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Geothermal Small Business Workbook [Geothermal Outreach and Project Financing]

Description: Small businesses are the cornerstone of the American economy. Over 22 million small businesses account for approximately 99% of employers, employ about half of the private sector workforce, and are responsible for about two-thirds of net new jobs. Many small businesses fared better than the Fortune 500 in 2001. Non-farm proprietors income rose 2.4% in 2001 while corporate profits declined 7.2%. Yet not all is rosy for small businesses, particularly new ones. One-third close within two years of opening. From 1989 to 1992, almost half closed within four years; only 39.5% were still open after six years. Why do some new businesses thrive and some fail? What helps a new business succeed? Industry knowledge, business and financial planning, and good management. Small geothermal businesses are no different. Low- and medium-temperature geothermal resources exist throughout the western United States, the majority not yet tapped. A recent survey of ten western states identified more than 9,000 thermal wells and springs, over 900 low- to moderate-temperature geothermal resource areas, and hundreds of direct-use sites. Many opportunities exist for geothermal entrepreneurs to develop many of these sites into thriving small businesses. The ''Geothermal Small Business Workbook'' (''Workbook'') was written to give geothermal entrepreneurs, small businesses, and developers the tools they need to understand geothermal applications--both direct use and small-scale power generation--and to write a business and financing plan. The Workbook will: Provide background, market, and regulatory data for direct use and small-scale (< 1 megawatt) power generation geothermal projects; Refer you to several sources of useful information including owners of existing geothermal businesses, trade associations, and other organizations; Break down the complicated and sometimes tedious process of writing a business plan into five easy steps; Lead you--the geothermal entrepreneur, small company, or project developer--step-by-step through the process needed to structure a business and financing ...
Date: May 1, 2003
Creator: Battocletti, Elizabeth
Partner: UNT Libraries Government Documents Department

Exploration of the Upper Hot Creek Ranch Geothermal Resource, Nye County, Nevada

Description: The Upper Hot Creek Ranch (UHCR) geothermal system had seen no significant exploration activity prior to initiation of this GRED III project. Geochemical geothermometers calculated from previously available but questionable quality analyses of the UHCR hot spring waters indicated possible subsurface temperatures of +320 oF. A complex Quaternary and Holocene faulting pattern associated with a six mile step over of the Hot Creek Range near the UHCR also indicated that this area was worthy of some exploration activity. Permitting activities began in Dec. 2004 for the temperature-gradient holes but took much longer than expected with all drilling permits finally being received in early August 2005. The drilling and geochemical sampling occurred in August 2005. Ten temperature gradient holes up to 500’ deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400’ encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The fifth hole, located within a narrow part of Hot Creek Canyon, encountered a maximum temperature of 81 oF at a depth of 105’ but had cooler temperatures at greater depth. Temperature data from this hole can not be extrapolated to greater depths. Any thermal anomaly associated with the UHCR geothermal system is apparently confined to the immediate vicinity of Hot Creek Canyon where challenges such as topography, a wilderness study area, and wetlands issues will make further exploration time consuming and costly. Ten water samples were collected for chemical analysis and interpretation. Analyses of three samples of the UHCR thermal give predicted subsurface temperatures ranging from 317 to 334 oF from the Na-K-Ca, silica (quartz), ...
Date: October 31, 2005
Creator: Benoit, Dick & Blackwell, David
Partner: UNT Libraries Government Documents Department

