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Chemical hydrofracturing of the Hot Dry Rock reservoir

Description: The experimental study of the water-rock interaction shows that the secondary mineral assemblage depends on the water composition. For example, granite-pure water interaction produces zeolites (relatively low-dense, Mg-poor minerals), whereas seawater yields chlorites (high-dense, Mg-rich minerals). The reactions have volumetric effects from several % to 20 % in magnitude. Volume deformations in the heterogeneous matrix cause uneven mechanical strains. Reactions with the effect of about 0,1 vol… more
Date: January 24, 1996
Creator: Yakovlev, Leonid
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Partner: UNT Libraries Government Documents Department
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Stimulation of well SN-12 in the Seltjarnarnes low-temperature field in SW-Iceland

Description: Well SN-12 in the Seltjarnarnes low-temperature field in SW-Iceland was drilled to a depth of 2714 m in the fall of 1994. The well appeared to be almost non-productive at the end of drilling. A comprehensive ten day stimulation program was, therefore, initiated. The program involved, firstly, high-pressure wellhead injection and, secondly, high-pressure injection below a packer placed at 1412 m depth. After about twelve hours of wellhead stimulation the pressure dropped suddenly, indicating tha… more
Date: January 24, 1996
Creator: Tulinius, Helga; Axelsson, Gudni; Tomasson, Jens; Kristmannsdottir, Hrefna & Gudmundsson, Asgrimur
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Partner: UNT Libraries Government Documents Department
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Natural analogs for enhanced heat recovery from geothermal systems

Description: High-temperature hydrothermal systems are physically and chemically zoned with depth. The energy input is from a magmatic zone, intruded by igneous bodies, that may also contribute variable amounts of magmatic fluid to the system. The heat source is directly overlain by a section of rocks, that due to their elevated temperature, respond to stress in a ductile fashion. The ductile zone is, in turn, overlain by a section of rocks that respond to stress in a brittle fashion, where water is able to… more
Date: January 24, 1996
Creator: Nielson, Dennis L.
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Partner: UNT Libraries Government Documents Department
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Simulation studies for wells AH-4bis/AH-17 and AH-18, Ahuachapan Geothermal Field

Description: Well AH-4<sub>bis</sub>, at the Ahuachapan Geothermal Field is planned to be drilled on the same pad as the former AH-4. A simulation study was carried out for two casing dameters 13 5/8 and 9 5/8” in order to estimate its production and to know its economic feasibility. The simulation results indcate a high probability of production in the range of 7 Mwe, equivalent to 120 kg/s total mass flow rate, 1250 kJ/kg at 6 bar-a for the new well AH-4<sub>bis</sub>. Well AH- 17 is good producer, during… more
Date: January 24, 1996
Creator: Monterrosa, Manuel Ernesto
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Partner: UNT Libraries Government Documents Department
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Permeability, electrical impedance, and acoustic velocities on reservoir rocks from the Geysers geothermal field

Description: Previous measurements of acoustic velocities on NEGU- 17 cores indicate that saturation effects are significant enough to cause V<sub>p</sub>/V<sub>s</sub> anomalies observed in the field. In this study we report on the results of new measurements on core recently recovered from SB-15-D along with some additional measurements on the NEGU-17 cores. The measurements indicate correlations between mechanical, transport, and water storage properties of the matrix which may prove useful for reservoir… more
Date: January 24, 1996
Creator: Boitnott, G.N. & Boyd, P.J.
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Partner: UNT Libraries Government Documents Department
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Tough2/PC application simulation project for Heber geothermal field, California, a progress report

Description: A numerical simulation model for the Heber geothermal field in Southern California is being developed under a technology transfer agreement between the Department of Energy/Lawrence Berkeley National Laboratory (LBNL) and the California Department of Conservation, Division of Oil, Gas, and Geothermal Resources (DOGGR). The main objectives of the cooperation are (1) to train DOGGR personnel in the use of the TOUGH2PC computer code; and (2) to develop a module compatible with TOUGH2 to investigat… more
Date: January 24, 1996
Creator: Boardman, Timothy S.; Khan, M. Ali & Antunez, Emilio
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Partner: UNT Libraries Government Documents Department
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Interpretation of interference effects in three production wells in the Kawerau geothermal field, New Zealand

