Numerical experiments are performed to investigate the rock thermal conductivity influence in the formation of the thermodynamic initial conditions of two-phase systems located in volcanic rocks. These systems exhibit pressure and temperature profiles characterized by a sudden change or discontinuity in their vertical gradients. Vapor dominated, two-phase fluids are found at the upper reservoir's levels. Liquid is the dominated phase within the layers below some critical point. Numerical results presented in this paper, suggest that the vertical location of this point of discontinuity be controlled by the thermal conductivity existing between the limit of the reservoir and the caprock. Too high values could originate liquid dominated reservoirs. Small values would be at the origin of vapor dominated reservoirs. A characteristic middle value could be responsible for the formation of a counter flow mechanism originating the initial conditions observed at some locations of the Los Azufres, Mexico, geothermal field.

A detailed three-dimensional numerical model has been developed for the low-temperature hydrothermal system at Botn in Central North Iceland. It is based on a conceptual reservoir model which has evolved during two decades of geothermal research in the area and on the 10 year production history of the system. The model consists of (1) A powerful recharge system at depth, (2) a shallow production reservoir and (3) a cold ground-water system at the surface. About 10 million tons of hot water have been extracted from the production reservoir since late 1981. The presence of the powerful recharge system results in a very slow long-term pressure decline. Flow of water in the production reservoir appears to be controlled by a highly permeable, vertical fracture-zone confined by low-permeability rocks. Cold ground-water flows down into the fracture-zone during production causing some cooling of the extracted water.

A new equation-of-state module has been developed for the TOUGH2 simulator, belonging to the MULKOM family of computer codes developed at LBL. This EOS module is able to handle three-component mixtures of water, sodium chloride, and a non-condensible gas. It can describe liquid and gas phases, and includes precipitation and dissolution of solid salt. The dependence of density, viscosity, enthalpy, and vapor pressure of brine on salt concentration is taken into account, as well as the effects of salinity on gas solubility in the liquid phase and related heat of solution. The main assumptions made in developing this EOS module are discussed, together with the correlations employed to calculate the thermophysical properties of multiphase multicomponent mixtures. At present the non-condensible gas can be chosen to be air, CO₂, CH₄, H₂, or N₂. This paper focuses on H₂O-NaCI-CO₂ mixtures and describes new correlations obtained from fitting of published experimental data. Illustrative results for geothermal reservoir depletion in the presence of salinity and non-condensible gas are presented. We demonstrate and analyze effects of vapor pressure lowering and gas solubility decrease from salinity, and loss of reservoir porosity and permeability from salt precipitation during boiling of brines.

Photograph used for a newspaper owned by the Oklahoma Publishing Company.

Photograph used for a newspaper owned by the Oklahoma Publishing Company.

Photograph used for a newspaper owned by the Oklahoma Publishing Company.

Photograph used for a story in the Daily Oklahoman newspaper. Caption: "Joy Willingham Owens stands before a wall mural of the Chisholm Trail which she painted for the city of Yukon."

Weekly newspaper from Emory, Texas that includes local, state, and national news along with advertising.

The performance of the 1986 three-dimensional numerical model of the Nesjavellir geothermal field for predicting the deliverabilities and pressure decline of the wells during the period 1987 through 1991 is investigated. The model predicted adequately the flow rate and enthalpy transients of most wells, but overpredicted the pressure decline by 3 to 4 bars.

Weekly newspaper from Goldthwaite, Texas that includes local, state, and national news along with extensive advertising.

Through mid-December 1992, long-term flow testing of the Phase I1 Hot Dry Rock (HDR) reservoir at Fenton Hill, NM has been conducted for an aggregate of 24 weeks at near-optimum aseismic injection conditions. This period of flow testing, which began on April 9, 1992, included several reservoir shut-ins due to equipment problems and an intervening lower-injection-rate Interim Flow Test lasting about 6 weeks. With the exceptions noted above, the majority of the flow testing for that period was conducted at an average injection rate of 7.2 l/s and at pressures up to 27.3 MPa. However, this high level of injection pressure has not produced any discernible reservoir microseismicity, indicating that we have been operating the reservoir at pressures below the threshold for fracture extension. The permeation loss from the boundaries of the reservoir at these elevated pressures has averaged about 0.7 l/s, a very low rate of water loss considering the very large volume of fractured rock (about 16x10⁶ m³) comprising the pressure-stimulated reservoir region. Temperature logging across the 350-m production interval, centered at a depth of about 3500 m, indicates that there has been no measurable drop in the mixed-mean reservoir production temperature at the top of this interval …

Estimates of temperatures, past and present, in geothermal reservoirs can be made by using now standard mineralogical techniques, including fluid inclusion geothermometry, vitrinite reflectance, calc-silicate and clay occurrence, the extent of clay interlayering, and measuring clay crystallinity. Recent studies of clays in 60 drillcores from 6 wells at Wairakei, for example, show an inverse relationship between reservoir temperatures and crystallinities from 90&deg; to 225&deg;C (195 to 435°F) (K&uuml;bler Indices: 1.40 to 0.44 <FONT FACE="Symbol">D</FONT>&deg;2<FONT FACE="Symbol">q</FONT>). Fluid inclusion geothermometry results require careful interpretation but the method need not be calibrated with respect to the reservoir, as do other geothermometric methods.