Exploration of the Upper Hot Creek Ranch Geothermal Resource, Nye County, Nevada

Description: The Upper Hot Creek Ranch (UHCR) geothermal system had seen no significant exploration activity prior to initiation of this GRED III project. Geochemical geothermometers calculated from previously available but questionable quality analyses of the UHCR hot spring waters indicated possible subsurface temperatures of +320 oF. A complex Quaternary and Holocene faulting pattern associated with a six mile step over of the Hot Creek Range near the UHCR also indicated that this area was worthy of some exploration activity. Permitting activities began in Dec. 2004 for the temperature-gradient holes but took much longer than expected with all drilling permits finally being received in early August 2005. The drilling and geochemical sampling occurred in August 2005. Ten temperature gradient holes up to 500’ deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400’ encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The fifth hole, located within a narrow part of Hot Creek Canyon, encountered a maximum temperature of 81 oF at a depth of 105’ but had cooler temperatures at greater depth. Temperature data from this hole can not be extrapolated to greater depths. Any thermal anomaly associated with the UHCR geothermal system is apparently confined to the immediate vicinity of Hot Creek Canyon where challenges such as topography, a wilderness study area, and wetlands issues will make further exploration time consuming and costly. Ten water samples were collected for chemical analysis and interpretation. Analyses of three samples of the UHCR thermal give predicted subsurface temperatures ranging from 317 to 334 oF from the Na-K-Ca, silica (quartz), ...
Date: January 1, 2006
Creator: Benoit, Dick & Blackwell, David
Partner: UNT Libraries Government Documents Department

Geothermal Energy Information Dissemination and Outreach

Description: The objective of this project is to continue on-going work by the Geo-Heat Center to develop and disseminate information; provide educational materials; develop short courses and workshops; maintain a comprehensive geothermal resource database; respond to inquiries from the public, industry and government; provide engineering, economic and environmental information and analysis on geothermal technology to potential users and developers; and provide information on market opportunities for geothermal development. These efforts are directed towards increasing the utilization of geothermal energy in the US and developing countries, by means of electric power generation and direct-use.
Date: December 31, 2005
Creator: Lund, Dr. John W.
Partner: UNT Libraries Government Documents Department

Geochemical Enhancement Of Enhanced Geothermal System Reservoirs: An Integrated Field And Geochemical Approach

Description: The geochemical effects of injecting fluids into geothermal reservoirs are poorly understood and may be significantly underestimated. Decreased performance of injection wells has been observed in several geothermal fields after only a few years of service, but the reasons for these declines has not been established. This study had three primary objectives: 1) determine the cause(s) of the loss of injectivity; 2) utilize these observations to constrain numerical models of water-rock interactions; and 3) develop injection strategies for mitigating and reversing the potential effects of these interactions. In this study rock samples from original and redrilled injection wells at Coso and the Salton Sea geothermal fields, CA, were used to characterize the mineral and geochemical changes that occurred as a result of injection. The study documented the presence of mineral scales and at both fields in the reservoir rocks adjacent to the injection wells. At the Salton Sea, the scales consist of alternating layers of fluorite and barite, accompanied by minor anhydrite, amorphous silica and copper arsenic sulfides. Amorphous silica and traces of calcite were deposited at Coso. The formation of silica scale at Coso provides an example of the effects of untreated (unacidified) injectate on the reservoir rocks. Scanning electron microscopy and X-ray diffractometry were used to characterize the scale deposits. The silica scale in the reservoir rocks at Coso was initially deposited as spheres of opal-A 1-2 micrometers in diameter. As the deposits matured, the spheres coalesced to form larger spheres up to 10 micrometer in diameter. Further maturation and infilling of the spaces between spheres resulted in the formation of plates and sheets that substantially reduce the original porosity and permeability of the fractures. Peripheral to the silica deposits, fluid inclusions with high water/gas ratios provide a subtle record of interactions between the injectate and reservoir rocks. ...
Date: December 31, 2007
Creator: Moore, Joseph N.
Partner: UNT Libraries Government Documents Department