Description: Downhole temperature and pressure, mass flow, and enthalpy measurements on three production wells at Kawerau geothermal field are interpretted to illustrate interference effects between these wells. Feed zone locations within the wells, together with geology and chemistry are discussed. Downhole measurements are made in one well while production flow changes are made on another well to monitor pressure transient effects. The interference effects have implications for planning future production … more
Date: January 24, 1996
Creator: Stevens, Lynell & Koorey, Kevin J.
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Partner: UNT Libraries Government Documents Department
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CT imaging of two phase flow in fractured porous media

Description: This paper describes the design, construction, and preliminary results of an experiment that studies imbibition displacement in two fracture blocks. Three core configurations were constructed. The configurations are a compact core, a two-block system with a 1 mm spacer between the blocks, and a two-block system with no spacer. The blocks are sealed in epoxy so that saturation measurements can be made throughout the displacement experiments using a Computed Tomography (CT) scanner. Preliminary r… more
Date: January 24, 1996
Creator: Hughes, Richard G.; Brigham, William E. & Castanier, Louis M.
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Partner: UNT Libraries Government Documents Department
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Fracture permeability in the Matalibong-25 corehole, Tiwi geothermal field, Philippines

Description: The Tiwi geothermal field is located in southern Luzon on the northeast flank of Mt. Malinao, an andesitic volcano that was active 0.5 to 0.06 Ma. Matalibong-25 (Mat-25) was drilled through the Tiwi reservoir to investigate lithologic and fracture controls on reservoir permeability and to monitor reservoir pressure. Continuous core was collected from 2586.5 to 8000 feet (789 to 2439 meters) with greater than 95% recovery. The reservoir rocks observed in Mat-25 consist mainly of andesitic and ba… more
Date: January 24, 1996
Creator: Nielson, Dennis L.; Clemente, Wilson C.; Moore, Joseph N. & Powell, Thomas S.
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Partner: UNT Libraries Government Documents Department
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Reservoir investigations on the Hot Dry Rock geothermal system, Fenton Hill, New Mexico: Tracer test results

Description: A closed-loop circulation test was conducted from 10 May to 14 July 1995 on the Hot Dry Rock (HDR) reservoir at Fenton Hill, New Mexico after a hiatus of nearly two years. Changes in heat transfer and reservoir volume were investigated and compared to previous circulation tests. Chemical tracers can be used to measure the volume of flow paths in hydrologic systems. Usually, tracers are used in low temperature situations, but the application to high temperature systems has been established for c… more
Date: January 24, 1996
Creator: Callahan, Timothy J.
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Partner: UNT Libraries Government Documents Department
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Permeability decrease in argillaceous sandstone; experiments and modelling

Description: Core flooding experiments on argillaceous sandstone are carried out showing that for high injection flow rates permeability reduction occurs. The decrease of permeability is a consequence of the migration of insitu particles. Two models are used to simulate the observed phenomena. The so-called network model is able to give insight in the physics behind the particle migration. The other model based on mass balance and constitutive laws is used for quantitative and qualitative comparison with th… more
Date: January 24, 1996
Creator: Egberts, Paul; van Soest, Lennard & Vernoux, Jean-Francois
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Partner: UNT Libraries Government Documents Department
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A study of relative permeability for steam-water flow in porous media

Description: We report on continuing experimental and numerical efforts to obtain steam-water relative permeability functions and to assess effect of heat transfer and phase change. To achieve these, two sets of steady-state flow experiments were conducted: one with nitrogen and water and another with steam and water. During these experiments, a mixture of nitrogen-water (or steam-water) was injected into a Berea sandstone core. At the onset of steady state conditions, three-dimensional saturation distribut… more
Date: January 24, 1996
Creator: Ambusso, Willis; Satik, Cengiz & Horne, Roland
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Partner: UNT Libraries Government Documents Department
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A study of electrical generating capacities of self-discharging slim holes

