The thermal conductivities of most major rock-forming minerals vary with both temperature and confining pressure, leading to substantial changes in the thermal properties of some rocks at the high temperatures characteristic of geothermal systems. In areas with large geothermal gradients, the successful use of near-surface heat flow measurements to predict temperatures at depth depends upon accurate corrections for varying thermal conductivity. Previous measurements of the thermal conductivity of dry rock samples as a function of temperature were inadequate for porous rocks and susceptible to thermal cracking effects in nonporous rocks. We have developed an instrument for measuring the thermal conductivity of water-saturated rocks at temperatures from 20 to 350 °C and confining pressures up to 100 MPa. A transient line-source of heat is applied through a needle probe centered within the rock sample, which in turn is enclosed within a heated pressure vessel with independent controls on pore and confining pressure. Application of this technique to samples of Franciscan graywacke from The Geysers reveals a significant change in thermal conductivity with temperature. At reservoir-equivalent temperatures of 250 °C, the conductivity of the graywacke decreases by approximately 25% relative to the room temperature value. Where heat flow is constant with depth …

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 …

The Fiji Department of Energy (DOE) has a comprehensive resource assessment programme which assesses and promotes the use of local renewable energy resources where they are economically viable. DOE is currently involved in the investigation of the extent of geothermal resources for future energy planning and supply purposes. The aim is to determine (a) whether exploitable geothermal fields exist in the Savusavu or Labasa areas. the two geothermal fields with the greatest potential, (b) the cost of exploiting these fields for electricity generation/process heat on Vanua Levu. (c) the comparative cost per mega-watt-hour (MWh) of geothermal electricity generation with other generating options on Vanua Levu, and. (d) to promote the development of the geothermal resource by inviting BOO/BOOT schemes. Results to date have indicated that prospects for using geothermal resource for generating electricity lies in Savusavu only - whereas the Labasa resource can only provide process heat. All geophysical surveys have been completed and the next stage is deep drilling to verify the theoretical findings and subsequent development.

Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with superheated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200 °C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220 °C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: 1. At relative pressures over 0.6 the capillarity forces are very important. 2. There is no significant temperature effect. 3. Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. 4. Pores smaller than 15 Å do not contribute to the adsorbed mass.

The complexities of operating a geothermal field make it useful to incorporate reservoir simulation in the suite of tools available for the management of the resource. The criteria used in selecting a useful numerical simulator include such issues as ease of use, input/output options, and continued user support. The simulator must be validated to ensure that it yields ''correct'' results. Having been validated, the simulator can then be used to improve the predictive capabilities required to optimize geothermal resource management. The simulator TETRAD is used by INEL's Geothermal Reservoir Technology Program, based on the selection criteria noted above. Code validation was achieved through the solution of the Stanford Geothermal Problem Set. TETRAD was then used in a parametric evaluation of reservoir properties. The parametric study demonstrates the importance of various input parameters to accurate simulation. Parameters investigated include reservoir structure, relative permeability- and capillary pressure-saturation relationships, and dual porosity parameters. field scale study is also presented that shows the importance of considering reservoir structure and the location of other wells in siting new wells.

Technology transfer to the industrial sector for geopressured-geothermal technology has included diverse strategies, with successes and obstacles or roadblocks. Numerical data are tabulated in terms of response to the various strategies. Strategy categories include the following: feasibility studies and reports, consortium activities and proceedings, the Geothermal Resource Council, national and international meetings of the American Association of Petroleum Geologists, other societal and organizational meetings, and conferences, Department of Energy solicitation of interest in the Commerce Business Daily, industry peer review panels, and the Secretary's Technology Initiative. Additionally, the potential of a 12-page color brochure on the geopressured-geothermal resource, workshops, and cooperative research and development agreement (CRADA) is discussed. In conclusion, what is the best way to reach the market and what is the winning combination? All of the above strategies contribute to technology transfer and are needed in some combination for the desired success. The most successful strategy activities for bringing in the interest of the largest number of industries and the independents are the consortium meetings, one-on-one telephone calling, and consortium proceedings with information service followup. the most successful strategy activities for bringing in the interest and participation of ''majors'' are national and international peer reviewed papers at internationally …