Characterization of EGS Fracture Network Lifecycles

Description: Geothermal energy is relatively clean, and is an important non-hydrocarbon source of energy. It can potentially reduce our dependence on fossil fuels and contribute to reduction in carbon emissions. High-temperature geothermal areas can be used for electricity generation if they contain permeable reservoirs of hot water or steam that can be extracted. The biggest challenge to achieving the full potential of the nation’s resources of this kind is maintaining and creating the fracture networks required for the circulation, heating, and extraction of hot fluids. The fundamental objective of the present research was to understand how fracture networks are created in hydraulic borehole injection experiments, and how they subsequently evolve. When high-pressure fluids are injected into boreholes in geothermal areas, they flow into hot rock at depth inducing thermal cracking and activating critically stressed pre-existing faults. This causes earthquake activity which, if monitored, can provide information on the locations of the cracks formed, their time-development and the type of cracking underway, e.g., whether shear movement on faults occurred or whether cracks opened up. Ultimately it may be possible to monitor the critical earthquake parameters in near-real-time so the information can be used to guide the hydraulic injection while it is in progress, e.g., how to adjust factors such as injectate pressure, volume and temperature. In order to achieve this, it is necessary to mature analysis techniques and software that were, at the start of this project, in an embryonic developmental state. Task 1 of the present project was to develop state-of-the-art techniques and software for calculating highly accurate earthquake locations, earthquake source mechanisms (moment tensors) and temporal changes in reservoir structure. Task 2 was to apply the new techniques to hydrofracturing (Enhanced Geothermal Systems, or “EGS”) experiments performed at the Coso geothermal field, in order to enhance productivity there. Task 3 ...
Date: March 31, 2008
Creator: Foulger, Gillian R.
Partner: UNT Libraries Government Documents Department

Geothermal Money Book [Geothermal Outreach and Project Financing]

Description: Small business lending is big business and growing. Loans under $1 million totaled $460 billion in June 2001, up $23 billion from 2000. The number of loans under $100,000 continued to grow at a rapid rate, growing by 10.1%. The dollar value of loans under $100,000 increased 4.4%; those of $100,000-$250,000 by 4.1%; and those between $250,000 and $1 million by 6.4%. But getting a loan can be difficult if a business owner does not know how to find small business-friendly lenders, how to best approach them, and the specific criteria they use to evaluate a loan application. This is where the Geothermal Money Book comes in. Once a business and financing plan and financial proposal are written, the Geothermal Money Book takes the next step, helping small geothermal businesses locate and obtain financing. The Geothermal Money Book will: Explain the specific criteria potential financing sources use to evaluate a proposal for debt financing; Describe the Small Business Administration's (SBA) programs to promote lending to small businesses; List specific small-business friendly lenders for small geothermal businesses, including those which participate in SBA programs; Identify federal and state incentives which are relevant to direct use and small-scale (< 1 megawatt) power generation geothermal projects; and Provide an extensive state directory of financing sources and state financial incentives for the 19 states involved in the GeoPowering the West (GPW). GPW is a U.S. Department of Energy-sponsored activity to dramatically increase the use of geothermal energy in the western United States by promoting environmentally compatible heat and power, along with industrial growth and economic development. The Geothermal Money Book will not: Substitute for financial advice; Overcome the high exploration, development, and financing costs associated with smaller geothermal projects; Remedy the lack of financing for the exploration stage of a geothermal project; or Solve ...
Date: February 1, 2004
Creator: Battocletti, Elizabeth
Partner: UNT Libraries Government Documents Department

Geothermal Outreach and Project Financing

Description: The ?Geothermal Outreach and Project Financing? project substantially added to the understanding of geothermal resources, technology, and small business development by both the general public as well as those in the geothermal community.
Date: April 6, 2006
Creator: Battocletti, Elizabeth
Partner: UNT Libraries Government Documents Department

Imaging Multi-Dimensional Electrical Resistivity Structure as a Tool in Developing Enhanced Geothermal Systems (EGS)

