from and injection into a single sedimentary formation.

Augustine, C.

2013-10-01

166

National Geothermal Data System: State Geological Survey Contributions to Date  

NASA Astrophysics Data System (ADS)

In collaboration with the Association of American State Geologists the Arizona Geological Survey is leading the effort to bring legacy geothermal data to the U.S. Department of Energy's National Geothermal Data System (NGDS). NGDS is a national, sustainable, distributed, interoperable network of data and service (application) providers entering its final stages of development. Once completed the geothermal industry, the public, and policy makers will have access to consistent and reliable data, which in turn, reduces the amount of staff time devoted to finding, retrieving, integrating, and verifying information. With easier access to information, the high cost and risk of geothermal power projects (especially exploration drilling) is reduced. This presentation focuses on the scientific and data integration methodology as well as State Geological Survey contributions to date. The NGDS is built using the U.S. Geoscience Information Network (USGIN) data integration framework to promote interoperability across the Earth sciences community and with other emerging data integration and networking efforts. Core to the USGIN concept is that of data provenance; by allowing data providers to maintain and house their data. After concluding the second year of the project, we have nearly 800 datasets representing over 2 million data points from the state geological surveys. A new AASG specific search catalog based on popular internet search formats enables end users to more easily find and identify geothermal resources in a specific region. Sixteen states, including a consortium of Great Basin states, have initiated new field data collection for submission to the NGDS. The new field data includes data from at least 21 newly drilled thermal gradient holes in previously unexplored areas. Most of the datasets provided to the NGDS are being portrayed as Open Geospatial Consortium (OGC) Web Map Services (WMS) and Web Feature Services (WFS), meaning that the data is compatible with a variety of visualization software. Web services are ideal for the NGDS data for a number of reasons including that they preserve data ownership in that they are read only and new services can be deployed to meet new requirements without modifying existing applications.

Patten, K.; Allison, M. L.; Richard, S. M.; Clark, R.; Love, D.; Coleman, C.; Caudill, C.; Matti, J.; Musil, L.; Day, J.; Chen, G.

2012-12-01

167

Assessing the role of ancient and active geothermal systems in oil-reservoir evolution in the eastern Basin and Range province, western USA. Annual progress report, June 1, 1992--May 31, 1993  

SciTech Connect

Results of our research on the oil fields of the Basin and Range province of the western USA continue to support the following concept: Convecting, moderate-temperature geothermal systems in this region have fostered and in some cases critically influenced the generation, migration, and entrapment of oil. At one Basin-Range field (Grant Canyon), oil-bearing and aqueous fluid inclusions in late-stage hydrothermal quartz were entrapped at temperatures comparable to those now prevailing at reservoir depths (120--130{degrees}C); apparent salinities of the aqueous varieties match closely the actual salinity of the modern, dilute oil-field waters. The inclusion-bearing quartz has the oxygen-isotopic signature for precipitation of the mineral at contemporary temperatures from modern reservoir waters. Measured and fluid-inclusion temperatures define near-coincident isothermal profiles through the oil-reservoir interval, a phenomenon suggesting ongoing heat and mass transfer. These findings are consistent with a model whereby a still-active, convectively circulating, meteoric-hydrothermal system: (1) enhanced porosity in the reservoir rock through dissolution of carbonate; (2) hydrothermally sealed reservoir margins; (3) transported oil to the reservoirs from a deep source of unknown size and configuration; and (4) possibly accelerated source-rock maturation through an increase in the local thermal budget. Grant Canyon and other Basin-Range oil fields are similar to the oil-bearing, Carlin-type, sediment-hosted, disseminated gold deposits of the nearby Alligator Ridge district. The oil fields could represent either weakly mineralized analogues of these deposits, or perhaps an incipient phase in their evolution.

Hulen, J.B.

1993-07-01

168

Geologic and preliminary reservoir data on the Los Humeros Geothermal System, Puebla, Mexico  

SciTech Connect

Exploratory drilling has confirmed the existence of a geothermal system in the Los Humeros volcanic center, located 180 km east of Mexico City. Volcanic activity in the area began with the eruption of andesites, followed by two major caldera-forming pyroclastic eruptions. The younger Los Potreros caldera is nested inside the older Los Humeros caldera. At later stages, basaltic andesite, dacite, and olivine basalt lavas erupted along the ring-fracture zones of both calderas. Geologic interpretation of structural, geophysical, and drilling data suggests that: (1) the water-dominated geothermal reservoir is hosted by the earliest andesitic volcanic pile, is bounded by the ring-fracture zone of the Los Potreros caldera, and is capped by the products of the oldest caldera-forming eruption; (2) permeability within the andesitic pile is provided by faults and fractures related to intracaldera uplift; (3) the geothermal system has potential for a large influx of meteoric water through portions of the ring-fracture zones of both calderas; and (4) volcanic centers with similar magmatic and structural conditions can be found in the eastern Cascades, USA.

Ferriz, H.

1982-01-01

169

A geochemical reconnaissance of the Alid volcanic center and geothermal system, Danakil depression, Eritrea  

USGS Publications Warehouse

Geological and geochemical studies indicate that a high-temperature geothermal system underlies the Alid volcanic center in the northern Danakil depression of Eritrea. Alid is a very late-Pleistocene structural dome formed by shallow intrusion of rhyolitic magma, some of which vented as lavas and pyroclastic flows. Fumaroles and boiling pools distributed widely over an area of ~10 km2 on the northern half of Alid suggest that an active hydrothermal system underlies much of that part of the mountain. Geothermometers indicate that the fumarolic gases are derived from a geothermal system with temperatures >225??C. The isotopic composition of condensed fumarolic steam is consistent with these temperatures and implies that the source water is derived primarily from either lowland meteoric waters or fossil Red Sea water, or both. Some gases vented from the system (CO2, H2S and He) are largely magmatic in origin. Permeability beneath the volcanic center may be high, given the amount of intrusion-related deformation and the active normal faulting within the Danakil depression.Geological and geochemical studies indicate that a high-temperature geothermal system underlies the Alid volcanic center in the northern Danakil depression of Eritrea. Alid is a very late-Pleistocene structural dome formed by shallow intrusion of rhyolitic magma, some of which vented as lavas and pyroclastic flows. Fumaroles and boiling pools distributed widely over an area of approx. 10 km2 on the northern half of Alid suggest that an active hydrothermal system underlies much of that part of the mountain. Geothermometers indicate that the fumarolic gases are derived from a geothermal system with temperatures >225??C. The isotopic composition of condensed fumarolic steam is consistent with these temperatures and implies that the source water is derived primarily from either lowland meteoric waters or fossil Red Sea water, or both. Some gases vented from the system (CO2, H2S and He) are largely magmatic in origin. Permeability beneath the volcanic center may be high, given the amount of intrusion-related deformation and the active normal faulting within the Danakil depression.

Lowenstern, J. B.; Janik, C.J.; Fournier, R.O.; Tesfai, T.; Duffield, W.A.; Clynne, M.A.; Smith, James G.; Woldegiorgis, L.; Weldemariam, K.; Kahsai, G.

1999-01-01

170

Chemistry of gases associated with geothermal activity and volcanism in Iceland: A review  

Microsoft Academic Search

The concentrations of CO2, H2S, and H2 in geothermal reservoir fluids in Iceland are fixed by equilibria with alteration minerals. CH4 concentrations are typically very low, and gas-gas equilibria involving CO2, H2, and CH4 are generally not closely approached. In some geothermal systems the N2 is atmospheric only, but a magmatic N2 contribution is significant in others. N2\\/Ar ratios lie

Stefn Arnrsson

1986-01-01

171

Long-term predictions of minewater geothermal systems heat resources  

NASA Astrophysics Data System (ADS)

Abandoned underground mines usually flood due to the natural rise of the water table. In most cases the process is relatively slow giving the mine water time to equilibrate thermally with the the surrounding rock massif. Typical mine water temperature is too low to be used for direct heating, but is well suited to be combined with heat pumps. For example, heat extracted from the mine can be used during winter for space heating, while the process could be reversed during summer to provide space cooling. Altough not yet widely spread, the use of low temperature geothermal energy from abandoned mines has already been implemented in the Netherlands, Spain, USA, Germany and the UK. Reliable reservoir modelling is crucial to predict how geothermal minewater systems will react to predefined exploitation schemes and to define the energy potential and development strategy of a large-scale geothermal - cold/heat storage mine water systems. However, most numerical reservoir modelling software are developed for typical environments, such as porous media (a.o. many codes developed for petroleum reservoirs or groundwater formations) and cannot be applied to mine systems. Indeed, mines are atypical environments that encompass different types of flow, namely porous media flow, fracture flow and open pipe flow usually described with different modelling codes. Ideally, 3D models accounting for the subsurface geometry, geology, hydrogeology, thermal aspects and flooding history of the mine as well as long-term effects of heat extraction should be used. A new modelling approach is proposed here to predict the long-term behaviour of Minewater geothermal systems in a reactive and reliable manner. The simulation method integrates concepts for heat and mass transport through various media (e.g., back-filled areas, fractured rock, fault zones). As a base, the standard software EPANET2 (Rossman 1999; 2000) was used. Additional equations for describing heat flow through the mine (both through open pipes and from the rock massif) have been implemented. Among others, parametric methods are used to bypass some shortcomings in the physical models used for the subsurface. The advantage is that the complete geometry of the mine workings can be integrated and that computing is fast enough to allow implementing and testing several scenarios (e.g. contributions from fault zones, different assumptions about the actual status of shafts, drifts and mined out areas) in an efficient way (Ferket et al., 2011). EPANET allows to incorporate the full complexity of the subsurface mine structure. As a result, the flooded mine is considered as a network of pipes, each with a custom-defined diameter, length and roughness.

Harcout-Menou, Virginie; de ridder, fjo; laenen, ben; ferket, helga

2014-05-01

172

Geothermal pump down-hole energy regeneration system  

DOEpatents

Geothermal deep well energy extraction apparatus is provided of the general kind in which solute-bearing hot water is pumped to the earth's surface from a subterranean location by utilizing thermal energy extracted from the hot water for operating a turbine motor for driving an electrical power generator at the earth 3 s surface, the solute bearing water being returned into the earth by a reinjection well. Efficiency of operation of the total system is increased by an arrangement of coaxial conduits for greatly reducing the flow of heat from the rising brine into the rising exhaust of the down-well turbine motor.

Matthews, Hugh B. (Boylston, MA)

1982-01-01

173

COMPLETION OF HOT DRY ROCK GEOTHERMAL WELL SYSTEMS  

Microsoft Academic Search

In the hot-dry-rock (HDR) concept of extracting geothermal energy, a manmade geothermal reservoir is created by drilling a deep hole into relatively impermeable hot rocks, creating a large surface area for heat transfer by hydraulic fracturing, then drilling a second hole to intersect the fracture to complete the closed circulation loop. The completion of HDR geothermal wells presents cementing problems

Roland Pettitt

1979-01-01

174

Geological interpretation of Mount Ciremai geothermal system from remote sensing and magneto-teluric analysis  

E-print Network

The exploration of geothermal system at Mount Ciremai has been started since the early 1980s and has just been studied carefully since the early 2000s. Previous studies have detected the potential of geothermal system and also the groundwater mechanism feeding the system. This paper will discuss the geothermal exploration based on regional scale surface temperature analysis with Landsat image to have a more detail interpretation of the geological setting and magneto-telluric or MT survey at prospect zones, which identified by the previous method, to have a more exact and in depth local scale structural interpretation. Both methods are directed to pin point appropriate locations for geothermal pilot hole drilling and testing. We used four scenes of Landsat Enhanced Thematic Mapper or ETM+ data to estimate the surface manifestation of a geothermal system. Temporal analysis of Land Surface Temperature or LST was applied and coupled with field temperature measurement at seven locations. By combining the TTM with ...

Sumintadireja, Prihadi; Irawan, Dasapta E; Irawan, Diky; Fadillah, Ahmad

2015-01-01

175

Electronic Submersible Pump (ESP) Technology and Limitations with Respect to Geothermal Systems (Fact Sheet)  

SciTech Connect

The current state of geothermal technology has limitations that hinder the expansion of utility scale power. One limitation that has been discussed by the current industry is the limitation of Electric Submersible Pump (ESP) technology. With the exception of a few geothermal fields artificial lift technology is dominated by line shaft pump (LSP) technology. LSP's utilize a pump near or below reservoir depth, which is attached to a power shaft that is attached to a motor above ground. The primary difference between an LSP and an ESP is that an ESP motor is attached directly to the pump which eliminates the power shaft. This configuration requires that the motor is submersed in the geothermal resource. ESP technology is widely used in oil production. However, the operating conditions in an oil field vary significantly from a geothermal system. One of the most notable differences when discussing artificial lift is that geothermal systems operate at significantly higher flow rates and with the potential addition of Enhanced Geothermal Systems (EGS) even greater depths. The depths and flow rates associated with geothermal systems require extreme horsepower ratings. Geothermal systems also operate in a variety of conditions including but not limited to; high temperature, high salinity, high concentrations of total dissolved solids (TDS), and non-condensable gases.

Not Available

2014-09-01

176

Geopressured-geothermal well activities in Louisiana. Annual report, 1 January 1991--31 December 1991  

SciTech Connect

Since September 1978, microseismic networks have operated continuously around US Department of Energy (DOE) geopressured-geothermal well sites to monitor any microearthquake activity in the well vicinity. Microseismic monitoring is necessary before flow testing at a well site to establish the level of local background seismicity. Once flow testing has begun, well development may affect ground elevations and/or may activate growth faults, which are characteristic of the coastal region of southern Louisiana and southeastern Texas where these geopressured-geothermal wells are located. The microseismic networks are designed to detest small-scale local earthquakes indicative of such fault activation. Even after flow testing has ceased, monitoring continues to assess any microearthquake activity delayed by the time dependence of stress migration within the earth. Current monitoring shows no microseismicity in the geopressured-geothermal prospect areas before, during, or after flow testing.

John, C.J.

1992-10-01

177

Low Temperature Geothermal Electricity Generation: Google Earth Virtual Field Trip Activity  

NSDL National Science Digital Library

This exploration takes students to Chena Hot Springs Resort in Alaska where they will learn how to produce low temperature geothermal electricity. Teacher's guide, activity sheet and PowerPoint presenation included. The 2008 ATEEC Fellows Institute brought 18 environmental science community college and high school instructors to Alaska. They created virtual field trips using Google Earth. In the activity, explore Chena Hot Springs Resort in Alaska to learn about low temperature geothermal electricity generation. Chena Hot Springs runs their entire facility on renewable energy. Learn how they do it why they do it and the engineering challenges along the way. This activity includes numerous turnkey teaching resources such as a PowerPoint presentation explaining the geothermal heat exchanging process, video interviews with environmental engineers, a teacher's guide and student activity. Users must create a free login to access this resource.

178

Laboratory testing and modeling to evaluate perfluorocarbon compounds as tracers in geothermal systems  

SciTech Connect

The thermal stability and adsorption characteristics of three perfluorinated hydrocarbon compounds were evaluated under geothermal conditions to determine the potential to use these compounds as conservative or thermally-degrading tracers in Engineered (or Enhanced) Geothermal Systems (EGS). The three compounds tested were perfluorodimethyl-cyclobutane (PDCB), perfluoromethylcyclohexane (PMCH), and perfluorotrimethylcyclohexane (PTCH), which are collectively referred to as perfluorinated tracers, or PFTs. Two sets of duplicate tests were conducted in batch mode in gold-bag reactors, with one pair of reactors charged with a synthetic geothermal brine containing the PFTs and a second pair was charged with the brine-PFT mixture plus a mineral assemblage chosen to be representative of activated fractures in an EGS reservoir. A fifth reactor was charged with deionized water containing the three PFTs. The experiments were conducted at {approx}100 bar, with temperatures ranging from 230 C to 300 C. Semi-analytical and numerical modeling was also conducted to show how the PFTs could be used in conjunction with other tracers to interrogate surface area to volume ratios and temperature profiles in EGS reservoirs. Both single-well and cross-hole tracer tests are simulated to illustrate how different suites of tracers could be used to accomplish these objectives. The single-well tests are especially attractive for EGS applications because they allow the effectiveness of a stimulation to be evaluated without drilling a second well.

Reimus, Paul W [Los Alamos National Laboratory

2011-01-21

179

Characterization of a deep geothermal reservoir in an active volcanic area  

NASA Astrophysics Data System (ADS)

In this study an integrated methodological approach to characterize a complex deep geothermal reservoir located in an active volcanic setting in Indonesia is presented. The methods applied include hydraulic and hydrogeochemical (incl. isotope tracer) techniques to model groundwater flow, heat transport, and hydro-geochemical properties of the reservoir. 3D geological and hydraulic models of the area were constructed based on deep drill profiles, collected fluid and rock samples, and mapping of geological structures. First results show that the geothermal reservoir is composed of major geological units such as altered andesite, basalt, breccia, and tuff layers. Several tectonic faults crosscut the geological units into individual blocks and reservoirs and influence hydraulic pathways in multiple ways. Hot water and steam are produced by nine wells. Fluids are reinjected into the reservoir through one injection well. Currently, a geothermal plant produces 60 MWe from steam withdrawn. Temperatures of the geothermal system range between 250 and 350 C (Koestono et al. 2010). Based on the chemical composition of fluids from the production wells (concentration of major ions and physicochemical parameters) at least two different hydro-geochemical reservoirs could be identified. The deep reservoir with a moderate pH of 5 is marked by total silica concentrations up to 350 mg/L and high chloride concentrations of 430 mg/L. For the shallow reservoir, highly acidic conditions with pH values of 2.9 are analysed for water, while steam shows pH values around 4. Furthermore, high chloride (1550 mg/L), total silica (460 mg/L), and sulphate concentrations (1600 mg/L) are characteristic for the shallow reservoir. According to Giggenbach (1988) and Nicholson (1993) the water can be classified into sulphate-rich waters and neutral chloride-waters. Sulphate-rich water is expected to occur near to the heat source while chloride-rich waters discharge near the outflow zone. Surface reservoirs, e.g. an acid lake and several hot springs seem to be in close contact with the shallow reservoir.

Brehme, M.; Kamah, Y.; Koestono, H.; Zimmermann, G.; Regenspurg, S.; Erba?, K.; Wiegand, B.; Sauter, M.

2012-04-01

180

Development of geothermal logging systems in the United States  

SciTech Connect

Logging technologies developed for hydrocarbon resource evaluation have not migrated into geothermal applications even though data so obtained would strengthen reservoir characterization efforts. Two causative issues have impeded progress: (1) there is a general lack of vetted, high-temperature instrumentation, and (2) the interpretation of log data generated in a geothermal formation is in its infancy. Memory-logging tools provide a path around the first obstacle by providing quality data at a low cost. These tools feature on-board computers that process and store data, and newer systems may be programmed to make decisions. Since memory tools are completely self-contained, they are readily deployed using the slick line found on most drilling locations. They have proven to be rugged, and a minimum training program is required for operator personnel. Present tools measure properties such as temperature and pressure, and the development of noise, deviation, and fluid conductivity logs based on existing hardware is relatively easy. A more complex geochemical tool aimed at a quantitative analysis of (potassium, uranium and thorium) is in the calibration phase, and it is expandable into all nuclear measurements common in the hydrocarbon industry. A fluid sampling tool is in the design phase. All tools are designed for operation at conditions exceeding 400 C, and for deployment in the slim holes produced by mining-coring operations. Partnerships are being formed between the geothermal industry and scientific drilling programs to define and develop inversion algorithms relating raw tool data to more pertinent information. These cooperative efforts depend upon quality guidelines such as those under development within the international Ocean Drilling Program.

Lysne, P.

1994-04-01

181

Active Management of Integrated Geothermal-CO2 Storage Reservoirs in Sedimentary Formations  

SciTech Connect

Active Management of Integrated GeothermalCO2 Storage Reservoirs in Sedimentary Formations: An Approach to Improve Energy Recovery and Mitigate Risk: FY1 Final Report The purpose of phase 1 is to determine the feasibility of integrating geologic CO2 storage (GCS) with geothermal energy production. Phase 1 includes reservoir analyses to determine injector/producer well schemes that balance the generation of economically useful flow rates at the producers with the need to manage reservoir overpressure to reduce the risks associated with overpressure, such as induced seismicity and CO2 leakage to overlying aquifers. Based on a range of well schemes, techno-economic analyses of the levelized cost of electricity (LCOE) are conducted to determine the economic benefits of integrating GCS with geothermal energy production. In addition to considering CO2 injection, reservoir analyses are conducted for nitrogen (N2) injection to investigate the potential benefits of incorporating N2 injection with integrated geothermal-GCS, as well as the use of N2 injection as a potential pressure-support and working-fluid option. Phase 1 includes preliminary environmental risk assessments of integrated geothermal-GCS, with the focus on managing reservoir overpressure. Phase 1 also includes an economic survey of pipeline costs, which will be applied in Phase 2 to the analysis of CO2 conveyance costs for techno-economics analyses of integrated geothermal-GCS reservoir sites. Phase 1 also includes a geospatial GIS survey of potential integrated geothermal-GCS reservoir sites, which will be used in Phase 2 to conduct sweet-spot analyses that determine where promising geothermal resources are co-located in sedimentary settings conducive to safe CO2 storage, as well as being in adequate proximity to large stationary CO2 sources.

Buscheck, Thomas A.

2012-01-01

182

Federal Geothermal Research Program Update - Fiscal Year 2004  

SciTech Connect

The Department of Energy (DOE) and its predecessors have conducted research and development (R&D) in geothermal energy since 1971. The Geothermal Technologies Program (GTP) works in partnership with industry to establish geothermal energy as an economically competitive contributor to the U.S. energy supply. Geothermal energy production, a $1.5 billion a year industry, generates electricity or provides heat for direct use applications. The technologies developed by the Geothermal Technologies Program will provide the Nation with new sources of electricity that are highly reliable and cost competitive and do not add to America's air pollution or the emission of greenhouse gases. Geothermal electricity generation is not subject to fuel price volatility and supply disruptions from changes in global energy markets. Geothermal energy systems use a domestic and renewable source of energy. The Geothermal Technologies Program develops innovative technologies to find, access, and use the Nation's geothermal resources. These efforts include emphasis on Enhanced Geothermal Systems (EGS) with continued R&D on geophysical and geochemical exploration technologies, improved drilling systems, and more efficient heat exchangers and condensers. The Geothermal Technologies Program is balanced between short-term goals of greater interest to industry, and long-term goals of importance to national energy interests. The program's research and development activities are expected to increase the number of new domestic geothermal fields, increase the success rate of geothermal well drilling, and reduce the costs of constructing and operating geothermal power plants. These improvements will increase the quantity of economically viable geothermal resources, leading in turn to an increased number of geothermal power facilities serving more energy demand. These new geothermal projects will take advantage of geothermal resources in locations where development is not currently possible or economical.

Patrick Laney

2005-03-01

183

Federal Geothermal Research Program Update Fiscal Year 2004  

SciTech Connect

The Department of Energy (DOE) and its predecessors have conducted research and development (R&D) in geothermal energy since 1971. The Geothermal Technologies Program (GTP) works in partnership with industry to establish geothermal energy as an economically competitive contributor to the U.S. energy supply. Geothermal energy production, a $1.5 billion a year industry, generates electricity or provides heat for direct use applications. The technologies developed by the Geothermal Technologies Program will provide the Nation with new sources of electricity that are highly reliable and cost competitive and do not add to America's air pollution or the emission of greenhouse gases. Geothermal electricity generation is not subject to fuel price volatility and supply disruptions from changes in global energy markets. Geothermal energy systems use a domestic and renewable source of energy. The Geothermal Technologies Program develops innovative technologies to find, access, and use the Nation's geothermal resources. These efforts include emphasis on Enhanced Geothermal Systems (EGS) with continued R&D on geophysical and geochemical exploration technologies, improved drilling systems, and more efficient heat exchangers and condensers. The Geothermal Technologies Program is balanced between short-term goals of greater interest to industry, and long-term goals of importance to national energy interests. The program's research and development activities are expected to increase the number of new domestic geothermal fields, increase the success rate of geothermal well drilling, and reduce the costs of constructing and operating geothermal power plants. These improvements will increase the quantity of economically viable geothermal resources, leading in turn to an increased number of geothermal power facilities serving more energy demand. These new geothermal projects will take advantage of geothermal resources in locations where development is not currently possible or economical.

Not Available

2005-03-01

184

Geochemical exploration of a promissory Enhanced Geothermal System (EGS): the Acoculco caldera, Mexico.  

NASA Astrophysics Data System (ADS)

The Acoculco caldera (Puebla, Mexico) has been identified by the Mexican Federal Electricity Company (in Spanish 'Comisin Federal de Electricidad', CFE) as a potential Enhanced Geothermal System (EGS) candidate. Two exploration wells were drilled and promising temperatures of ~300 C have been measured at a depth of 2000 m with a geothermal gradient of 11oC/100m, which is three times higher than the baseline gradient measured within the Trans-Mexican Volcanic Belt. As usually observed in Hot Dry Rock systems, thermal manifestations in surface are scarce and consist in low-temperature bubbling springs and soil degassing. The goals of this study were to identify the origin of these fluids, to estimate the soil degassing rate and to explore new areas for a future detailed exploration and drilling activities. Water and gas samples were collected for chemical and isotopic analysis (?18O, ?D, 3He/4He, 13C, 15N) and a multi-gas (CO2, CH4, H2S) soil survey was carried out using the accumulation chamber method. Springs' compositions indicate a meteoric origin and the dissolution of CO2 and H2S-rich gases, while gas compositions reveal a MORB-type origin mixed with some arc-type contribution. Gas geothermometry results are similar to temperatures measured during well drilling (260 C-300 C). Amongst all measured CO2 fluxes, only 5% (mean: 5543 g m-2 day-1) show typical geothermal values, while the remaining fluxes are low and correspond to biogenic degassing (mean: 18 g m-2 day-1). The low degassing rate of the geothermal system is a consequence of the intense hydrothermal alteration observed in the upper 800 m of the system which acts as an impermeable caprock. Highest measured CO2 fluxes (above > 600 g m-2 day-1) have corresponding CH4/CO2 flux ratios similar to mass ratios of sampled gases, which suggest an advective fluid transport. To represent field conditions, a numerical model was also applied to simulate the migration of CO2 towards the surface through a shallow aquifer under fully saturated conditions. By changing some of the aquifer properties (i.e., depth, permeability and porosity), it was found how geothermal CO2 fluxes can show values similar to a biogenic background flux. Future field work at Acoculco will include ?13C analysis together with soil flux measurements for a better discrimination of the degassing origin, and a thinner flux measurement grid will be defined for a better detection of any possible gas flux anomaly.

Peiffer, Loic; Romero, Ruben Bernard; Prez-Zarate, Daniel; Guevara, Mirna; Santoyo Gutirrez, Edgar

2014-05-01

185

Enhanced Geothermal Systems (EGS) well construction technology evaluation report.  

SciTech Connect

Electricity production from geothermal resources is currently based on the exploitation of hydrothermal reservoirs. Hydrothermal reservoirs possess three ingredients critical to present day commercial extraction of subsurface heat: high temperature, in-situ fluid and high permeability. Relative to the total subsurface heat resource available, hydrothermal resources are geographically and quantitatively limited. A 2006 DOE sponsored study led by MIT entitled 'The Future of Geothermal Energy' estimates the thermal resource underlying the United States at depths between 3 km and 10 km to be on the order of 14 million EJ. For comparison purposes, total U.S. energy consumption in 2005 was 100 EJ. The overwhelming majority of this resource is present in geological formations which lack either in-situ fluid, permeability or both. Economical extraction of the heat in non-hydrothermal situations is termed Enhanced or Engineered Geothermal Systems (EGS). The technologies and processes required for EGS are currently in a developmental stage. Accessing the vast thermal resource between 3 km and 10 km in particular requires a significant extension of current hydrothermal practice, where wells rarely reach 3 km in depth. This report provides an assessment of well construction technology for EGS with two primary objectives: (1) Determining the ability of existing technologies to develop EGS wells. (2) Identifying critical well construction research lines and development technologies that are likely to enhance prospects for EGS viability and improve overall economics. Towards these ends, a methodology is followed in which a case study is developed to systematically and quantitatively evaluate EGS well construction technology needs. A baseline EGS well specification is first formulated. The steps, tasks and tools involved in the construction of this prospective baseline EGS well are then explicitly defined by a geothermal drilling contractor in terms of sequence, time and cost. A task and cost based analysis of the exercise is subsequently conducted to develop a deeper understanding of the key technical and economic drivers of the well construction process. Finally, future research & development recommendations are provided and ranked based on their economic and technical significance.

Capuano, Louis, Jr. (Thermasource Inc.); Huh, Michael; Swanson, Robert (Thermasource Inc.); Raymond, David Wayne; Finger, John Travis; Mansure, Arthur James; Polsky, Yarom; Knudsen, Steven Dell

2008-12-01

186

Outstanding Issues in the Assessment of Enhanced Geothermal Systems Resources  

NASA Astrophysics Data System (ADS)

The successful implementation of Enhanced Geothermal Systems (EGS) technology has the potential to dramatically expand both the magnitude and spatial extent of geothermal energy production, and the U.S. Geological Survey (USGS) has been working to develop a comprehensive EGS resource assessment for the United States. However, a number of outstanding scientific and technical issues must be resolved in order to ensure the accuracy and reliability of this assessment. Among these are determining those conditions under which it is possible to replicate the high average permeability (approximately 10-15 to 10-13 m2) characteristic of natural hydrothermal reservoirs, evaluating the likely heterogeneity of fracture permeability within EGS reservoirs and its influence on the geothermal recovery factor, Rg, which is defined as the ratio of produced thermal energy to the thermal energy contained in the stimulated volume comprising the reservoir, and improving estimates of temperature in the upper crust to better quantify the thermal energy available at those depths viable for EGS reservoir creation. Models for the development of fracture permeability from the shear slip along pre-existing natural fractures induced by hydraulic stimulation indicate that production from EGS reservoirs will be sensitive to the influence of effective stress and rock properties on the processes of shear fracture formation and closure. Calibration of model parameters with results from EGS field experiments and demonstration projects suggests that sufficient permeability may be difficult to attain through shear stimulation at depths greater than approximately 6 km, particularly in regions characterized by high normal stress on pre-existing faults and fractures. In addition, the expected heterogeneity of fracture permeability within EGS reservoirs may limit Rg to values on the order of 0.05 to 0.1, which is at the lower end of the observed range for producing natural geothermal reservoirs. Although there are significant gaps in the spatial coverage of heat flow measurements in much of the United States and some uncertainty in the estimation of thermal properties at depth, analysis of the existing thermal data indicates that even with the possible constraints outlined above, large areas of the western United States will be suitable for EGS development. However, this provisional interpretation is compromised by the limited number of cases in which model predictions can be compared to laboratory or in situ data. The key challenge for improved EGS resource assessments is acquiring and interpreting comprehensive laboratory and field data that can provide quantitative constraints on the recovery of heat from EGS reservoirs in diverse settings.

Williams, C.; Deangelo, J.

2010-12-01

187

Local Magmatic Episodes and Heat Sources for Hydrothermal Activity in the Kawerau Geothermal Field, Taupo Volcanic Zone, New Zealand  

NASA Astrophysics Data System (ADS)

Kawerau Geothermal Field is the most northeasterly of the major, high-temperature geothermal fields in the central Taupo Volcanic Zone (TVZ, New Zealand), an intensely active Quaternary arc locus of rhyolitic volcanism and thermal output. Kawerau is situated at a transition where the voluminous silicic volcanism and associated magmatism of the central TVZ merge into the andesite-dacite dominated northern TVZ. Structurally, the Kawerau system lies within the southern part of the northeast-trending Whakatane Graben, in a zone where the active TVZ rift structures intersect the north-trending strike-slip faults of the North Island Shear Belt. The field is hosted in 600-1000 m of volcanic rocks and sediments overlying faulted Mesozoic basement greywacke. Fractured coherent rhyolite lava bodies occur between 0 and -1000 m below sea level, with several bodies intersected by drilling. These rhyolites represent local upper-crustal sources of magma, which could have provided heat input for past geothermal systems. Differentiating these rhyolites is important in deciphering the timing of past thermal events, and whether the modern field is long-lived or episodically rejuvenated. Age determinations obtained from samples of the rhyolite using single-crystal U-Pb dating on zircon (Secondary Ion Mass Spectrometry, using the SHRIMP-RG instrument) show the rhyolite bodies to belong to two periods of eruptive activity, one around 360 ka, the other around 140 ka. The older, more voluminous episode is represented by two petrographic magma types, each sampled as a buried surficial lava dome, and one or more buried intersections of sills. The younger episode is represented by modern surficial domes and by two intersections of dike feeders within the greywacke basement. Previous interpretations of the current Kawerau Geothermal Field as a long-lived system are now questioned, as it is apparent that only at long-spaced intervals is there evidence of magma at shallow enough crustal levels beneath the field to generate vigorous hydrothermal activity (as at the present day). The contrast between earlier sill emplacement and later diking is taken as reflecting a change in orientation of the principal stress axes at the field from ?3 vertical around 360 ka, to ?3 horizontal and orientated northwest-southeast (i.e., the modern TVZ orientation) by ca. 140 ka. The age data have provided key insights into the temporal evolution of rhyolitic magmatic activity at Kawerau, with the intrusive complexes representing past heat sources that have given rise to temporally discrete, geographically coincident 'Kawerau geothermal systems'.

