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Comparing FRACHEM and TOUGHREACT for reactive transport modelingof brine-rock interactions in enhanced geothermal systems (EGS)

Description: Coupled modelling of fluid flow and reactive transport ingeothermal systems is challenging because of reservoir conditions such ashigh temperatures, elevated pressures and sometimes high salinities ofthe formation fluids. Thermal hydrological-chemical (THC) codes, such asFRACHEM and TOUGHREACT, have been developed to evaluate the long-termhydrothermal and chemical evolution of exploited reservoirs. In thisstudy, the two codes were applied to model the same geothermal reservoir,to forecast reservoir evolution using respective thermodynamic andkinetic input data. A recent (unreleased) TOUGHREACT version allows theuse of either an extended Debye-Hu?ckel or Pitzer activity model forcalculating activity coefficients, while FRACHEM was designed to use thePitzer formalism. Comparison of models results indicate that differencesin thermodynamic equilibrium constants, activity coefficients andkinetics models can result in significant differences in predictedmineral precipitation behaviour and reservoir-porosity evolution.Differences in the calculation schemes typically produce less differencein model outputs than differences in input thermodynamic and kineticdata, with model results being particularly sensitive to differences inion-interaction parameters for highsalinity systems.
Date: November 15, 2005
Creator: Andre, L.; Spycher, N.; Xu, T.; Pruess, K. & Vuataz, F.-D.
Partner: UNT Libraries Government Documents Department

Geology, resistivity, and hydrochemistry of the Ojo Caliente hot springs area, northern New Mexico

Description: Geothermal fluids of the Ojo Caliente area discharge from a northeast trending normal fault that juxtaposes Precambrian metarhyolite and Tertiary sediments. An electrical resistivity survey shows that the fluids emerge from the fault and flow as a plume of thermal water into cold aquifers east of the fault. Geochemistry of fluids indicates a maximum reservoir temperature at depth of 80/sup 0/C with no suggestion of high temperature isotopic exchange between water and reservoir rocks. From this data, it is believed that the Ojo Caliente system is suitable only for small-scale direct use geothermal applications.
Date: January 1, 1982
Creator: Stix, J.; Pearson, C.; Vuataz, F.; Goff, F.; East, J. & Hoffers, B.
Partner: UNT Libraries Government Documents Department

Hydrogeochemical data for thermal and nonthermal waters and gases of the Valles Caldera- southern Jemez Mountains region, New Mexico

Description: This report presents field, chemical, gas, and isotopic data for thermal and nonthermal waters of the southern Jemez Mountains, New Mexico. This region includes all thermal and mineral waters associated with Valles Caldera and many of those located near the Nacimiento Uplift, north of San Ysidro. Waters of the region can be categorized into five general types: (1) surface and near-surface meteoric waters; (2) acid-sulfate waters at Sulphur Springs (Valles Caldera); (3) thermal meteoric waters in the ring fracture zone (Valles Caldera); (4) deep geothermal waters of the Baca geothermal field and derivative waters in the Soda Dam and Jemez Springs area (Valles Caldera); and (5) mineralized waters near San Ysidro. Some waters display chemical and isotopic characteristics intermediate between the types listed. Data in this report will help in interpreting the geothermal potential of the Jemez Mountains region and will provide background for investigating problems in hydrology, structural geology, hydrothermal alterations, and hydrothermal solution chemistry.
Date: March 1, 1987
Creator: Shevenell, L.; Goff, F.; Vuataz, F.; Trujillo, P.E. Jr.; Counce, D.; Janik, C.J. et al.
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: January 1, 1984
Creator: Goff, F. & Vuataz, F.D.
Partner: UNT Libraries Government Documents Department

Low-temperature geothermal potential of the Ojo Caliente warm springs area, northern New Mexico