I think it is wonderful that our Country can support research projects. Innovations and the development of cost-effective technology is a strategic issue for our industry. We all know that this is important--in fact, required to keep the industry healthy. The objective must be to continuously develop technology which will do things better for less money. This is the ultimate goal of research. I've been asked to comment on production research issues. And so, I will limit my discussion to just that. I think what we've heard in the last few days concerning cements, waste processing, and scale prediction is encouraging. In particular, the work that is being conducted on polymer cements may be of significant importance. As you may know, many parts of The Geysers and other fields are incurring high corrosion rates. The question before us is, do we plug and abandon these wells? Install hangdown strings of small diameter liner using expensive metallurgy such as Inconnel, Hastelloy or Titanium? Or, drill new wells? With current economics, it behooves them to seek the least expensive option which can extend the economic life of these deteriorating facilities. Our current option may be to run inner-liners utilizing these new polymer …

Dr. Mock began the session by paying tribute to Dr. Myron Dorfman, Professor of Petroleum Engineering at the University of Texas, who had just passed away after a protracted illness. Dr. Dorfman, more than other any individual, was responsible for bringing the geopressured-geothermal state-of-the-art to its present technological readiness for commercialization by industry. Allan Jelacic, Geosciences Team Leader, Geothermal Division, chaired the formal session and gave a historic overview of the conference that defined research needs and economic potential of the resource. First the Nevada Field Office and later the Idaho Field Office took the lead in setting research directions and managing the program. The major research activity was to flow-test ten Wells of Opportunity, provided by industry, as well as the Design Wells, of which four were drilled. Initial problems with calcium carbonate scale deposition and the safe handling and disposition of up to 30,000 barrels of geopressured brine per day were solved. A series of seminal conferences followed so that by the mid-eighties, the resource's extent and productivity were understood, and DOE's Geothermal Division was proceeding with technology transfer to industry. Allan Jelacic pointed out that currently the program is phasing down, with only three active wells remaining: …

Numerical simulations were carried out to predict pressure transients in a hypothetical deep geothermal well which penetrates a reservoir at super-critical conditions. Production at about 4000 m depth was assumed. In many cases, two-phase conditions develop due to high temperature and production-induced pressure decrease. Several cases in which single-phase conditions are maintained were studied in detail. Pressure transients are influenced by the reservoir temperature distribution - in particular, a temperature distribution with subcritical conditions at the well but supercritical conditions farther away causes a characteristic nonlinear pressure response whlch is influenced by the large compressibility and small kinematic viscosity near the critical point.

Most geothermal reservoirs are extensively fractured and injected fluids usually enter the reservoir formation at distinct feed points. As the cold water passes through the hot rock, it is heated, and may be recovered at production wells for power production. The influence of fractures is two-fold. Firstly, preferential pathways exist along major faults and the general motion of fluids away from injection wells is controlled by the effective permeability structure. Secondly, since fractures can be spaced several metres or more apart and the flow rates within each fracture can be relatively high, the injected fluid does not necessarily attain thermal equilibrium will all of the host rock at a given distance from the injection well. It is important that sufficient heat transfer between the fluid and rock occurs before the injected fluid is recovered at an injection well in order to prevent thermal breakthrough. In this paper we present preliminary results of an experimental research program examining the effects of injection into fractures. We build upon previous theoretical work by seeking to confirm the results and then discuss the initial results of injection into superheated reservoirs.

Source mechanisms of 985 microearthquakes at the Southeast Geysers geothermal field, are investigated using a moment tensor formulation. P- and S-wave amplitude and polarity are utilized to estimate the full, second-order moment tensor, which is then decomposed into isotropic, double-couple, and compensated linear vector dipole components. The moment tensor principal axes are used to infer the directions of principal stress associated with the double-couple component of the source mechanism. Most of the events can be modeled as primarily double-couple; however, a small but significant isotropic component, which can be either positive or negative, is also needed to explain the observed waveforms. Events with positive isotropic components and events with negative isotropic components both occur in areas of steam extraction and in areas of fluid injection. Principal axes of moment tensors with negative isotropic components are aligned with the regional stress field, while those of moment tensors with positive isotropic components differ significantly from the regional stress field. This suggests that two differing inducing mechanisms are required: negative-type events involve local stress perturbations that are small compared to the regional stress, while positive-type events involve stress perturbations which locally dominate over the regional stress.