Milicich, S. D.; Wilson, C. J.; Bignall, G.; Pezaro, B.

2012-12-01

188

Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia  

NASA Astrophysics Data System (ADS)

The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS (< 500mg/l) Ca-Mg-HCO3 dominated water at recharge area in the highlands and escarpments evolve progressively into Ca-Na-HCO3 and Na-Ca-HCO3 type waters along the rift ward groundwater flow paths. These waters finally appear as moderate TDS (mean 960mg/l) Na-HCO3 type and as high TDS (> 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98?g/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (<30mg/l) thermal waters indicated a dilution by cold waters. Laboratory batch leaching experiments showed that fast dissolution of fluoride from the sediment samples suddenly leached into the interacting water at the first one hour and then remain stable throughout the experiment. The concentrations of leached fluoride from the hot spring deposits, the lacustrine sediments, and the pyroclastic rock are usually low (1% of the total or less than the content in the sediment or rock) but strongly correlated with the concentrations in groundwaters in the local vicinity. The readily leachable hot spring deposits and local lacustrine sediments, which were leached easily as high as three fold of other sediments leachability, are considered as the reservoir for the potential fluoride contamination of the rift groundwater. Leaching of fluoride in the sub-surface system is simulated with sediment-packed column leached by flowing water and applying temporary interruption of flow during the experiment. The result indicated that a sharp increase of fluoride concentration (up to 58mg/kg) observed in leachates before one pore-volume of water eluted from the column. The concentration of leached fluoride consequently declined with the increased flowing pore-volume of water and finally the lowest concentrations of leached fluoride occurred in the end of the experiment. Flow interruption during column leaching experiment causes a noticeable fluoride concentration perturbation due to the heterogeneity of the sediment.

Weldesenbet, S. F.

2012-12-01

189

High Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia  

NASA Astrophysics Data System (ADS)

The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS (< 500mg/l) Ca-Mg-HCO3 dominated water at recharge area in the highlands and escarpments evolve progressively into Ca-Na-HCO3 and Na-Ca-HCO3 type waters along the rift ward groundwater flow paths. These waters finally appear as moderate TDS (mean 960mg/l) Na-HCO3 type and as high TDS (> 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98?g/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (<30mg/l) thermal waters indicated a dilution by cold waters. Laboratory batch leaching experiments showed that fast dissolution of fluoride from the sediment samples suddenly leached into the interacting water at the first one hour and then remain stable throughout the experiment. The concentrations of leached fluoride from the hot spring deposits, the lacustrine sediments, and the pyroclastic rock are usually low (1% of the total or less than the content in the sediment or rock) but strongly correlated with the concentrations in groundwaters in the local vicinity. The readily leachable hot spring deposits and local lacustrine sediments, which were leached easily as high as three fold of other sediments leachability, are considered as the reservoir for the potential fluoride contamination of the rift groundwater. Leaching of fluoride in the sub-surface system is simulated with sediment-packed column leached by flowing water and applying temporary interruption of flow during the experiment. The result indicated that a sharp increase of fluoride concentration (up to 58mg/kg) observed in leachates before one pore-volume of water eluted from the column. The concentration of leached fluoride consequently declined with the increased flowing pore-volume of water and finally the lowest concentrations of leached fluoride occurred in the end of the experiment. Flow interruption during column leaching experiment causes a noticeable fluoride concentration perturbation due to the heterogeneity of the sediment.

Weldesenbet, S. F.; Wohnlich, S.

2012-12-01

190

Warren Estates-Manzanita Estates Reno, Nevada residential geothermal district heating system  

SciTech Connect

Warren Estates-Manzanita Estates is the largest privately-owned and operated residential geothermal district heating system in the State of Nevada. The system has operated for ten years and presently services 95 homes. Geothermal energy is used to heat homes, domestic water, spas, swimming pools, and greenhouses. Four homes have installed driveway deicing systems using geothermal energy. This paper briefly describes the geothermal resource, wells, system engineering, operation, applications, and economics. The accompanying posters illustrate the geothermal area, system design, and various applications. The resource is part of the Moana geothermal field, located in southwest Reno. Excluding the Warren-Manzanita Estates, the well-known Moana field supports nearly 300 geothermal wells that supply fluids to individual residences, several motels, a garden nursery, a few churches, and a municipal swimming pool. The Warren-Manzanita Estates is ideally suited for residential district space heating because the resource is shallow, moderate-temperature, and chemically benign. The primary reservoir rock is the Kate Peak andesite, a Tertiary volcanic lahar that has excellent permeability within the narrow fault zones that bisect the property. The Kate Peak formation is overlain by impermeable Tertiary lake sediments and alluvium. Two production wells, each about 240 m deep, are completed near the center of the residential development at the intersection of two fault zones. Geothermal fluids are pumped at a rate of 15 to 25 l/s (260-400 gpm) from one of two wells at a temperature of 95{degrees}C (202{degrees}F) to two flat-plate heat exchangers. The heat exchangers transfer energy from the geothermal fluids to a second fluid, much like a binary geothermal power plant.

McKay, F.; McKay, G.; McKay, S.; Flynn, T. [McKay Pump and Drilling, Reno, NV (United States)

1995-12-31

191

The application of unmanned aerial systems (UAS) in geophysical investigations of geothermal systems  

NASA Astrophysics Data System (ADS)

Investigations of geothermal systems typically involve ground-based geological and geophysical studies in order to map structures that control and facilitate fluid flow. The spatial extent of ground-based investigations can be limited, however, by surficial hot springs, dense foliage, and roadless or private lands. This can result in data gaps in key areas, particularly around active hydrothermal springs. Manned aircraft can provide access to these areas and can yield broad and uniform data coverage, but high-resolution surveys are costly and relatively inflexible to changes in the survey specifications that may arise as data are collected. Unmanned aerial systems (UAS) are well suited for conducting these surveys, but until recently, various factors (scientific instrumentation requirements, platform limitations, and size of the survey area) have required the use of large UAS platforms, rendering unmanned aerial surveys unsuitable for most investigations. We have developed and tested a new cesium magnetometer system to collect magnetic data using two different small-platform UAS that overcomes many of the challenges described above. We are deploying this new system in Surprise Valley, CA, to study the area's active geothermal field. Surprise Valley is ideally suited to testing UAS due to its low population density, accessible airspace, and broad playa that provides ample opportunity to safely land the aircraft. In combination with gravity and topographic data, magnetic data are particularly useful for identifying buried, intra-basin structures, especially in areas such as Surprise Valley where highly magnetic, dense mafic volcanic rocks are interbedded with and faulted against less magnetic, less dense sedimentary rock. While high-resolution gravity data must be collected at point locations on the ground, high-resolution magnetic data can be obtained by UAS that provide continuous coverage. Once acquired, the magnetic data obtained by the UAS will be combined with high-resolution airborne lidar data in order to correlate subsurface structures with subtle surface features, to identify possible conduits for, or barriers to, geothermal fluid circulation. Our September 2012 mission will deploy NASA's SIERRA UAS platform to perform a reconnaissance survey of the entire valley. Results from ground and flight tests indicate that magnetic "noise" from the SIERRA platform is low, and can be effectively compensated to provide data comparable with high-resolution commercial methods. A second mission will be flown in summer 2013 using the SWIFT platform, which will analyze data from its onboard sensors to continuously optimize its flight path in real-time to autonomously investigate regions of interest such as steep magnetic gradients or abrupt changes in anomaly amplitudes and wavelengths. The SWIFT also has the advantage that it can be flown as a glider, further reducing magnetic noise of the platform arising from the engine. This innovative use of UAS and intelligent automation in geophysical investigations offers the ability to obtain higher-resolution and more comprehensive and targeted data at a lower cost than is presently possible, expanding our ability to explore a wide variety of geothermal systems.

Glen, J. M.; Egger, A. E.; Ippolito, C.; Phelps, G. A.; Berthold, R.; Lee, R.; Spritzer, J. M.; Tchernychev, M.

2012-12-01

192

Energetic, Exergetic, Economic and Environmental Assessments of the Bigadic Geothermal District Heating System as a Potential Green Solution  

Microsoft Academic Search

In this study, we assess the Bigadic Geothermal District Heating System (GDHS), which has the world's third longest and Turkey's longest geothermal pipeline, for its energetic, exergetic, economic and environmental factors. The thermal energy capacity of the Bigadic geothermal field is rated as 31.83 MW for a discharge temperature of 45C. As of the end of 2006, there were two

Z. Oktay; I. Dincer

2007-01-01

193

Exploration drilling and reservoir model of the Platanares geothermal system, Honduras, Central America  

USGS Publications Warehouse

Results of drilling, logging, and testing of three exploration core holes, combined with results of geologic and hydrogeochemical investigations, have been used to present a reservoir model of the Platanares geothermal system, Honduras. Geothermal fluids circulate at depths ??? 1.5 km in a region of active tectonism devoid of Quaternary volcanism. Large, artesian water entries of 160 to 165??C geothermal fluid in two core holes at 625 to 644 m and 460 to 635 m depth have maximum flow rates of roughly 355 and 560 l/min, respectively, which are equivalent to power outputs of about 3.1 and 5.1 MW(thermal). Dilute, alkali-chloride reservoir fluids (TDS ??? 1200 mg/kg) are produced from fractured Miocene andesite and Cretaceous to Eocene redbeds that are hydrothermally altered. Fracture permeabillity in producing horizons is locally greater than 1500 and bulk porosity is ??? 6%. A simple, fracture-dominated, volume-impedance model assuming turbulent flow indicates that the calculated reservoir storage capacity of each flowing hole is approximately 9.7 ?? 106 l/(kg cm-2), Tritium data indicate a mean residence time of 450 yr for water in the reservoir. Multiplying the natural fluid discharge rate by the mean residence time gives an estimated water volume of the Platanares system of ??? 0.78 km3. Downward continuation of a 139??C/km "conductive" gradient at a depth of 400 m in a third core hole implies that the depth to a 225??C source reservoir (predicted from chemical geothermometers) is at least 1.5 km. Uranium-thorium disequilibrium ages on calcite veins at the surface and in the core holes indicate that the present Platanares hydrothermal system has been active for the last 0.25 m.y. ?? 1991.

Goff, F.; Goff, S.J.; Kelkar, S.; Shevenell, L.; Truesdell, A.H.; Musgrave, J.; Rufenacht, H.; Flores, W.

1991-01-01

194

Screening for Heat Transport by Groundwater in Closed Geothermal Systems.  

PubMed

Heat transfer due to groundwater flow can significantly affect closed geothermal systems. Here, a screening method is developed, based on Peclet numbers for these systems and Darcy's law. Conduction-only conditions should not be expected where specific discharges exceed 10(-8) ?m/s. Constraints on hydraulic gradients allow for preliminary screening for advection based on rock or soil types. Identification of materials with very low hydraulic conductivity, such as shale and intact igneous and metamorphic rock, allow for analysis with considering conduction only. Variability in known hydraulic conductivity allows for the possibility of advection in most other rocks and soil types. Further screening relies on refinement of estimates of hydraulic gradients and hydraulic conductivity through site investigations and modeling until the presence or absence of conduction can be confirmed. PMID:24438345

Ferguson, Grant

2014-01-17

195

Geothermal Reservoir Dynamics - TOUGHREACT  

SciTech Connect

This project has been active for several years and has focused on developing, enhancing and applying mathematical modeling capabilities for fractured geothermal systems. The emphasis of our work has recently shifted towards enhanced geothermal systems (EGS) and hot dry rock (HDR), and FY05 is the first year that the DOE-AOP actually lists this project under Enhanced Geothermal Systems. Our overall purpose is to develop new engineering tools and a better understanding of the coupling between fluid flow, heat transfer, chemical reactions, and rock-mechanical deformation, to demonstrate new EGS technology through field applications, and to make technical information and computer programs available for field applications. The objectives of this project are to: (1) Improve fundamental understanding and engineering methods for geothermal systems, primarily focusing on EGS and HDR systems and on critical issues in geothermal systems that are difficult to produce. (2) Improve techniques for characterizing reservoir conditions and processes through new modeling and monitoring techniques based on ''active'' tracers and coupled processes. (3) Improve techniques for targeting injection towards specific engineering objectives, including maintaining and controlling injectivity, controlling non-condensable and corrosive gases, avoiding scale formation, and optimizing energy recovery. Seek opportunities for field testing and applying new technologies, and work with industrial partners and other research organizations.

Pruess, Karsten; Xu, Tianfu; Shan, Chao; Zhang, Yingqi; Wu,Yu-Shu; Sonnenthal, Eric; Spycher, Nicolas; Rutqvist, Jonny; Zhang,Guoxiang; Kennedy, Mack

2005-03-15

196

Geothermal Case Studies  

SciTech Connect

The US Geological Survey (USGS) resource assessment (Williams et al., 2009) outlined a mean 30GWe of undiscovered hydrothermal resource in the western US. One goal of the Geothermal Technologies Office (GTO) is to accelerate the development of this undiscovered resource. The Geothermal Technologies Program (GTP) Blue Ribbon Panel (GTO, 2011) recommended that DOE focus efforts on helping industry identify hidden geothermal resources to increase geothermal capacity in the near term. Increased exploration activity will produce more prospects, more discoveries, and more readily developable resources. Detailed exploration case studies akin to those found in oil and gas (e.g. Beaumont, et al, 1990) will give operators a single point of information to gather clean, unbiased information on which to build geothermal drilling prospects. To support this effort, the National Renewable Energy laboratory (NREL) has been working with the Department of Energy (DOE) to develop a template for geothermal case studies on the Geothermal Gateway on OpenEI. In fiscal year 2013, the template was developed and tested with two case studies: Raft River Geothermal Area (http://en.openei.org/wiki/Raft_River_Geothermal_Area) and Coso Geothermal Area (http://en.openei.org/wiki/Coso_Geothermal_Area). In fiscal year 2014, ten additional case studies were completed, and additional features were added to the template to allow for more data and the direct citations of data. The template allows for: Data - a variety of data can be collected for each area, including power production information, well field information, geologic information, reservoir information, and geochemistry information. Narratives ? general (e.g. area overview, history and infrastructure), technical (e.g. exploration history, well field description, R&D activities) and geologic narratives (e.g. area geology, hydrothermal system, heat source, geochemistry.) Exploration Activity Catalog - catalog of exploration activities conducted in the area (with dates and references.) NEPA Analysis ? a query of NEPA analyses conducted in the area (that have been catalogued in the OpenEI NEPA database.) In fiscal year 2015, NREL is working with universities to populate additional case studies on OpenEI. The goal is to provide a large enough dataset to start conducting analyses of exploration programs to identify correlations between successful exploration plans for areas with similar geologic occurrence models.

Young, Katherine

2014-09-30

197

Thermal and chemical evolution of The Geysers geothermal system, California  

SciTech Connect

Fluid inclusions and mineral assemblages provide a reward of the thermal and chemical changes that occurred during the evolution of The Geysers geothermal system. The data document the presence of an extensive liquid dominated geothermal system that developed in response to felsite intrusion and its evolution to a vapor-dominated regime. Temperatures within the early liquid-dominated system ranged from 175 C at a distance of 7200 feet from the felsite to more than 350 C near the contact while salinities varied from 5 equivalent weight percent NaCl (at a distance of 5500 feet) to more than 26 weight percent NaCl. As temperatures around the felsite declined, the liquid-dominated system collapsed upon itself. Downward migration of the low salinity waters resulted in dilution of the fluids present in regions now occupied by the caprock and normal vapor-dominated reservoir. In contrast, dilution was minor in rocks now hosting the high-temperature vapor-dominated reservoir. This suggests that low permeabilities are the primary reason for the development of the high-temperature reservoir. Boiling within the caprock produced late-stage veins of calcite and quartz. As the fluid boiled off, condensate was trapped as low salinity fluid inclusions. Within the main body of the reservoir, a liquid phase with salinities of up to 7 equivalent weight percent NaCl persisted to temperatures between 250 and 270 C. However, except for the presence of vapor-rich inclusions, little evidence of boiling within the reservoir rocks was preserved.

Moore, J.N.

1992-01-01

198

Phase relations and adiabats in boiling seafloor geothermal systems  

NASA Astrophysics Data System (ADS)

Observations of large salinity variations and vent temperatures in the range of 380-400C suggest that boiling or two-phase separation may be occurring in some seafloor geothermal systems. Consideration of flow rates and the relatively small differences in density between vapors and liquids at the supercritical pressures at depth in these systems suggests that boiling is occurring under closed-system conditions. Salinity and temperature of boiling vents can be used to estimate the pressure-temperature point in the subsurface at which liquid seawater first reached the two-phase boundary. Data are reviewed to construct phase diagrams of coexisting brines and vapors in the two-phase region at pressures corresponding to those of the seafloor geothermal systems. A method is developed for calculating the enthalpy and entropy of the coexisting mixtures, and results are used to construct adiabats from the seafloor to the P-T two-phase boundary. Results for seafloor vents discharging at 2300 m below sea level indicate that a 385C vent is composed of a brine (7% NaCl equivalent) in equilibrium with a vapor (0.1% NaCl). Brine constitutes 45% by weight of the mixture, and the fluid first boiled at approximately 1 km below the seafloor at 415C, 330 bar. A 400C vent is primarily vapor (88 wt.%, 0.044% NaCl) with a small amount of brine (26% NaCl) and first boiled at 2.9 km below the seafloor at 500C, 520 bar. These results show that adiabatic decompression in the two-phase region results in dramatic cooling of the fluid mixture when there is a large fraction of vapor.

Bischoff, James L.; Pitzer, Kenneth S.

1985-11-01

199

Phase relations and adiabats in boiling seafloor geothermal systems  

USGS Publications Warehouse

Observations of large salinity variations and vent temperatures in the range of 380-400??C suggest that boiling or two-phase separation may be occurring in some seafloor geothermal systems. Consideration of flow rates and the relatively small differences in density between vapors and liquids at the supercritical pressures at depth in these systems suggests that boiling is occurring under closed-system conditions. Salinity and temperature of boiling vents can be used to estimate the pressure-temperature point in the subsurface at which liquid seawater first reached the two-phase boundary. Data are reviewed to construct phase diagrams of coexisting brines and vapors in the two-phase region at pressures corresponding to those of the seafloor geothermal systems. A method is developed for calculating the enthalpy and entropy of the coexisting mixtures, and results are used to construct adiabats from the seafloor to the P-T two-phase boundary. Results for seafloor vents discharging at 2300 m below sea level indicate that a 385??C vent is composed of a brine (7% NaCl equivalent) in equilibrium with a vapor (0.1% NaCl). Brine constitutes 45% by weight of the mixture, and the fluid first boiled at approximately 1 km below the seafloor at 415??C, 330 bar. A 400??C vent is primarily vapor (88 wt.%, 0.044% NaCl) with a small amount of brine (26% NaCl) and first boiled at 2.9 km below the seafloor at 500??C, 520 bar. These results show that adiabatic decompression in the two-phase region results in dramatic cooling of the fluid mixture when there is a large fraction of vapor. ?? 1985.

Bischoff, J.L.; Pitzer, K.S.

1985-01-01

200

Geothermal Energy.  

ERIC Educational Resources Information Center

This curriculum unit describes geothermal energy in the context of the world's energy needs. It addresses renewable and nonrenewable energy sources with an in-depth study of geothermal energy--its geology, its history, and its many uses. Included are integrated activities involving science, as well as math, social studies, and language arts.

Nemzer, Marilyn; Page, Deborah

201

The Future of Geothermal Energy  

E-print Network

The Future of Geothermal Energy Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century #12;The Future of Geothermal Energy Impact of Enhanced Geothermal Systems (EGS and Renewable Energy, Office of Geothermal Technologies, Under DOE Idaho Operations Office Contract DE-AC07-05ID

Laughlin, Robert B.

202

Addressing Questions on Life in Terrestrial Geothermal Systems  

NASA Astrophysics Data System (ADS)

A binational research team met on the campus of Yunnan University in Kunming, China, to discuss recent progress and future plans to leverage binational support to address major questions on life in terrestrial geothermal systems. The symposium included about 90 faculty, postdocs, and students from China and about 30 faculty, postdocs, students, and high school teachers from the United States. The introductory session reviewed the progress of the Tengchong PIRE project funded by the U.S. National Science Foundation (NSF) Partnerships for International Research and Education (PIRE) program (OISE-0836450). It also introduced a new collaborative project funded as a Key Project of International Cooperation by the Chinese Ministry of Science and Technology (MOST, 2013DFA31980), which is the first project funded through a memorandum of understanding between NSF and MOST to promote China-U.S. collaboration.

Hedlund, Brian P.; Li, Wen-Jun; Zhang, Chuanlun

2013-09-01

203

The Earth-Coupled or Geothermal Heat Pump Air Conditioning System  

E-print Network

" and next at proper home insulation, window coverings, etc. The other electrical appliances in the home use relatively minor amounts of electricity compared to the air conditioning and hot water heating system. This paper will describe the geothermal heat...

Wagers, H. L.; Wagers, M. C.

1985-01-01

204

Design, fabrication, delivery, operation and maintenance of a geothermal power conversion system  

NASA Technical Reports Server (NTRS)

The design, fabrication, delivery, operation and maintenance of an Hydrothermal Power Company 1250 KVA geothermal power conversion system using a helical screw expander as the prime mover is described. Hydrostatic and acceptance testing are discussed.

1980-01-01

205

Hydrothermal spallation drilling and advanced energy conversion technologies for Engineered Geothermal Systems  

E-print Network

The purpose of this research was to study the various factors affecting the economic and technical feasibility of Engineered Geothermal Systems, with a special emphasis on advanced drilling technologies. The first part of ...

Augustine, Chad R

2009-01-01

206

Value analysis of advanced heat rejection systems for geothermal power plants  

Microsoft Academic Search

A computer model is developed to evaluate the performance of the binary geothermal power plants (Organic Rankine Cycles) with various heat rejection systems and their impact on the levelized cost of electricity.

Vahab Hassani

1996-01-01

207

Method for inhibiting silica precipitation and scaling in geothermal flow systems  

DOEpatents

A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds.

Harrar, Jackson E. (Castro Valley, CA); Lorensen, Lyman E. (Orinda, CA); Locke, Frank E. (Lafayette, CA)

1982-01-01

208

The origin of high-temperature zones in vapor-dominated geothermal systems  

SciTech Connect

Vapor-dominated geothermal systems are proposed to originate by downward extension (by the ''heat pipe'' mechanism) into hot dry fractured rock above a large cooling igneous intrusion. High temperature zones found by drilling are shallow parts of the original hot dry rock where the penetration of the vapor reservoir was limited, and hot dry rock may extend under much of these reservoirs. An earlier hot water geothermal system may have formed during an early phase of the heating episode.

Truesdell, Alfred H.

1991-01-01

209

Geothermal system at 21??N, East Pacific Rise: Physical limits on geothermal fluid and role of adiabatic expansion  

USGS Publications Warehouse

Pressure-volume-temperature relations for water at the depth of the magma chamber at 21??N on the East Pacific Rise suggest that the maximum sub-surface temperature of the geothermal fluid is about 420??C. Both the chemistry of the discharging fluid and thermal balance considerations indicate that the effective water/rock ratios in the geothermal system are between 7 and 16. Such low ratios preclude effective metal transport at temperatures below 350??C, but metal solubilization at 400??C and above is effective even at such low ratios. It is proposed that the 420??C fluid ascends essentially adiabatically and in the process expands, cools, and precipitates metal sulfides within the upper few hundred meters of the sea floor and on the sea floor itself. Copyright ?? 1980 AAAS.

Bischoff, J.L.

1980-01-01

210

Geothermal system at 21/sup 0/N, East Pacific Rise: physical limits on geothermal fluid and role of adiabatic expansion  

SciTech Connect

Pressure-volume-temperature relations for water at the depth of the magma chamber at 21/sup 0/N on the East Pacific Rise suggest that the maximum subsurface temperature of the geothermal fluid is about 420/sup 0/C. Both the chemistry of the discharging fluid and thermal balance considerations indicate that the effective water/rock ratios in the geothermal system are between 7 and 16. Such low ratios preclude effective metal transport at temperatures below 350/sup 0/C, but metal solubilization at 400/sup 0/C and above is effective even at such low ratios. It is proposed that the 420/sup 0/C fluid ascends essentially adiabatically and in the process expands, cools, and precipitates metal sulfides within the upper few hundred meters of the sea floor and on the sea floor itself.

Bischoff, J.L.

1980-03-28

211

Coniform stromatolites from geothermal systems, North Island, New Zealand  

USGS Publications Warehouse

Coniform stromatolites are found in several sites in the Tokaanu and Whakarewarewa geothermal areas of North Island, New Zealand. At Tokaanu, silicification of these stromatolites is taking place in Kirihoro, a shallow hot springfed pool. At Whakarewarewa, subfossil silicified coniform stromatolites are found on the floor of "Waikite Pool" on the discharge apron below Waikite Geyser, and in an old sinter succession at Te Anarata. The microbes in the coniform stromatolites from Tokaanu, Waikite Pool, and Te Anarata have been well preserved through rapid silicification. Nevertheless, subtle differences in the silicification style induced morphological variations that commonly mask or alter morphological features needed for identification of the microbes in terms of extant taxa. The coniform stromatolites in the New Zealand hotspring pools are distinctive because (1) they are formed of upward tapering (i.e., conical) columns, (2) neighboring columns commonly are linked by vertical sheets or bridges, (3) internally, they are formed of alternating high- and low-porosity laminae that have a conical vertical profile, and (4) Phormidium form more than 90% of the biota. As such, they are comparable to modern coniform mats and stromatolites found in the geothermal systems of Yellowstone National Park and ice-covered lakes in Antarctica. Formation of the coniform stromatolites is restricted to pools that are characterized by low current energy and a microflora that is dominated by Phormidium. These delicate and intricate stromatolites could not form in areas characterized by fast flowing water or a diverse microflora. Thus, it appears that the distribution of these distinctive stromatolites is controlled by biological constraints that are superimposed on environmental needs.

Jones, B.; Renaut, R.W.; Rosen, Michael R.; Ansdell, K.M.

2002-01-01

212

Enhanced Geothermal Systems (EGS) R&D Program: Monitoring EGS-Related Research  

SciTech Connect

This report reviews technologies that could be applicable to Enhanced Geothermal Systems development. EGS covers the spectrum of geothermal resources from hydrothermal to hot dry rock. We monitored recent and ongoing research, as reported in the technical literature, that would be useful in expanding current and future geothermal fields. The literature review was supplemented by input obtained through contacts with researchers throughout the United States. Technologies are emerging that have exceptional promise for finding fractures in nonhomogeneous rock, especially during and after episodes of stimulation to enhance natural permeability.

McLarty, Lynn; Entingh, Daniel; Carwile, Clifton

2000-09-29

213

Enhanced Geothermal System Development of the AmeriCulture Leasehold in the Animas Valley  

SciTech Connect

Working under the grant with AmeriCulture, Inc., and its team of geothermal experts, assembled a plan to apply enhanced geothermal systems (EGS) techniques to increase both the temperature and flow rate of the geothermal waters on its leasehold. AmeriCulture operates a commercial aquaculture facility that will benefit from the larger quantities of thermal energy and low cost electric power that EGS technology can provide. The project brought together a team of specialists that, as a group, provided the full range of expertise required to successfully develop and implement the project.

Duchane, David V; Seawright, Gary L; Sewright, Damon E; Brown, Don; Witcher, James c.; Nichols, Kenneth E.

2001-03-02

214

Importance of Hydrogeological Conditions on Open-loop Geothermal System  

NASA Astrophysics Data System (ADS)

The open-loop geothermal system has been known as an eco-friendly, energy-saving, and cost-efficient alternative for the cooling and heating of buildings with directly using the relatively stable temperature of groundwater. Thus, hydrogeological properties of aquifer, such as hydraulic conductivity and storage, must be important in the system application. The study site is located near Han-river, Korea, and because of the well-developed alluvium it might be a typical site appropriate to this system requiring an amount of groundwater. In this study, the first objective of numerical experiments was to find the best distributions of pumping and injection wells suitable to the hydrogeological conditions of the site for the efficient and sustainable system operation. The aquifer has a gravel layer at 15m depth below the ground surface and the river and the agricultural field, which may be a potential contaminant source, are located at the west and east sides, respectively. Under the general conditions that the regional groundwater flows from the east to the river, the locally reversed well distribution, locating the pumping well at upgradient and the injection well at downgradient of the regional flow, was most sustainable. The gravel layer with high hydraulic conductivity caused a little drawdown despite of an amount of pumping and allowed to stably reinject the used groundwater in all the cases, but it provided a passage transferring the injected heat to the pumping well quickly, particularly in the cases locating the injection well at the upgradient. This thermal interference was more severe in the cases of the short distance between the wells. The high conductive layer is also a reason that the seasonal role conversion of wells for the aquifer thermal energy storage was ineffective in this site. Furthermore, the well distribution vertical to the regional groundwater flow was stable, but not best, and, thus, it may be a good choice in the conditions that the regional groundwater flow direction has often been changed. Any effects of the seasonal river temperature variation and contaminant sources were not found on the wells because of the well screen installed at only the relatively deep gravel layer. Finally, it was evaluated whether if these results are valid in a homogeneous aquifer with the full screen of wells and the aquifer having a sediment layer with high hydraulic conductivity at a shallow depth, which are also typical aquifers near river. All the results concluded that it is essential to investigate and understand the site-specific hydrogeological conditions for the successful application of open-loop geothermal system.

Park, D.; Bae, G.; Kim, S.; Lee, K.

2013-12-01

215

The volcanic and geothermally active Campi Flegrei caldera: an integrated multidisciplinary image of its buried structure  

NASA Astrophysics Data System (ADS)

The Campi Flegrei caldera in southern Italy is one of the greatest geohazard areas on Earth. Evidence of an active magmatic and geothermal system is provided by ongoing ground uplift, with volcano-tectonic and long-period (LP) seismicity, the persistent degassing of ~1500 tonnes of CO2 per day, the presence of hot fumaroles at temperatures of 90-150 C, brine-rich aquifers (with total dissolved solids up to 33 g l-1) and high thermal gradients in the crust (with temperatures reaching 420 C at 3,050 m b.s.l.). Since the 1940s, more than 100 exploratory boreholes have been drilled in the area to depths of 80-3,100 m by the Azienda Geologica Italiana Petroli (AGIP) and the Societ Anonima Forze Endogene Napoletane (SAFEN). To date, however, no systematic reanalysis of the drilling data has been carried out, and the buried volcanic structure has not been updated using the most recent scientific results and previous findings. By integrating unpublished data from the AGIP and SAFEN reports with published information from geological, volcanological, petrological, petrophysical and geophysical studies, this paper presents an improved picture of the Campi Flegrei caldera that will be useful for volcanic hazard assessment and mitigation in the Naples area and for future research planning. The results suggest that intra-caldera activity has been influenced by how the magmatic system at depths greater than about 4 km has determined the transfer of magma, volatiles, and heat to the overlying geothermal system and, ultimately, to the surface. In particular, intriguing is that the most volcanically active central-eastern sector of the caldera, which is subject to intense bradyseismic ground movement and gas emission, coincides with a structurally delimited subsurface rock volume characterized by an uprising of the 100 C isotherm, a deep water supply to the shallower aquifer, the early disappearance of secondary calcite, LP seismicity and high seismic S-wave attenuation. In this area, we also document evidence of repeated injection at depths of c. 1.5-3.0 km of isolated and small-volume batches of magma, where occurred their crystallization and degassing. Shallow intrusions and degassing of magma are thus identified as two of the key processes that drive unrest in Campi Flegrei.