Description: Theoretical calculations have been performed to estimate the electrical generating capacities of small-diameter geothermal wells for off-grid rural electrification using wellhead generators. In these applications, generating capacities of interest are typically in the range 100-1000 kWe. The approach amounted to (1) calculating the “wellhead discharge characteristics” (water/steam discharge rates as functions of wellhead pressure) for a variety of hypothetical well and reservoir descriptions, (… more
Date: January 24, 1996
Creator: Pritchett, J. W.
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Partner: UNT Libraries Government Documents Department
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Environmental impact of landfill disposal of selected geothermal residues

Description: A solid waste is classified as hazardous if it contains sufficient leachable components to contaminate the groundwater and the environment if disposed in a landfill. Scale, sludge and drilling mud from three geothermal fields (Bulalo, Phlippines; Cerro Prieto, Mexico; and Dixie Valley, USA) containing regulated elements at levels above the earth‘s crustal abundance were studied for their leachability. Cr, As, Cu, Zn and Pb were detected at levels which could impair groundwater quality if leachi… more
Date: January 24, 1996
Creator: Peralta, G.L.; Graydon, J.W.; Seyfried, P.L. & Kirk, D.W.
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Partner: UNT Libraries Government Documents Department
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Experimental verification of the load-following potential of a Hot Dry Rock geothermal reservoir

Description: A recent 6-day flow experiment conducted at the Los Alamos National Laboratory's Fenton Hill Hot Dry Rock (HDR) test site in north-central New Mexico has verified that an HDR reservoir has the capability for a significant, and very rapid, increase in power output upon demand. The objective of this cyclic load-following experiment was to investigate the performance of the reservoir in a nominal high-backpressure (2200 psi) baseload operating condition upon which was superimposed greatly increase… more
Date: January 24, 1996
Creator: Brown, Donald
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Partner: UNT Libraries Government Documents Department
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Simple numerical simulation for liquid dominated geothermal reservoir

Description: A numerical model for geothermal reservoir has been developed. The model used is based on an idealized, two-dimensional case, where the porous medium is isotropic, nonhomogeneous, filled with saturated liquid. The fluids are assumed to have constant and temperature dependent viscosity. A Boussinesq approximation and Darcy’s law are used. The model will utilize a simple hypothetical geothermal system, i.e. graben within horsts structure, with three layers of different permeabilities. Vorticity p… more
Date: January 24, 1996
Creator: Wintolo, Djoko; Sutrisno; Sudjatmiko & Sudarman, S.
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Partner: UNT Libraries Government Documents Department
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New Mechanisms of rock-bit wear in geothermal wells

Description: This paper presents recent results of an investigation on failure mode and wear of rock-bits used to drill geothermal wells located in the area of Larderello (Italy). A new wear mechanism, conceived from drilling records and dull bit evaluation analysis, has been identified and a particular configuration of rock-bit has been developed and tested in order to reduce drilling costs. The role of high Bottom Hole Temperature (BHT) on rock-bit performances seems not yet very well understood: so far, … more
Date: January 24, 1996
Creator: Macini, Paolo
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Partner: UNT Libraries Government Documents Department
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Classification of Geothermal Resources - An engineering approach

Description: Geothermal resources have been classified into low, intermediate and high enthalpy resources by their reservoir temperatures. The temperature ranges used are arbitrary and there is not a general agreement. Geothermal resources should be classified by two independent thermodynamic properties of their fluids at the wellhead. They should reflect the fluids availability to do work. By setting the triple point of water as the sink condition, and normalising the fluids specific exergies by the maximu… more
Date: January 24, 1996
Creator: Lee, K. C.
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Partner: UNT Libraries Government Documents Department
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Structural interpretation of the Kakkonda deep geothermal reservoir

Description: The Kakkonda geothermal field is known as a unique field such that a new reservoir was found at about 2500 m in depth after the shallow reservoir ranging from 1000 m to 1500 m had been produced for about eight years. The shallow reservoir is composed of sedimentary rock with igneous rock intrusions, while the deep reservoir is a fractured thin zone located at the top of a large granite intrusion. Between the two, there exist thermally metamorphosed zones. This study aims at integrated interpret… more
Date: January 24, 1996
Creator: Kobayashi, Osamu; Arihara, Norio & Hanano, Mineyuki
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Partner: UNT Libraries Government Documents Department
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Modelling chloride and CO{sub 2} chemistry at the Wairakei geothermal field, New Zealand