X-ray attenuation, electrical conductivity, and ultrasonic velocity are reported for a segment of preserved core from SB-15D, 918 ft. X-ray tomography and ultrasonic measurements change as the core dries, providing information regarding handling and disturbance of the core. Electrical conductivity measurements at reservoir conditions indicate that pore fluid properties and pore microstructure control bulk conductivity. These data are useful for calibration and interpretation of field geophysical measurements.

This paper reports on a continuing experimental effort to characterize the adsorption behavior of rocks from The Geysers steam field in California. We show adsorption results obtained for 36 rock samples. All of the adsorption isotherms plotted on the same graph exhibit an envelope of isotherms. The minimum and the maximum values of the slope (or rate of adsorption) and of the magnitude within this envelope of isotherms belonged to the UOC-1 (felsite) and NCPA B-5 (serpentine) samples. The values of surface area and porosity, and pore size distribution for 19 of the samples indicated a very weak correlation with adsorption. An interpretation of the pore size distributions and the liquid saturation isotherms suggests that the change in the slope and the magnitude of the adsorption isotherms within the envelope is controlled primarily by the physical adsorption mechanism instead of capillary condensation. Grain-size and framework grain to matrix ratio are found to be insufficient to characterize this adsorption behavior. An accurate identification of the mineralogy of the samples will be essential to complete this analysis.

Acoustic telemetry has been a dream of the drilling industry for the past 50 years. It offers the promise of data rates which are one-hundred times greater than existing technology. Such a system would open the door to true logging-while-drilling technology and bring enormous profits to its developers. The oil and gas industry has led in most of the attempts to develop this type of telemetry system; however, very substantial efforts have also been made through government sponsored work in the geothermal industry. None of these previous attempts have lead to a commercial telemetry system. Conceptually, the problem looks easy. The basic idea is to produce an encoded sound wave at the bottom of the well, let it propagate up the steel drillpipe, and extract the data from the signal at the surface. Unfortunately, substantial difficulties arise. The first difficult problem is to produce the sound wave. Since the most promising transmission wavelengths are about 20 feet, normal transducer efficiencies are quite low. Compounding this problem is the structural complexity of the bottomhole assembly and drillstring. For example, the acoustic impedance of the drillstring changes every 30 feet and produces an unusual scattering pattern in the acoustic transmission. This scattering …

Extracellular matrix and extracellular matrix-degrading matrix metalloproteinases play a key role in interactions between the epithelium and the mesenchyme during mammary gland development and disease. In patients with breast cancer, the mammary mesenchyme undergoes a stromal reaction, the etiology of which is unknown. We previously showed that targeting of an autoactivating mutant of the matrix metalloproteinase stromelysin-1 to mammary epithelia of transgenic mice resulted in reduced mammary function during pregnancy and development of preneoplastic and neoplastic lesions. Here we examine the cascade of alterations before breast tumor formation in the mammary gland stroma once the expression of the stromelysin-1 transgene commences. Beginning in postpubertal virgin animals, low levels of transgene expression in mammary epithelia led to increased expression of endogenous stromelysin-1 in stromal fibroblasts and up-regulation of other matrix metalloproteinases, without basement membrane disruption. These changes were accompanied by the progressive development of a compensatory reactive stroma, characterized by increased collagen content and vascularization in glands from virgin mice. This remodeling of the gland affected epithelial-mesenchymal communication as indicated by inappropriate expression of tenascin-C starting by day 6 of pregnancy. This, together with increased transgene expression, led to basement membrane disruption starting by day 15 of pregnancy. We propose that …

A new heterotic N = 2 string with manifest target space supersymmetry is constructed by combining a conventional N = 2 string in the right-moving sector and a Green-Schwarz-Berkovits type string in the left-moving sector. The corresponding sigma model is then obtained by turning on background fields for the massless excitations. We compute the beta functions and we partially check the OPE's of the superconformal algebra perturbatively in {alpha}{prime}, all in superspace. The resulting field equations describe N = 1 self-dual supergravity.

Composites of carbon black particles in polyethylene are known to exhibit an unusually rapid increase in resistivity as the applied field is increased, making this material useful in automatically resettable fuses. In this application the composite is in series with the circuit it is protecting: at low applied voltages this circuit is the load, but at high applied voltages the composite becomes the load, limiting the current to the circuit. We present a simple model of this behavior in terms of a network of nonlinear conductors. Each conductor has a conductance that depends on its instantaneous Joule heating. It is shown that in the fusing regime, where the current through the composite decreases with increasing voltage, an plate-like dissipation instability develops normal to the applied field. Experimental evidence of this phenomena is described.