Piochi, M.; Kilburn, C. R. J.; Di Vito, M. A.; Mormone, A.; Tramelli, A.; Troise, C.; De Natale, G.

2014-03-01

216

Earthquakes, active faults, and geothermal areas in the Imperial Valley, California  

USGS Publications Warehouse

A dense seismograph network in the Imperial Valley recorded a series of earthquake swarms along the Imperial and Brawley faults and a diffuse pattern of earthquakes along the San Jacinto fault. Two known geothermal areas are closely associated with these earthquake swarms. This seismicity pattern demonstrates that seismic slip is occurring along both the Imperial-Brawley and San Jacinto fault systems.

Hill, D.P.; Mowinckel, P.; Peake, L.G.

1975-01-01

217

Systems study of drilling for installation of geothermal heat pumps  

SciTech Connect

Geothermal, or ground-source, heat pumps (GHP) are much more efficient than air-source units such as conventional air conditioners. A major obstacle to their use is the relatively high initial cost of installing the heat-exchange loops into the ground. In an effort to identify drivers which influence installation cost, a number of site visits were made during 1996 to assess the state-of-the-art in drilling for GHP loop installation. As an aid to quantifying the effect of various drilling-process improvements, we constructed a spread-sheet based on estimated time and material costs for all the activities required in a typical loop-field installation. By substituting different (improved) values into specific activity costs, the effect on total project costs can be easily seen. This report contains brief descriptions of the site visits, key points learned during the visits, copies of the spread-sheet, recommendations for further work, and sample results from sensitivity analysis using the spread-sheet.

Finger, J.T.; Sullivan, W.N.; Jacobson, R.D.; Pierce, K.G.

1997-09-01

218

Dixie Valley Engineered Geothermal System Exploration Methodology Project, Baseline Conceptual Model Report  

SciTech Connect

The Engineered Geothermal System (EGS) Exploration Methodology Project is developing an exploration approach for EGS through the integration of geoscientific data. The Project chose the Dixie Valley Geothermal System in Nevada as a field laboratory site for methodlogy calibration purposes because, in the public domain, it is a highly characterized geothermal systems in the Basin and Range with a considerable amount of geoscience and most importantly, well data. This Baseline Conceptual Model report summarizes the results of the first three project tasks (1) collect and assess the existing public domain geoscience data, (2) design and populate a GIS database, and (3) develop a baseline (existing data) geothermal conceptual model, evaluate geostatistical relationships, and generate baseline, coupled EGS favorability/trust maps from +1km above sea level (asl) to -4km asl for the Calibration Area (Dixie Valley Geothermal Wellfield) to identify EGS drilling targets at a scale of 5km x 5km. It presents (1) an assessment of the readily available public domain data and some proprietary data provided by Terra-Gen Power, LLC, (2) a re-interpretation of these data as required, (3) an exploratory geostatistical data analysis, (4) the baseline geothermal conceptual model, and (5) the EGS favorability/trust mapping. The conceptual model presented applies to both the hydrothermal system and EGS in the Dixie Valley region.

Iovenitti, Joe

2013-05-15

219

Dixie Valley Engineered Geothermal System Exploration Methodology Project, Baseline Conceptual Model Report  

DOE Data Explorer

The Engineered Geothermal System (EGS) Exploration Methodology Project is developing an exploration approach for EGS through the integration of geoscientific data. The Project chose the Dixie Valley Geothermal System in Nevada as a field laboratory site for methodlogy calibration purposes because, in the public domain, it is a highly characterized geothermal systems in the Basin and Range with a considerable amount of geoscience and most importantly, well data. This Baseline Conceptual Model report summarizes the results of the first three project tasks (1) collect and assess the existing public domain geoscience data, (2) design and populate a GIS database, and (3) develop a baseline (existing data) geothermal conceptual model, evaluate geostatistical relationships, and generate baseline, coupled EGS favorability/trust maps from +1km above sea level (asl) to -4km asl for the Calibration Area (Dixie Valley Geothermal Wellfield) to identify EGS drilling targets at a scale of 5km x 5km. It presents (1) an assessment of the readily available public domain data and some proprietary data provided by Terra-Gen Power, LLC, (2) a re-interpretation of these data as required, (3) an exploratory geostatistical data analysis, (4) the baseline geothermal conceptual model, and (5) the EGS favorability/trust mapping. The conceptual model presented applies to both the hydrothermal system and EGS in the Dixie Valley region.

Iovenitti, Joe

220

Evaluation of Oil-Industry Stimulation Practices for Engineered Geothermal Systems  

Microsoft Academic Search

Geothermal energy extraction is typically achieved by use of long open-hole intervals in an attempt to connect the well with;\\u000athe greatest possible rock mass. This presents a problem for the development of Enhanced (Engineered) Geothermal;\\u000aSystems (EGS), owing to the challenge of obtaining uniform stimulation throughout the open-hole interval. Fluids are often;\\u000ainjected in only a fraction of that

Peter Van Dyke; Leen Weijers; Ann Robertson-Tait; Norm Warpinski; Mike Mayerhofer; Bill Minner; Craig Cipolla

2007-01-01

221

Energy Returned On Investment of Engineered Geothermal Systems Annual Report FY2010  

SciTech Connect

Energy Return On Investment (EROI) is an important figure of merit for assessing the viability of energy alternatives. EROI analyses of geothermal energy are either out of date or presented online with little supporting documentation. Often comparisons of energy systems inappropriately use 'efficiency' when EROI would be more appropriate. For geothermal electric power generation, EROI is determined by the electric energy delivered to the consumer compared to the energy consumed to build, operate, and decommission the facility.

Mansure, A.J.

2010-12-31

222

Hybrid Cooling Systems for Low-Temperature Geothermal Power Production  

SciTech Connect

This paper describes the identification and evaluation of methods by which the net power output of an air-cooled geothermal power plant can be enhanced during hot ambient conditions with a minimal amount of water use.

Ashwood, A.; Bharathan, D.

2011-03-01

223

Technical support for geopressured-geothermal well activities in Louisiana. Annual report, 1 November 1982-31 October 1983  

SciTech Connect

This annual report describes environmental monitoring of microseismic activity, land-surface elevations, and surface and ground-water quality at three designed geopressured-geothermal test well sites in Louisiana.

Not Available

1984-10-31

224

Plant adaptation to extreme environments: the example of Cistus salviifolius of an active geothermal alteration field.  

PubMed

Cistus salviifolius is able to colonise one of the most extreme active geothermal alteration fields in terms of both soil acidity and hot temperatures. The analyses of morpho-functional and physiological characters, investigated in leaves of plants growing around fumaroles (G leaves) and in leaves developed by the same plants after transfer into growth chamber under controlled conditions (C leaves) evidenced the main adaptive traits developed by this pioneer plant in a stressful environment. These traits involved leaf shape and thickness, mesophyll compactness, stomatal and trichome densities, chloroplast size. Changes of functional and physiological traits concerned dry matter content, peroxide and lipid peroxidation, leaf area, relative water and pigment contents. A higher reducing power and antioxidant enzymatic activity were typical of G leaves. Though the high levels of stress parameters, G leaves showed stress-induced specific morphogenic and physiological responses putatively involved in their surviving in active geothermal habitats. PMID:24581804

Bartoli, Giacomo; Bottega, Stefania; Forino, Laura M C; Ciccarelli, Daniela; Span, Carmelina

2014-02-01

225

Development of a Deep-Penetrating, Compact Geothermal Heat Flow System for Robotic Lunar Geophysical Missions  

NASA Technical Reports Server (NTRS)

Geothermal heat flow measurements are a high priority for the future lunar geophysical network missions recommended by the latest Decadal Survey of the National Academy. Geothermal heat flow is obtained as a product of two separate measurements of geothermal gradient and thermal conductivity of the regolith/soil interval penetrated by the instrument. The Apollo 15 and 17 astronauts deployed their heat flow probes down to 1.4-m and 2.3-m depths, respectively, using a rotary-percussive drill. However, recent studies show that the heat flow instrument for a lunar mission should be capable of excavating a 3-m deep hole to avoid the effect of potential long-term changes of the surface thermal environment. For a future robotic geophysical mission, a system that utilizes a rotary/percussive drill would far exceed the limited payload and power capacities of the lander/rover. Therefore, we are currently developing a more compact heat flow system that is capable of 3-m penetration. Because the grains of lunar regolith are cohesive and densely packed, the previously proposed lightweight, internal hammering systems (the so-called moles ) are not likely to achieve the desired deep penetration. The excavation system for our new heat flow instrumentation utilizes a stem which winds out of a pneumatically driven reel and pushes its conical tip into the regolith. Simultaneously, gas jets, emitted from the cone tip, loosen and blow away the soil. Lab tests have demonstrated that this proboscis system has much greater excavation capability than a mole-based heat flow system, while it weighs about the same. Thermal sensors are attached along the stem and at the tip of the penetrating cone. Thermal conductivity is measured at the cone tip with a short (1- to 1.5-cm long) needle sensor containing a resistance temperature detector (RTD) and a heater wire. When it is inserted into the soil, the heater is activated. Thermal conductivity of the soil is obtained from the rate of temperature increase during the heating. By stopping during the excavation, it is possible to measure thermal conductivities at different depths. The gas jets are turned off when the penetrating cone reaches the target depth. Then, the stem pushes the needle sensor into the undisturbed soil at the bottom of the hole and carries out a thermal conductivity measurement. When the measurement is complete, the system resumes excavation. RTDs, placed along the stem at short (approx 30 cm) intervals, will monitor long-term temperature stability of the subsurface. Temperature in the shallow subsurface would fluctuate with the diurnal, annual, and precession cycles of the Moon. These thermal waves penetrate to different depths into the regolith. Longterm monitoring of the subsurface temperature would allow us to accurately delineate these cyclic signals and separate them from the signal associated with the outward flow of the Moon s endogenic heat. Further, temperature toward bottom of the 3-m hole should be fairly stable after the heat generated during the excavation dissipates into the surrounding soil. The geothermal gradient may be determined reliably from temperature measurements at the RTDs near the bottom. In order to minimize the heat conduction along the stem from affecting the geothermal gradient measurements, we plan to use low-conductive materials for the stem and develop a mechanism to achieve close coupling between the RTDs and the wall of the excavated hole.

Nagihara, Seiichi; Zacny, Kris; Hedlund, Magnus; Taylor, Patrick T.

2012-01-01

226

Recovery Act: Geothermal Data Aggregation: Submission of Information into the National Geothermal Data System, Final Report DOE Project DE-EE0002852 June 24, 2014  

SciTech Connect

The National Geothermal Data System (NGDS) is a Department of Energy funded effort to create a single cataloged source for a variety of geothermal information through a distributed network of databases made available via web services. The NGDS will help identify regions suitable for potential development and further scientific data collection and analysis of geothermal resources as a source for clean, renewable energy. A key NGDS repository or node is located at Southern Methodist University developed by a consortium made up of: SMU Geothermal Laboratory Siemens Corporate Technology, a division of Siemens Corporation Bureau of Economic Geology at the University of Texas at Austin Cornell Energy Institute, Cornell University Geothermal Resources Council MLKay Technologies Texas Tech University University of North Dakota. The focus of resources and research encompass the United States with particular emphasis on the Gulf Coast (on and off shore), the Great Plains, and the Eastern U.S. The data collection includes the thermal, geological and geophysical characteristics of these area resources. Types of data include, but are not limited to, temperature, heat flow, thermal conductivity, radiogenic heat production, porosity, permeability, geological structure, core geophysical logs, well tests, estimated reservoir volume, in situ stress, oil and gas well fluid chemistry, oil and gas well information, and conventional and enhanced geothermal system related resources. Libraries of publications and reports are combined into a unified, accessible, catalog with links for downloading non-copyrighted items. Field notes, individual temperature logs, site maps and related resources are included to increase data collection knowledge. Additional research based on legacy data to improve quality increases our understanding of the local and regional geology and geothermal characteristics. The software to enable the integration, analysis, and dissemination of this teams NGDS contributions was developed by Siemens Corporate Technology. The SMU Node interactive application is accessible at http://geothermal.smu.edu. Additionally, files may be downloaded from either http://geothermal.smu.edu:9000/geoserver/web/ or through http://geothermal.smu.edu/static/DownloadFilesButtonPage.htm. The Geothermal Resources Council Library is available at https://www.geothermal-library.org/.

Blackwell, David D. [SMU Geothermal Laboratory; Chickering Pace, Cathy [SMU Geothermal Laboratory; Richards, Maria C. [SMU Geothermal Laboratory

2014-06-24

227

Real-time fracture monitoring in Engineered Geothermal Systems with seismic waves  

SciTech Connect

As proposed, the main effort in this project is the development of software capable of performing real-time monitoring of micro-seismic activity recorded by an array of sensors deployed around an EGS. The main milestones are defined by the development of software to perform the following tasks: Real-time micro-earthquake detection and location Real-time detection of shear-wave splitting Delayed-time inversion of shear-wave splitting These algorithms, which are discussed in detail in this report, make possible the automatic and real-time monitoring of subsurface fracture systems in geothermal fields from data collected by an array of seismic sensors. Shear wave splitting (SWS) is parameterized in terms of the polarization of the fast shear wave and the time delay between the fast and slow shear waves, which are automatically measured and stored. The measured parameters are then combined with previously measured SWS parameters at the same station and used to invert for the orientation (strike and dip) and intensity of cracks under that station. In addition, this grant allowed the collection of seismic data from several geothermal regions in the US (Coso) and Iceland (Hengill) to use in the development and testing of the software.

Jose A. Rial; Jonathan Lees

2009-03-31

228

Impact of enhanced geothermal systems on US energy supply in the twenty-first century.  

PubMed

Recent national focus on the value of increasing US supplies of indigenous renewable energy underscores the need for re-evaluating all alternatives, particularly those that are large and well distributed nationally. A panel was assembled in September 2005 to evaluate the technical and economic feasibility of geothermal becoming a major supplier of primary energy for US base-load generation capacity by 2050. Primary energy produced from both conventional hydrothermal and enhanced (or engineered) geothermal systems (EGS) was considered on a national scale. This paper summarizes the work of the panel which appears in complete form in a 2006 MIT report, 'The future of geothermal energy' parts 1 and 2. In the analysis, a comprehensive national assessment of US geothermal resources, evaluation of drilling and reservoir technologies and economic modelling was carried out. The methodologies employed to estimate geologic heat flow for a range of geothermal resources were utilized to provide detailed quantitative projections of the EGS resource base for the USA. Thirty years of field testing worldwide was evaluated to identify the remaining technology needs with respect to drilling and completing wells, stimulating EGS reservoirs and converting geothermal heat to electricity in surface power and energy recovery systems. Economic modelling was used to develop long-term projections of EGS in the USA for supplying electricity and thermal energy. Sensitivities to capital costs for drilling, stimulation and power plant construction, and financial factors, learning curve estimates, and uncertainties and risks were considered. PMID:17272236

Tester, Jefferson W; Anderson, Brian J; Batchelor, Anthony S; Blackwell, David D; DiPippo, Ronald; Drake, Elisabeth M; Garnish, John; Livesay, Bill; Moore, Michal C; Nichols, Kenneth; Petty, Susan; Toksoz, M Nafi; Veatch, Ralph W; Baria, Roy; Augustine, Chad; Murphy, Enda; Negraru, Petru; Richards, Maria

2007-04-15

229

Creation of an Enhanced Geothermal System through Hydraulic and Thermal Stimulation  

SciTech Connect

This report describes a 10-year DOE-funded project to design, characterize and create an Engineered Geothermal System (EGS) through a combination of hydraulic, thermal and chemical stimulation techniques. Volume 1 describes a four-year Phase 1 campaign, which focused on the east compartment of the Coso geothermal field. It includes a description of the geomechanical, geophysical, hydraulic, and geochemical studies that were conducted to characterize the reservoir in anticipation of the hydraulic stimulation experiment. Phase 1 ended prematurely when the drill bit intersected a very permeable fault zone during the redrilling of target stimulation well 34-9RD2. A hydraulic stimulation was inadvertently achieved, however, since the flow of drill mud from the well into the formation created an earthquake swarm near the wellbore that was recorded, located, analyzed and interpreted by project seismologists. Upon completion of Phase 1, the project shifted focus to a new target well, which was located within the southwest compartment of the Coso geothermal field. Volume 2 describes the Phase 2 studies on the geomechanical, geophysical, hydraulic, and geochemical aspects of the reservoir in and around target-stimulation well 46A-19RD, which is the deepest and hottest well ever drilled at Coso. Its total measured depth exceeding 12,000 ft. It spite of its great depth, this well is largely impermeable below a depth of about 9,000 ft, thus providing an excellent target for stimulation. In order to prepare 46A-19RD for stimulation, however, it was necessary to pull the slotted liner. This proved to be unachievable under the budget allocated by the Coso Operating Company partners, and this aspect of the project was abandoned, ending the program at Coso. The program then shifted to the EGS project at Desert Peak, which had a goal similar to the one at Coso of creating an EGS on the periphery of an existing geothermal reservoir. Volume 3 describes the activities that the Coso team contributed to the Desert Peak project, focusing largely on a geomechanical investigation of the Desert Peak reservoir, tracer testing between injectors 21-2 and 22-22 and the fieldâ??s main producers, and the chemical stimulation of target well 27-15.

Rose, Peter Eugene [Energy and Geoscience Institute at the Univerity of Utah

2013-04-15

230

Creation of an Enhanced Geothermal System through Hydraulic and Thermal Stimulation  

SciTech Connect

This report describes a 10-year DOE-funded project to design, characterize and create an Engineered Geothermal System (EGS) through a combination of hydraulic, thermal and chemical stimulation techniques. Volume 1 describes a four-year Phase 1 campaign, which focused on the east compartment of the Coso geothermal field. It includes a description of the geomechanical, geophysical, hydraulic, and geochemical studies that were conducted to characterize the reservoir in anticipation of the hydraulic stimulation experiment. Phase 1 ended prematurely when the drill bit intersected a very permeable fault zone during the redrilling of target stimulation well 34-9RD2. A hydraulic stimulation was inadvertently achieved, however, since the flow of drill mud from the well into the formation created an earthquake swarm near the wellbore that was recorded, located, analyzed and interpreted by project seismologists. Upon completion of Phase 1, the project shifted focus to a new target well, which was located within the southwest compartment of the Coso geothermal field. Volume 2 describes the Phase 2 studies on the geomechanical, geophysical, hydraulic, and geochemical aspects of the reservoir in and around target-stimulation well 46A-19RD, which is the deepest and hottest well ever drilled at Coso. Its total measured depth exceeding 12,000 ft. It spite of its great depth, this well is largely impermeable below a depth of about 9,000 ft, thus providing an excellent target for stimulation. In order to prepare 46A-19RD for stimulation, however, it was necessary to pull the slotted liner. This proved to be unachievable under the budget allocated by the Coso Operating Company partners, and this aspect of the project was abandoned, ending the program at Coso. The program then shifted to the EGS project at Desert Peak, which had a goal similar to the one at Coso of creating an EGS on the periphery of an existing geothermal reservoir. Volume 3 describes the activities that the Coso team contributed to the Desert Peak project, focusing largely on a geomechanical investigation of the Desert Peak reservoir, tracer testing between injectors 21-2 and 22-22 and the field???????¢????????????????s main producers, and the chemical stimulation of target well 27-15.

Rose, Peter Eugene [Energy and Geoscience Institute at the University of Utah

2013-04-15

231

Increasing the efficiency of geothermal power plants using optimum pressures for turbocompressors and steam jet ejectors in gas extraction systems  

NASA Astrophysics Data System (ADS)

Geothermal power plants generate electricity by extracting energy from the earth's interior. The radioactive decay of the earth's core causes heat to conduct towards the surface. When water flows into the fissures of this hot rock a naturally occurring geothermal well is formed. Geothermal power plants use the steam in these wells to drive a turbine and thus generate electricity. The steam in the earth however, is always accompanied by a small fraction of non-condensable gases that build up in the power plant's condenser unless actively removed by some gas extraction system. Because these gases contribute significantly to the total backpressure on the turbine, it is in the interest of power generation to remove them from the condenser. The industry standard for removing these non-condensable gases has been steam jet ejectors or a hybrid system of steam jet ejectors and liquid ring vacuum pumps. This thesis focuses on finding the optimum operating pressures for a hybrid steam jet ejector system and a hybrid turbocompressor system. It was found that plants with steam jet ejectors and liquid ring vacuum pumps provide maximum power output when the liquid ring vacuum pump is operated at its maximum pressure ratio. However, plants with a turbocompressor and liquid ring vacuum pump were found to provide maximum power output when the turbocompressor was operated at its maximum pressure ratio.

Harns, Karsten Franz

232

Modeling the effects of silica deposition and fault rupture on natural geothermal systems  

NASA Astrophysics Data System (ADS)

Natural geothermal convection abounds within the Taupo Volcanic Zone (TVZ) of New Zealand's Central North Island. In many locations the highly porous eruptive products that blanket the landscape have been altered by the throughput of hydrothermal fluids and the consequent deposition of silica. We detail a numerical model that considers the evolution of a geothermal plume in the presence of silica deposition/dissolution that controls an evolving permeability distribution. Precipitation of silica occurs according to a gradient reaction regime, in which the dissolved silica concentration is controlled by the temperature dependent silica solubility. Over a period of 120 kyr, continuous geothermal circulation leads to the development of a low permeability cap-zone, approximately 200 m thick, above the main geothermal upflow zone. The cap-zone encourages lateral flow of rising fluids, increasing the area across which geothermal expression is observed. It also has an insulating effect on fluids below the cap, causing increases in temperature, enthalpy, and the reservoir potential of the field. A second model is constructed to consider the specific scenario of fault rupture through the impermeable cap-zone. Coseismic increases in permeability along the fault plane produce vigorous, renewed flow through the center of the geothermal field, temporarily reducing lateral flows. However, resealing of near surface permeability is rapid, and the restoration of lateral flows and recovery of the geothermal reservoir occurs within 10 kyr. These effects are discussed in the context of two TVZ geothermal fields: the extinct Ohakuri field, and Te Kopia, which is situated on a major active normal fault.

Dempsey, D. E.; Rowland, J. V.; Zyvoloski, G. A.; Archer, R. A.

2012-05-01

233

Balancing reservoir creation and seismic hazard in enhanced geothermal systems  

NASA Astrophysics Data System (ADS)

Fracture shear-dilatancy is an essential process for enhancing the permeability of deep geothermal reservoirs, and is usually accompanied by the radiation of seismic waves. However, the hazard and risk perspective of induced seismicity research typically focuses only on the question of how to reduce the occurrence of induced earthquakes. Here we present a quantitative analysis of seismic hazard as a function of the two key factors defining an enhanced geothermal system: The permeability enhancement, and the size of the stimulated reservoir. Our model has two coupled components: (1) a pressure diffusion model and (2) a stochastic seismicity model. Permeability is increased in the source area of each induced earthquake depending on the amount of slip, which is determined by the magnitude. We show that the few largest earthquakes (i.e. 5-10 events with M ? 1.5) contribute more than half of the total reservoir stimulation. The results further indicate that planning and controlling of reservoir engineering operations may be compromised by the considerable variability of maximum observed magnitude, reservoir size, the Gutenberg-Richter b-value and Shapiro's seismogenic index (i.e. a measure of seismic reactivity of a reservoir) that arises from the intrinsic stochastic nature of induced seismicity. We also find that injection volume has a large impact on both reservoir size and seismic hazard. Injection rate and injection scheme have a negligible effect. The impact of site-specific parameters on seismicity and reservoir properties is greater than that of the injected volume. In particular, conditions that lead to high b-values-possibly a low differential stress level-have a high impact on seismic hazard, but also reduce the efficiency of the stimulation in terms of permeability enhancement. Under such conditions, target reservoir permeability can still be achieved without reaching an unacceptable level of seismic hazard, if either the initial reservoir permeability is high or if several fractures are stimulated. The proposed methodology is a first step towards including induced seismic hazard analysis into the design of reservoir stimulation in a quantitative and robust manner.

Gischig, V.; Wiemer, S.; Alcolea, A.

2014-09-01

234

Deep geothermal resources and energy: Current research and developments  

NASA Astrophysics Data System (ADS)

Energy from deep geothermal resources plays an increasing role in many European countries in their efforts to increase the proportion of renewables in their energy portfolio. Deep geothermal heat and electric power have a high load factor, are sustainable and environmentally friendly. However, the safe, sustainable, and economic development of deep geothermal resources, also in less favourable regions, faces a number of issues requiring substantial research efforts: (1) The probability of finding an unknown geothermal reservoir has to be improved. (2) Drilling methods have to be better adapted and developed to the specific needs of geothermal development. (3) The assessment of the geothermal potential should provide more reliable and clear guidelines for the development. (4) Stimulation methods for enhanced geothermal systems (EGS) have to be refined to increase the success rate and reduce the risk associated with induced seismicity. (5) Operation and maintenance in aggressive geothermal environments require specific solutions for corrosion and scaling problems. (6) Last but not least, emerging activities to harness energy from supercritical reservoirs would make significant progress with qualified input from research. In particular, sedimentary basins like e.g. the North German and Polish Basin, the Pannonian Basin, the Po Valley, the Bavarian Molasse Basin or the Upper Rhine Graben have a high geothermal potential, even if geothermal gradients are moderate. We will highlight projects that aim at optimizing exploration, characterization, and modeling prior to drilling and at a better understanding of physical, hydraulic and chemical processes during operation of a geothermal power plant. This includes geophysical, geological and geochemical investigations regarding potential geothermal reservoirs in sedimentary basins, as well as modelling of geothermally relevant reservoir parameters that influence the potential performance and long-term behavior of a future geothermal power plant. In our overview we will also highlight contributions of EGU2012-sessions ERE1.6 (Geothermal energy from deep sedimentary basins - exploration, exploitation, characterization and modeling) and ERE1.7 (Development of deep geothermal resources).

Manzella, A.; Milsch, H.; Hahne, B.; van Wees, J. D.; Bruhn, D.

2012-04-01

235

Geothermal exploration in Indonesia  

SciTech Connect

Indonesia is blessed with geothermal resources. This fortunate aspect is directly related to the fact that the archipelago is an island arc created by a subduction zone. Evidence of geothermal activity is common throughout the Islands. Among the islands' many active volcanos are numerous geothermal phenomena. Almost half of the volcanic centers in Indonesia (88 out of 177 centers) contain fumarole and sulfatare features. A brief history of the exploration for geothermal energy in Indonesia is presented.

Radja, V.T.

1984-03-01

236

The Role of Boron-Chloride and Noble Gas Isotope Ratios in TVZ Geothermal Systems  

SciTech Connect

The model of the geothermal system in which deep circulating groundwater containing noble gases, at air saturated water concentrations, mixes with hot fluids of mantle origin at depth, is extended to include the effect of interaction of the ascending fluid with both solid and gaseous phases of basement (or other) rocks en route to the surface. It is demonstrated that this interaction is responsible for most of the CO{sub 2} in the Taupo Volcanic Zone (TVZ) geothermal systems. It is proposed that the modeling of this interaction might be accomplished by techniques similar to those used for the understanding of the oxygen isotope shift found in geothermal systems. The water rock interaction experiments of Ellis and Mahon (1964, 1967) provides some data on the kinetic rates for B and Cl dissolution from rocks likely to be encountered in the geothermal system, but further information on the behavior of B may be needed. If these problems can be overcome this modeling technique has promise for the estimation of the recharge of geothermal systems and hence the sustainability of these systems.

Hulston, J.R.

1995-01-01

237

Direct utilization of geothermal heat in cascade application to aquaculture and greenhouse systems at Navarro College. Annual report, January 1984-September 1984  

SciTech Connect

Progress is reported on a project to use the 130/sup 0/F geothermal resource in central Texas. The system for cascading geothermal energy through aquaculture and greenhouse systems was completed and the first shrimp harvest was held. (MHR)

Smith, K.

1984-09-01

238

Strategies for Detecting Hidden Geothermal Systems by Near-Surface Gas Monitoring  

SciTech Connect

''Hidden'' geothermal systems are those systems above which hydrothermal surface features (e.g., hot springs, fumaroles, elevated ground temperatures, hydrothermal alteration) are lacking. Emissions of moderate to low solubility gases (e.g., CO2, CH4, He) may be one of the primary near-surface signals from these systems. Detection of anomalous gas emissions related to hidden geothermal systems may therefore be an important tool to discover new geothermal resources. This study investigates the potential for CO2 detection and monitoring in the subsurface and above ground in the near-surface environment to serve as a tool to discover hidden geothermal systems. We focus the investigation on CO2 due to (1) its abundance in geothermal systems, (2) its moderate solubility in water, and (3) the wide range of technologies available to monitor CO2 in the near-surface environment. However, monitoring in the near-surface environment for CO2 derived from hidden geothermal reservoirs is complicated by the large variation in CO2 fluxes and concentrations arising from natural biological and hydrologic processes. In the near-surface environment, the flow and transport of CO2 at high concentrations will be controlled by its high density, low viscosity, and high solubility in water relative to air. Numerical simulations of CO2 migration show that CO2 concentrations can reach very high levels in the shallow subsurface even for relatively low geothermal source CO2 fluxes. However, once CO2 seeps out of the ground into the atmospheric surface layer, surface winds are effective at dispersing CO2 seepage. In natural ecological systems in the absence of geothermal gas emissions, near-surface CO2 fluxes and concentrations are primarily controlled by CO2 uptake by photosynthesis, production by root respiration, and microbial decomposition of soil/subsoil organic matter, groundwater degassing, and exchange with the atmosphere. Available technologies for monitoring CO2 in the near-surface environment include (1) the infrared gas analyzer (IRGA) for measurement of concentrations at point locations, (2) the accumulation chamber (AC) method for measuring soil CO2 fluxes at point locations, (3) the eddy covariance (EC) method for measuring net CO2 flux over a given area, (4) hyperspectral imaging of vegetative stress resulting from elevated CO2 concentrations, and (5) light detection and ranging (LIDAR) that can measure CO2 concentrations over an integrated path. Technologies currently in developmental stages that have the potential to be used for CO2 monitoring include tunable lasers for long distance integrated concentration measurements and micro-electronic mechanical systems (MEMS) that can make widespread point measurements. To address the challenge of detecting potentially small-magnitude geothermal CO2 emissions within the natural background variability of CO2, we propose an approach that integrates available detection and monitoring methodologies with statistical analysis and modeling strategies. Within the area targeted for geothermal exploration, point measurements of soil CO2 fluxes and concentrations using the AC method and a portable IRGA, respectively, and measurements of net surface flux using EC should be made. Also, the natural spatial and temporal variability of surface CO2 fluxes and subsurface CO2 concentrations should be quantified within a background area with similar geologic, climatic, and ecosystem characteristics to the area targeted for geothermal exploration. Statistical analyses of data collected from both areas should be used to guide sampling strategy, discern spatial patterns that may be indicative of geothermal CO2 emissions, and assess the presence (or absence) of geothermal CO2 within the natural background variability with a desired confidence level. Once measured CO2 concentrations and fluxes have been determined to be of anomalous geothermal origin with high confidence, more expensive vertical subsurface gas sampling and chemical and isotopic analyses can be undertaken. Integrated analysis of all measurements will d

Lewicki, Jennifer L.; Oldenburg, Curtis M.

2004-12-15

239

(Sulfide-oxide-silicate phase equilibria and associated fluid inclusion properties in the Salton Sea geothermal system, California)  

SciTech Connect

Our studies involved petrographic, fluid inclusion, geochemical and stable isotopic studies of drillcores and fluids from the Salton Sea geothermal system. Our initial studies revealed the presence of previously-unrecognized evaporitic anhydrite at depth throughout the geothermal system. The high salinity of the Salton Sea geothermal brines previously had been attributed to low-temperature dissolution of surficial evaporitic deposits by meteoric waters. Our microthermometric studies of halite--containing fluid inclusions in the meta-evaporites indicated that the high salinity of the geothermal brines is derived in part from the hydrothermal metamorphism of relatively deeply-buried salt and evaporites. In addition, our research concentrated on mineralized fractures in drillcores.

McKibben, M.A.