Description: The overall goal of this project has been to develop desktop capability for 3-D EM inversion as a complement or alternative to existing massively parallel platforms. We have been fortunate in having a uniquely productive cooperative relationship with Kyushu University (Y. Sasaki, P.I.) who supplied a base-level 3-D inversion source code for MT data over a half-space based on staggered grid finite differences. Storage efficiency was greatly increased in this algorithm by implementing a symmetric L-U parameter step solver, and by loading the parameter step matrix one frequency at a time. Rules were established for achieving sufficient jacobian accuracy versus mesh discretization, and regularization was much improved by scaling the damping terms according to influence of parameters upon the measured response. The modified program was applied to 101 five-channel MT stations taken over the Coso East Flank area supported by the DOE and the Navy. Inversion of these data on a 2 Gb desktop PC using a half-space starting model recovered the main features of the subsurface resistivity structure seen in a massively parallel inversion which used a series of stitched 2-D inversions as a starting model. In particular, a steeply west-dipping, N-S trending conductor was resolved under the central-west portion of the East Flank. It may correspond to a highly saline magamtic fluid component, residual fluid from boiling, or less likely cryptic acid sulphate alteration, all in a steep fracture mesh. This work gained student Virginia Maris the Best Student Presentation at the 2006 GRC annual meeting.
Date: December 31, 2007
Creator: Wannamaker, Philip E.
Partner: UNT Libraries Government Documents Department

Structural controls, alteration, permeability and thermal regime of Dixie Valley from new-generation MT/galvanic array profiling

Description: State-of-the-art MT array measurements in contiguous bipole deployments across the Dixie Valley thermal area have been integrated with regional MT transect data and other evidence to address several basic geothermal goals. These include 1), resolve a fundamental structural ambiguity at the Dixie Valley thermal area (single rangefront fault versus shallower, stepped pediment; 2), delineate fault zones which have experienced fluid flux as indicated by low resistivity; 3), infer ultimate heat and fluid sources for the thermal area; and 4), from a generic technique standpoint, investigate the capability of well-sampled electrical data for resolving subsurface structure. Three dense lines cross the Senator Fumaroles area, the Cottonwood Creek and main producing area, and the low-permeability region through the section 10-15 area, and have stand-alone MT soundings appended at one or both ends for local background control. Regularized 2-D inversion implies that shallow pediment basement rocks extend for a considerable distance (1-2 km) southeastward from the topographic scarp of the Stillwater Range under all three dense profiles, but especially for the Senator Fumaroles line. This result is similar to gravity interpretations in the area, but with the intrinsic depth resolution possible from EM wave propagation. Low resistivity zones flank the interpreted main offsetting fault especially toward the north end of the field which may be due to alteration from geothermal fluid outflow and upflow. The appended MT soundings help to substantiate a deep, subvertical conductor intersecting the base of Dixie Valley from the middle crust, which appears to be a hydrothermal conduit feeding from deep crustal magmatic underplating. This may supply at least part of the high temperature fluids and explain enhanced He-3 levels in those fluids.
Date: November 30, 2007
Creator: Wannamaker, Philip E.
Partner: UNT Libraries Government Documents Department

Geothermal Progress Monitor. Report No. 18

Description: The near-term challenges of the US geothermal industry and its long-range potential are dominant themes in this issue of the US Department of Energy (DOE) Geothermal Progress Monitor which summarizes calendar-year 1996 events in geothermal development. Competition is seen as an antidote to current problems and a cornerstone of the future. Thus, industry's cost-cutting strategies needed to increase the competitiveness of geothermal energy in world markets are examined. For example, a major challenge facing the US industry today is that the sales contracts of independent producers have reached, or soon will, the critical stage when the prices utilities must pay them drop precipitously, aptly called the cliff. However, Thomas R. Mason, President and CEO of CalEnergy told the DOE 1996 Geothermal Program Review XIV audience that while some of his company's plants have ''gone over the cliff, the world is not coming to an end.'' With the imposition of severe cost-cutting strategies, he said, ''these plants remain profitable... although they have to be run with fewer people and less availability.'' The Technology Development section of the newsletter discusses enhancements to TOUGH2, the general purpose fluid and heat flow simulator and the analysis of drill cores from The Geysers, but the emphasis is on advanced drilling technologies.
Date: December 31, 1996
Partner: UNT Libraries Government Documents Department

Geothermal Program Review XVII: proceedings. Building on 25 years of Geothermal Partnership with Industry