Description: A detailed geochemical investigation of 17 waters (thermal and cold, mineralized and dilute) was performed in the Ojo Caliente-La Madera area. Two types of thermomineral waters have separate and distinctive geologic, geochemical, and geothermal characteristics. The water from Ojo Caliente Resort emerges with temperatures less than or equal to 54/sup 0/C from a Precambrian metarhyolite. Its chemistry, typically Na-HCO/sub 3/, has a total mineralization of 3600 mg/l. Isotopic studies have shown that the thermal water emerges from the springs and a hot well without significant mixing with the cold shallow aquifer of the valley alluvium. However, the cold aquifer adjacent to the resort does contain varying amounts of thermal water that originates from the warm spring system. Geothermometry calculations indicate that the thermal water may be as hot as 85/sup 0/C at depth before its ascent toward surface. Thermodynamic computations on the reaction states of numerous mineral phases suggest that the thermal water will not cause major scaling problems if the hot water is utilized for direct-use geothermal applications. By means of a network of very shallow holes, temperature and electrical conductivity anomalies have been found elsewhere in the valley around Ojo Caliente, and resistivity soundings have confirmed the presence of a plume of thermal water entering the shallow aquifer. The group of lukewarm springs around La Madera, with temperatures less than or equal to 29/sup 0/C, chemical type of NaCaMg-HCO/sub 3/Cl and with a total mineralization less than or equal to 1500 mg/l behaves as a different system without any apparent relation to the Ojo Caliente system. Its temperature at depth is not believed to exceed 35 to 40/sup 0/C.
Date: May 1, 1984
Creator: Vuataz, F.D.; Stix, J.; Goff, F. & Pearson, C.F.
Partner: UNT Libraries Government Documents Department

Roosevelt Hot Springs/hot-dry-rock prospect and evaluation of the Acord 1-26 well

Description: Previous hot, dry rock (HDR) geothermal resource evaluation efforts have identified the Roosevelt Hot Springs KGRA as a prime HDR target. The size of the HDR resource is estimated to be at least eight times larger than the adjacent hydrothermal resource. Further research activities to evaluate this HDR resource have involved review of data from the Acord hot dry well, the seismic structure of the area, fluid geochemistry, and hydrology of a shallow aquifer. These recent results are summarized and the most likely HDR prospect area is identified.
Date: January 1, 1983
Creator: Shannon, S.S. Jr.; Goff, F.; Rowley, J.C.; Pettitt, R.A. & Vuataz, F.D.
Partner: UNT Libraries Government Documents Department

Water geochemistry and hydrogeology of the shallow aquifer at Roosevelt Hot Springs, southern Utah: A hot dry rock prospect

Description: On the western edge of the geothermal field, three deep holes have been drilled that are very hot but mostly dry. Two of them (Phillips 9-1 and Acord 1-26 wells) have been studied by Los Alamos National Laboratory for the Hot Dry Rock (HDR) resources evaluation program. A review of data and recommendations have been formulated to evaluate the HDR geothermal potential at Roosevelt. The present report is directed toward the study of the shallow aquifer of the Milford Valley to determine if the local groundwater would be suitable for use as make-up water in an HDR system. This investigation is the result of a cooperative agreement between Los Alamos and Phillips Petroleum Co., formerly the main operator of the Roosevelt Hot Springs Unit. The presence of these hot dry wells and the similar setting of the Roosevelt area to the prototype HDR site at Fenton Hill, New Mexico, make Roosevelt a very good candidate site for creation of another HDR geothermal system. This investigation has two main objectives: to assess the water geochemistry of the valley aquifer, to determine possible problems in future make-up water use, such as scaling or corrosion in the wells and surface piping, and to assess the hydrogeology of the shallow groundwaters above the HDR zone, to characterize the physical properties of the aquifer. These two objectives are linked by the fact that the valley aquifer is naturally contaminated by geothermal fluids leaking out of the hydrothermal reservoir. In an arid region where good-quality fresh water is needed for public water supply and irrigation, nonpotable waters would be ideal for an industrial use such as injection into an HDR energy extraction system. 50 refs., 10 figs., 10 tabs.
Date: December 1, 1987
Creator: Vuataz, F.D. & Goff, F.
Partner: UNT Libraries Government Documents Department