1988-06-01

240

Three-dimensional upper crustal structure of the geothermal system in Tarutung (North Sumatra, Indonesia) revealed by seismic attenuation tomography  

NASA Astrophysics Data System (ADS)

The geothermal potential in Tarutung is controlled by both the Sumatra Fault system and young arc volcanism. In this study we use the spatial distribution of seismic attenuation, calculated from local earthquake recordings, to image the 3-D seismic attenuation of the area and relate it with the temperature anomalies and the fluid distribution of the subsurface. A temporary seismic network of 42 stations was deployed around Tarutung and Sarulla (south of Tarutung) for a period of 10 months starting in 2011 May. Within this period, the network recorded 2586 local events. A high-quality subset of 229 events recorded by at least 10 stations was used for the attenuation inversion (tomography). Path-average attenuation (tp^{*}) was calculated by using a spectral inversion method. The spread function, the contour lines of the model resolution matrix and the recovery test results show that our 3-D attenuation model (Qp) has good resolution around the Tarutung Basin and along the Sarulla graben. High attenuation (low Qp) related to the geothermal system is found in the northeast of the Tarutung Basin suggesting fluid pathways from below the Sumatra Fault. The upper part of the studied geothermal system in the Tarutung district seems to be mainly controlled by the fault structure rather than by magmatic activities. In the southwest of the Tarutung Basin, the high attenuation zone is associated with the Martimbang volcano. In the Sarulla region, a low-Qp anomaly is found along the graben within the vicinity of the Hopong caldera.

Muksin, Umar; Haberland, Christian; Bauer, Klaus; Weber, Michael

2013-12-01

241

The Iceland Deep Drilling Project (IDDP): (6) Hydrothermal minerals record CO2 partial pressures in the Reykjanes Geothermal System, Iceland  

NASA Astrophysics Data System (ADS)

The Reykjanes Geothermal system, a target site for drilling by the IDDP, is located on the Reykjanes Peninsula in southwest Iceland, the landward extension of the Mid-Atlantic Ridge spreading center. Seawater penetrates the coastal Reykjanes geothermal system at depth, mixing with magmatic volatiles and reacting with the basaltic host rock to form secondary hydrothermal minerals. Within this system, epidote-prehnite-calcite- quartz-fluid constitutes a quadra-variant assemblage that, under conditions of specified temperature, pressure, and activity of H2O allows prediction of geothermal fluid pCO2 as a function of the composition of the solid solution minerals epidote or prehnite. This assemblage is typically found at temperatures >250C and <~310C, and potentially provides a mineralogical recorder that constrains fluid CO2 concentrations based on compositional zoning in hydrothermal epidote. Analysis of epidote crystals separated from drillhole-cuttings from three geothermal wells (RN-9, RN-10, RN-17) display complex chemical zoning, generally with Fe(III)-rich cores and Al-rich rims. The Fe(III)-mol fraction of epidote ranges 0.17 to 0.48. The Fe(III)-mol fraction of prehnite ranges from 0.11 to 0.59 in the upper portions of drillhole RN-17, where the highest Fe(III) content in epidote is 0.36, which serves as the upper Fe(III) limit for epidotes coexisting with prehnite in this study. Because most observed prehnite crystals in the drillhole-cuttings are too small for electron microprobe analyses (<20?m), we employed a sigmoidal correlation of available compositional data from active geothermal systems to calculate the Fe(III)-Al composition of prehnite using measured compositions of epidote in the Reykjanes system. In drill cuttings that contain epidote, prehnite, quartz and calcite, using measured epidote compositions between the reference temperatures of 275C and 310C, we calculated values of pCO2 for the geothermal fluids range from ~0.6 to ~6.2 bars. When only epidote, prehnite and quartz are observed in the drill cuttings, the calculated range of pCO2 is from ~1.3 to ~6.8 bars, which provides the maximum value of pCO2 at which calcite will not be present. Present day pCO2 values of geothermal fluids from the Reykjanes system were derived from analytical data on liquid and vapor samples collected at the surface using both the WATCH and SOLVEQ. At reference temperatures between 275C and 310C, these fluids have pCO2 concentrations ranging from 1.3 bars to 4.0 bars. The calculated pCO2 values based on epidote compositions are in close agreement with present-day fluid pCO2 in the Reykjanes geothermal system. 72% of the calculated pCO2 values based on epidote compositions where the assemblage of epidote, prehnite, quartz and calcite are observed in drill cuttings are within the range of measured present-day fluids, while 58% of the calculated pCO2 values fall within the range when calcite is not present in the drill cuttings.

Freedman, A. J.; Bird, D. K.; Arnrsson, S.; Fridriksson, T.; Elders, W. A.; Fridleifsson, G. O.

2009-12-01

242

Geothermal direct-heat utilization assistance. Quarterly project progress report, January--March 1996  

SciTech Connect

This report summarizes geothermal technical assistance, R&D, and technology transfer activities of the Geo-Heat Center. It describes 95 contacts with parties during this period related to technical assistance with goethermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics, and resources. Research activities are summarized on geothermal district heating system cost evaluation and silica waste utilization project. Outreach activities include publication of a geothermal direct use Bulletin, dissemination of information, goethermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

NONE

1996-05-01

243

Secondary mineral growth in fractures in the Miravalles geothermal system, Costa Rica  

SciTech Connect

A mineralogical, fluid-chemical, and theoretical study of hydrothermal alteration in veins from drillcore from the Miravalles geothermal field, Costa Rica has revealed a complex history of mineral-fluid reaction which may be used to characterize changes in temperature and fluid composition with time. Mineralogical and mineral-chemical data are consistent with hydrothermal alteration in the temperature range 200{sup 0}-270{sup 0}C, with deeper portions of the system having undergone temperatures in excess of 300{sup 0}C. Thermodynamic calculations suggest that the observed alteration assemblage is not equilibrium with current well fluids, unless estimates of reservoir pH are incorrect. Fe-Al zoning of prehnite and epidote in veins is consistent with rapid, isothermal fluctuations in fluid composition at current reservoir temperatures, and may be due to changes in volatile content of the fluid due to tectonic activity.

Rochelle, C.A. (Leeds Univ. (UK). Dept. of Earth Sciences); Milodowski, A.E.; Savage, D. (British Geological Survey, Keyworth (UK). Fluid Processes Research Group); Corella, M. (Instituto Costarricense de Electricidad, San Jose (Costa Rica))

1989-01-01

244

3D Velocity Tomographic Study of the Larderello Geothermal System, Tuscany -Italy  

NASA Astrophysics Data System (ADS)

The steam-dominated geothermal system of Larderello is located in Tuscany and is the largest Italian area of electricity generation from geothermal resources. Enel Green Power, the company of the ENEL Group involved in the renewable resources development, has drilled several wells down to maximum depth of about 4.0 km below see level in order to exploit deep and hot steam reservoirs. In the explored area, about 400 km^2 wide, two steam-dominated reservoirs were tapped by wells at different depth. The shallowest one is hosted in very permeable carbonate formations at depth of about 1 km having pressure between 0.2 and 1.5 MPa and temperatures ranging between 150C and 260C. The deepest reservoir is located in the metamorphic basement up to depth of 3-4 km b.s.l. and is characterized by pressure of about 7.0 MPa and temperature ranging between 300 and 350C. Water reinjection is operating in the shallow reservoir of the geothermal area with the aim of both sustaining and increasing reservoir pressures as well as steam production. Main goals of this study have been both to determine reliable earthquakes locations in a detailed 3- D velocity model and to define deep structural features of the geothermal field. A high-resolution 3D-velocity model of subsurface structures was lacking for this area. Therefore, this research has been addressed to image the seismic velocity structures by 3D microearthquakes tomographic inversion. Enel Green Power continuously surveys the seismic activity in the Larderello area since 1977 by using a digital local network consisting of 26 seismic stations, three of which are three components. The analyzed data set consists of approximately 500 microearthquakes occurring from January 1994 through September 2000. The good quality of recorded waveforms allowed us for high precision readings of P- and S- wave first arrivals providing a total of about 5,000 P- and 2,500 S- arrival time readings. Results of 3D velocity tomographic inversion have shown both vertical and lateral variations in term of Vp and Vp/Vs ratio that have been correlated to the main geological features of the geothermal system. In particular a low P- velocity structure lies in the middle west of the investigated area from the surface up to 3km depth. At 3 km depth, the existence of a well constrained high velocity zone delineates the morphology of the metamorphic basement which is consistent with the emplacement of the deeper reservoir. Cross sections show that the top of the metamorphic basement uplifts up to 3-4 km in the central part of the area and dips towards SE up to 10 km. By correlation with gravity data, the recovered high velocity anomalies match quite well residual Bouguer gravity highs. Furthermore, earthquake locations in the 3- D velocity model are distributed within peculiar areas clustering by linear features along the thermo-metamorphic basement top up to 13 km. This might indicate either a regional stress zone or preferential fluid propagation paths into the fracture systems.

de Matteis, R.; Vanorio, T.; Ciulli, B.; Spinelli, E.; Fiordelisi, A.; Zollo, A.

2003-04-01

245

Design of a low cost space heating system using warm geothermal or industrial effluents  

Microsoft Academic Search

The design of an effective heating system employing moderate temperature (100 to 150 F) geothermal waters to heat greenhouses without any backup conventional system is discussed. The use of nonspecialized materials is emphasized with the result that maintenance is simple, fast, and requires no skilled labor. The heat exchanger system development starts with conventional methods and evolves, through heat transfer

A. J. Pate; J. C. Batty

1977-01-01

246

Assessment of the Geothermal System Near Stanley, Idaho  

SciTech Connect

The City of Stanley, Idaho (population 63) is situated in the Salmon River valley of the central Idaho highlands. Due to its location and elevation (6270 feet amsl) it is one of the coldest locales in the continental U.S., on average experiencing frost 290 days of the year as well as 60 days of below zero (oF) temperatures. Because of high snowfall (76 inches on average) and the fact that it is at the terminus of its rural grid, the city also frequently endures extended power outages during the winter. To evaluate its options for reducing heating costs and possible local power generation, the city obtained a rural development grant from the USDA and commissioned a feasibility study through author Roy Mink to determine whether a comprehensive site characterization and/or test drilling program was warranted. Geoscience students and faculty at Idaho State University (ISU), together with scientists from the Idaho Geological Survey (IGS) and Idaho National Laboratory (INL) conducted three field data collection campaigns between June, 2011 and November, 2012 with the assistance of author Beckwith who arranged for food, lodging and local property access throughout the field campaigns. Some of the information collected by ISU and the IGS were compiled by author Mink and Boise State University in a series of progress reports (Makovsky et al., 2011a, b, c, d). This communication summarizes all of the data collected by ISU including data that were compiled as part of the IGSs effort for the National Geothermal Data Systems (NGDS) data compilation project funded by the Department of Energy and coordinated by the Arizona Geological Survey.

Trent Armstrong; John Welhan; Mike McCurry

2012-06-01

247

Characterization of a geothermal system in the Upper Arkansas Valley, CO Thomas Blum*, Kasper van Wijk and Lee Liberty, Boise State University  

E-print Network

Characterization of a geothermal system in the Upper Arkansas Valley, CO Thomas Blum*, Kasper van a geothermal system in the Mt. Princeton area. We conclude that a shallow orthogonal fault system in this area appears to be responsible for the local geothermal signature at and near the surface. The extent to which

248

Mapping seismic attenuation within geothermal systems using teleseisms with application to the Geysers-Clear Lake region  

Microsoft Academic Search

Though the exact relationship between temperature and seismic attenuation has not been defined, the thermal regime of geothermal systems exhibit high seismic attenuation. The attenuation of a seismic wave is proportional to Q-1, the reciprocal of the quality factor. The reduced spectral ratio technique has been used to infer Q structure. This technique is adapated to study a geothermal system.

Ronald W. Ward; Chi-Yuh Young

1980-01-01

249

California Geothermal Energy Collaborative  

E-print Network

the quality of life in California by bringing environmentally safe, affordable, and reliable energy services Research · Energy Systems Integration · Environmentally Preferred Advanced Generation · Industrial/Agricultural/Water California Geothermal Energy Collaborative Geothermal Education and Outreach Guide

250

Selected data for low-temperature (less than 90{sup 0}C) geothermal systems in the United States: reference data for US Geological Survey Circular 892  

SciTech Connect

Supporting data are presented for the 1982 low-temperature geothermal resource assessment of the United States. Data are presented for 2072 geothermal sites which are representative of 1168 low-temperature geothermal systems identified in 26 States. The low-temperature geothermal systems consist of 978 isolated hydrothermal-convection systems, 148 delineated-area hydrothermal-convection systems, and 42 delineated-area conduction-dominated systems. The basic data and estimates of reservoir conditions are presented for each geothermal system, and energy estimates are given for the accessible resource base, resource, and beneficial heat for each isolated system.

Reed, M.J.; Mariner, R.H.; Brook, C.A.; Sorey, M.L.

1983-12-15

251

Wine Valley Inn: A mineral water spa in Calistoga, California. Geothermal-energy-system conceptual design and economic feasibility  

SciTech Connect

The purpose of this study is to determine the engineering and economic feasibility for utilizing geothermal energy for air conditioning and service water heating at the Wine Valley Inn, a mineral water spa in Calistoga, California. The study evaluates heating, ventilating, air conditioning and water heating systems suitable for direct heat geothermal application. Due to the excellent geothermal temperatures available at this site, the mechanics and economics of a geothermally powered chilled water cooling system are evaluated. The Wine Valley Inn has the resource potential to have one of the few totally geothermal powered air conditioning and water heating systems in the world. This total concept is completely developed. A water plan was prepared to determine the quantity of water required for fresh water well development based on the special requirements of the project. An economic evaluation of the system is included to justify the added capital investment needed to build the geothermally powered mineral spa. Energy payback calculations are presented. A thermal cascade system is proposed to direct the geothermal water through the energy system to first power the chiller, then the space heating system, domestic hot water, the two spas and finally to heat the swimming pool. The Energy Management strategy required to automatically control this cascade process using industrial quality micro-processor equipment is described. Energy Management controls are selected to keep equipment sizing at a minimum, pump only the amount of geothermal water needed and be self balancing.

Not Available

1981-10-26

252

Heat and mass transfer in the Klamath Falls, Oregon, geothermal system  

SciTech Connect

Over the last 50 years significant amounts of data have been obtained from the Klamath Falls geothermal resource. To date, the complexity of the system has perplexed researchers, leading to the development of only very generalized hydrogeologic and geothermal models of the area. Based on reevaluation of all available data, a detailed conceptual model for the Klamath Falls geothermal resource is proposed. A comprehensive 3-dimensional numerical model, based on the proposed conceptual model is also presented. This numerical model incorporates all of the main reservoir characteristics. Hot water recharge flows from depth, along a large normal fault, and flows into near surface permeable strata where it loses heat to surrounding beds and to mixing with cold regional groundwaters introduced from the north. By matching calculated and measured temperatures and pressures, hot and cold water recharge rates and the permeability distribution for the geothermal system are estimated. A semi-analytic solution and simple lumped parameter methods are also compared to the numerical analysis. Results suggest that the flow patterns within the geothermal system at Klamath Falls are complex and intimately associated with the permeability distribution and the pressures and temperatures at depth, within the faults.

Prucha, R.H.

1987-05-01

253

Western Sicily (Italy), a key area for understanding geothermal system within carbonate reservoirs  

NASA Astrophysics Data System (ADS)

Oil exploration in western Sicily started in the late 1950s when several exploration wells were drilled, and continued with the acquisition of many seismic reflection profiles and the drilling of new wells in the1980s. The geological interpretation of these data mainly provided new insights for the definition of geometric relationships between tectonic units and structural reconstruction at depth. Although it has not produced completely satisfactory results for oil industry, this hydrocarbon exploration provided a great amount of data, resulting very suitable for geothermal resource assessment. From a geothermal point of view western Sicily is, indeed, a very promising area, with the manifestation at surface of several thermal springs, localized areas of high heat flux and thick carbonates units uninterruptedly developing from surface up top great depths. These available data were often collected with the modalities and purposes typical of oil exploration, not always the finest for geothermal exploration as in the case of temperature measurements. The multidisciplinary and integrated review of these data, specifically corrected for geothermal purposes, and the integration with new data acquired in particular key areas such as the Mazara Del Vallo site in the southern part of western Sicily, allowed us to better understand this medium-enthalpy geothermal system, to reconstruct the modalities and peculiarities of fluids circulation, and to evaluate the geothermal potentialities of western Sicily. We suggest that western Sicily can be taken as a reference for the understanding of geothermal systems developed at a regional scale within carbonate rocks. This study was performed within the framework of the VIGOR project (http://www.vigor-geotermia.it).

Montanari, D.; Bertini, G.; Botteghi, S.; Catalano, R.; Contino, A.; Doveri, M.; Gennaro, C.; Gianelli, G.; Gola, G.; Manzella, A.; Minissale, A.; Montegrossi, G.; Monteleone, S.; Trumpy, E.

2012-12-01

254

Hydrology of the Greater Tongonan geothermal system, Philippines, as deduced from geochemical and isotopic data  

SciTech Connect

Fluids in the Greater Tongonan geothermal system exhibit a large positive {sup 18}O shift from the Leyte meteoric water line. However, there is also a significant shift in {sup 2}H. The {delta}{sup 2}H-{delta}{sup 18}O plot shows that the geothermal fluids may be derived by the mixing of meteoric water with local magmatic water. The most enriched water in the Greater Tongonan system, in terms of {delta}{sup 18}O, {delta}{sup 2}H and Cl, is comprised of approximately 40% magmatic water. Baseline isotope results support a hydrogeochemical model in which there is increasing meteoric water dilution to the southeast, from Mahiao to Sambaloran and towards Malitbog. The Cl-{delta}{sup 18}O plot confirms that the geothermal fluid in Mahanagdong, further southeast, is distinct from that of the Mahiao-Sambaloran-Malitbog system.

Alvis-Isidro, R.R.; Solana, R.R. [Philippine National Oil Co.-Energy Development Corp., Fort Bonifacio (Philippines)] [Philippine National Oil Co.-Energy Development Corp., Fort Bonifacio (Philippines); D`amore, F.; Nuti, S. [Inst. Internazionale per le Ricerche Geotermiche, Pisa (Italy)] [Inst. Internazionale per le Ricerche Geotermiche, Pisa (Italy); Gonfiantini, R. [International Atomic Energy Agency, Vienna (Austria)] [International Atomic Energy Agency, Vienna (Austria)

1993-10-01

255

Final report. Geothermal Energy Program: Information dissemination, public outreach, and technical analysis activities. April 1, 1999 to December 31, 2001. USDOE Grant No. DE-FG01-99-EE35098  

SciTech Connect

This is the final report of the accomplishments of the geothermal energy program: information dissemination, public outreach, and technical analysis activities by the project team consisting of the Geo-Heat Center, Geothermal Resources Council, Geothermal Education Office, Geothermal Energy Association, and the Washington State University Energy Program.

Lund, John W.

2002-03-22

256

Pre- and post-exploitation variations in hydrothermal activity in Los Humeros geothermal field, Mexico  

NASA Astrophysics Data System (ADS)

Los Humeros geothermal field is a remarkable example of the lack of water-rock equilibrium. Significant variations of hydrothermal activity have occurred before and after exploitation started. Presently, discharged water is not in equilibrium with the alteration suite observed in the reservoir rocks. Hydrothermal minerals identified in core and cuttings define the occurrence of several stages of hydrothermal activity. Cooling at depth is inferred from fluid inclusion and alteration mineralogy data from the wells located nearby Los Humeros fault. Most wells produce a two-phase fluid with excess enthalpy, this accounts for the high CO 2 content observed in the discharged fluid. Sulfur and carbon isotopic data indicate that volatile species in the geothermal fluid have magmatic as well as sedimentary components, while strontium isotopic composition shows that calcium is provided by the andesitic rocks that form the reservoir. As exploitation of the field started, concentration of HCl increased in the discharged fluids. This shows that recharge of the reservoir is not enough to balance the output for production, and drying out of the field may be taking place at depth. The lack of chemical equilibrium and the presence of gases of magmatic origin suggest that Los Humeros is a relatively young geothermal field related to a recent magmatic intrusion.

Prol-Ledesma, R. M.

1998-08-01

257

Geothermal energy in Nevada  

SciTech Connect

The nature of goethermal resources in Nevada and resource applications are discussed. The social and economic advantages of utilizing geothermal energy are outlined. Federal and State programs established to foster the development of geothermal energy are discussed. The names, addresses, and phone numbers of various organizations actively involved in research, regulation, and the development of geothermal energy are included. (MHR)

Not Available

1980-01-01

258

A geochemical model of the Platanares geothermal system, Honduras  

USGS Publications Warehouse

Results of exploration drilling combined with results of geologic, geophysical, and hydrogeochemical investigations have been used to construct a geochemical model of the Platanares geothermal system, Honduras. Three coreholes were drilled, two of which produced fluids from fractured Miocene andesite and altered Cretaceous to Eocene conglomerate at 450 to 680 m depth. Large volume artesian flows of 160-165??C, predominantly bicarbonate water are chemically similar to, but slightly less saline than widespread boiling hot-spring waters. The chemistry of the produced fluid is dominated by equilibrium reactions in sedimentary rocks at greater depths and higher temperatures than those measured in the wells. Chemical, isotope, and gas geothermometers indicate a deep fluid temperature of 200-245??C and reflect a relatively short residence time in the fractures feeding the wells. Chloride-enthalpy relations as well as isotopic and chemical compositions of well discharges, thermal springs, and local cold waters support a conceptual model of ascending high-temperature (minimum 225??C) parent fluid that has cooled conductively to form the 160-165??C shallow (to 680 m) fluid encountered by the wells. The hot-spring waters are formed by boiling and steam loss from more or less conductively cooled parent fluid. The more dilute boiling spring waters (Cl = ???32 mg/kg) have cooled from > 225??C to about 160??C by conduction and from 160??C to 98??C by boiling. The most concentrated boiling spring waters (Cl = 37 mg/kg) have cooled from > 225??C to about 200??C by conduction and from 200??C to 98??C by boiling. Intermediate concentrations reflect mixed cooling paths. ?? 1991.

Janik, C.J.; Truesdell, A.H.; Goff, F.; Shevenell, L.; Stallard, M.L.; Trujillo, P.E., Jr.; Counce, D.

1991-01-01

259

Comparison of Selective Culturing and Biochemical Techniques for Measuring Biological Activity in Geothermal Process Fluids  

SciTech Connect

For the past three years, scientists at the Idaho National Engineering and Environmental Laboratory have been conducting studies aimed at determining the presence and influence of bacteria found in geothermal plant cooling water systems. In particular, the efforts have been directed at understanding the conditions that lead to the growth and accumulation of biomass within these systems, reducing the operational and thermal efficiency. Initially, the methods selected were based upon the current practices used by the industry and included the collection of water quality parameters, the measurement of soluble carbon, and the use of selective medial for the determination of the number density of various types of organisms. This data has been collected on a seasonal basis at six different facilities located at the Geysers in Northern California. While this data is valuable in establishing biological growth trends in the facilities and providing an initial determination of upset or off-normal conditions, more detailed information about the biological activity is needed to determine what is triggering or sustaining the growth in these facilities in order to develop improved monitoring and treatment techniques. In recent years, new biochemical approaches, based upon the analyses of phospholipid fatty acids and DNA recovered from environmental samples, have been developed and commercialized. These techniques, in addition to allowing the determination of the quantity of biomass, also provide information on the community composition and the nutritional status of the organisms. During the past year, samples collected from the condenser effluents of four of the plants from The Geysers were analyzed using these methods and compared with the results obtained from selective culturing techniques. The purpose of this effort was to evaluate the cost-benefit of implementing these techniques for tracking microbial activity in the plant study, in place of the selective culturing analyses that are currently the industry standard.

Pryfogle, Peter Albert

2000-09-01

260

Dispersion in tracer flow in fractured geothermal systems  

Microsoft Academic Search

Interpretation of tracer tests is commonly based on the analysis of flow through a porous medium. In geothermal reservoirs however the principal permeability arises from fractures, and a porous medium approach is not applicable. The dispersion of tracer material flowing in a fracture is shown to be dominated by molecular diffusion across the fracture-a mechanism known as Taylor dispersion. For

Roland N. Horne; Fernando Rodriguez

1983-01-01

261

A chlorite solid solution geothermometer the Los Azufres (Mexico) geothermal system  

NASA Astrophysics Data System (ADS)

Chlorite constitutes a major hydrothermal alteration product of metamorphism of andesites, in the active geothermal system of Los Azufres (Mexico). Electron microprobe analyses performed on a set of crystals from each sample show wide variations in composition. Correlation coefficients among chemical constituents were calculated. It is shown that the tetrahedral charge is positively correlated with the octahedral vacancy and negatively with the iron content, and there is almost no correlation with the octahedral aluminium and magnesium content. A procedure is proposed to select end-members and substitution vectors, and to give a general formula for these chlorites. Their formation temperatures are estimated with great accuracy, combining results of microthermometric data on fluid inclusions from gangue minerals of chlorites (quartz, calcite), direct measurements in wells (Kuster equipment), and chemical geothermometers. Correlations between chlorite compositions, range and nature of site occupancy, and temperature are good. Formation temperatures of chlorites range from 130 C to 300 C. As no other thermodynamic parameter varies significantly in the studied field (composition of the host rocks, nature of the geothermal fluids, pressure, ...), these variations of site occupancy (mainly Al(IV) and the octahedral occupancy (6-Al(VI)-(Mg+Fe(2+)) = VAC) are considered mainly as temperature dependent. Molar fractions of each end-member show very different variations with increasing temperature: X-kaolinite decreases, and X-chamosite increases, while X-talc-3 brucite does not show significant change. From these data, activity coefficients and standard state chemical potential of major components, and molar free energy formation of chlorite have been calculated for each temperature of crystallisation.

Cathelineau, Michel; Nieva, David

1985-11-01

262

ASSESSMENT OF HIGH-TEMPERATURE GEOTHERMAL RESOURCES IN HYDROTHERMAL CONVECTION SYSTEMS IN THE UNITED STATES.  

USGS Publications Warehouse

The amount of thermal energy in high-temperature geothermal systems (>150 degree C) in the United States has been calculated by estimating the temperature, area, and thickness of each identified system. These data, along with a general model for recoverability of geothermal energy and a calculation that takes account of the conversion of thermal energy to electricity, yield a resource estimate of 23,000 MWe for 30 years. The undiscovered component was estimated based on multipliers of the identified resource as either 72,000 or 127,000 MWe for 30 years depending on the model chosen for the distribution of undiscovered energy as a function of temperature.

Nathenson, Manuel

1984-01-01

263

The Suitability of Conductive and Convective Geothermal Resources in New Mexico for EGS Systems  

NASA Astrophysics Data System (ADS)

The State of New Mexico is endowed with both deep conductive and shallow convective geothermal prospects. Shallow convective resources are associated with relatively permeable, fractured crystalline plutonic, volcanic and sedimentary bedrock units. In most instances, hot springs associated with these systems are located along gaps in Paleozoic to Tertiary confining units that form hydrogeologic windows. Hydrogeologic windows are created either from tectonic or erosional unroofing of permeable units or juxtaposition of permeable units by fault block rotation or the emplacement of fractured volcanic dikes. Other hydrogeologic windows form as a result of close-spaced faulting associated with normal fault accommodation or transfer zones. These systems have broad areas of low and background heat flow in recharge areas and deep lateral flow domains with narrow regions of extremely high heat flow over the upflow zones and associated shallow lateral outflow plumes. These systems can show isothermal conditions at depth in the upflow zones that feed shallow outflow plumes and hot springs. The Socorro geothermal system is a prime example of this type of a geothermal prospect. Deeper conductive targets are overlain by relatively thick low permeability sedimentary or volcanoclastic sequences that have relatively, low thermal conductivity and higher temperature gradients. Portions of the San Juan Basin and Rio Grande rift are characterized by this type of geothermal prospect. NM Tech is currently developing a state-wide assessment of New Mexicos geothermal resources for the New Mexico Energy Conservation and Management Division. We present two finite element models of conductive-convective heat transfer along the Rio Grande Rift and San Juan Basin to evaluate the suitability of these two types of geothermal resources for EGS systems.

Person, M. A.; Owens, L.; Hubbling, J.; Kelley, S.; Witcher, J. C.; Lucero, S.

2010-12-01

264

Understanding the Chena Hot Springs, Alaska, geothermal system using temperature and pressure data from exploration boreholes  

Microsoft Academic Search

Chena Hot Springs is a small, moderate temperature, deep circulating geothermal system, apparently typical of those associated to hot springs of interior Alaska. Multi-stage drilling was used in some exploration boreholes and was found to be useful for understanding subsurface flow characteristics and developing a conceptual model of the system. The results illustrate how temperature profiles illuminate varying pressure versus

Kamil Erkan; Gwen Holdmann; Walter Benoit; David Blackwell

2008-01-01

265

Development of Models to Simulate Tracer Behavior in Enhanced Geothermal Systems  

SciTech Connect

A recent report found that power and heat produced from engineered (or enhanced) geothermal systems (EGSs) could have a major impact on the United States while incurring minimal environmental impacts. EGS resources differ from high-grade hydrothermal resources in that they lack sufficient temperature distributions, permeability/porosity, fluid saturation, or recharge of reservoir fluids. Therefore, quantitative characterization of temperature distributions and the surface area available for heat transfer in EGS is necessary for commercial development of geothermal energy. The goal of this project is to provide integrated tracer and tracer interpretation tools to facilitate this characterization. Modeling capabilities are being developed as part of this project to support laboratory and field testing to characterize engineered geothermal systems in single- and multi-well tests using tracers. The objective of this report is to describe the simulation plan and the status of model development for simulating tracer tests for characterizing EGS.

Williams, Mark D.; Vermeul, Vincent R.; Reimus, P. W.; Newell, D.; Watson, Tom B.

2010-06-01

266

Geothermal Systems of the Great Basin and U.S. Geological Survey Plans for a Regional Resource Assessment  

USGS Publications Warehouse

Based on current projections, the United States faces the need to increase its electrical power generating capacity by 40% (approximately 300,000 Megawatts-electrical or MWe) over the next 20 years (Energy Information Administration, EIA - Department of Energy). A critical question for the near future is the extent to which geothermal resources can contribute to this increasing demand for electricity. Geothermal energy constitutes one of the nation's largest sources of renewable and environmentally benign electrical power, yet the installed capacity of 2860 MWe falls far short of estimated geothermal resources. This is particularly true for the Great Basin region of the western United States, which has an installed capacity of about 500 MWe, much lower than the 7500 MWe resource estimated by the U.S. Geological Survey (USGS) in the late 1970s. The reasons for the limited development of geothermal power are varied, but political, economic and technological developments suggest the time is ripe for a new assessment effort. Technologies for power production from geothermal systems and scientific understanding of geothermal resource occurrence have improved dramatically in recent years. The primary challenges facing geothermal resource studies are (1) understanding the thermal, chemical and mechanical processes that lead to the colocation of high temperatures and high permeabilities necessary for the formation of geothermal systems and (2) developing improved techniques for locating, characterizing and exploiting these systems. Starting in the fall of 2002, the USGS will begin work with institutions funded by the Department of Energy's (DOE) Geothermal Research Program to investigate the nature and extent of geothermal systems in the Great Basin and to produce an updated assessment of available geothermal resources.

Williams, C.F.

2002-01-01

267

NATIONAL GEOTHERMAL DATA SYSTEM: AN EXEMPLAR OF OPEN ACCESS TO DATA  

SciTech Connect

The formal launch of National Geothermal Data System (NGDS www.geothermaldata.org) in 2014 will provide open access to technical geothermal-relevant data from all of the Department of Energy- sponsored geothermal development and research projects and geologic data from all 50 states. By making data easily discoverable and accessible this system will open new exploration opportunities and shorten project development. The prototype data system currently includes multiple data nodes, and nationwide data online and available to the public, indexed through a single catalog under construction at http://search.geothermaldata.org. Data from state geological surveys and partners includes more than 5 million records online, including 1.48 million well headers (oil and gas, water, geothermal), 732,000 well logs, and 314,000 borehole temperatures and is growing rapidly. There are over 250 Web services and another 138 WMS (Web Map Services) registered in the system as of August, 2013. Additional data record is being added by companion projects run by Boise State University, Southern Methodist University, and the USGS. The National Renewable Energy Laboratory is managing the Geothermal Data Repository, an NGDS node that will be a clearinghouse for data from hundreds of DOE-funded geothermal projects. NGDS is built on the US Geoscience Information Network (USGIN) data integration framework, which is a joint undertaking of the USGS and the Association of American State Geologists (AASG). NGDS is fully compliant with the White House Executive Order of May 2013, requiring all federal agencies to make their data holdings publicly accessible online in open source, interoperable formats with common core and extensible metadata. The National Geothermal Data System is being designed, built, deployed, and populated primarily with grants from the US Department of Energy, Geothermal Technologies Office. To keep this operational system sustainable after the original implementation will require four core elements: continued serving of data and applications by providers; maintenance of system operations; a governance structure; and an effective business model. Each of these presents a number of challenges currently under consideration.