Description: The US Department of Energy's Office (DOE) of Geothermal Technologies conducted its annual Program Review XVII in Berkeley, California, on May 18--20, 1999. The theme this year was "Building on 25 Years of Geothermal Partnership with Industry". In 1974, Congress enacted Public Law 93-410 which sanctioned the Geothermal Energy Coordination and Management Project, the Federal Government's initial partnering with the US geothermal industry. The annual program review provides a forum to foster this federal partnership with the US geothermal industry through the presentation of DOE-funded research papers from leaders in the field, speakers who are prominent in the industry, topical panel discussions and workshops, planning sessions, and the opportunity to exchange ideas. Speakers and researchers from both industry and DOE presented an annual update on research in progress, discussed changes in the environment and deregulated energy market, and exchanged ideas to refine the DOE Strategic Plan for research and development of geothermal resources in the new century. A panel discussion on Climate Change and environmental issues and regulations provided insight into the opportunities and challenges that geothermal project developers encounter. This year, a pilot peer review process was integrated with the program review. A team of geothermal industry experts were asked to evaluate the research in progress that was presented. The evaluation was based on the Government Performance and Results Act (GPRA) criteria and the goals and objectives of the Geothermal Program as set forth in the Strategic Plan. Despite the short timeframe and cursory guidance provided to both the principle investigators and the peer reviewers, the pilot process was successful. Based on post review comments by both presenters and reviewers, the process will be refined for next year's program review.
Date: October 1, 1999
Partner: UNT Libraries Government Documents Department

Phase I Report, US DOE GRED II Program

Description: Noramex Corporation Inc, a Nevada company, owns a 100% interest in geothermal leases at the Blue Mountain Geothermal Area, Humboldt County, Nevada. The company is exploring the site for a geothermal resource suitable for development for electric power generation or In the spring of 2002, Noramex drilled the first geothermal observation hole at Blue Mountain, under a cost-share program with the U.S Department of Energy (DOE), under the DOE's Geothermal Exploration and Resource Definition (GRED) program, (Cooperative Agreement No. DE-FC04-00AL66972). DEEP BLUE No.1 was drilled to a total depth of 672.1 meters (2205 feet) and recorded a maximum temperature of 144.7 C (292.5 F). Noramex Corporation will now drill a second slim geothermal observation test hole at Blue Mountain, designated DEEP BLUE No.2. The hole will be drilled under a cost-share program with the DOE, under the DOE's Geothermal Exploration and Resource Definition II (GRED II) program, (Cooperative Agreement No. DE-FC04-2002AL68297). This report comprises Phase I of Cooperative Agreement No. DE-FC04-2002AL68297 of the GRED II program. The report provides an update on the status of resource confirmation at the Blue Mountain Geothermal Area, incorporating the results from DEEP BLUE No.1, and provides the technical background for a second test hole. The report also outlines the proposed drilling program for slim geothermal observation test hole DEEP BLUE No.2.
Date: April 23, 2003
Creator: Ltd., Fairbank Engineering
Partner: UNT Libraries Government Documents Department

Final Report DOE Contract No. DE-FG36-04G014294 ICEKAP 2004: A Collaborative Joint Geophysical Imaging Project at Krafla and IDDP P.E. Malin, S.A. Onacha, E. Shalev Division of Earth and Ocean Sciences Nicholas School of the Environment Duke University Durham, NC 27708