Description: The chloride and CO<sub>2</sub> chemistry at the Wairakei geothermal field, New Zealand has been modelled using an extended version of the geothermal simulator TOUGH2 which solves the equations for the transport of reacting chemical species in multi-phase fluids. Reactions involving the speciation of aqueous CO<sub>2</sub> to H<sub>2</sub>CO<sub>3</sub> and HCO<sub>3</sub><sup>-</sup>, are included in the model. Because CO<sub>2</sub> speciation in water is pH dependent, a reaction involving th… more
Date: January 24, 1996
Creator: Kissling, W. M.; White, S. P.; O'Sullivan, M. J.; Bullivant, D. P. & Brown, K. L.
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Partner: UNT Libraries Government Documents Department
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Non-linear flow transients in fractured rock masses - the 1995 injection experiment in Soultz

Description: In July 1995 in the course of the Hot Dry Rock (HDR) site investigation studies in Soultz s.F. (France) multi rate hydraulic injection tests were conducted in the borehole GPK2. The downhole pressure records obtained from the lowermost depth domain between 3211 m and 3876 m demonstrate non-laminar hydraulic behavior. Such behavior was also observed earlier during a similar set of flow step tests in the GPKl borehole Soultz. Like the analysis of these earlier data sets, it could be shown that th… more
Date: January 24, 1996
Creator: Kohl, T.; Jung, R.; Hopkirk, R.J. & Rybach, L.
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Partner: UNT Libraries Government Documents Department
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Structural control is a strategy for exploitation well at Kamojang Geothermal Field, West Java, Indonesia

Description: Kamojang Geothermal Field is one of the best geothermal field in the world, explored since 1918. The field lies 33 km south-east Bandung, West Java. It is located in the centre of a volcanic chain which has progressively grown from WSW to ENE. Three tectonic activities have created current Kamojang structures. Firstly, the circular collapse of Pangkalan, 2 km in diameter whch occupies the central part of the Kamojang field; secondly, NE -SW flults of tensional and lateral origin, are parallel t… more
Date: January 24, 1996
Creator: Hantono, Djoko; Mulyono, Agus & Hasibuan, Aidil
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Partner: UNT Libraries Government Documents Department
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Overview of the Hijiori shallow reservoir circulation tests and reservoir fluid storage analysis

Description: Since 1985, NEDO has advanced a]Hot Dry Rock project in Hijiori, Japan. Circulation tests have been performed in FY1991 (in a shallow reservoir), and in FY1995 (in both shallow and deep reservoirs). In 1991 circulation test, the result was that 78% fluid recovery at an injection rate of 60 tons/hour and production temperatures of 150 &deg;C - 190 &deg;C . However no detailed analysis of flow conditions was given. Therefore, a simplified HDR model has been proposed to understand the Hijion HDR r… more
Date: January 24, 1996
Creator: Shiga, Takahiro; Hyodo, Masami; Takasugi, Shinji; Wright, C. A. & Conant, R. A.
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Partner: UNT Libraries Government Documents Department
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Hydrothermal surface alteration in the Copahue Geothermal Field (Argentina)

Description: In the area of the Copahue Geothermal Field, there are five active geothermal manifestations, which mainly consist of fumaroles, hot springs and mud pots. Four of these manifestations are located in Argentina: Las M&aacute;quinas, Termas de Copahue, Las Maquinitas and El Anfiteatro, and the fifth on the Chilean side: Chancho Co. All of them present a strong acid sulfate country rock alteration, characterized by the assemblage alunite + kaolinite + quartz + cristobalite + pyrite + sulfur + jaros… more
Date: January 24, 1996
Creator: Mas, Graciela R.; Mas, Luis C. & Bengochea, Leandro
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Partner: UNT Libraries Government Documents Department
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