Blackman, Harold [Arizona Geological Survey; Blackman, Harold M. [Arizona Geological Survey; Blackman, Harold M. [Arizona Geological Survey; Blackman, Harold [Boise State University; Blackman, Harold [United States Department of Energy; Blackman, Harold

2013-10-01

268

National Geothermal Data System: an Exemplar of Open Access to Data  

NASA Astrophysics Data System (ADS)

The National Geothermal Data System's (NGDS - www.geothermaldata.org) formal launch in 2014 will provide open access to millions of datasets, sharing technical geothermal-relevant data across the geosciences to propel geothermal development and production. With information from all of the Department of Energy's sponsored development and research projects and geologic data from all 50 states, this free, interactive tool is opening new exploration opportunities and shortening project development by making data easily discoverable and accessible. We continue to populate our prototype functional data system with multiple data nodes and nationwide data online and available to the public. Data from state geological surveys and partners includes more than 5 million records online, including 1.48 million well headers (oil and gas, water, geothermal), 732,000 well logs, and 314,000 borehole temperatures and is growing rapidly. There are over 250 Web services and another 138 WMS (Web Map Services) registered in the system as of August, 2013. Companion projects run by Boise State University, Southern Methodist University, and USGS are adding millions of additional data records. The National Renewable Energy Laboratory is managing the Geothermal Data Repository which will serve as a system node and clearinghouse for data from hundreds of DOE-funded geothermal projects. NGDS is built on the US Geoscience Information Network data integration framework, which is a joint undertaking of the USGS and the Association of American State Geologists (AASG). NGDS is fully compliant with the White House Executive Order of May 2013, requiring all federal agencies to make their data holdings publicly accessible online in open source, interoperable formats with common core and extensible metadata. The National Geothermal Data System is being designed, built, deployed, and populated primarily with grants from the US Department of Energy, Geothermal Technologies Office. To keep this operational system sustainable after the original implementation will require four core elements: continued serving of data and applications by providers; maintenance of system operations; a governance structure; and an effective business model. Each of these presents a number of challenges currently under consideration.

Allison, M. L.; Richard, S. M.; Blackman, H.; Anderson, A.

2013-12-01

269

Hydrochemistry and geothermometrical modeling of low-temperature Panticosa geothermal system (Spain)  

NASA Astrophysics Data System (ADS)

The chemical characteristics of the low-temperature geothermal system of Panticosa (Spain) were investigated in order to determine the water temperature at the reservoir and to identify the main geochemical processes that affect the water composition during the ascent of the thermal waters. In general, the studied waters are similar to other geothermal systems in the Pyrenees, belonging to the group of granite-related alkaline thermal waters (high pH, low total dissolved solids, very low magnesium concentration, and sodium as the dominant cation). According to the alkaline pH of these waters, they have a very low CO2 partial pressure, bicarbonate is the dominant anion and silica is partially ionized as H3SiO4-. The unusually active acid-base pairs (HCO3-/CO32 - and, mainly, H4SiO4/H3SiO4-) act as homogeneous pH buffers and contribute to the total alkalinity in these alkaline waters. On the basis of the study of the conservative elements, a mixing process between a hot and a cold end-member has been identified. Additionally, in order to determinate the water temperature at the reservoir, several geothermometric techniques have been applied, including both geothermometrical modeling and classical geothermometrical calculations. The geothermometrical modeling seems to indicate that thermal waters re-equilibrate with respect to calcite and kaolinite during their ascent to the surface. Modeling results suggest that these thermal waters would be in equilibrium with respect to albite, K-feldspar, quartz, calcite, kaolinite and zoisite at a similar temperature of 90 20 C in the reservoir, which is in good agreement with the results obtained by applying the classical geothermometers.

Asta, Maria P.; Gimeno, Maria J.; Auqu, Luis F.; Gmez, Javier; Acero, Patricia; Lapuente, Pilar

2012-08-01

270

Numerical modeling of geothermal heat pump system: evaluation of site specific groundwater thermal impact  

NASA Astrophysics Data System (ADS)

A pilot plant using a geothermal open-loop heat pump system has been realized in the city of Vicenza (Northern Italy), in order to meet the heating and cooling needs of the main monumental building in the historical center, the Palladian Basilica. The low enthalpy geothermal system consists of a pumping well and a reinjection well, both intercepting the same confined aquifer; three other monitoring wells have been drilled and then provided with water level and temperature dataloggers. After about 1 year and a half of activity, during a starting experimental period of three years, we have now the opportunity to analyze long term groundwater temperature data series and to evaluate the numerical modeling reliability about thermal impact prediction. The initial model, based on MODFLOW and SHEMAT finite difference codes, has been calibrated using pumping tests and other field investigations data, obtaining a valid and reliable groundwater flow simulation. But thermal parameters, such as thermal conductivity and volumetric heat capacity, didn't have a site specific direct estimation and therefore they have been assigned to model cells referring to bibliographic standards, usually derived from laboratory tests and barely representing real aquifer properties. Anyway preliminary heat transport results have been compared with observed temperature trends, showing an efficient representation of the thermal plume extension and shape. The ante operam simulation could not consider heat pump real utilization, that happened to be relevantly different from the expected project values; so the first numerical model could not properly simulate the groundwater temperature evolution. Consequently a second model has been implemented, in order to calibrate the mathematical simulation with monitored groundwater temperature datasets, trying to achieve higher levels of reliability in heat transport phenomena interpretation. This second step analysis focuses on aquifer thermal parameters calibration and includes a new finite element FEFLOW simulation, as an useful comparison between different approaches to heat transport modeling.

Pedron, Roberto; Sottani, Andrea; Vettorello, Luca

2014-05-01

271

Upscaling of Thermal Transport Properties in Enhanced Geothermal Systems  

NASA Astrophysics Data System (ADS)

: Engineered Geothermal Systems (EGS) have garnered significant attention as a possible source of geographically disperse, carbon-free energy without the environmental impact of many other renewable energy sources. However, a significant barrier to the adoption of EGS is the uncertainty in whether a specific site is amenable to engineering and how fluid injection rates can affect, either through stimulation of the fracture network or through deleterious channeling of the thermal fluid, the heat extraction rate possible in a specific reservoir. Because of the uncertainties involved in determining the exact fracture network topology extant in any particular reservoir, it is desirable to have a stochastic description (distribution) of the possible heat extraction rates that could be achieved. This work provides both an approach and application of the approach for simulating several synthetic fracture networks. The approach uses a coupled geomechanics and discrete fracture network (DFN) solver coupled uni-directionally with a reservoir scale, hydro-thermal transport code, the Non-isothermal Unsaturated-Saturated Flow and Transport simulation code (NUFT), to capture the coupled hydro-thermo-mechanical behavior of these synthetic networks. Particular attention is paid to the upscaling approach used to determine effective permeability and thermal transfer coefficients that are used in the dual porosity/permeability (DKM) model employed in NUFT. This upscaling is based on a multi-scale treatment of the domain, starting with the upscaling of permeability from explicitly represented fractures in the DFN model, which considers the fracture-scale effects of fluid injection, to a finely resolved, unstructured mesh representation of the subdomain. Effective properties of this subdomain are then determined for a variety of sub-sampled discrete fracture network topologies. The result catalog of spatially correlated thermal and fluid properties are then used to populate the properties of an anisotropic regular grid representation of the reservoir. The resultant reservoir-scale system considering the fully-coupled hydro-thermo-mechanical problem is then simulated to determine the resultant heat transfer rate for each synthetic fracture network realization. To complete the parametric study, several fractally spatially distributed systems are realized for each fractal dimension value. The resultant distributions of heat transfer rate and the trends emergent from this study will be presented. Auspices: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Johnson, S.; Hao, Y.; Chiaramonte, L.

2010-12-01

272

Near-Surface CO2 Monitoring And Analysis To Detect Hidden Geothermal Systems  

SciTech Connect

''Hidden'' geothermal systems are systems devoid of obvious surface hydrothermal manifestations. Emissions of moderate-to-low solubility gases may be one of the primary near-surface signals from these systems. We investigate the potential for CO2 detection and monitoring below and above ground in the near-surface environment as an approach to exploration targeting hidden geothermal systems. We focus on CO2 because it is the dominant noncondensible gas species in most geothermal systems and has moderate solubility in water. We carried out numerical simulations of a CO2 migration scenario to calculate the magnitude of expected fluxes and concentrations. Our results show that CO2 concentrations can reach high levels in the shallow subsurface even for relatively low geothermal source CO2 fluxes. However, once CO2 seeps out of the ground into the atmospheric surface layer, winds are effective at dispersing CO2 seepage. In natural ecological systems in the absence of geothermal gas emissions, near-surface CO2 fluxes and concentrations are predominantly controlled by CO2 uptake by photosynthesis, production by root respiration, microbial decomposition of soil/subsoil organic matter, groundwater degassing, and exchange with the atmosphere. Available technologies for monitoring CO2 in the near-surface environment include the infrared gas analyzer, the accumulation chamber method, the eddy covariance method, hyperspectral imaging, and light detection and ranging. To meet the challenge of detecting potentially small-magnitude geothermal CO2 emissions within the natural background variability of CO2, we propose an approach that integrates available detection and monitoring techniques with statistical analysis and modeling strategies. The proposed monitoring plan initially focuses on rapid, economical, reliable measurements of CO2 subsurface concentrations and surface fluxes and statistical analysis of the collected data. Based on this analysis, are as with a high probability of containing geothermal CO2 anomalies can be further sampled and analyzed using more expensive chemical and isotopic methods. Integrated analysis of all measurements will determine definitively if CO2 derived from a deep geothermal source is present, and if so, the spatial extent of the anomaly. The suitability of further geophysical measurements, installation of deep wells, and geochemical analyses of deep fluids can then be determined based on the results of the near surface CO2 monitoring program.

Lewicki, Jennifer L.; Oldenburg, Curtis M.

2005-01-19

273

Application of an expert system for analysis of geothermal well tests  

SciTech Connect

WES is an expert system designed at Lawrence Berkeley Laboratory for interpreting well test data. The results of WES's analyses of two geothermal well tests are compared to those calculated using traditional methods. WES is well suited for analyzing well tests in geothermal systems because it is robust enough to carry out analyses of data sets that are noisy or incomplete. It also has a broad knowledge base that recognizes most of the hydrogeologic characteristics observed in geothermal systems, such as double- porosity, fractures, and leaky or sealed boundaries. Application of expert systems for analyzing geothermal well tests has several advantages, including: providing clear documentation of the procedures used in the analysis; providing on-site expertise to guide the testing program; providing a greater knowledge base than a single expert may have; and, greatly decreasing the time required for these analyses. Over the next decade expert systems will become an integral part of resource definition and development programs. This paper provides just one example of how expert systems can be used. 25 refs., 16 figs., 3 tabs.

Mensch, A.; Benson, S.M.

1990-03-01

274

A proposal to investigate higher enthalpy geothermal systems in the USA  

NASA Astrophysics Data System (ADS)

After more than 50 years of development only ~3,400 MWe of electric power is currently being produced from geothermal resources in the USA. That is only about 0.33% of the country's total installed electrical capacity. In spite of the large demonstrated potential of geothermal resources, only ~2,500 MWe of new geothermal electrical capacity are under development, and the growth rate of this environmentally benign energy resource is overshadowed by the rapid increase in the installed capacity of wind and solar energy. Most of the new geothermal developments in the USA involve relatively small, moderate-temperature, geothermal systems. In contrast, development of higher enthalpy geothermal systems for power production has obvious advantages; specifically higher temperatures yield higher power outputs per well so that fewer wells are needed, leading to smaller environmental footprints for a given size of power plant. Disadvantages include that the fact that locations of suitable geothermal systems are restricted to young volcanic terrains, production of very high enthalpy fluids usually requires drilling deeper wells and may require enhanced geothermal (EGS) technology, and drilling deep into hot hostile environments is technologically challenging. However the potential for very favorable economic returns suggests that the USA should begin developing such a program. One approach to mitigating the cost issue is to form a consortium of industry, government and academia to share the costs and broaden the scope an investigation. An excellent example of such a collaboration is the Iceland Deep Drilling Project (IDDP) which is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs. This industry-government consortium planned to drill a deep well in the volcanic caldera of Krafla in NE Iceland. However drilling had to be terminated at 2.1 km depth when 900C rhyolite magma flowed into the well. The resultant well was highly productive capable of generating >35 MWe from superheated steam at a well-head temperature of ~450C. Plans for deep drilling to explore for deeper, much higher enthalpy, geothermal resources are already underway in the Taupo Volcanic Zone of New Zealand (Project HADES), and in northeast Japan the 'Beyond Brittle Project' (Project JBBP) is an ambitious program attempting to create an EGS reservoir in ~500oC rocks. However in the USA there is no comparable national program to develop such resources. There is a significant undeveloped potential for developing high-enthalpy geothermal systems in the western USA, Hawaii and Alaska. The purpose of this paper is to encourage the formation of a consortium to systematically explore, assess, and eventually develop such higher-enthalpy geothermal resources. Not only would this help develop large new sources of energy but it would permit scientific studies of pressure-temperature regimes not otherwise available for direct investigation, such as the coupling of magmatic and hydrothermal systems.

Elders, W. A.

2013-12-01

275

Thermal and hydrochemical anomalies due to large-scale thermohaline convection in Seferihisar-Balova Geothermal system, Western Anatolia, Turkey  

NASA Astrophysics Data System (ADS)

The Seferihisar-Balova Geothermal system (SBG), Western Anatolia, Turkey, is characterized by complex temperature and hydrochemical anomalies which causes are not fully understood. Previous geophysical investigations suggested that hydrothermal convection in the faulted areas of the SBG and recharge flow from the Horst may be possible transport mechanisms underlying the observed patterns. A numerical model of thermohaline flow along a North-South transect has been built in order to study the possible fluid-fluid dynamics of deep geothermal groundwater flow in the SBG. The results support the hypothesis derived from interpreted data. The interaction between forced convection from the Seferihisar Highs and free convection in the faults (i.e. mixed convection) is likely the major transport mechanism responsible for the observed anomalies. Furthermore the simulations scenarios allowed to gain a better understanding of the geophysical conditions under which the different fluid-dynamics are likely to develop. At weak recharge conditions, the convective patterns in the faults can extend to surrounding reservoir-units or below seafloor. These fault-induced drag forces can extend from the seafloor to the faults and induce natural seawater intrusion. In the units of the Seferihisar Horst, the regional flow patterns are modified by the buoyant-driven flow focused in the series of vertical faults. As a result, the main groundwater divide in the basin can shift. Sealing caprocks prevent fault-induced cells from being overwhelmed by vigorous regional flow. In this case, over-pressured blind geothermal reservoirs are likely to form below the caprocks. Transient results showed that the front of rising hot waters in faults is unstable: the tip of the hydrothermal plumes can split and lead to periodical temperature oscillations in more permeable unit. This phenomenon known as the Taylor-Saffman fingering has been described in mid-ocean ridge hydrothermal systems. Our findings suggest that this type of thermal pulsing could also develop in active faulted geothermal systems. To some extent the role of an impervious fault-core on the flow patterns has also been investigated. Although it is not possible to reproduce basin-scale transport processes of coupled heat and fluid flow in faulted hydrothermal systems, this first attempt to model deep geothermal groundwater flow in the SBG qualitatively supported the interpreted data and described the different fluid-dynamics of the basin.

Magri, F.; Pekdeger, A.; Gemici; Akar, T.

2009-12-01

276

Enhanced Geothermal Systems in Urban Areas - Lessons Learned from the 2006 Basel ML3.4 Earthquake  

NASA Astrophysics Data System (ADS)

We report on a recent deep-heat mining experiment carried out in 2006/2007 in the city of Basel (Switzerland). This pilot project was designed to produce renewable geothermal energy using the Enhanced Geothermal System (EGS) methodology. For developing the geothermal reservoir, a deep borehole was brought down to 5 km depth. Then, in December 2006, the deep-heat-mining project entered the first critical phase when the water injections started for generating micro-fracturing of the rock. These fractures increase the permeability of the host rock, needed for efficient heat exchange between the rock and the cold water; however, these fracture are also source of micro-seismicity - small earthquakes that are continuously recorded and monitored by dedicated local seismic networks. In this stimulation phase, the seismic activity increased rapidly above the usual background seismicity, and culminated in a widely felt ML 3.4 earthquake, which caused some damage in the city of Basel. Due to the higher-than-expected seismic activity, and the reaction of the population, the media, and the politicians, the experiment was stalled only 6 days after the stimulations began. Although the injected water was allowed to escape immediately after the mainshock and pressure at the wellhead dropped rapidly, the seismic activity declined only slowly, with three ML > 3 events occurring one to two months later. Although the EGS technology has been applied and studied at various sites since the 1970s, the physical processes and parameters that control injection-induced seismicity - in terms of earthquake rate, size distribution and maximum magnitude - are still poorly understood. Consequently, the seismic hazard and risk associated with the creation and operation of EGS are difficult to estimate. The very well monitored Basel seismic sequence provides an excellent opportunity to advance the understanding of the physics of EGS. The Swiss Seismological Service (SED) is investigating the Basel dataset in the framework of the multidisciplinary research project GEOTHERM (www.geotherm.ethz.ch) Left) Seismic network in Basel, Switzerland. An epicenter map of the fluid injection-induced seismicity recorded by the seismic network, indicating high event densities in hot colors, is shown in the inset. Right) Fluid injection-induced seismicity recorded by the seismic network.

Kraft, T.; Mai, P. M.; Wiemer, S.; Deichmann, N.; Ripperger, J.; Kstli, P.; Bachmann, C. E.; Fh, D.; Woessner, J.; Giardini, D.

2009-12-01

277

HIGH-TEMPERATURE GEOTHERMAL RESOURCES IN HYDROTHERMAL CONVECTION SYSTEMS IN THE UNITED STATES.  

USGS Publications Warehouse

The calculation of high-temperature geothermal resources ( greater than 150 degree C) in the United States has been done by estimating the temperature, area, and thickness of each identified system. These data, along with a general model for recoverability of geothermal energy and a calculation that takes account of the conversion of thermal energy to electricity, yielded an estimate of 23,000 MW//e for 30 years. The undiscovered component was estimated based on multipliers of the identified resource as either 72,000 or 127,000 MW//e for 30 years depending on the model chosen for the distribution of undiscovered energy as a function of temperature.

Nathenson, Manuel

1983-01-01

278

Module 7: Geothermal for Agriculture  

NSDL National Science Digital Library

Eastern Iowa Community College provides this learning module to teach students about sources of geothermal energy, geothermal energy production, components of geothermal systems, potential applications of geothermal energy, and a variety of related topics. Users candownload a zip file in which they will find asyllabus, student handouts, a quiz, and 58slide PowerPoint presentation.

279

Laboratory and theoretical models of fluid recharge in superheated geothermal systems  

NASA Astrophysics Data System (ADS)

The phase changes that occur as water invades a superheated geothermal reservoir were studied experimentally. Cold liquid ether was injected into a hot, isothermal bed of sand, and the rate of vaporization and thermal evolution of the sand bed were measured. When the ether was injected from below, the ascending vaporization front remained nearly planar. In accord with theoretical models, an isothermal layer of saturated liquid developed behind the front, and the mass fraction vaporizing was proportional to the reservoir superheat. In a second experiment, liquid was injected from below into a thermally stratified reservoir in which an initially superheated layer was overlain by a supercooled layer. As vapor produced at the ascending front rose into the supercooled region, it condensed and produced a two-phase saturated layer above the superheated zone, even though injection was from below. In a third experiment, liquid was injected from above into an isothermal superheated bed of sand. As the vaporizing liquid front migrated downward, hot vapor rose through the descending liquid. This vapor maintained the upper part of the reservoir close to the saturation temperature even though cold liquid was continuously supplied from above. In addition, fingers of liquid descended ahead of the main front into the superheated zone. Liquid transported in these fingers accumulated at the base of the reservoir in a layer of saturated liquid. Much of the subsequent vaporization occurred at the ascending front as the thickness of this liquid layer increased. Only the intermediate part of the reservoir remained superheated. Our experiments demonstrate that the geometry of recharge and the initial thermal structure of the reservoir have an important control on the phase changes in active geothermal systems. In many cases, recharge of liquid in a superheated region of a reservoir can lead to vapor production and transport and this may cause initially supercooled regions to become saturated. Also, if the liquid front becomes unstable, a two-phase zone may develop from an initially superheated region.

Woods, Andrew W.; Fitzgerald, Shaun D.

1996-09-01

280

Geochemical and Energetic Variability across Geothermal Systems in Yellowstone National Park (YNP)  

NASA Astrophysics Data System (ADS)

The physical and chemical characteristics of geothermal outflow channels have been evaluated and correlated with microbial community structure within a variety of geothermal springs in Yellowstone National Park (YNP). Several high-temperature (75-90 C), low to near-neutral pH hot springs in YNP were characterized over a two-year period for a comprehensive understanding of the possible geochemical controls on resident chemolithotrophic microbial populations. Our goal was to analyze and compare YNP geothermal systems in terms of the free energy (Grxn) available from various exergonic oxidation/reduction (redox) reactions. Important electron donors in YNP geothermal systems were measured and include H2, H2S , S0, Fe2+, CH4, and NH4+; terminal electron acceptors of noted importance include O2, NO3-, Fe3+, , S0, SO42- and CO2. Thermodynamic modeling of aqueous chemical species was used to calculate the non-standard state free energy values for a variety of oxidation-reduction reactions potentially important for chemolithotrophic metabolism. Energetic profiles as a function of distance from spring source and temperature were calculated for a series of redox reactions in several YNP springs. Variable temperatures and reactant concentrations across several geothermal springs (pH ranges 2.5-6.8) generally did not significantly change the favorability of many of the reactions considered. These findings imply that observable changes in the distribution of microbial populations are likely linked to physical (e.g. mass transfer, temperature) and biological factors. There are, however, important comparisons to be made among exergonic reactions and presumed metabolisms of resident microbial populations. Both energetic and kinetic considerations will be necessary for understanding which oxidation-reduction reactions provide a competitive metabolic advantage to primary producers in geothermal springs.

Ackerman, G. G.; Macur, R. E.; Taylor, W. P.; Kozubal, M. A.; Korf, S.; Inskeep, W. P.

2005-12-01

281

A materials and equipment review of selected US geothermal district heating systems  

SciTech Connect

This collection of information was assembled for the benefit of future geothermal system designers and existing system operators. It is intended to provide insight into the experience gained from the operation of 13 major geothermal systems over the past several years. Each chapter contains six or seven sections depending upon the type of system: introduction, production facilities, distribution, customer connections, metering and disposal. Some chapters, covering systems which incorporate a closed distribution design include a section on the central mechanical room. Each section details the original equipment and materials installed in that portion of the system. Following each section is a discussion of the subsequent problems, solutions and modifications relating to the equipment. The extent to which information was available varied from system to system. This is reflected in the length and level of detail of the chapters.

Rafferty, K.D.

1989-07-01

282

Evaluation of noise associated with geothermal-development activities. Final report, July 31, 1979-April 30, 1982  

SciTech Connect

This report was prepared for the purpose of ascertaining the current state of noise generation, suppression, and mitigation techniques associated with geothermal development. A description of the geothermal drilling process is included as well as an overview of geothermal development activities in the United States. Noise sources at the well site, along geothermal pipelines, and at the power plants are considered. All data presented are measured values by workers in the field and by Marshall Long/Acoustics. One particular well site was monitored for a period of 55 continuous days, and includes all sources of noise from the time that the drilling rig was brought in until the time that it was moved off site. A complete log of events associated with the drilling process is correlated with the noise measurements including production testing of the completed well. Data are also presented which compare measured values of geothermal noise with federal, state, county, and local standards. A section on control of geothermal noise is also given. Volume I of this document presents summary information.

Long, M.; Stern, R.

1982-01-01

283

National Geothermal Data System (USA): an Exemplar of Open Access to Data  

NASA Astrophysics Data System (ADS)

The National Geothermal Data System's (NGDS - www.geothermaldata.org) formal launch in April, 2014 will provide open access to millions of data records, sharing -relevant geoscience and longer term to land use data to propel geothermal development and production. NGDS serves information from all of the U.S. Department of Energy's sponsored development and research projects and geologic data from all 50 states, using free and open source software. This interactive online system is opening new exploration opportunities and potentially shortening project development by making data easily discoverable, accessible, and interoperable. We continue to populate our prototype functional data system with multiple data nodes and nationwide data online and available to the public. Data from state geological surveys and partners includes more than 6 million records online, including 1.72 million well headers (oil and gas, water, geothermal), 670,000 well logs, and 497,000 borehole temperatures and is growing rapidly. There are over 312 interoperable Web services and another 106 WMS (Web Map Services) registered in the system as of January, 2014. Companion projects run by Southern Methodist University and U.S. Geological Survey (USGS) are adding millions of additional data records. The DOE Geothermal Data Repository, currently hosted on OpenEI, is a system node and clearinghouse for data from hundreds of U.S. DOE-funded geothermal projects. NGDS is built on the US Geoscience Information Network (USGIN) data integration framework, which is a joint undertaking of the USGS and the Association of American State Geologists (AASG). NGDS complies with the White House Executive Order of May 2013, requiring all federal agencies to make their data holdings publicly accessible online in open source, interoperable formats with common core and extensible metadata. The National Geothermal Data System is being designed, built, deployed, and populated primarily with support from the US Department of Energy, Geothermal Technologies Office. To keep this system operational after the original implementation will require four core elements: continued serving of data and applications by providers; maintenance of system operations; a governance structure; and an effective business model. Each of these presents a number of challenges currently under consideration.

Allison, M. Lee; Richard, Stephen; Blackman, Harold; Anderson, Arlene; Patten, Kim

2014-05-01

284

Gravitational stability of water over steam in vapor-dominated geothermal systems  

Microsoft Academic Search

Vapor-dominated geothermal systems exist in a most extraordinary state: a condensate or water layer several hundred meters thick overlies a main steam zone of undetermined thickness. Why doesn't the water fall down? We show that a heavy fluid phase overlying a light phase of the same fluid in a porous medium can be stable provided the permeability in the vicinity

Gerald Schubert; Joe M. Straus

1980-01-01

285

Energy and exergy analysis of a ground source (geothermal) heat pump system  

Microsoft Academic Search

Ground source heat pumps (GSHPs), often referred to as geothermal heat pumps (GHPs), offer an attractive option for heating and cooling residential and commercial buildings owing to their higher energy efficiency compared with conventional systems. GSHPs have been used for four years in the Turkish market, although they have been in use for more years in developed countries. The purpose

A. Hepbasli; O. Akdemir

2004-01-01

286

Variation in sericite compositions from fracture zones within the Coso Hot Springs geothermal system  

Microsoft Academic Search

Two types of white micas are found in drillhole samples within the geothermal system at Coso Hot Springs. Low-permeability zones of the crystalline basement contain coarse-grained relict muscovite, whereas rock alteration near fracture zones at temperatures > 150C is characterized by abundant finegrained sericite in association with secondary calcite and quartz and unaltered relict microcline. In this hydrothermal sericite there

Barbara P. Bishop; Dennis K. Bird

1987-01-01

287

Dynamics in a Complex-Fracture-Subterranean-System with Application to HDR Geothermal Reservoirs  

Microsoft Academic Search

Hydraulic fracturing or hydraulic stimulation is one of the most effective methods of enhancing hot dry rock (HDR) geothermal system productivity. In the present study, network models of ``fractal geometry'' approximate a 3D structure of fractured rocks. The fracture network models are generated by distributing fractures randomly in space and assuming the fractal equation correlating the number of fractures and

Kei Yoshida; Sergei Fomin; Zhenzi Jing; Toshiyuki Hashida

2004-01-01

288

A three-dimensional stochastic rock mechanics model of engineered geothermal systems in fractured crystalline rock  

Microsoft Academic Search

A three-dimensional (3-D) stochastic network model for simulating a hot dry rock (HDR) or hot wet rock (HWR) engineered geothermal system formed in fractured crystalline rock is presented. The model addresses the problems of fracture network characterization from in situ field data, such as fracture orientation, size, spacing, and other mechanical properties. The model can simulate the changes that occur

Z. Jing; J. Willis-Richards; K. Watanabe; T. Hashida

2000-01-01

289

Design and Implementation of Geothermal Energy Systems at West Chester University  

Microsoft Academic Search

West Chester University is launching a comprehensive transformation of its campus heating and cooling systems from traditional fossil fuels (coal, oil and natural gas) to geothermal. This change will significantly decrease the institution's carbon footprint and serve as a national model for green campus efforts. The institution is in the process of designing and implementing this project to build well

Greg Cuprak

2011-01-01

290

Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources  

SciTech Connect

A variable phase turbine assembly will be designed and manufactured having a turbine, operable with transcritical, two-phase or vapor flow, and a generator on the same shaft supported by process lubricated bearings. The assembly will be hermetically sealed and the generator cooled by the refrigerant. A compact plate-fin heat exchanger or tube and shell heat exchanger will be used to transfer heat from the geothermal fluid to the refrigerant. The demonstration turbine will be operated separately with two-phase flow and with vapor flow to demonstrate performance and applicability to the entire range of low temperature geothermal resources. The vapor leaving the turbine is condensed in a plate-fin refrigerant condenser. The heat exchanger, variable phase turbine assembly and condenser are all mounted on single skids to enable factory assembly and checkout and minimize installation costs. The system will be demonstrated using low temperature (237F) well flow from an existing large geothermal field. The net power generated, 1 megawatt, will be fed into the existing power system at the demonstration site. The system will demonstrate reliable generation of inexpensive power from low temperature resources. The system will be designed for mass manufacturing and factory assembly and should cost less than $1,200/kWe installed, when manufactured in large quantities. The estimated cost of power for 300F resources is predicted to be less than 5 cents/kWh. This should enable a substantial increase in power generated from low temperature geothermal resources.

Hays, Lance G

2014-07-07

291

Progress toward a stochastic rock mechanics model of engineered geothermal systems  

Microsoft Academic Search

Hot dry rock geothermal energy extraction experiments in artificial reservoirs created by hydraulic stimulation in naturally fractured crystalline rocks have been undertaken in several countries over the last 20 years. The experiments have had mixed results in terms of fluid recovery, system impedance, and heat extraction. Numerical models have not yet delivered a generally agreed understanding of the processes and

J. Willis-Richards; K. Watanabe; H. Takahashi

1996-01-01

292

36Cl/Cl ratios in geothermal systems: preliminary measurements from the Coso Field  

SciTech Connect

The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results indicate that most of the chlorine is not derived from the dominant granitoid that host the geothermal system. If the chlorine was originally input into the Coso subsurface through meteoric recharge, that input occurred at least 1-1.25 million years ago. The results suggest that the thermal waters could be connate waters derived from sedimentary formations, presumably underlying and adjacent top the granitic rocks, which have recently migrated into the host rocks. Alternatively, most of the chlorine but not the water, may have recently input into the system from magmatic sources. In either case, the results indicate that most of the chlorine in the thermal waters has existed within the granitoid host rocks for no more than about 100,00-200,00 years. this residence time for the chlorine is similar to residence times suggested by other researchers for chlorine in deep groundwaters of the Mono Basin north of the Coso field.

Nimz, G.J.; Moore, J.N.; Kasameyer, P.W.

1997-07-01

293

Exergoeconomic evaluation on the optimum heating circuit system of Simav geothermal district heating system  

Microsoft Academic Search

Simav is one of the most important 15 geothermal areas in Turkey. It has several geothermal resources with the mass flow rate ranging from 35 to 72kg\\/s and temperature from 88 to 148C. Hence, these geothermal resources are available to use for several purposes, such as electricity generation, district heating, greenhouse heating, and balneological purposes. In Simav, the 5000 residences

Oguz Arslan; M. Arif Ozgur; Ramazan Kose; Abtullah Tugcu

2009-01-01

294

Integrated mineralogical and fluid inclusion study of the Coso geothermal systems, California  

SciTech Connect

Coso is one of several high-temperature geothermal systems on the margins of the Basin and Range province that is associated with recent volcanic activity. This system, which is developed entirely in fractured granitic and metamorphic rocks, consists of a well-defined thermal plume that originates in the southern part of the field and then flows upward and laterally to the north. Fluid inclusion homogenization temperatures and salinities demonstrate that cool, low salinity ground waters were present when the thermal plume was emplaced. Dilution of the thermal waters occurred above and below the plume producing strong gradients in their compositions. In response to heating and mixing, clays and carbonate minerals precipitated, sealing the fractures along the margins of the reservoir and strongly influencing its geometry. The alteration mineralogy varies systematically with depth and temperature. Based on the clay mineralogy, three zones can be recognized: the smectite zone, the illite-smectite zone, and the illite zone. The smectite zone thickens from the north to south and is characterized by smectite, kaolin, stilbite and a variety of carbonate minerals. The illite-smectite zone contains mixed-layer clays and also thickens to the south. The deepest zone (the illite zone) contains illite, chlorite, epidote, and wairakite. Quartz and calcite veins occur in all three zones. Comparison of mineral and fluid inclusion based temperatures demonstrates that cooling has occurred along the margins of the thermal system but that the interior of the system is still undergoing heating.