Description: In this final report, we discuss both theoretical and applied research resulting from our DOE project, ICEKAP 2004: A Collaborative Joint Geophysical Imaging Project at Krafla and IDDP. The abstract below begins with a general discussion of the problem we addressed: the location and characterization of “blind” geothermal resources using microearthquake and magnetotelluric measurements. The abstract then describes the scientific results and their application to the Krafla geothermal area in Iceland. The text following this abstract presents the full discussion of this work, in the form of the PhD thesis of Stephen A. Onacha. The work presented here was awarded the “Best Geophysics Paper” at the 2005 Geothermal Resources Council meeting, Reno. This study presents the modeling of buried fault zones using microearthquake and electrical resistivity data based on the assumptions that fluid-filled fractures cause electrical and seismic anisotropy and polarization. In this study, joint imaging of electrical and seismic data is used to characterize the fracture porosity of the fracture zones. P-wave velocity models are generated from resistivity data and used in locating microearthquakes. Fracture porosity controls fluid circulation in the hydrothermal systems and the intersections of fracture zones close to the heat source form important upwelling zones for hydrothermal fluids. High fracture porosity sites occur along fault terminations, fault-intersection areas and fault traces. Hydrothermal fault zone imaging using resistivity and microearthquake data combines high-resolution multi-station seismic and electromagnetic data to locate rock fractures and the likely presence fluids in high temperature hydrothermal systems. The depths and locations of structural features and fracture porosity common in both the MT and MEQ data is incorporated into a joint imaging scheme to constrain resistivity, seismic velocities, and locations of fracture systems. The imaging of the fault zones is constrained by geological, drilling, and geothermal production data. The objective is to determine ...
Date: December 15, 2006
Creator: Malin, Peter E.; Shalev, Eylon & Onacha, Stepthen A.
Partner: UNT Libraries Government Documents Department

Geothermal Information Dissemination and Outreach

Description: Project Purpose To enhance technological and topical information transfer in support of industry and government efforts to increase geothermal energy use in the United States (power production, direct use, and geothermal groundsource heat pumps). Project Work GRC 2003 Annual Meeting. The GRC convened the meeting on Oct. 12-15, 2003, at Morelia's Centro de Convenciones y ExpoCentro in Mexico under the theme, International Collaboration for Geothermal Energy in the Americas. The event was also sponsored by the Comision Federal de Electricidad. ~600 participants from more than 20 countries attended the event. The GRC convened a Development of Geothermal Projects Workshop and Geothermal Exploration Techniques Workshop. GRC Field Trips included Los Azufres and Paricutin Volcano on Oct. 11. The Geothermal Energy Association (Washington, DC) staged its Geothermal Energy Trade Show. The Annual Meeting Opening Session was convened on Oct. 13, and included the governor of Michoacan, the Mexico Assistant Secretary of Energy, CFE Geothermal Division Director, DOE Geothermal Program Manager, and private sector representatives. The 2003 Annual Meeting attracted 160 papers for oral and poster presentations. GRC 2004. Under the theme, Geothermal - The Reliable Renewable, the GRC 2004 Annual Meeting convened on Aug. 29-Sept. 1, 2004, at the Hyatt Grand Champions Resort at Indian Wells, CA. Estimated total attendance (including Trade Show personnel, guests and accompanying persons) was ~700. The event included a workshop, Geothermal Production Well Pump Installation, Operation and Maintenance. Field trips went to Coso/Mammoth and Imperial Valley/Salton Sea geothermal fields. The event Opening Session featured speakers from the U.S. Department of Energy, U.S. Department of the Interior, and the private sector. The Geothermal Energy Association staged its Geothermal Energy Trade Show. The Geothermal Education Office staged its Geothermal Energy Workshop. Several local radio and TV station interviews were conducted during the event. Technical Program included 136 technical papers. ...
Date: February 18, 2005
Creator: Ted J. Clutter, Geothermal Resources Council Executive Director
Partner: UNT Libraries Government Documents Department