Weekly newspaper from Llano, Texas that includes local, state, and national news along with advertising.

Letter from Bob Bullock to Joseph P. Luce discussing his inability to attend the 50th Anniversary Women Airforce Service Pilots Celebration.

Student newspaper of the University of Oklahoma in Norman, Oklahoma that includes national, local, and campus news along with advertising.

Weekly newspaper from Ingleside, Texas that includes local, state, and national news along with advertising.

Using thermodynamic gas equilibria to calculate temperature and steam fraction in the reservoir, three main physical phenomena due to exploitation of Palinpinon field are identified. 1) Pressure drawdown producing a local increase in the computed steam fraction, with the fluid maintaining high temperature values (close to 300°C). Strong decline in flow rate is observed. 2) Irreversible steam losses from the original high temperature liquid phase during its ascent through fractures in upper zones of the reservoir. Steam is generally lost at temperatures (e.g. 240°C) lower then those of the original aquifer. 3) Dilution and cooling effects due to reinjection fluid returns. These are function of the local geostructural conditions linking through fractures the injectors and production wells. The computed fraction of the recovered reinjected brine can in some case exceed 80% of the total produced fluid. At the same time the computed gas equilibration temperatures can decline from 280-300°C to as low as 215-220°C. Comparing these values with the well bottom measured temperatures, the proposed methodology based on gas chemistry gives more reliable temperature estimate than water chemistry based geothermometers for fluids with high fractions of injected brine.

Gas chemistry from 28 wells complement water chemistry and physical data in developing a reservoir model for the Bacon-Manito geothermal project (BMGP), Philippines. Reservoir temperature, T_HSH, and steam fraction, y, are calculated or extrapolated from the grid defined by the Fischer-Tropsch (FT) and H₂-H₂S (HSH) gas equilibria reactions. A correction is made for H₂ that is lost due to preferential partitioning into the vapor phase and the reequilibration of H₂S after steam loss.

Large-scale use of geothermal energy is likely to result in depletion of natural resources that support both biodiversity and other human uses. Most of the problems could be averted with competent planning and adherence to agreed conditions, but they commonly develop because they are not perceived to be directly geothermal in origin and hence are not taken into account adequately. Some of the implications of such issues are discussed below, with particular reference to countries where all or most resources are held under traditional principals of custom ownership.

New Energy and Industrial Technology Development Organization (NEDO) did "Geothermal Development Promotion Survey" in the Hachijojima Island which is a volcanic island with 70km&sup2; located in the Izu-Mariana Island Arc. In that national project, NEDO drilled 8 wells in the field and the maximum temperature of the field was 317&deg;C at 1200m depth of a well. Of these survey NEDO confirmed the existence of geothermal reservoir, and using a well named HJ-5, NEDO did short time discharge test. The authors calculated borehole temperature and pressure under production the of the well in comparison with the measured data. The authors also calculated productive performance of another well named HJ-8.

Daily newspaper from Baytown, Texas that includes local, state, and national news along with advertising.

The data from flow tests which employed two different production zones in a well at Fenton Hill indicates the flow impedance of a wellbore zone damaged by rapid depressurization was altered, possibly by pressure spallation, which appears to have mechanically propped the joint apertures of outlet flow paths intersecting the altered wellbore. The rapid depressurization and subsequent flow test data derived from the damaged well has led to the hypothesis that pressure spallation and the resultant mechanical propping of outlet flow paths reduced the outlet flow impedance of the damaged wellbore. Furthermore, transient pressure data shows the largest pressure drop between the injection and production wellheads occurs near the production wellbore, so lowering the outlet impedance by increasing the apertures of outlet flow paths will have the greatest effect on reducing the overall reservoir impedance. Fenton Hill data also reveals that increasing the overall reservoir pressure dilates the apertures of flow paths, which likewise serves to reduce the reservoir impedance. Data suggests that either pressure dilating the wellbore connected joints with high production wellhead pressure, or mechanically propping open the outlet flow paths will increase the near-wellbore permeability. Finally, a new method for calculating and comparing near-wellbore outlet impedances has …

Semi-weekly newspaper from Burleson, Texas that includes local, state, and national news along with advertising.

A managed injection program implemented by the NCPA in The Southeast Geysers reservoir continues to positively impact reservoir performance. Injection effects are determined by the application of geochemical and geophysical techniques to track the movement of injectate. This information, when integrated with reservoir pressure, flowrate, and thermodynamic data, is used to quantify the overall performance and efficiency of the injection program. Data analysis indicates that injected water is boiling near the injection wells, without deeper migration, and is recovered as superheated steam from nearby production wells. Injection derived steam (IDS) currently accounts for 25 to 35 percent of total production in the NCPA steamfield. Most importantly, 80 to 100% of the injectate is flashing and being recovered as steam. The amount of IDS has increased since 1988 due to both a change in injection strategy and a drying out of the reservoir. However, significant areas of the reservoir still remain relatively unaffected by injection because of the limited amount of injectate presently available. That the reservoir has been positively impacted in the injection areas is evidenced by a decrease in the rate of pressure decline from 1989 through 1992. Correspondingly, there has been a reduction in the rate of steam …