Lutz, Susan J.; Moore, Joseph N.; Copp, John F.

1996-01-24

295

Investigating ultra high-enthalpy geothermal systems: a collaborative initiative to promote scientific opportunities  

NASA Astrophysics Data System (ADS)

Scientists, engineers, and policy makers gathered at a workshop in the San Bernardino Mountains of southern California in October 2013 to discuss the science and technology involved in developing high-enthalpy geothermal fields. A typical high-enthalpy geothermal well between 2000 and 3000 m deep produces a mixture of hot water and steam at 200-300 C that can be used to generate about 5-10 MWe of electric power. The theme of the workshop was to explore the feasibility and economic potential of increasing the power output of geothermal wells by an order of magnitude by drilling deeper to reach much higher pressures and temperatures. Development of higher enthalpy geothermal systems for power production has obvious advantages; specifically higher temperatures yield higher power outputs per well so that fewer wells are needed, leading to smaller environmental footprints for a given size of power plant. Plans for resource assessment and drilling in such higher enthalpy areas are already underway in Iceland, New Zealand, and Japan. There is considerable potential for similar developments in other countries that already have a large production of electricity from geothermal steam, such as Mexico, the Philippines, Indonesia, Italy, and the USA. However drilling deeper involves technical and economic challenges. One approach to mitigating the cost issue is to form a consortium of industry, government and academia to share the costs and broaden the scope of investigation. An excellent example of such collaboration is the Iceland Deep Drilling Project (IDDP), which is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs, and this approach could serve as model for future developments elsewhere. A planning committee was formed to explore creating a similar initiative in the USA.

Elders, W. A.; Nielson, D.; Schiffman, P.; Schriener, A., Jr.

2014-12-01

296

Climate change and geothermal ecosystems: natural laboratories, sentinel systems, and future refugia.  

PubMed

Understanding and predicting how global warming affects the structure and functioning of natural ecosystems is a key challenge of the 21st century. Isolated laboratory and field experiments testing global change hypotheses have been criticized for being too small-scale and overly simplistic, whereas surveys are inferential and often confound temperature with other drivers. Research that utilizes natural thermal gradients offers a more promising approach and geothermal ecosystems in particular, which span a range of temperatures within a single biogeographic area, allow us to take the laboratory into nature rather than vice versa. By isolating temperature from other drivers, its ecological effects can be quantified without any loss of realism, and transient and equilibrial responses can be measured in the same system across scales that are not feasible using other empirical methods. Embedding manipulative experiments within geothermal gradients is an especially powerful approach, informing us to what extent small-scale experiments can predict the future behaviour of real ecosystems. Geothermal areas also act as sentinel systems by tracking responses of ecological networks to warming and helping to maintain ecosystem functioning in a changing landscape by providing sources of organisms that are preadapted to different climatic conditions. Here, we highlight the emerging use of geothermal systems in climate change research, identify novel research avenues, and assess their roles for catalysing our understanding of ecological and evolutionary responses to global warming. PMID:24729541

O'Gorman, Eoin J; Benstead, Jonathan P; Cross, Wyatt F; Friberg, Nikolai; Hood, James M; Johnson, Philip W; Sigurdsson, Bjarni D; Woodward, Guy

2014-11-01

297

Experimentally determined rock-fluid interactions applicable to a natural hot dry rock geothermal system  

SciTech Connect

The Los Alamos Scientific Laboratory is pursuing laboratory and field experiments in the development of the Hot Dry Rock concept of geothermal energy. The field program consists of experiments in a hydraulically fractured region of low permeability in which hot rock is intercepted by two wellbores. These experiments are designed to test reservoir engineering parameters such as: heat extraction rates, water loss rates, flow characteristics including impedance and buoyancy, seismic activity and fluid chemistry. Laboratory experiments have been designed to provide information on the mineral reactivity which may be encountered in the field program. Two experimental circulation systems have been built to study the rates of dissolution and alteration in dynamic flow. Solubility studies have been done in agitated systems. To date, pure minerals, samples of the granodiorite from the actual reservoir and Tijeras Canyon granite have been reacted with distilled water and various solutions of NaCl, NaOH, and Na/sub 2/CO/sub 3/. The results of these experimental systems are compared to observations made in field experiments done in a hot dry rock reservoir at a depth of approximately 3 km with initial rock temperatures of 150 to 200/sup 0/C.

Charles, R.W.; Holley, C.E. Jr.; Tester, J.W.; Blatz, L.A.; Grigsby, C.O.

1980-02-01

298

The Occurrence of Pyrrhotite in the Ngawha Geothermal System, New Zealand  

SciTech Connect

The Ngawha geothermal system is low in all sulfide minerals, but in comparison to systems in the Taupo Volcanic Zone it contains more widely distributed pyrrhotite which is currently depositing, mainly in fractures. This reflects the high proportion of vapor in the Ngawha system. Pyrrhotite is most common in the upper part of the reservoir and lower part of the aquitard. The Ngawha pyrrhotite is of monoclinic and monoclinic + hexagonal structure.

Cox, M.E.; Browne, P.R.L.

1995-01-01

299

Development of Models to Simulate Tracer Tests for Characterization of Enhanced Geothermal Systems  

SciTech Connect

A recent report found that power and heat produced from enhanced (or engineered) geothermal systems (EGSs) could have a major impact on the U.S energy production capability while having a minimal impact on the environment. EGS resources differ from high-grade hydrothermal resources in that they lack sufficient temperature distribution, permeability/porosity, fluid saturation, or recharge of reservoir fluids. Therefore, quantitative characterization of temperature distributions and the surface area available for heat transfer in EGS is necessary for the design and commercial development of the geothermal energy of a potential EGS site. The goal of this project is to provide integrated tracer and tracer interpretation tools to facilitate this characterization. This project was initially focused on tracer development with the application of perfluorinated tracer (PFT) compounds, non-reactive tracers used in numerous applications from atmospheric transport to underground leak detection, to geothermal systems, and evaluation of encapsulated PFTs that would release tracers at targeted reservoir temperatures. After the 2011 midyear review and subsequent discussions with the U.S. Department of Energy Geothermal Technology Program (GTP), emphasis was shifted to interpretive tool development, testing, and validation. Subsurface modeling capabilities are an important component of this project for both the design of suitable tracers and the interpretation of data from in situ tracer tests, be they single- or multi-well tests. The purpose of this report is to describe the results of the tracer and model development for simulating and conducting tracer tests for characterizing EGS parameters.

Williams, Mark D.; Reimus, Paul; Vermeul, Vincent R.; Rose, Peter; Dean, Cynthia A.; Watson, Tom B.; Newell, D.; Leecaster, Kevin; Brauser, Eric

2013-05-01

300

A Case Study of Wide Diameter Casing for Geothermal Systems  

SciTech Connect

Three wells have been drilled in the central resistivity area of a geothermal field in the Taupo Volcanic Zone, New Zealand. Using a well bore simulator, WELL SIM V3.0, reservoir conditions and well characteristics are evaluated to determine the increase in output by increasing production casing diameters from either 8-5/8 inches OD or 9-5/8 inches OD to 13-3/8 inches OD. Increases in well drilling costs are determined to provide a commentary on the economics. While open hole size is effectively doubled, well costs increase by 10% and, in this study, output increases by an average of 18%.

King, T.R.; Freeston, D.H.; Winmill, R.L.

1995-01-01

301

Geochemistry of sericite and chlorite in well 14-2 Roosevelt Hot Springs geothermal system and in mineralized hydrothermal systems  

SciTech Connect

Chemical compositions of chlorite and sericite from one production well in the Roosevelt geothermal system have been determined by electron probe methods and compared with compositions of chlorite and sericite from porphyry copper deposits. Modern system sericite and chlorite occur over a depth interval of 2 km and a temperature interval of 250/sup 0/C.

Ballantyne, J.M.

1980-06-01

302

Geochemistry of sericite and chlorite in well 14-2 Roosevelt Hot Springs geothermal system and in mineralized hydrothermal systems  

Microsoft Academic Search

Chemical compositions of chlorite and sericite from one production well in the Roosevelt geothermal system have been determined by electron probe methods and compared with compositions of chlorite and sericite from porphyry copper deposits. Modern system sericite and chlorite occur over a depth interval of 2 km and a temperature interval of 250°C.

Ballantyne

1980-01-01

303

Fluid-rock interactions in CO2-saturated, granite-hosted geothermal systems: Implications for natural and engineered systems from geochemical experiments and models  

NASA Astrophysics Data System (ADS)

Hydrothermal experiments were conducted and geochemical models constructed to evaluate the geochemical and mineralogical response of fractured granite and granite + epidote in contact with thermal water, with and without supercritical CO2, at 250 C and 25-45 MPa. Illite smectite zeolite(?) precipitate as secondary minerals at the expense of K-feldspar, oligoclase, and epidote. Illite precipitates in experiments reacting granite and granite + epidote with water; metastable smectite forms in the experiments injected with supercritical CO2. Waters are supersaturated with respect to quartz and saturated with respect to chalcedony in CO2-charged experiments, but neither mineral formed. Carbonate formation is predicted for experiments injected with supercritical CO2, but carbonate only formed during cooling and degassing of the granite + epidote + CO2 experiment. Experimental results provide insight into the buffering capacity of granites as well as the drivers of clay formation. Metastable smectite in the experiments is attributed to high water-rock ratios, high silica activities, and high CO2 and magnesium-iron concentrations. Smectite precipitation in supercritical CO2-bearing geothermal systems may affect reservoir permeability. Silicate formation may create or thicken caps within or on the edges of geothermal reservoirs. Carbonate formation, as desired for carbon sequestration projects coinciding with geothermal systems, may require extended periods of time; cooling and degassing of CO2-saturated waters leads to carbonate precipitation, potentially plugging near-surface production pathways.

Lo R, Caroline; Kaszuba, John P.; Moore, Joseph N.; McPherson, Brian J.

2014-09-01

304

THERMO-HYDRO-MECHANICAL SIMULATION OF GEOTHERMAL  

E-print Network

THERMO-HYDRO-MECHANICAL SIMULATION OF GEOTHERMAL RESERVOIR STIMULATIONRESERVOIR STIMULATION Silvia Seminario del Grupo de Hidrologa Subterrnea - UPC, Barcelona #12;INTRODUCTION Enhanced geothermal systems Geothermal gradient ~ 33 C/Km Hydraulic stimulation enhances fracture permeability (energy

Politcnica de Catalunya, Universitat

305

IGA: International Geothermal Association  

NSDL National Science Digital Library

The International Geothermal Association's (IGA) goal is "to encourage research, development, and utilization of geothermal resources worldwide through the compilation, publication, and dissemination of scientific and technical data and information." The website offers a multitude of information about geothermal energy around the world. Students can find educational resources about the history, nature, classification, utilization, and exploration of geothermal systems. Through an interactive map, users can find data on geothermal energy. Researchers can discover journals and upcoming conferences. Visitors can also learn how to take part in the IGA panel and discussion group.

306

GEOGRAPHIC INFORMATION SYSTEMS IN MANAGING OF TERRITORIAL RESOURCES: AN EXAMPLE FOR THE SABATINI GEOTHERMAL SYSTEM (CENTRAL ITALY)  

NASA Astrophysics Data System (ADS)

Geographic Information System (GIS) is very important tool in managing the interdisciplinary researches and territorial resources. GIS integrates data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. They can represent a scientific and social benefit. Here we present an application of GIS to a potentially exploitable geothermal area. The geothermal resource can be used either indirectly or directly. In the first case electricity is produced from high enthalpy systems. In second case heating and cooling systems are obtained from medium or low enthalpy systems. Italian geothermal resources employment is still poorly developed in direct use sector, despite the great geothermal potentials suitable for this purpuse. Often this limited application is due mainly to a inadequate territory knowledge and sometimes by difficulties in obtaining required information. In this case the creation of a geo-database can be extremely helpful. The studied area is located in Central Italy, just north of Rome, and comprise the western part of the Sabatini Volcanic District, Tolfa Mountains, extending up to Civitavecchia. Exploration surveys investigated this area during 70s-90s for geothermal purpose, but the area still results unexploited. The presence of thermal waters and of anomalous heat flow, together with demographical growing of the last years, make this site a suitable location for direct applications of the geothermal resource. Previews work and new data about geological, structural, hydrogeological, geochemical features have been processed to be recorded in a geo-database . Further, social data about demographical trend and available scientific record concerning the studied area fulfill the database. The majority of available geological information date back to early 90s; an important part of the work consisted in the digitalization and updating of pre-existent data. The final product is a WEB-GIS that can facilitate diffusion and consultation of geographically referenced data, which can be easily managed by public and private infrastructures, research institutes and universities, allowing a better development of the territorial resources.

Procesi, M.; Cinti, D.; Poncia, P.; de Rita, D.

2009-12-01

307

Strategic optimization of large-scale vertical closed-loop shallow geothermal systems  

NASA Astrophysics Data System (ADS)

Vertical closed-loop geothermal systems or ground source heat pump (GSHP) systems with multiple vertical borehole heat exchangers (BHEs) are attractive technologies that provide heating and cooling to large facilities such as hotels, schools, big office buildings or district heating systems. Currently, the worldwide number of installed systems shows a recurrent increase. By running arrays of multiple BHEs, the energy demand of a given facility is fulfilled by exchanging heat with the ground. Due to practical and technical reasons, square arrays of the BHEs are commonly used and the total energy extraction from the subsurface is accomplished by an equal operation of each BHE. Moreover, standard designing practices disregard the presence of groundwater flow. We present a simulation-optimization approach that is able to regulate the individual operation of multiple BHEs, depending on the given hydro-geothermal conditions. The developed approach optimizes the overall performance of the geothermal system while mitigating the environmental impact. As an example, a synthetic case with a geothermal system using 25 BHEs for supplying a seasonal heating energy demand is defined. The optimization approach is evaluated for finding optimal energy extractions for 15 scenarios with different specific constant groundwater flow velocities. Ground temperature development is simulated using the optimal energy extractions and contrasted against standard application. It is demonstrated that optimized systems always level the ground temperature distribution and generate smaller subsurface temperature changes than non-optimized ones. Mean underground temperature changes within the studied BHE field are between 13% and 24% smaller when the optimized system is used. By applying the optimized energy extraction patterns, the temperature of the heat carrier fluid in the BHE, which controls the overall performance of the system, can also be raised by more than 1 C.

Hecht-Mndez, J.; de Paly, M.; Beck, M.; Blum, P.; Bayer, P.

2012-04-01

308

Development of an Enhanced Two-Phase Production System at the Geysers Geothermal Field  

SciTech Connect

A method was developed to enhance geothermal steam production from two-phase wells at THE Geysers Geothermal Field. The beneficial result was increased geothermal production that was easily and economically delivered to the power plant.

Steven Enedy

2001-12-14

309

Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary Formations  

SciTech Connect

There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. Terralog USA, in collaboration with the University of California, Irvine (UCI), are currently investigating advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. This two-year research project, funded by the US Department of Energy, includes combined efforts for: 1) Resource characterization; 2) Small and large scale laboratory investigations; 3) Numerical simulation at both the laboratory and field scale; and 4) Engineering feasibility studies and economic evaluations. The research project is currently in its early stages. This paper summarizes our technical approach and preliminary findings related to potential resources, small-scale laboratory simulation, and supporting numerical simulation efforts.

Mike Bruno; Russell L. Detwiler; Kang Lao; Vahid Serajian; Jean Elkhoury; Julia Diessl; Nicky White

2012-09-30

310

Fracture Characterization in Enhanced Geothermal Systems by Wellbore and Reservoir Analysis  

SciTech Connect

This report highlights the work that was done to characterize fractured geothermal reservoirs using production data. That includes methods that were developed to infer characteristic functions from production data and models that were designed to optimize reinjection scheduling into geothermal reservoirs, based on these characteristic functions. The characterization method provides a robust way of interpreting tracer and flow rate data from fractured reservoirs. The flow-rate data are used to infer the interwell connectivity, which describes how injected fluids are divided between producers in the reservoir. The tracer data are used to find the tracer kernel for each injector-producer connection. The tracer kernel describes the volume and dispersive properties of the interwell flow path. A combination of parametric and nonparametric regression methods were developed to estimate the tracer kernels for situations where data is collected at variable flow-rate or variable injected concentration conditions. The characteristic functions can be used to calibrate thermal transport models, which can in turn be used to predict the productivity of geothermal systems. This predictive model can be used to optimize injection scheduling in a geothermal reservoir, as is illustrated in this report.

Roland N. Horne, Kewen Li, Mohammed Alaskar, Morgan Ames, Carla Co, Egill Juliusson, Lilja Magnusdottir

2012-06-30

311

Exergy analysis of the performance of low-temperature district heating system with geothermal heat pump  

NASA Astrophysics Data System (ADS)

Exergy analysis of low temperature geothermal heat plant with compressor and absorption heat pump was carried out. In these two concepts heat pumps are using geothermal water at 19.5 oC with spontaneous outflow 24 m3/h as a heat source. The research compares exergy efficiency and exergy destruction of considered systems and its components as well. For the purpose of analysis, the heating system was divided into five components: geothermal heat exchanger, heat pump, heat distribution, heat exchanger and electricity production and transportation. For considered systems the primary exergy consumption from renewable and non-renewable sources was estimated. The analysis was carried out for heat network temperature at 50/40 oC, and the quality regulation was assumed. The results of exergy analysis of the system with electrical and absorption heat pump show that exergy destruction during the whole heating season is lower for the system with electrical heat pump. The exergy efficiencies of total system are 12.8% and 11.2% for the system with electrical heat pump and absorption heat pump, respectively.

Sekret, Robert; Nitkiewicz, Anna

2014-03-01

312

The Iceland Deep Drilling Project: (II) Hydrothermal Minerals Record Variations in CO2 Flux of the Mid-Atlantic Ridge, Reykjanes Geothermal System, Iceland  

NASA Astrophysics Data System (ADS)

The Mid-Atlantic Ridge spreading center is exposed on land at the Reykjanes geothermal system in southwest Iceland. This is one of the sites that was considered for the location of the Iceland Deep Drilling Project. Seawater that penetrates this coastal geothermal system at depth reacts with the host rock basalt to form secondary geothermal minerals in progressively higher-grade mineral alteration zones with depth at temperatures over 300C. Within the epidote-chlorite and epidote-actinolite alteration zones, epidote- prehnite-calcite-quartz-fluid forms a trivariant assemblage that, under conditions of specified temperature and pressure, allows predictions of geothermal fluid PCO2 to be made as a function of the composition of the solid solution minerals epidote and prehnite. Epidote crystals display complex chemical zoning, generally with Fe(III)-rich cores and Al-rich rims. The Fe(III)-mol fraction of epidote at depths between 0.5 to 1 km ranges from 0.24 to 0.38, between 1 to 2 km depth the range is 0.17 to 0.48 and between 2-3 km it is 0.17 to 0.30. A second order polynomial relationship is used to calculate the Fe(III)-Al composition of prehnite based on published compositions of coexisting epidote and prehnite in active geothermal systems. Using epidote and prehnite compositions and thermodynamic analysis of this assemblage, the calculated PCO2 of the fluid that formed Fe(III)-rich cores from 1 to 2 km depth was between ~0.2 and 1.0 bar, while the Al-rich rims formed from calculated fluid PCO2 levels of between 1.0 and 6.5 bars. The Fe(III)-rich epidote between 0.5 and 1 km indicates a paragenesis with PCO2 levels of between 0.008 and ~2.0 bars while Al-rich epidote between 2 and 3 km depth intimate fluid PCO2 levels of between 3.5 and 10.0 bars. Ultimately, the data suggests that the fluid PCO2 has increased during the evolution of this geothermal system, likely due to periodic magma injection and degassing during dike emplacement. In addition, the calculated PCO2 values of the Al-rich epidote rims are in excellent agreement with present-day measured CO2 in the Reykjanes geothermal system. The correlation between measured and predicted fluid compositions provides invaluable insight into future abilities to characterize regional and global CO2 flux from mid-ocean ridge spreading centers.

Freedman, A. J.; Bird, D. K.; Arnrsson, S.; Fridriksson, T.; Elders, W. A.; Fridleifsson, G. O.

2006-12-01

313

Critiquing ';pore connectivity' as basis for in situ flow in geothermal systems  

NASA Astrophysics Data System (ADS)

Geothermal system in situ flow systematics derived from detailed examination of grain-scale structures, fabrics, mineral alteration, and pore connectivity may be extremely misleading if/when extrapolated to reservoir-scale flow structure. In oil/gas field clastic reservoir operations, it is standard to assume that small scale studies of flow fabric - notably the Kozeny-Carman and Archie's Law treatments at the grain-scale and well-log/well-bore sampling of formations/reservoirs at the cm-m scale - are adequate to define the reservoir-scale flow properties. In the case of clastic reservoirs, however, a wide range of reservoir-scale data wholly discredits this extrapolation: Well-log data show that grain-scale fracture density fluctuation power scales inversely with spatial frequency k, S(k) ~ 1/k^?, 1.0 < ? < 1.2, 1cycle/km < k < 1cycle/cm; the scaling is a ';universal' feature of well-logs (neutron porosity, sonic velocity, chemical abundance, mass density, resistivity, in many forms of clastic rock and instances of shale bodies, for both horizontal and vertical wells). Grain-scale fracture density correlates with in situ porosity; spatial fluctuations of porosity ? in well-core correlate with spatial fluctuations in the logarithm of well-core permeability, ?? ~ ?log(?) with typical correlation coefficient ~ 85%; a similar relation is observed in consolidating sediments/clays, indicating a generic coupling between fluid pressure and solid deformation at pore sites. In situ macroscopic flow systems are lognormally distributed according to ? ~ ?0 exp(?(?-?0)), ? >>1 an empirical parameter for degree of in situ fracture connectivity; the lognormal distribution applies to well-productivities in US oil fields and NZ geothermal fields, ';frack productivity' in oil/gas shale body reservoirs, ore grade distributions, and trace element abundances. Although presently available evidence for these properties in geothermal reservoirs is limited, there are indications that geothermal system flow essentially obeys the same ';universal' in situ flow rules as does clastic rock: Well-log data from Los Azufres, MX, show power-law scaling S(k) ~ 1/k^?, 1.2 < ? < 1.4, for spatial frequency range 2cycles/km to 0.5cycle/m; higher ?-values are likely due to the relatively fresh nature of geothermal systems; Well-core at Bulalo (PH) and Ohaaki (NZ) show statistically significant spatial correlation, ?? ~ ?log(?) Well productivity at Ohaaki/Ngawha (NZ) and in geothermal systems elsewhere are lognormally distributed; K/Th/U abundances lognormally distributed in Los Azufres well-logs We therefore caution that small-scale evidence for in situ flow fabric in geothermal systems that is interpreted in terms of ';pore connectivity' may in fact not reflect how small-scale chemical processes are integrated into a large-scale geothermal flow structure. Rather such small scale studies should (perhaps) be considered in term of the above flow rules. These flow rules are easily incorporated into standard flow simulation codes, in particular the OPM = Open Porous Media open-source industry-standard flow code. Geochemical transport data relevant to geothermal systems can thus be expected to be well modeled by OPM or equivalent (e.g., INL/LANL) codes.

Kenedi, C. L.; Leary, P.; Malin, P.

2013-12-01

314

Application of Microearthquake(MEQ)Monitoring for Characterizing the Performance of Enhanced Geothermal Systems  

NASA Astrophysics Data System (ADS)

Microearthquake monitoring for fracture enhancement and imaging of fracture systems will play a crucial role in the success of EGS, both from a reservoir management and public acceptance point of view. One controversial issue associated with EGS is the impact of induced seismicity or microseismicity, which has been the cause of delays and threatened cancellation of at EGS projects worldwide. LBNL is installing, operating , and/or interfacing MEQ seismic arrays at multiple EGS sites which are in collaboration with the USDOE Geothermal EGS Program. The overall goal is to gather high resolution MEQ data before, during and after stimulation activities at the EGS projects. This will include both surface and borehole deployments (as necessary and in conjunction with available boreholes) to not only use MEQ data for understanding the creation and monitoring of fracture stimulation of EGS reservoirs, but for using both active and passive monitoring of the fracture systems. Current EGS DOE Project sites include Desert Peak, Bradys Hot Springs, and New York Canyon, Nevada, the NW Geysers, and the SE Geysers, California, Raft River, Idaho, and Newberry Caldera in Oregon. A possible additional site in Alaska. Additional sites will be instrumented as DOE adds projects. A second goal is to provide high quality MEQ data, improved processing methodologies to detect and understand fracture and fault mechanics,and advanced analysis of the data to the research community in order to develop, test and apply MEQ methods for understanding the performance of the EGS systems,as well as aid in developing induced seismicity mitigation techniques that can be used for a variety of EGS systems in the future. Reported will be current status and results from the initial injections and how the research community can access the data.

Majer, E.

2010-12-01

315

Energy Returned On Investment of Engineered Geothermal Systems Annual Report FY2011  

SciTech Connect

Energy Return On Investment (EROI) is an important figure of merit for assessing the viability of energy alternatives. For geothermal electric power generation, EROI is determined by the electricity delivered to the consumer compared to the energy consumed to construct, operate, and decommission the facility. Critical factors in determining the EROI of Engineered Geothermal Systems (EGS) are examined in this work. These include the input energy embodied into the system. The embodied energy includes the energy contained in the materials, as well as, that consumed in each stage of manufacturing from mining the raw materials to assembling the finished plant. Also critical are the system boundaries and value of the energy - heat is not as valuable as electrical energy.

Mansure, A.J.

2011-12-31

316

Geothermal energy: 1992 program overview  

SciTech Connect

Geothermal energy is described in general terms with drawings illustrating the technology. A map of known and potential geothermal resources in the US is included. The 1992 program activities are described briefly. (MHR)

Not Available

1993-04-01

317

Pumpernickel Valley Geothermal Project Thermal Gradient Wells  

SciTech Connect

The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined with geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermal production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for

Z. Adam Szybinski

2006-01-01

318

Iceland is a country of breathtaking natural beauty, geothermal activity and volcanoes that, as we all know by  

E-print Network

Iceland is a country of breathtaking natural beauty, geothermal activity and volcanoes that, as we and informative, survey of the research work in computer science that is going on "under the volcano". I, Volcanoes and... Computer Science! 27-10-2010 14:00 Sala de Grados Facultad de Informática Luca Aceto

Tradacete, Pedro

319

Chemical geothermometers and mixing models for geothermal systems  

USGS Publications Warehouse

Qualitative chemical geothermometers utilize anomalous concentrations of various "indicator" elements in groundwaters, streams, soils, and soil gases to outline favorable places to explore for geothermal energy. Some of the qualitative methods, such as the delineation of mercury and helium anomalies in soil gases, do not require the presence of hot springs or fumaroles. However, these techniques may also outline fossil thermal areas that are now cold. Quantitative chemical geothermometers and mixing models can provide information about present probable minimum subsurface temperatures. Interpretation is easiest where several hot or warm springs are present in a given area. At this time the most widely used quantitative chemical geothermometers are silica, Na/K, and Na-K-Ca. ?? 1976.

Fournier, R.O.

1977-01-01

320

Recent drilling activities at the earth power resources Tuscarora geothermal power project's hot sulphur springs lease area.  

SciTech Connect

Earth Power Resources, Inc. recently completed a combined rotary/core hole to a depth of 3,813 feet at it's Hot Sulphur Springs Tuscarora Geothermal Power Project Lease Area located 70-miles north of Elko, Nevada. Previous geothermal exploration data were combined with geologic mapping and newly acquired seismic-reflection data to identify a northerly tending horst-graben structure approximately 2,000 feet wide by at least 6,000 feet long with up to 1,700 feet of vertical offset. The well (HSS-2) was successfully drilled through a shallow thick sequence of altered Tertiary Volcanic where previous exploration wells had severe hole-caving problems. The ''tight-hole'' drilling problems were reduced using drilling fluids consisting of Polymer-based mud mixed with 2% Potassium Chloride (KCl) to reduce Smectite-type clay swelling problems. Core from the 330 F fractured geothermal reservoir system at depths of 2,950 feet indicated 30% Smectite type clays existed in a fault-gouge zone where total loss of circulation occurred during coring. Smectite-type clays are not typically expected at temperatures above 300 F. The fracture zone at 2,950 feet exhibited a skin-damage during injection testing suggesting that the drilling fluids may have caused clay swelling and subsequent geothermal reservoir formation damage. The recent well drilling experiences indicate that drilling problems in the shallow clays at Hot Sulphur Springs can be reduced. In addition, average penetration rates through the caprock system can be on the order of 25 to 35 feet per hour. This information has greatly reduced the original estimated well costs that were based on previous exploration drilling efforts. Successful production formation drilling will depend on finding drilling fluids that will not cause formation damage in the Smectite-rich fractured geothermal reservoir system. Information obtained at Hot Sulphur Springs may apply to other geothermal systems developed in volcanic settings.

Goranson, Colin

2005-03-01

321

Active Management of Integrated Geothermal-CO2 Storage Reservoirs in Sedimentary Formations  

SciTech Connect

Active Management of Integrated GeothermalCO2 Storage Reservoirs in Sedimentary Formations: An Approach to Improve Energy Recovery and Mitigate Risk : FY1 Final Report The purpose of phase 1 is to determine the feasibility of integrating geologic CO2 storage (GCS) with geothermal energy production. Phase 1 includes reservoir analyses to determine injector/producer well schemes that balance the generation of economically useful flow rates at the producers with the need to manage reservoir overpressure to reduce the risks associated with overpressure, such as induced seismicity and CO2 leakage to overlying aquifers. This submittal contains input and output files of the reservoir model analyses. A reservoir-model "index-html" file was sent in a previous submittal to organize the reservoir-model input and output files according to sections of the FY1 Final Report to which they pertain. The recipient should save the file: Reservoir-models-inputs-outputs-index.html in the same directory that the files: Section2.1.*.tar.gz files are saved in.

Buscheck, Thomas A.

2012-01-01

322

Geothermal Energy.  

ERIC Educational Resources Information Center

Described are the origin and nature of geothermal energy. Included is the history of its development as an energy source, technological considerations affecting its development as an energy source, its environmental effects, economic considerations, and future prospects of development in this field. Basic system diagrams of the operation of a

Eaton, William W.

323

Enhanced Geothermal Systems Project Development Solicitation - Final Report - 09/30/2000 - 02/01/2001  

SciTech Connect

The Enhanced Geothermal System concept is to develop the technology required to extract energy from the reduced permeability zones that underlie all high-temperature geothermal systems. Our concept is that injection wells will be drilled into the high temperature zone. The wells will identify fractures that are only poorly connected to the overlying reservoir. Water injected into these fractures will cause them to propagate through thermal contraction, increase in hydrostatic pressure, and reduction of effective stress. The fractures will connect with the overlying normal temperature reservoir, and steam will be produced from existing production wells. The injection water will generate high thermal quality steam while mitigating problems relating to high gas and chloride.

Nielson, Dennis L.

2001-05-07

324

Interaction of cold-water aquifers with exploited reservoirs of the Cerro Prieto geothermal system  

USGS Publications Warehouse

Cerro Prieto geothermal reservoirs tend to exhibit good hydraulic communication with adjacent cool groundwater aquifers. Under natural state conditions the hot fluids mix with the surrounding colder waters along the margins of the geothermal system, or discharge to shallow levels by flowing up fault L. In response to exploitation reservoir pressures decrease, leading to changes in the fluid flow pattern in the system and to groundwater influx. The various Cerro Prieto reservoirs have responded differently to production, showing localized near-well or generalized boiling, depending on their access to cool-water recharge. Significant cooling by dilution with groundwater has only been observed in wells located near the edges of the field. In general, entry of cool water at Cerro Prieto is beneficial because it tends to maintain reservoir pressures, restrict boiling, and lengthen the life and productivity of wells.