Blue Mountain, Humboldt County, Nevada, U.S.A

Description: The report documents the drilling of well Deep Blue No.2, the second deep geothermal test hole at the Blue Mountain Geothermal Area, Humboldt County, Nevada. The well was drilled by Noramex Corp, a Nevada company, with funding support from the US Department of Energy, under the DOE’s GRED II Program. Deep Blue No.2 was drilled as a ‘step-out’ hole from Deep Blue No.1, to further evaluate the commercial potential of the geothermal resource. Deep Blue No.2 was designed as a vertical, slim observation test hole to a nominal target depth of 1000 meters (nominal 3400 feet). The well tests an area of projected high temperatures at depth, from temperature gradients measured in a group of shallow drill holes located approximately one kilometer to the northeast of observation hole Deep Blue No.1. The well is not intended for, or designed as, a commercial well or a production well. Deep Blue No.2 was spudded on March 25, 2004 and completed to a total depth of 1127.76m (3700 ft) on April 28, 2004. The well was drilled using conventional rotary drilling techniques to a depth of 201.17 m (660 ft), and continuously cored from 201.17m (660 ft) to 1127.76m (3700 ft). A brief rig-on flow-test was conducted at completion to determine basic reservoir parameters and obtain fluid samples. A permeable fracture zone with measured temperatures of 150 to 167°C (302 to 333°F) occurs between 500 to 750m (1640 to 2461ft). The well was left un-lined in anticipation of the Phase III - Flow and Injection Testing. A further Kuster temperature survey was attempted after the well had been shut in for almost 3 weeks. The well appears to have bridged off at 439m (1440ft) as the Kuster tool was unable to descend past this point. Several attempts to dislodge the obstruction using tube ...
Date: April 1, 2005
Creator: Ted Fitzpatrick, Brian D. Fairbank
Partner: UNT Libraries Government Documents Department

Enhanced Geothermal Systems Research and Development: Models of Subsurface Chemical Processes Affecting Fluid Flow

Description: Successful exploitation of the vast amount of heat stored beneath the earth’s surface in hydrothermal and fluid-limited, low permeability geothermal resources would greatly expand the Nation’s domestic energy inventory and thereby promote a more secure energy supply, a stronger economy and a cleaner environment. However, a major factor limiting the expanded development of current hydrothermal resources as well as the production of enhanced geothermal systems (EGS) is insufficient knowledge about the chemical processes controlling subsurface fluid flow. With funding from past grants from the DOE geothermal program and other agencies, we successfully developed advanced equation of state (EOS) and simulation technologies that accurately describe the chemistry of geothermal reservoirs and energy production processes via their free energies for wide XTP ranges. Using the specific interaction equations of Pitzer, we showed that our TEQUIL chemical models can correctly simulate behavior (e.g., mineral scaling and saturation ratios, gas break out, brine mixing effects, down hole temperatures and fluid chemical composition, spent brine incompatibilities) within the compositional range (Na-K-Ca-Cl-SO4-CO3-H2O-SiO2-CO2(g)) and temperature range (T < 350°C) associated with many current geothermal energy production sites that produce brines with temperatures below the critical point of water. The goal of research carried out under DOE grant DE-FG36-04GO14300 (10/1/2004-12/31/2007) was to expand the compositional range of our Pitzer-based TEQUIL fluid/rock interaction models to include the important aluminum and silica interactions (T < 350°C). Aluminum is the third most abundant element in the earth’s crust; and, as a constituent of aluminosilicate minerals, it is found in two thirds of the minerals in the earth’s crust. The ability to accurately characterize effects of temperature, fluid mixing and interactions between major rock-forming minerals and hydrothermal and/or injected fluids is critical to predict important chemical behaviors affecting fluid flow, such as mineral precipitation/dissolution reactions. We successfully achieved the project goal and ...
Date: May 29, 2008
Creator: Moller, Nancy & H., Weare J.
Partner: UNT Libraries Government Documents Department

Seismic monitoring of EGS tests at the Coso Geothermal area, California, using accurate MEQ locations and full moment tensors