Designing and developing the 1.7 to 2. 1-MJ Power Conditioning System (PCS) that powers the flashlamps for the National Ignition Facility (NIF), currently being constructed at Lawrence Livermore National Labs (LLNL), is one of several responsibilities assumed by Sandia National Labs (SNL) in support of the NIF Project. The test facility that has evolved over the last three years to satisfy the project requirements is called FANTM. It was built at SNL and has operated for about 17,000 shots to demonstrate component performance expectations over the lifetime of NIF. A few modules similar to the one shown in Fig. 1 will be used initially in the amplifier test phase of the project. The final till NIF system will require 192 of them (48 in each of four capacitor bays). This paper briefly summarizes the final design of the FANTM facility and compares its performance with the predictions of circuit simulations for both normal operation and fault-mode response. Applying both the measured and modeled power pulse waveforms as input to a physics-based, semi-empirical amplifier gain code indicates that the 20-capacitor PCS can satisfy the NIF requirement for an average gain coefficient of 5.00 %/cm and can exceed 5.20%/cm with 24 capacitors.

From an estimate of the meson-meson inelastic scattering at 5 GeV it is concluded that a typical strong phase in B decays to two mesons is of order of 20{sup o}. For a particular final state an estimate of the phase depends on whether that state is more or less probable as a final state compared to those states to which it is connected by the strong interaction S matrix.

Magnetic field-structured-composites (FSCs) are made by structuring magnetic particle suspensions in uniaxial or biaxial (e.g. rotating) magnetic fields, while polymerizing the suspending resin. A uniaxial field produces chain-like particle structures, and a biaxial field produces sheet-like particle structures. In either case, these anisotropic structures affect the measured magnetic hysteresis loops, with the magnetic remanence and susceptibility increased significantly along the axis of the structuring field, and decreased slightly orthogonal to the structuring field, relative to the unstructured particle composite. The coercivity is essentially unaffected by structuring. We present data for FSCs of magnetically soft particles, and demonstrate that the altered magnetism can be accounted for by considering the large local fields that occur in FSCs. FSCS of magnetically hard particles show unexpectedly large anisotropies in the remanence, and this is due to the local field effects in combination with the large crystalline anisotropy of this material.

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The compact multi-pass laser design and the extensive use of optical component assemblies as line replaceable units (LRU) are essential to achieve the cost efficiency of the National Ignition Facility design. These design philosophies require a new approach to start-up operation of the NIF 192-beam-line high-energy laser compared to existing fusion laser facilities. The limited access to the beam-line optics and the limited on-line verification and maintenance capability require that extensive component verification and alignment take place in off-line facilities before the LRUÕs are installed in the laser structure. We are developing a detailed plan for the start-up of the NIF facility. This plan includes systematic off-line component and LRU verification tests, LRU installation and prealignment, and sub-system acceptance tests, followed by a well defined set of operational test procedures to verify integrated performance. During integrated performance testing laser performance parameters of individual beam lines will be verified using a precision diagnostic system located in the NIF switchyard. If additional on-line calibration or performance testing is required, the LRU based architecture can accommodate the insertion of specialized in-line diagnostic LRUs at locations that require such additional testing during start-up. Multiple beam focal spot characteristics on disk targets in the NIF …

An extended throat flow nozzle has been examined as a device for the measurement of very high void fraction multi-phase flows. Due to its greater density and partial contact with the wall, the equilibrium velocity of the liquid phase appreciably lags that of the lighter gas phase. The two phases are strongly coupled resulting in pressure drops across the contraction and in the extended throat that are significantly different than those experienced in single-phase flow. Information about the mass flow rates of the two phases can be extracted from the measured pressure drops. The performance of an extended throat flow nozzle has been evaluated under multi-phase conditions using natural gas and hydrocarbon liquids at 400 and 500 psi. Two hydrocarbon solvents were used as the test liquids, Isopar M (sp=0.79) and Aromatic 100 (sp=0.87). These data are compared to prior air-water data at nominally 15 psi. The high and low pressure data were found to be consistent, confirming that the temperature, pressure, and size scaling of the extended throat venturi are correctly represented. This consistency allows different sized devices to be applied under different fluid conditions (temperature, pressure, gas and liquid phase composition, etc) with confidence.