Truesdell, Alfred; Lippmann, Marcelo

1990-01-01

325

Hydrogeochemistry of the Qualibou Caldera Geothermal System, St. Lucia, West Indies  

SciTech Connect

Interpretation of hydrogeochemical data and supporting geologic and electric resistivity data have been used to define the basic structure of the Qualibou Caldera geothermal system and propose a model of hydrologic flow. The geothermal system at Sulphur Springs consists of three layers: (1) an upper steam condensate zone; (2) an intermediate vapor zone, which may be restricted to the Sulphur Springs area only; and (3) a lower brine zone. Four lines of evidence suggest that temperatures of the brine layer may exceed 230/sup 0/C at depths of perhaps 1 km. Outlying thermal springs along the northwest side of the caldera do not indicate derivation from underlying high-temperature sources. It is suggested that the main reservoir upflows in the Belfond-Sulphur Springs area and flows laterally in the subsurface toward the northwest caldera wall.

Goff, F.; Vuataz, F.D.

1984-01-01

326

Interaction of cold-water aquifers with exploited reservoirs of the Cerro Prieto geothermal system  

SciTech Connect

Cerro Prieto geothermal reservoirs tend to exhibit good hydraulic communication with adjacent cool groundwater aquifers. Under natural state conditions the hot fluids mix with the surrounding colder waters along the margins of the geothermal system, or discharge to shallow levels by flowing up fault L. In response to exploitation reservoir pressures decrease, leading to changes in the fluid flow pattern in the system and to groundwater influx. The various Cerro Prieto reservoirs have responded differently to production, showing localized near-well or generalized boiling, depending on their access to cool-water recharge. Significant cooling by dilution with groundwater has only been observed in wells located near the edges of the field. In general, entry of cool water at Cerro Prieto is beneficial because it tends to maintain reservoir pressures, restrict boiling, and lengthen the life and productivity of wells. 15 refs., 10 figs., 1 tab.

Truesdell, A.H. (Geological Survey, Menlo Park, CA (USA)); Lippmann, M.J. (Lawrence Berkeley Lab., CA (USA))

1990-04-01

327

Applications of fractured continuum model to enhanced geothermal system heat extraction problems.  

PubMed

This paper describes the applications of the fractured continuum model to the different enhanced geothermal systems reservoir conditions. The capability of the fractured continuum model to generate fracture characteristics expected in enhanced geothermal systems reservoir environments are demonstrated for single and multiple sets of fractures. Fracture characteristics are defined by fracture strike, dip, spacing, and aperture. The paper demonstrates how the fractured continuum model can be extended to represent continuous fractured features, such as long fractures, and the conditions in which the fracture density varies within the different depth intervals. Simulations of heat transport using different fracture settings were compared with regard to their heat extraction effectiveness. The best heat extraction was obtained in the case when fractures were horizontal. A conventional heat extraction scheme with vertical wells was compared to an alternative scheme with horizontal wells. The heat extraction with the horizontal wells was significantly better than with the vertical wells when the injector was at the bottom. PMID:24600552

Kalinina, Elena A; Klise, Katherine A; McKenna, Sean A; Hadgu, Teklu; Lowry, Thomas S

2014-01-01

328

Imperial County geothermal development. Quarterly report, January 1-March 31, 1982  

SciTech Connect

The activities of the Geothermal Office are reported including: important geothermal events, geothermal waste disposal, grant applications to the California Energy Commission, the planned geothermal development meeting, and other geothermal planning activities. The activities of the Geothermal Planner include processing of applications for geothermal permits, processing of environmental impact reports, and other geothermal planning activities. The progress on the VTN Corporation direct heat study is discussed.

Not Available

1982-03-31

329

Be in the Salton Sea Geothermal System, California (USA): Salton Sea Scientific Drilling Project, California State 2-14 well: Final report  

SciTech Connect

The Salton Sea Geothermal System lies in the old Colorado River Delta, where sediments have been metamorphosed by hydrothermal processes. Fluids, from well Fee No. 5 and deep hole SSSDP California State 2-14, as well as rocks from the deep hole were studied for /sup 10/Be and /sup 9/Be. In the solid samples /sup 10/Be concentration ranges from 29 to 259 /times/ 10/sup 6/ atom/g and /sup 9/Be from 0.49 to 2.52 ppM. The /sup 10/Be concentration in the geothermal waters ranges from 2 /times/ 10/sup 3/ to 2.9 /times/ 10/sup 6/ atom/g and /sup 9/Be from 0.7 to 16.6 ppB. Compared to the steady-state inventory which represents the quantity of /sup 10/Be expected from rain deposition alone (/approximately/1 /times/ 10/sup 12/ atom/cm/sup 2/), the /sup 10/Be inventory in the deep core is 3 orders of magnitude higher (>1 /times/ 10/sup 15/ atom/cm/sup 2/). This indicates that most /sup 10/Be is inherited and that the sediments hosting the geothermal field down to 3250m are young, less than few million year old. /sup 10/Be and /sup 9/Be Kds decrease from surface to bottom (3333 to 48 and 727 to 393, respectively) expressing the strong leaching effect of the solid material by the geothermal waters. This process is more active at depth where pH is <5.3 and salinity high (approx. =25%). Compared to other natural systems, Salton Sea Geothermal fluids are strongly enriched in /sup 10/Be and /sup 9/Be. Finally, contamination has been observed in the fluids samples and we developed a tool that is helping in detecting which samples are contaminated.

Valette-Silver, N.J.

1988-06-01

330

Multielement geochemistry of solid materials in geothermal systems and its applications. Part 1. Hot-water system at the Roosevelt Hot Springs KGRA, Utah  

SciTech Connect

Geochemical studies of the geothermal system at Roosevelt Hot Springs, Utah, have led to development of chemical criteria for recognition of major features of the system and to a three-dimensional model for chemical zoning in the system. Based on this improved level of understanding several new or modified geochemical exploration and assessment techniques have been defined and are probably broadly applicable to evaluation of hot-water geothermal systems. The main purpose of this work was the development or adaptation of solids geochemical exploration techniques for use in the geothermal environment. (MHR)

Bamford, R.W.; Christensen, O.D.; Capuano, R.M.

1980-02-01

331

Development of the well trajectory prediction system as a part of the MWD system for geothermal wells  

SciTech Connect

MWD (Measurement while drilling) system for geothermal wells has been developed by NEDO (the New Energy and Industrial Technology Development Organization) since 1991. As a part of this system, the drilling support system has been also developed. The well trajectory prediction system is one of this drilling support system including the well trajectory planning system, the well trajectory visualization system, the temperature analysis system and so on, and this system will be used for prediction of well trajectory while drilling and for design of BHA (bottom hole assembly) before drilling. We discussed about the theory of the well trajectory prediction system and its case studies in this paper.

Nakashima, S.; Nakata, H.; Takasugi, S. [Geothermal Energy Research and Development Co., Ltd., Tokyo (Japan)

1995-12-31

332

Assessment of the Enhanced Geothermal System Resource Base of the United States  

Microsoft Academic Search

This paper describes an assessment of the enhanced geothermal system (EGS) resource base of the conterminous United States,\\u000a using constructed temperature at depth maps. The temperature at depth maps were computed from 3 to 10km, for every km. The\\u000a methodology is described. Factors included are sediment thickness, thermal conductivity variations, distribution of the radioactive\\u000a heat generation and surface temperature based

David D. Blackwell; Petru T. Negraru; Maria C. Richards

2006-01-01

333

Geothermal systems of the Mono Basin-Long Valley region, eastern California and western Nevada  

SciTech Connect

The region that includes Mono Basin, Long Valley, the Bridgeport-Bodie Hills area, and Aurora, in eastern California and western Nevada was studied to determine the possible causes and interactions of the geothermal anomalies in the Mono Basin-Long Valley region as a whole. A special goal of the study was to locate possible shallow bodies of magma and to determine their influence on the hydrothermal systems in the region. (ACR)

Higgins, C.T.; Flynn, T.; Chapman, R.H.; Trexler, D.T.; Chase, G.R.; Bacon, C.F.; Ghusn, G. Jr.

1985-01-01

334

A re-evaluation of the Moyuta geothermal system, Southern Guatemala  

Microsoft Academic Search

Chemical and isotopic data from four fumarole sites combined with prefeasibility assessments obtained in the 1970s have resulted in a re-evaluation of the Moyuta geothermal system. Moyuta consists of an east-west trending complex of Quaternary andesite\\/dacite domes and flows cut by north-trending faults. Areas of fumaroles, acid springs, and bicarbonate-rich thermal springs flank the north and south sides of the

F. Goff; A. Adams; P. E. Trujillo; D. Counce; C. Janik; L. Fahlquist; A. Roldan; M. Revolorio

1991-01-01

335

Geothermal direct-heat utilization assistance: Federal assistance program. Quarterly project progress report, October--December 1995  

SciTech Connect

The report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the first quarter of FY-96. It describes 90 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment and resources. Research activities are summarized on low-temperature resource assessment, geothermal district heating system cost evaluation and silica waste utilization project. Outreach activities include the publication of a geothermal direct use Bulletin, dissemination of information, geothermal library, technical papers and seminars, development of a webpage, and progress monitor reports on geothermal resources and utilization.

NONE

1996-02-01

336

Geothermal Water Use: Life Cycle Water Consumption, Water Resource Assessment, and Water Policy Framework  

DOE Data Explorer

This report examines life cycle water consumption for various geothermal technologies to better understand factors that affect water consumption across the life cycle (e.g., power plant cooling, belowground fluid losses) and to assess the potential water challenges that future geothermal power generation projects may face. Previous reports in this series quantified the life cycle freshwater requirements of geothermal power-generating systems, explored operational and environmental concerns related to the geochemical composition of geothermal fluids, and assessed future water demand by geothermal power plants according to growth projections for the industry. This report seeks to extend those analyses by including EGS flash, both as part of the life cycle analysis and water resource assessment. A regional water resource assessment based upon the life cycle results is also presented. Finally, the legal framework of water with respect to geothermal resources in the states with active geothermal development is also analyzed.

Schroeder, Jenna N.

337

Geothermal Water Use: Life Cycle Water Consumption, Water Resource Assessment, and Water Policy Framework  

SciTech Connect

This report examines life cycle water consumption for various geothermal technologies to better understand factors that affect water consumption across the life cycle (e.g., power plant cooling, belowground fluid losses) and to assess the potential water challenges that future geothermal power generation projects may face. Previous reports in this series quantified the life cycle freshwater requirements of geothermal power-generating systems, explored operational and environmental concerns related to the geochemical composition of geothermal fluids, and assessed future water demand by geothermal power plants according to growth projections for the industry. This report seeks to extend those analyses by including EGS flash, both as part of the life cycle analysis and water resource assessment. A regional water resource assessment based upon the life cycle results is also presented. Finally, the legal framework of water with respect to geothermal resources in the states with active geothermal development is also analyzed.

Schroeder, Jenna N.

2014-06-10

338

Simulation of water-rock interaction in the yellowstone geothermal system using TOUGHREACT  

SciTech Connect

The Yellowstone geothermal system provides an ideal opportunity to test the ability of reactive transport models to accurately simulate water-rock interaction. Previous studies of the Yellowstone geothermal system have characterized water-rock interaction through analysis of rocks and fluids obtained from both surface and downhole samples. Fluid chemistry, rock mineralogy, permeability, porosity, and thermal data obtained from the Y-8 borehole in Upper Geyser Basin were used to constrain a series of reactive transport simulations of the Yellowstone geothermal system using TOUGHREACT. Three distinct stratigraphic units were encountered in the 153.4 m deep Y-8 drill core: volcaniclastic sandstone, perlitic rhyolitic lava, and nonwelded pumiceous tuff. The main alteration phases identified in the Y-8 core samples include clay minerals, zeolites, silica polymorphs, adularia, and calcite. Temperatures observed in the Y-8 borehole increase with depth from sub-boiling conditions at the surface to a maximum of 169.8 C at a depth of 104.1 m, with near-isothermal conditions persisting down to the well bottom. 1-D models of the Y-8 core hole were constructed to determine if TOUGHREACT could accurately predict the observed alteration mineral assemblage given the initial rock mineralogy and observed fluid chemistry and temperatures. Preliminary simulations involving the perlitic rhyolitic lava unit are consistent with the observed alteration of rhyolitic glass to form celadonite.

Dobson, P.F.; Salah, S.; Spycher, N.; Sonnenthal, E.

2003-04-28

339

A hydrogeological and geochemical model of the high-temperature geothermal system of Amatitlan, Guatemala  

SciTech Connect

Geological, geophysical and geochemical data from deep and shallow wells indicate the presence of a large geothermal system fed by upflow beneath Volcan de Pacaya, with source temperatures {ge} 330{degrees}C and chloride contents on the order of 2,500 mg/l. A considerable contribution of magmatic water is suggested by chemical and isotopic data, provided that water-rock interactions have substantially neutralized the acidity of the magmatic component. The areal extent of the upflow zone is unknown, and can only be delimited by further drilling to the south and southeast of deep well AMF-2, which encounters the two-phase upflow zone. Outflow is directed to the north, towards Lago de Amatitlan. The outflow path is long (more than 7 km), and lateral cooling occurs both via conduction and dilution with cool groundwater. Vertical cooling is also indicated by temperature reversals of up to 60{degrees}C beneath the outflow tongue, attributed to a regional underflow of cool groundwater. Outflow paths do not appear to be controlled by geologic structures or aquifers; instead, the hot water appears to {open_quotes}float{close_quotes} on top of the gently sloping unconfined groundwater table. These aspects of the geothermal system were used to develop the numerical model of the Amatitlan geothermal system, which is the subject of a separate paper.

Lima, E.; Fujino, T. [West Japan Engineering Consultants, Inc., Fukuoka (Japan); McNitt, J.R.; Klein, C.W. [GeothermEx, Inc., Richmond, CA (United States)] [and others

1996-12-31

340

Simulation of water-rock interaction in the Yellowstone geothermal system using TOUGHREACT  

SciTech Connect

The Yellowstone geothermal system provides an ideal opportunity to test the ability of reactive transport models to simulate the chemical and hydrological effects of water-rock interaction. Previous studies of the Yellowstone geothermal system have characterized water-rock interaction through analysis of rocks and fluids obtained from both surface and downhole samples. Fluid chemistry, rock mineralogy, permeability, porosity, and thermal data obtained from the Y-8 borehole in Upper Geyser Basin were used to constrain a series of reactive transport simulations of the Yellowstone geothermal system using TOUGHREACT. Three distinct stratigraphic units were encountered in the 153.4 m deep Y-8 drill core: volcaniclastic sandstone, perlitic rhyolitic lava, and nonwelded pumiceous tuff. The main alteration phases identified in the Y-8 core samples include clay minerals, zeolites, silica polymorphs, adularia, and calcite. Temperatures observed in the Y-8 borehole increase with depth from sub-boiling conditions at the surface to a maximum of 169.8 C at a depth of 104.1 m, with near-isothermal conditions persisting down to the well bottom. 1-D models of the Y-8 core hole were constructed to simulate the observed alteration mineral assemblage given the initial rock mineralogy and observed fluid chemistry and temperatures. Preliminary simulations involving the perlitic rhyolitic lava unit are consistent with the observed alteration of rhyolitic glass to form celadonite.

Dobson, Patrick F.; Salah, Sonia; Spycher, Nicolas; Sonnenthal, Eric L.

2003-04-28

341

COTHERM: Numerical modeling of the deep roots of volcanic geothermal systems  

NASA Astrophysics Data System (ADS)

We report numerical simulations of the transient evolution of fluid flow and heat transport in high-enthalpy geothermal systems around cooling intrusions, including the deep, 'supercritical' roots. We employ the CSMP++ fluid flow and heat transport code, and analyze the temperature, pressure, phase state distribution etc. during the whole lifetime of a geothermal system. Such simulations are of high relevance to projects like the Iceland Deep Drilling Project, which aim to dramatically improve the economics of geothermal power production by tapping such 'supercritical' reservoirs. We study the effects of the depth of the intrusion, the system-scale permeability and the permeability change across the brittle-ductile transition. While previous studies have commonly adopted a temperature-dependent parameterization, with permeability decreasing in a log-linear fashion at temperatures above 360 C, this study explores a variety of different potential temperature dependencies of permeability and their effects on model results. These effects are large and namely affect the thickness of the conductive boundary layer, which impacts the overall rate of cooling of the intrusion.

Scott, Samuel; Weis, Philipp; Driesner, Thomas

2014-05-01

342

Review of international geothermal activities and assessment of US industry opportunities: Summary report  

SciTech Connect

This report summarizes a study initiated to review and assess international developments in the geothermal energy field and to define business opportunities for the US geothermal industry. The report establishes data bases on the status of worldwide geothermal development and the competitiveness of US industry. Other factors identified include existing legislation, tax incentives, and government institutions or agencies and private sector organizations that promote geothermal exports. Based on the initial search of 177 countries and geographic entities, 71 countries and areas were selected as the most likely targets for the expansion of the geothermal industry internationally. The study then determined to what extent their geothermal resource had been developed, what countries had aided or participated in this development, and what plans existed for future development. Data on the energy, economic, and financial situations were gathered.

Not Available

1987-08-01

343

Review of international geothermal activities and assessment of US industry opportunities: Final report  

SciTech Connect

This study was initiated to review and assess international developments in the geothermal energy field and to define business opportunities for the US geothermal industry. The report establishes data bases on the status of worldwide geothermal development and the competitiveness of US industry. Other factors identified include existing legislation, tax incentives, and government institutions or agencies and private sector organizations that promote geothermal exports. Based on the initial search of 177 countries and geographic entities, 71 countries and areas were selected as the most likely targets for the expansion of the geothermal industry internationally. The study then determined to what extent their geothermal resource had been developed, what countries had aided or participated in this development, and what plans existed for future development. Data on the energy, economic, and financial situations were gathered.

Not Available

1987-08-01

344

Imperial County geothermal development. Quarterly report, April 1-June 30, 1982  

SciTech Connect

The activities of the Geothermal Office during the quarter are discussed, including: important geothermal events, geothermal waste disposal, a grant award by the California Energy Commission, the geothermal development meeting, and the current status of geothermal development in Imperial County. Activities of the Geothermal Planner are addressed, including permits, processing of EIR's, and other planning activities. Progress on the direct heat study is reported.

Not Available

1982-06-30

345

Development of Genetic Occurrence Models for Geothermal Prospecting  

NASA Astrophysics Data System (ADS)

Exploration for utility-grade geothermal resources has mostly relied on identifying obvious surface manifestations of possible geothermal activity, e.g., locating and working near steaming ground or hot springs. This approach has lead to the development of over 130 resources worldwide, but geothermal exploration done in this manner is akin to locating hydrocarbon plays by searching for oil seeps. Confining exploration to areas with such features will clearly not discover a blind resource, that is, one that does not have surface expression. Blind resources, however, constitute the vast majority of hydrocarbon plays; this may be the case for geothermal resources as well. We propose a geothermal exploration strategy for finding blind systems that is based on an understanding of the geologic processes that transfer heat from the mantle to the upper crust and foster the conditions for hydrothermal circulation or enhanced geothermal exploration. The strategy employs a genetically based screening protocol to assess potential geothermal sites. The approach starts at the plate boundary scale and progressively focuses in on the scale of a producing electrical-grade field. Any active margin or hot spot is a potential location for geothermal resources. Although Quaternary igneous activity provides a clear indication of active advection of hot material into the upper crust, it is not sufficient to guarantee a potential utility-grade resource. Active faulting and/or evidence of high strain rates appear to be the critical features associated with areas of utility-grade geothermal potential. This is because deformation on its own can advect sufficient heat into the upper crust to create conditions favorable for geothermal exploitation. In addition, active deformation is required to demonstrate that open pathways for circulation of geothermal fluids are present and/or can be maintained. The last step in the screening protocol is to identify any evidence of geothermal activity, including high heat flow, anomalous temperature water wells, high-temperature indications from aqueous geothermometry and geochemistry, Pliocene or younger ages from low-temperature thermochronometers, as well as more obvious factors such as geysers and fumaroles (which by definition will be missing for blind resources). Our occurrence-model strategy inverts the current approach that relies first on obvious evidence of geothermal activity. We evaluated our approach by retrospectively applying the protocol to the characteristics of producing geothermal fields, and in all cases, known resource areas fit the parameters identified from a genetic perspective.

Walker, J. D.; Sabin, A.; Unruh, J.; Monastero, F. C.; Combs, J.

2007-12-01

346

Review of International Geothermal Activities and Assessment of US Industry Opportunites: Final Report  

SciTech Connect

This report contains detailed summaries, with bibliographies, of past, present, and planned geothermal development in 71 selected countries and areas. The report gives a pretty good description of types of work that had been done in each country by the mid 1980s, but does not tell much about which geothermal-provider country did the work. There are maps for most of the countries. There are numbers for market factors, but not for estimated geothermal potential. The information in this document has been superceded by the country summaries in the World Geothermal Congress Transactions of 1995, 2000, and 2005. This report was prepared by Meridian Corporation, Alexandria, VA. (DJE 2005)

None

1987-08-01

347

Optimization of Integrated Reservoir, Wellbore, and Power Plant Models for Enhanced Geothermal Systems  

NASA Astrophysics Data System (ADS)

Geothermal energy has the potential to become a substantially greater contributor to the U.S. energy market. An adequate investment in Enhanced Geothermal Systems (EGS) technology will be necessary in order to realize the potential of geothermal energy. This study presents an optimization of a waterbased Enhanced Geothermal System (EGS) modeled for AltaRock Energy's Newberry EGS Demonstration location. The optimization successfully integrates all three components of the geothermal system: (1) the present wellbore design, (2) the reservoir design, and (3) the surface plant design. Since the Newberry EGS Demonstration will use an existing well (NWG 55-29), there is no optimization of the wellbore design, and the aim of the study for this component is to replicate the present wellbore conditions and design. An in-house wellbore model is used to accurately reflect the temperature and pressure changes that occur in the wellbore fluid and the surrounding casing, cement, and earth during injection and production. For the reservoir design, the existing conditions, such as temperature and pressure at depth and rock density, are incorporated into the model, and several design variables are investigated. The engineered reservoir is modeled using the reservoir simulator TOUGH2 while using the graphical interface PetraSim for visualization. Several fracture networks are investigated with the goal of determining which fracture network yields the greatest electrical output when optimized jointly with the surface plant. A topological optimization of the surface is completed to determine what type of power plant is best suited for this location, and a parametric optimization of the surface plant is completed to determine the optimal operating conditions. The conditions present at the Newberry, Oregon EGS project site are the basis for this optimization. The subsurface conditions are favorable for the production of electricity from geothermal energy with rock temperatures exceeding 300C at a well depth of 3 km. This research was completed in collaboration with AltaRock Energy, which has provided our research group with data from the Newberry well. The purpose of this thesis is to determine the optimal conditions for operating an Enhanced Geothermal System for the production of electricity at Newberry. It was determined that a fracture network consisting of five fractured zones carrying 15 kg/s of fluid is the best reservoir design out of those investigated in this study. Also, it was found that 100 m spacing between the fractured zones should be implemented as opposed to only 50 m of spacing. A double-flash steam power plant provides the best method of utilization of the geothermal fluid. For the maximum amount of electricity generation over the 30-year operating lifetime, the cyclone separator should operate at 205C and the flash vessel should operate at 125C.

Peluchette, Jason

348

Geothermal Energy.  

ERIC Educational Resources Information Center

An introduction to geothermal energy is provided in this discussion of: (1) how a geothermal reservoir works; (2) how to find geothermal energy; (3) where it is located; (4) electric power generation using geothermal energy; (5) use of geothermal energy as a direct source of heat; (6) geopressured reservoirs; (7) environmental effects; (8)

Conservation and Renewable Energy Inquiry and Referral Service (DOE), Silver Spring, MD.

349

Materials for geothermal production  

SciTech Connect

Advances in the development of new materials continue to be made in the geothermal materials project. Many successes have already been accrued and the results used commercially. In FY 1991, work was focused on reducing well drilling, fluid transport and energy conversion costs. Specific activities performed included lightweight CO{sub 2}-resistant well cements, thermally conductive and scale resistant protective liner systems, chemical systems for lost circulation control, corrosion mitigation in process components at The Geysers, and elastomer-metal bonding systems. Efforts to transfer the technologies developed in these efforts to other energy-related sectors of the economy continued and considerable success was achieved.

Kukacka, L.E.

1992-01-01

350

Hydrothermal fluids vented at shallow depths at the Aeolian islands: relationships with volcanic and geothermal systems.  

NASA Astrophysics Data System (ADS)

Scuba diving investigations carried out over the last two decades at the Aeolian islands revealed the existence of submarine magmatic and late-magmatic hydrothermalism at all the islands, despite the absence of on-shore activity at some of the islands. The results gained by diving activities provided useful information to evaluate the volcanic and geothermal activity and to manage the volcanic crisis occurred on November 2002 off the island of Panarea. Scuba diving investigations carried out from middle 80's, had shown that despite the absence of on shore volcanic manifestations, submarine hydrothermal activity is recognizable at shallow depth around all the Aeolian islands related either to volcanic and geothermal activity. The sampled gases are CO2-dominated with low amounts of oxygen and reactive gases (H2, CO, CH4 and H2S) with concentrations ranging from a few ppm to some mole percent. Sometimes significant N2 amount are detectable together with high helium contents. Samples having low CO2 content, besides relevant N2 and He amounts, are the consequence of CO2 dissolution in sea-water due to gas-water interactions (GWI) occurred before the sample collection. The high CO2 solubility (878 ml/l, T=20C, P=1bar) may, in fact, decrease the CO2 content in the venting gases thus increasing the concentrations of the less soluble species (e.g. He 8 ml/l, CO 23 ml/l and CH4 33.8 ml/l) in the gas mixture. Such a process might occur at any level, however, because of the slow water circulation in deep sediments, CO2 is able to saturate the circulating sea-water. The isotopic composition of carbon displays a small range of values while helium isotopes are in the range of 4.1active and extinct Volcanoes, their chemical composition is similar. Contrastingly the isotope composition of helium shows a large heterogeneity with the highest isotopic ratios surprisingly measured at the extinct volcanic islands in the western sector, and much lower values detected in venting gases from active volcanoes (e.g. Vulcano and Panarea). The explanation of such a difference is not related to the volcanic activity at all, but to the parent mantle that in the western side looks to be less contaminated compared to the eastern side. Crustal contamination has been invoked by several authors as the main factor that caused the dramatic 3He/4He decrease. Although the parent mantle produced magmas with different isotopic signature, the gas phase looks similar. To explain the results of the chemical analyses it is proposed that similar deep boundary conditions (pressure, temperature, oxidation level) act as buffers for the chemical composition of the venting gases. With the aim of investigating their origin, estimations of the deep equilibration conditions have been carried out. The reactive compounds detected in the sampled gases, largely used for geothermometric and geobarometric considerations of hydrothermal fluids were used in a system based on the CH4-CO-CO2 contents assuming the presence of a boiling aqueous solution. The equilibrium constants of the adopted reactions are a function of temperature and oxygen fugacity, being the latter buffered by the mineral assemblage of the host rocks. Due to the similarity in the chemical composition of the gases vented at all the islands, a theoretical model developed to interpret the chemical composition of the gases released at Panarea during the last volcanic crisis is here applied. The results have shown that geothermal boiling systems are detectable at all the islands with temperatures up to 350C. The adopted geo-thermobarometric system is more sensitive to the contents of CO and CH4 than that of CO2, implying that although GWI induce modifications in the chemical composition, the estimated equilibrium temperatures do not change very much for variations of the CO2 content in the range of several volume percent, thus, whether or not the gaseous mixture underwent GWI. Moreover, the slow reaction kinetics of CO and CH4 allow them to keep the deep equilibrium c

Italiano, Francesco; Caracausi, Antonio; Longo, Manfredi; Maugeri, Roberto; Paonita, Antonio

2010-05-01

351

Geothermal materials development  

SciTech Connect

Advances in the development of new materials, the commercial availabilities of which are essential for the attainment of Hydrothermal Category Level 1 and 2 Objectives, continue to be made in the Geothermal Materials Development Project. Many successes have already been accrued and the results transferred to industry. In FY 1990, the R D efforts were focused on reducing well drilling and completion costs and on mitigating corrosion in well casing. Activities on lost circulation control materials, CO{sub 2}- resistant lightweight cements, and thermally conductive corrosion and scale-resistant protective liner systems have reached the final development stages, and cost-shared field tests are planned for the FY 1991--1992 time frame. Technology transfer efforts on high temperature elastomers for use in drilling tools are continuing under Geothermal Drilling Organization (GDO) sponsorship.

Kukacka, L.E.

1991-02-01

352

Geothermal Progress Monitor 12  

SciTech Connect

Some of the more interesting articles in this GPM are: DOE supporting research on problems at The Geysers; Long-term flow test of Hot Dry Rock system (at Fenton Hill, NM) to begin in Fiscal Year 1992; Significant milestones reached in prediction of behavior of injected fluids; Geopressured power generation experiment yields good results. A number of industry-oriented events and successes are reported, and in that regard it is noteworthy that this report comes near the end of the most active decade of geothermal power development in the U.S. There is a table of all operating U.S. geothermal power projects. The bibliography of research reports at the end of this GPM is useful. (DJE 2005)

None

1990-12-01

353

Insights From Laboratory Experiments On Simulated Faults With Application To Fracture Evolution In Geothermal Systems  

SciTech Connect

Laboratory experiments provide a wealth of information related to mechanics of fracture initiation, fracture propagation processes, factors influencing fault strength, and spatio-temporal evolution of fracture properties. Much of the existing literature reports on laboratory studies involving a coupling of thermal, hydraulic, mechanical, and/or chemical processes. As these processes operate within subsurface environments exploited for their energy resource, laboratory results provide insights into factors influencing the mechanical and hydraulic properties of geothermal systems. I report on laboratory observations of strength and fluid transport properties during deformation of simulated faults. The results show systematic trends that vary with stress state, deformation rate, thermal conditions, fluid content, and rock composition. When related to geophysical and geologic measurements obtained from engineered geothermal systems (e.g. microseismicity, wellbore studies, tracer analysis), laboratory results provide a means by which the evolving thermal reservoir can be interpreted in terms of physico-chemical processes. For example, estimates of energy release and microearthquake locations from seismic moment tensor analysis can be related to strength variations observed from friction experiments. Such correlations between laboratory and field data allow for better interpretations about the evolving mechanical and fluid transport properties in the geothermal reservoir ultimately leading to improvements in managing the resource.

Stephen L. Karner, Ph.D

2006-06-01

354

Thermal regime of the Escalante Desert, Utah, with an analysis of the the Newcastle Geothermal System  

SciTech Connect

Twenty-five new heat flow measurements are presented for the Escalante Desert region within the Great Basin of the wester United States. Heat flow, excluding geothermal areas, ranges from 43 to 350 mW m/sup -2/, but much of the variability may be caused by deeply circulating groundwater redistributing the regional flux. A subset of 10 sites drilled specifically to characterize the heat flow of the region yielded a mean of 100 mW m/sup -2/ with a standard deviation of 22 mW m/sup -2/. A comparison of thermal conductivities of solid cylindrical discs and rock chips (rhyolite to andesite tuffs) confirmed the importance of porosity corrections to thermal conductivity measurements. A 'blind' geothermal system southwest of Newastle, Utah, situated within the Escalante Desert, has also been studied. Temperature Desert, has also been studied. Temperatures of 110/sup 0/C are observed only 75 m below the ground surface. Heat flow results from 11 drillholes in this region yield values between 163 and 3065 mW m/sup -2/. The 500 mW m/sup -2/ contour encloses an area of 9.4 km/sup 2/. By integrating the excess heat flux (above background) over the thermal anomaly, we deduce a thermal power loss of 12.8 MW for this geothermal system, which corresponds to a subsurface water discharge of 32 kg s/sup -1/.

Chapman, D.S.; Clement, M.D.; Mase, C.W.