Description: We studied high-resolution relative locations and full moment tensors of microearthquakes (MEQs) occurring before, during and following Enhanced Geothermal Systems (EGS) experiments in two wells at the Coso geothermal area, California. The objective was to map new fractures, determine the mode and sense of failure, and characterize the stress cycle associated with injection. New software developed for this work combines waveform crosscorrelation measurement of arrival times with relative relocation methods, and assesses confidence regions for moment tensors derived using linearprogramming methods. For moment tensor determination we also developed a convenient Graphical User Interface (GUI), to streamline the work. We used data from the U.S. Navy’s permanent network of three-component digital borehole seismometers and from 14 portable three-component digital instruments. The latter supplemented the permanent network during injection experiments in well 34A-9 in 2004 and well 34-9RD2 in 2005. In the experiment in well 34A-9, the co-injection earthquakes were more numerous, smaller, more explosive and had more horizontal motion, compared with the pre-injection earthquakes. In the experiment in well 34-9RD2 the relocated hypocenters reveal a well-defined planar structure, 700 m long and 600 m high in the depth range 0.8 to 1.4 km below sea level, striking N 20° E and dipping at 75° to the WNW. The moment tensors show that it corresponds to a mode I (opening) crack. For both wells, the perturbed stress state near the bottom of the well persisted for at least two months following the injection.
Date: April 1, 2008
Creator: Foulger, G.R.; B.R. Julian, B.R. & Monastero, F.
Partner: UNT Libraries Government Documents Department

Identifying Fracture Types and Relative Ages Using Fluid Inclusion Stratigraphy

Description: Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Understanding the life cycle of a fracture in a geothermal system is fundamental to the development of techniques for creating fractures. Recognizing the stage of a fracture, whether it is currently open and transmitting fluids; if it recently has closed; or if it is an ancient fracture would assist in targeting areas for further fracture stimulation. Identifying dense fracture areas as well as large open fractures from small fracture systems will also assist in fracture stimulation selection. Geothermal systems are constantly generating fractures, and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. Fluid inclusions trapped in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. Our hypothesis is that fractures over their life cycle have different chemical signatures that we can see in fluid inclusion gas analysis and by using the new method of fluid inclusion stratigraphy (FIS) the different stages of fractures, along with an estimate of fracture size can be identified during the well drilling process. We have shown with this study that it is possible to identify fracture locations using FIS and that different fractures have different chemical signatures however that signature is somewhat dependent upon rock type. Open, active fractures correlate with increase concentrations of CO2, N2, Ar, and to a lesser extent H2O. These fractures would be targets for further enhancement. The usefulness of this method is that it is low cost alternative to current well logging techniques and can be done as a well is being drilled.
Date: June 30, 2008
Creator: Dilley, Lorie M.; Norman, David & Owens, Lara
Partner: UNT Libraries Government Documents Department

Time-dependent seismic tomography and its application to the Coso geothermal area, 1996-2006

Description: Measurements of temporal changes in Earth structure are commonly determined using localearthquake tomography computer programs that invert multiple seismic-wave arrival time data sets separately and assume that any differences in the structural results arise from real temporal variations. This assumption is dangerous because the results of repeated tomography experiments would differ even if the structure did not change, simply because of variation in the seismic ray distribution caused by the natural variation in earthquake locations. Even if the source locations did not change (if only explosion data were used, for example), derived structures would inevitably differ because of observational errors. A better approach is to invert multiple data sets simultaneously, which makes it possible to determine what changes are truly required by the data. This problem is similar to that of seeking models consistent with initial assumptions, and techniques similar to the “damped least squares” method can solve it. We have developed a computer program, dtomo, that inverts multiple epochs of arrival-time measurements to determine hypocentral parameters and structural changes between epochs. We shall apply this program to data from the seismically active Coso geothermal area, California, in the near future. The permanent network operated there by the US Navy, supplemented by temporary stations, has provided excellent earthquake arrival-time data covering a span of more than a decade. Furthermore, structural change is expected in the area as a result of geothermal exploitation of the resource. We have studied the period 1996 through 2006. Our results to date using the traditional method show, for a 2-km horizontal grid spacing, an irregular strengthening with time of a negative VP/VS anomaly in the upper ~ 2 km of the reservoir. This progressive reduction in VP/VS results predominately from an increase of VS with respect to VP. Such a change is expected to result ...
Date: April 1, 2008
Creator: Julian, B.R.; Foulger, G.R. & Monastero, F.
Partner: UNT Libraries Government Documents Department