1981-12-10

355

Characterisation of induced fracture networks within an enhanced geothermal system using anisotropic electromagnetic modelling  

NASA Astrophysics Data System (ADS)

As opinions regarding the future of energy production shift towards renewable sources, enhanced geothermal systems (EGS) are becoming an attractive prospect. The characterisation of fracture permeability at depth is central to the success of EGS. Recent magnetotelluric (MT) studies of the Paralana geothermal system (PGS), an EGS in South Australia, have measured changes in MT responses which were attributed to fracture networks generated during fluid injection experiments. However, extracting permeabilities from these measurements remains problematic as conventional isotropic MT modelling is unable to accommodate for the complexities present within an EGS. To circumvent this problem, we introduce an electrical anisotropy representation to allow better characterisation of volumes at depth. Forward modelling shows that MT measurements are sensitive to subtle variations in anisotropy. Subsequent two-dimensional anisotropic forward modelling shows that electrical anisotropy is able to reproduce the directional response associated with fractures generated by fluid injection experiments at the PGS. As such, we conclude that MT monitoring combined with anisotropic modelling is a promising alternative to the micro-seismic method when characterising fluid reservoirs within geothermal and coal seam gas reservoirs.

MacFarlane, Jake; Thiel, Stephan; Pek, Josef; Peacock, Jared; Heinson, Graham

2014-11-01

356

The evolution of volcano-hosted geothermal systems based on deep wells from Karaha-Telaga Bodas, Indonesia  

USGS Publications Warehouse

Temperature and pressure surveys, fluid samples, and petrologic analyses of rock samples from deep drill holes at the Karaha - Telaga Bodas geothermal field on the volcanic ridge extending northward from Galunggung Volcano, West Java, have provided a unique opportunity to characterize the evolution of an active volcano-hosted geothermal system. Wells up to 3 km in depth have encountered temperatures as high as 353??C and a weakly altered granodiorite that intruded to within 2 to 3 km of the surface. The intrusion is shallowest beneath the southern end of the field where an acid lake overlies a nearly vertical low resistivity structure (<10 ohm-m) defined by magnetotelluric measurements. This structure is interpreted to represent a vapor-dominated chimney that provides a pathway to the surface for magmatic gases. Four distinct hydrothermal mineral assemblages document the evolution of the geothermal system and the transition from liquid- to vapor-dominated conditions. The earliest assemblage represents the initial liquid-dominated system generated during emplacement of the granodiorite between 5910 ?? 76 and 4200 ?? 150 y BP. Tourmaline, biotite, actinolite, epidote and clay minerals were deposited contemporaneously at progressively greater distances from the intrusive contact (assemblage 1). At 4200 ?? 150 y BP, flank collapse and the formation of the volcano's crater, Kawah Galunggung, resulted in catastrophic decompression and boiling of the hydrothermal fluids. This event initiated development of the modern vapor-dominated regime. Chalcedony and then quartz were deposited as the early low salinity liquids boiled (assemblage 2). Both vapor- and liquid-rich fluid inclusions were trapped in the quartz crystals. Liquid-rich fluid inclusions from the southern part of the field record salinities ranging from 0 to 26 weight percent NaCl- CaCl2 equivalent and locally contain fluorite daughter crystals. We suggest, based on temperature-salinity relationships and evidence of boiling, that these fluids were progressively concentrated as steam was lost from the system. However, mixing with fluids derived from the underlying intrusion or generated during the formation of acid SO4 water on the vapor-dominated chimney margins could have contributed to the observed salinities. As pressures declined, CO2- and SO4-rich steam-heated water drained downward, depositing anhydrite and calcite (assemblage 3) in the fractures, limiting further recharge. Fluid inclusions with salinities up to 31 weight percent NaCl equivalent were trapped in these minerals as the descending water vaporized. The final assemblage is represented by precipitates of NaCl, KCl and FeClx deposited on rock surfaces in portions of the vapor-dominated zone that boiled dry. Vapor-dominated conditions extend over a distance of at least 10 km and to depths below sea level. Deep wells drilled into the underlying liquid-dominated reservoir in the northern and central part of the volcanic ridge produce low salinity fluids representing recent recharge of meteoric and steam-heated water. The evolution of volcanic-hosted vapor-dominated geothermal systems can be described by a five stage model. Stage 1 involves the formation of an over-pressured liquid-dominated geothermal system soon after magmatic intrusion. In Stages 2 and 3, pressures progressively decrease, and a curtain of steam-heated water surrounding a magmatic vapor-dominated chimney at 350??C and 14 ?? 2 MPa develops. The relatively low pressure near the base of the chimney causes liquid inflow adjacent to the intrusion and the development of a secondary marginal vapor-dominated zone. In Stage 4, the magmatic vapor discharge from the intrusion becomes small, vapor pressure declines, and the secondary vapor-dominated zone expands above the intrusion. In Stage 5, the vapor-dominated zone floods because heat from the intrusion is insufficient to boil all liquid inflow. A more common, liquid-dominated volcanic-hosted system the

Moore, J.N.; Allis, R.G.; Nemcok, M.; Powell, T.S.; Bruton, C.J.; Wannamaker, P.E.; Raharjo, I.B.; Norman, D.I.

2008-01-01

357

Simulation of Enhanced Geothermal Systems: A Benchmarking and Code Intercomparison Study  

SciTech Connect

Numerical simulation codes have become critical tools for understanding complex geologic processes, as applied to technology assessment, system design, monitoring, and operational guidance. Recently the need for quantitatively evaluating coupled Thermodynamic, Hydrologic, geoMechanical, and geoChemical (THMC) processes has grown, driven by new applications such as geologic sequestration of greenhouse gases and development of unconventional energy sources. Here we focus on Enhanced Geothermal Systems (EGS), which are man-made geothermal reservoirs created where hot rock exists but there is insufficient natural permeability and/or pore fluids to allow efficient energy extraction. In an EGS, carefully controlled subsurface fluid injection is performed to enhance the permeability of pre-existing fractures, which facilitates fluid circulation and heat transport. EGS technologies are relatively new, and pose significant simulation challenges. To become a trusted analytical tool for EGS, numerical simulation codes must be tested to demonstrate that they adequately represent the coupled THMC processes of concern. This presentation describes the approach and status of a benchmarking and code intercomparison effort currently underway, supported by the U. S. Department of Energys Geothermal Technologies Program. This study is being closely coordinated with a parallel international effort sponsored by the International Partnership for Geothermal Technology (IPGT). We have defined an extensive suite of benchmark problems, test cases, and challenge problems, ranging in complexity and difficulty, and a number of modeling teams are applying various simulation tools to these problems. The descriptions of the problems and modeling results are being compiled using the Velo framework, a scientific workflow and data management environment accessible through a simple web-based interface.

Scheibe, Timothy D.; White, Mark D.; White, Signe K.; Sivaramakrishnan, Chandrika; Purohit, Sumit; Black, Gary D.; Podgorney, Robert; Boyd, Lauren W.; Phillips, Benjamin R.

2013-06-30

358

The geochemistry and sequestration of H 2S into the geothermal system at Hellisheidi, Iceland  

NASA Astrophysics Data System (ADS)

The geochemistry and mineralization of H 2S in the geothermal system hosted by basaltic rock formation at Hellisheidi, SW Iceland, was studied. Injection of mixtures of H 2S with geothermal waste water and condensed steam into the > 230 C geothermal aquifer is planned, where H 2S will hopefully be removed in the form of sulphides. The natural H 2S concentrations in the aquifer average 130 ppm. They are considered to be controlled by close approach to equilibrium with pyrite, pyrrhotite, prehnite and epidote. Injection of H 2S will increase significantly the reservoir H 2S equilibrium concentrations, resulting in mineralization of pyrite and possibly other sulphides as well as affecting the formation of prehnite and epidote. Based on reaction path modelling, the main factors affecting the H 2S mineralization capacity are related to the mobility and oxidation state of iron. At temperatures above 250 C the pyrite mineralization is greatly reduced upon epidote formation leading to the much greater basalt dissolution needed to sequestrate the H 2S. Based on these findings, the optimum conditions for H 2S injection are aquifers with temperatures below ~ 250 C where epidote formation is insignificant. Moreover, the results suggest that sequestration of H 2S into the geothermal system is feasible. The total flux of H 2S from the Hellisheidi power plant is 12,950 tonnes yr - 1 . Injection into 250 C aquifers would result in dissolution of ~ 1000 tonnes yr - 1 of basalt for mineralization of H 2S as pyrite, corresponding to ~ 320 m 3 yr - 1 .

Stefnsson, Andri; Arnrsson, Stefn; Gunnarsson, Ingvi; Kaasalainen, Hanna; Gunnlaugsson, Einar

2011-05-01

359

A Code Intercomparison Study for THMC Simulators Applied to Enhanced Geothermal Systems  

NASA Astrophysics Data System (ADS)

Numerical simulation codes have become critical tools for understanding complex geologic processes, as applied to technology assessment, system design, monitoring, and operational guidance. Recently the need for quantitatively evaluating coupled Thermodynamic, Hydrologic, geoMechanical, and geoChemical (THMC) processes has grown, driven by new applications such as geologic sequestration of greenhouse gases and development of unconventional energy sources. Here we focus on Enhanced Geothermal Systems (EGS), which are man-made geothermal reservoirs created where hot rock exists but there is insufficient natural permeability and/or pore fluids to allow efficient energy extraction. In an EGS, carefully controlled subsurface fluid injection is performed to enhance the permeability of pre-existing fractures, which facilitates fluid circulation and heat transport. EGS technologies are relatively new, and pose significant simulation challenges. To become a trusted analytical tool for EGS, numerical simulation codes must be tested to demonstrate that they adequately represent the coupled THMC processes of concern. This presentation describes the approach and status of a benchmarking and code intercomparison effort currently underway, supported by the U. S. Department of Energy's Geothermal Technologies Program. This study is being closely coordinated with a parallel international effort sponsored by the International Partnership for Geothermal Technology (IPGT). We have defined an extensive suite of benchmark problems, test cases, and challenge problems, ranging in complexity and difficulty, and a number of modeling teams are applying various simulation tools to these problems. The descriptions of the problems and modeling results are being compiled using the Velo framework, a scientific workflow and data management environment accessible through a simple web-based interface.

Scheibe, T. D.; White, M. D.; Wurstner White, S.; Sivaramakrishnan, C.; Purohit, S.; Black, G.; Podgorney, R. K.; Phillips, B. R.; Boyd, L.

2013-12-01

360

Geothermal direct-heat utilization assistance. Quarterly report, January - March 1997  

SciTech Connect

This report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the second quarter of FY-97. It describes 176 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics and resources. Research activities are summarized on well pumping in commercial groundwater heat pump systems. A memorandum of understanding between the GHC and EIA is described. Work accomplishments on the Guidebook are discussed. Outreach activities include the publication of a geothermal direct use Bulletin, dissemination of information, geothermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

Lienau, P.

1997-04-01

361

Geologic and hydrologic research on the Moana geothermal system, Washoe County, Nevada  

SciTech Connect

The Moana geothermal area is the largest single low- to moderate-temperature geothermal resource in the State of Nevada presently employed for direct-use applications. Approximately 150 individual wells, representing a total estimated investment of $5 to $7 million, are presently used to provide heat ahd hot water to more than 130 private residences, several churches and two large motels. Although most of the wells are constructed to meet the heating needs of individual homes, a large-scale district space heating system, designed to supply heat to 60 houses from a single well, is now being developed. Usable temperatures range from 50 to 99/sup 0/C (120 to 210/sup 0/F); well depths range from 60 to 400 m (100 to 1300 ft). The number of new wells coming on-line in Moana is two to three per month. Development of the resource has been largely unregulated and questions dealing with reported reservoir temperature and water level declines, loss of artesian flow, and fluid disposal have recently surfaced. In October 1982, a geologic and hydrologic research program began that was designed to provide detailed geothermal reservoir data to present or prospective developers. The program combines geophysical, geochemical, and geological surveys of the Moana resource area with a drilling program for 5 monitor/observation wells. Data from this program are supplied directly to developers as well as state and local government agencies to provide for prudent resource development. This paper summarizes the program elements and describes the present status.

Flynn, T.; Ghusn, G. Jr.

1983-12-01

362

Hydrogeochemistry and preliminary reservoir model of the Platanares Geothermal System, Honduras, Central America  

SciTech Connect

A detailed hydrogeochemical investigation has been performed at Platanares, Honduras in preparation for shallow geothermal exploration drilling. Platanares is not associated with any Quaternary volcanism but lies in a tectonic zone of late Tertiary to Quaternary extension. Thermal fluids are characterized by pH between 7 and 10, Cl < 40 mg/l, HCO/sub 3/ > SO/sub 4/ > Cl, B less than or equal to 17 mg/l, Li less than or equal to 4 mg/l and As less than or equal to 1.25 mg/l. Various geochemical indicators show that mixing of hot and cold end-member fluids is an important hydrologic process at this site. Geothermometers indicate the geothermal system equilibrated at roughly 225/sup 0/C while trace element chemistry indicates the reservoir resides in Cretaceous red beds of the Valle de Angeles Group. Based on the discharge rates of thermal features, the minimum power output of the Platanares geothermal site is about 45 MW (thermal).

Goff, F.; Shevenell, L.; Janik, C.J.; Truesdell, A.H.; Grigsby, C.O.; Paredes, R.

1986-01-01

363

Heat flow, depth-temperature variations and stored thermal energy for enhanced geothermal systems in Canada  

NASA Astrophysics Data System (ADS)

In order to help assessment of enhanced geothermal energy potential in Canada, we constructed a new series of heatflow and depth-temperature distribution maps (down to 10 km). We focus on high-temperature resources (>150 C) capable of electrical production. Maps presented show large temperature variability, related mainly to heat flow patterns. The highest temperatures occur in western and northern Canada. Here temperatures greater than 150 C, required for enhanced geothermal systems (EGS), can be reached at reasonable drilling depths of <5 km. Heat flow, by itself however, is not a sufficient tool to predict areas of high energy content. A combination of thick low thermal conductivity sedimentary blankets and moderate to high heat flow areas can generate targets that are as favorable as regions with high conductivity and high heat flow. Some moderate heat flow areas in the deeper parts of the Western Canada Sedimentary Basin have heat content comparable to high heat flow zones of the the Canadian Cordillera. The magnitude of in-place thermal energy available for future heat 'mining/farming' was esitmated throughout Canada by calculating heat released through cooling a defined rock volume through a fixed temperature change. These estimates show the first-order appoximation of available geothermal heat content. The fraction of true heat energy available will be as low as 0.02 of these values. However, even this more limited energy production could be large enough to be a considerable future renewable energy resource for Canada.

Majorowicz, Jacek; Grasby, Stephen E.

2010-09-01

364

Three-dimensional Numerical Analysis of Fracture propagation in a Multilayered Reservoir for Enhanced Geothermal System  

NASA Astrophysics Data System (ADS)

In Enhanced Geothermal System, characterization of Thermal/Hydrauric fracturing stimulation is important for optimizing the performance of geothermal reservoir. During geothermal process, thermal stress induced fracturing often caused secondary crack growth due to convective and conductive heat transfer from geothermal reservoir. However, the thermal induced process is not significant during the first stage of hydraulic fracturing, because the major fracture surface induced by hydraulic fracturing is generated rapidly, so the secondary thermal fracturing initiated from the major fracture surface. In this paper, sequential treatment process combining hydraulic and thermal fracturing stimulation is investigated using fully coupled poro-thermo-mechanical analysis and their influences on fracture propagation during reservoir stimulation are investigated using continuum damage mechanics with the embedded strong discontinuity approach. The numerical model of embedded strong discontinuity could provide explicit resolution of discontinuous behavior of fractures with strain localization scheme. The inelastic response of micro-crack growths of rock is described by the damage mechanics and the macroscopic fracture behaviors such as crack closure and opening effects are described by the embedded strong discontinuity approach. Also, statistical models of heterogeneity are used to account for a variety of rock fabric possibilities, because most rocks have strong internal heterogeneity, lateral variability and non-planar geometry. In many reservoir developments, multiply-fractured reservoirs are developed vertically or horizontally, so that estimation of crack paths in multi-layered reservoir formation is important to estimate the performance of reservoir. The role of coupled pore-thermal stresses induced by hydraulic pressure and convective and conductive heat source in the breakdown of rock in cold region is studied in multi-layered reservoir. The fracture propagation model in multi-layered reservoir will be combined with reservoir simulation in the future.

Min, K.; Ghassemi, A.

2011-12-01

365

Improved Detection of Microearthquakes: Application of Matched Field Processing (MFP) to Traditional and Enhanced Geothermal Systems  

NASA Astrophysics Data System (ADS)

We investigate the microseismicity in both traditional and Enhanced Geothermal Systems (EGS) and compare the temporal distribution of microseismic events to well fluid injection data. We apply the empirical and model-based Matched Field Processing (MFP) methods to continuous seismic data from the Salton Sea geothermal field and the DOE Newberry EGS site. MFP is a non-traditional event detection method that can identify more and smaller events than traditional detection methods alone. The empirical MFP method uses known catalog events as master templates to identify new microearthquakes while the model-based MFP method uses synthetic sources computed across a subsurface 3D grid as master templates. Salton Sea data between January 2008 and December 2011 was downloaded off the SCEDC website and high-quality master events were identified from the online catalog. We created empirical matched field steering vector calibrations for 7 three-component stations within the Salton Sea Geothermal Field. The original Salton Sea earthquake catalog identified 4202 events. When we applied the empirical MFP technique to the same data, we identified 5005 additional events (~119% more events). We compare the results from this traditional geothermal area with results obtained from the Newberry EGS site, for which we have 8 three-component stations. The Newberry catalog originally identified 204 events in 3 months while the MFP technique identified 249 additional events (~122% more events). We will compare the results from using the empirical MFP method at the Newberry EGS site with results obtained from using model-based master templates. Additionally, we compare the number of events in the improved earthquake catalogs with available fluid injection data. This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Templeton, D. C.; Harris, D.; Goebel, M.

2013-12-01

366

Geothermal pump program  

SciTech Connect

The geothermal pump program for developing and testing improved downhole pumps is reviewed. Topics discussed include the Geothermal Pump Test Facility, the 80 horsepower REDA pump test, pressurized lubrication systems, the 300 horsepower REDA pump test in a MAGMA production well, advanced power, cable systems, and the East Mesa Test Facility.

Hanold, R.J.

1982-01-01

367

Imperial County geothermal development quarterly report, July 1-September 30, 1983  

SciTech Connect

The highlights of geothermal development in Imperial County during July, August, and September 1983 are discussed. Topics include the status of geothermal development projects in the county, geothermal staff activities and research projects, and other geothermal-related topics.

Not Available

1983-10-01

368

Operations research and systems analysis of geopressured-geothermal energy in Louisiana. Final report for the period June 1, 1978-August 31, 1979  

SciTech Connect

The primary purpose was to provide a projection of the probable future contribution of the geopressured-geothermal energy resource in Louisiana to the overall energy requirements of the nation. A number of associated objectives were emphasized: namely, development of the tools and methodology for performing economic analyses, application of these tools to specific prospects about which adequate resource assessments have been made, identification of the impediments to resource development, and socio-economic analysis of the impact of development of the resource on these specific prospects. An overview of the geopressured-geothermal resource activities in Louisiana is provided first, followed by a detailed discussion and review of the achievements of this project. Finally the major conclusions and findings of this project with respect to commercial viability, impediments, and social and economic impact are presented, and recommendations are made for future systems analysis work.

Johnson, A.E. Jr.

1980-11-01

369

Naturally occurring arsenic in terrestrial geothermal systems of western Anatolia, Turkey: potential role in contamination of freshwater resources.  

PubMed

Arsenic (As) contamination in terrestrial geothermal systems has been identified in many countries worldwide. Concentrations higher than 0.01 mg/L are detrimental to human health. We examined potential consequences for As contamination of freshwater resources based on hydrogeochemical investigations of geothermal waters in deep wells and hot springs collected from western Anatolia, Turkey. We analyzed samples for major ions and trace element concentrations. Temperature of geothermal waters in deep wells showed extreme ranges (40 and 230 C), while, temperature of hot spring fluids was up to 90 C. The Piper plot illustrated two dominant water types: Na-HCO3(-) type for geothermal waters in deep wells and Ca-HCO3(-) type for hot spring fluids. Arsenic concentration ranged from 0.03 to 1.5mg/L. Dominance of reduced As species, i.e., As(III), was observed in our samples. The Eh value ranged between -250 and 119 mV, which suggests diverse geochemical conditions. Some of the measured trace elements were found above the World Health Organization guidelines and Turkish national safe drinking water limits. The variation in pH (range: 6.4-9.3) and As in geothermal waters suggest mixing with groundwater. Mixing of geothermal waters is primarily responsible for contamination of freshwater resources and making them unsuitable for drinking or irrigation. PMID:23498168

Bundschuh, Jochen; Maity, Jyoti Prakash; Nath, Bibhash; Baba, Alper; Gunduz, Orhan; Kulp, Thomas R; Jean, Jiin-Shuh; Kar, Sandeep; Yang, Huai-Jen; Tseng, Yu-Jung; Bhattacharya, Prosun; Chen, Chien-Yen

2013-11-15

370

Geothermal Program Review XI: proceedings. Geothermal Energy - The Environmental Responsible Energy Technology for the Nineties  

SciTech Connect

These proceedings contain papers pertaining to current research and development of geothermal energy in the USA. The seven sections of the document are: Overview, The Geysers, Exploration and Reservoir Characterization, Drilling, Energy Conversion, Advanced Systems, and Potpourri. The Overview presents current DOE energy policy and industry perspectives. Reservoir studies, injection, and seismic monitoring are reported for the geysers geothermal field. Aspects of geology, geochemistry and models of geothermal exploration are described. The Drilling section contains information on lost circulation, memory logging tools, and slim-hole drilling. Topics considered in energy conversion are efforts at NREL, condensation on turbines and geothermal materials. Advanced Systems include hot dry rock studies and Fenton Hill flow testing. The Potpourri section concludes the proceedings with reports on low-temperature resources, market analysis, brines, waste treatment biotechnology, and Bonneville Power Administration activities. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

Not Available

1993-10-01

371

US National Geothermal Data System: Web feature services and system operations  

NASA Astrophysics Data System (ADS)

The US National Geothermal Data System is being developed with support from the US Department of Energy to reduce risk in geothermal energy development by providing online access to the body of geothermal data available in the US. The system is being implemented using Open Geospatial Consortium web services for catalog search (CSW), map browsing (WMS), and data access (WFS). The catalog now includes 2427 registered resources, mostly individual documents accessible via URL. 173 WMS and WFS services are registered, hosted by 4 NGDS system nodes, as well as 6 other state geological surveys. Simple feature schema for interchange formats have been developed by an informal community process in which draft content models are developed based on the information actually available in most data provider's internal datasets. A template pattern is used for the content models so that commonly used content items have the same name and data type across models. Models are documented in Excel workbooks and posted for community review with a deadline for comment; at the end of the comment period a technical working group reviews and discusses comments and votes on adoption. When adopted, an XML schema is implemented for the content model. Our approach has been to keep the focus of each interchange schema narrow, such that simple-feature (flat file) XML schema are sufficient to implement the content model. Keeping individual interchange formats simple, and allowing flexibility to introduce new content models as needed have both assisted in adoption of the service architecture. One problem that remains to be solved is that off-the-shelf server packages (GeoServer, ArcGIS server) do not permit configuration of a normative schema location to be bound with XML namespaces in instance documents. Such configuration is possible with GeoServer using a more complex deployment process. XML interchange format schema versions are indicated by the namespace URI; because of the schema location problems, namespace URIs are redirected to the normative schema location. An additional issue that needs consideration is the expected lifetime of a service instance. A service contract should be accessible online and discoverable as part of the metadata for each service instance; this contract should specify the policy for service termination process--e.g. how notification will be made, if there is an expected end-of-life date. Application developers must be aware of these lifetime limitations to avoid unexpected failures. The evolution of the the service inventory to date has been driven primarily by data providers wishing to improve access to their data holdings. Focus is currently shifting towards improving tools for data consumer interaction--search, data inspection, and download. Long term viability of the system depends on business interdependence between the data providers and data consumers.

Richard, Stephen; Clark, Ryan; Allison, M. Lee; Anderson, Arlene

2013-04-01

372

Recirculation System for Geothermal Energy Recovery in Sedimentary Formations: Laboratory Experiments and Numerical Simulations  

NASA Astrophysics Data System (ADS)

Geothermal energy resources are more widespread than previously thought and have the potential for providing a significant amount of sustainable clean energy worldwide. In particular, hot permeable sedimentary formations provide many advantages over traditional geothermal recovery and enhanced geothermal systems in low permeability crystalline formations. These include: (1) eliminating the need for hydraulic fracturing, (2) significant reduction in risk for induced seismicity, (3) reducing the need for surface wastewater disposal, (4) contributing to decreases in greenhouse gases, and (5) potential use for CO2 sequestration. Advances in horizontal drilling, completion, and production technology from the oil and gas industry can now be applied to unlock these geothermal resources. Here, we present experimental results from a laboratory scale circulation system and numerical simulations aimed at quantifying the heat transfer capacity of sedimentary rocks. Our experiments consist of fluid flow through a saturated and pressurized sedimentary disc of 23-cm diameter and 3.8-cm thickness heated along its circumference at a constant temperature. Injection and production ports are 7.6-cm apart in the center of the disc. We used DI de-aired water and mineral oil as working fluids and explored temperatures from 20 to 150 oC and flow rates from 2 to 30 ml/min. We performed experiments on sandstone samples (Castlegate and Kirby) with different porosity, permeability and thermal conductivity to evaluate the effect of hydraulic and thermal properties on the heat transfer capacity of sediments. The producing fluid temperature followed an exponential form with time scale transients between 15 and 45 min. Steady state outflow temperatures varied between 60% and 95% of the set boundary temperature, higher percentages were observed for lower temperatures and flow rates. We used the flow and heat transport simulator TOUGH2 to develop a numerical model of our laboratory setting. Given the remarkable match between our observations and numerical results, we extended our model to explore a wider range of thermal and hydrological parameters beyond the experimental conditions. Our results prove the capability of heat transfer in sedimentary formations for geothermal energy production.) Sandstone sample with two thermally insulating Teflon caps (white discs). In and out arrows indicate the flow direction while the sample is heated along its circumference (heater not shown). B) Example of a 2D temperature distribution during injection. White x shows the location of the flow ports, inlet (left) and outlet (right). Red is the set boundary temperature and blue is the fluid temperature at the inlet.

Elkhoury, J. E.; Detwiler, R. L.; Serajian, V.; Bruno, M. S.

2012-12-01

373

Application of seismic tomographic techniques in the investigation of geothermal systems  

SciTech Connect

The utility of microearthquake data for characterizing the Northwest Geysers geothermal field and the Long Valley Caldera (LVC) was investigated. Three-dimensional (3-D) P- and S-wave seismic velocity models were estimated for the Coldwater Creek Steam Field (CCSF) in the Northwest Geysers region. Hypocenters relocated using these 3-D models appear to be associated with the steam producing zone, with a deeper cluster of hypocenters beneath an active injection well. Spatial and temporal patterns of seismicity exhibit strong correlation with geothermal exploitation. A 3-D differential attenuation model was also developed for the CCSF from spectral ratios corrected for strong site effects. High-velocity anomalies and low attenuation in the near surface correspond to Franciscan metagraywacke and greenstone units. Microearthquakes recorded at seismographic stations located near the metagraywacke unit exhibit high corner frequencies. Low-velocity anomalies and higher attenuation in the near surface are associated with sections of Franciscan melange. Near-surface high attenuation and high Vp/Vs are interpreted to indicate liquid-saturated regions affected by meteoric recharge. High attenuation and low Vp/Vs marks the steam producing zone, suggesting undersaturation of the reservoir rocks. The extent of the high attenuation and low Vp/Vs anomalies suggest that the CCSF steam reservoir may extend northwestward beyond the known producing zone. This study concludes that microearthquake monitoring may be useful as an active reservoir management tool. Seismic velocity and attenuation structures as well as the distribution of microearthquake activity can be used to identify and delineate the geothermal reservoir, while temporal variations in these quantities would be useful in tracking changes during exploitation.

Romero, A.E. Jr.

1995-05-01

374

Stanford Geothermal Program Stanford University  

E-print Network

s Stanford Geothermal Program Stanford University Stanford, California RADON MEASUEMENTS I N GEOTHERMAL SYSTEMS ? d by * ** Alan K. Stoker and Paul Kruger SGP-TR-4 January 1975 :: raw at Lcs Alams S c i and water, o i l and n a t u r a l gas wells. with radon i n geothermal reservoirs. Its presence i n

Stanford University

375

Accelerating Geothermal Research (Fact Sheet)  

SciTech Connect

Geothermal research at the National Renewable Energy Laboratory (NREL) is advancing geothermal technologies to increase renewable power production. Continuous and not dependent on weather, the geothermal resource has the potential to jump to more than 500 gigawatts in electricity production, which is equivalent to roughly half of the current U.S. capacity. Enhanced geothermal systems have a broad regional distribution in the United States, allowing the potential for development in many locations across the country.

Not Available

2014-05-01

376

Volcanology and volcanic activity with a primary focus on potential hazard impacts for the Hawaii geothermal project  

SciTech Connect

This annotated bibliography reviews published references about potential volcanic hazards on the Island of Hawaii that are pertinent to drilling and operating geothermal wells. The first two sections of this annotated bibliography list the most important publications that describe eruptions of Kilauea volcano, with special emphasis on activity in and near the designated geothermal subzones. References about historic eruptions from Mauna Loa`s northeast rift zone, as well as the most recent activity on the southern flank of dormant Mauna Kea, adjacent to the Humu`ula Saddle are described. The last section of this annotated bibliography lists the most important publications that describe and analyze deformations of the surface of Kilauea and Mauna Loa volcanoes.

Moore, R.B. [Federal Center, Denver, CO (United States); Delaney, P.T. [2255 North Gemini Drive, Flagstaff, AZ (United States); Kauahikaua, J.P. [Geological Survey, Hawaii National Park, HI (United States). Hawaiian Volcano Observatory

1993-10-01

377

Hydrothermal alteration in the Reykjanes geothermal system: Insights from Iceland deep drilling program well RN-17  

NASA Astrophysics Data System (ADS)

The Reykjanes geothermal system is a seawater-recharged hydrothermal system that appears to be analogous to seafloor hydrothermal systems in terms of host rock type and low water/rock alteration. The similarities make the Reykjanes system a useful proxy for seafloor vents. At some time during the Pleistocene, the system was dominated by meteoric water recharge, and fluid composition at Reykjanes has evolved through time as a result of changing proportions of meteoric water influx as well as differing pressure and temperature conditions. The purpose of this study is to characterize secondary mineralization, degree of metasomatic alteration, and bulk composition of cuttings from well RN-17 from the Reykjanes geothermal system. The basaltic host rock includes hyaloclastite, breccia, tuff, extrusive basalt, diabase, as well as a marine sedimentary sequence. The progressive hydrothermal alteration sequence observed with increasing depth results from reaction of geothermal fluids with the basaltic host rock. An assemblage of greenschist facies alteration minerals, including actinolite, prehnite, epidote and garnet, occurs at depths as shallow as 350 m; these minerals are commonly found in Icelandic geothermal systems at temperatures above 250 C (Bird and Spieler, 2004). This requires hydrostatic pressures that exceed the present-day depth to boiling point curve, and therefore must record alteration at higher fluid pressures, perhaps as a result of Pleistocene glaciation. Major, minor, and trace element profiles of the cuttings indicate transitional MORB to OIB composition with limited metasomatic shifts in easily mobilized elements. Changes in MgO, K 2O and loss on ignition indicate that metasomatism is strongly correlated with protolith properties. The textures of alteration minerals reveal alteration style to be strongly dependent on protolith as well. Hyaloclastites are intensely altered with calc-silicate alteration assemblages comprising calcic hydrothermal plagioclase, grandite garnet, prehnite, epidote, hydrothermal clinopyroxene, and titanite. In contrast, crystalline basalts and intrusive rocks display a range in alteration intensity from essentially unaltered to pervasive and nearly complete albitization of igneous feldspar and uralitization of clinopyroxene. Hydrothermal anorthite (An92-An98) occurs in veins in the most altered basalt cuttings and is significantly more calcic than igneous feldspar (An48-An79). Amphibole compositions change from actinolite to hornblende at depth. Hydrothermal clinopyroxene, which occurs in veins, has greater variation in Fe content and is systematically more calcic than igneous pyroxene and also lacks uralitic textures. Solid solutions of prehnite, epidote, and garnet indicate evolving equilibria with respect to aluminum and ferric iron.

Marks, Naomi; Schiffman, Peter; Zierenberg, Robert A.; Franzson, Hjalti; Fridleifsson, Gudmundur .

2010-01-01

378