The purpose of this paper is to describe the status of field and geochronology studies of the Lathrop Wells volcanic center. Our perspective is that it is critical to assess all possible methods for obtaining cross-checking data to resolve chronology and field problems. It is equally important to consider application of the range of chronology methods available in Quaternary geologic research. Such an approach seeks to increase the confidence in data interpretations through obtaining convergence among separate isotopic, radiogenic, and age-correlated methods. Finally, the assumptions, strengths, and weaknesses of each dating method need to be carefully described to facilitate an impartial evaluation of results. The paper is divided into two parts. The first part describes the status of continuing field studies for the volcanic center for this area south of Yucca Mountain, Nevada. The second part presents an overview of the preliminary results of ongoing chronology studies and their constraints on the age and stratigraphy of the Lathrop Wells volcanic center. Along with the chronology data, the assumptions, strengths, and limitations of each methods are discussed.

Combined reservoir simulation and geochemical data analysis are used to investigate the effects of recharge and other reservoir processes occurring in the western part of the Cerro Prieto, Mexico, geothermal field (i.e., Cerro Prieto I area). Enthalpy-based temperatures and bottomhole temperatures are calculated based on simplified models of the system, considering different reservoir boundary conditions and zones of contrasting initial temperatures and reservoir properties. By matching the computed trends with geothermometer-based temperature and enthalpy histories of producing wells, the main processes active in the western area of Cerro Prieto are identified. This part of the geothermal system is strongly influenced by nearby groundwater aquifers; cooler waters readily recharge the reservoirs. In response to exploitation, the natural influx of cold water into the shallower alpha reservoir is mainly from the west and down Fault L, while the recharge to the deeper beta reservoir in this part of the field, seems to be only lateral, from the west and possibly south. 11 refs., 12 figs.

Corrosion of well and surface equipment due to the presence of hot, corrosive brines is one of the major problems facing geothermal operators. For wellbore casing, this problem is complicated by the fact that in-place inspection is difficult at best. In an attempt to improve this situation, a prototype acoustic borehole televiewer designed to operate in geothermal wells was used to study the corrosion damage to casing in three commercial wells. The results of this experiment were promising. The televiewer returns helped to define areas of major corrosion damage and to indicate the extent of the damage. This paper briefly discusses the corrosion problem, describes the acoustic borehole televiewer, and then summarizes the results of the field test of the televiewer's capability for investigating corrosion.

Growing interest and exploration dollars within the geothermal sector have paved the way for increasingly sophisticated suites of geophysical and geochemical tools and methodologies. The efforts to characterize and assess known geothermal fields and find new, previously unknown resources has been aided by the advent of higher spatial resolution airborne geophysics (e.g. aeromagnetics), development of new seismic processing techniques, and the genesis of modern multi-dimensional fluid flow and structural modeling algorithms, just to name a few. One of the newest techniques on the scene, is hyperspectral imaging. Really an optical analytical geochemical tool, hyperspectral imagers (or imaging spectrometers as they are also called), are generally flown at medium to high altitudes aboard mid-sized aircraft and much in the same way more familiar geophysics are flown. The hyperspectral data records a continuous spatial record of the earth's surface, as well as measuring a continuous spectral record of reflected sunlight or emitted thermal radiation. This high fidelity, uninterrupted spatial and spectral record allows for accurate material distribution mapping and quantitative identification at the pixel to sub-pixel level. In volcanic/geothermal regions, this capability translates to synoptic, high spatial resolution, large-area mineral maps generated at time scales conducive to both the faster pace of …

Growing interest and exploration dollars within the geothermal sector have paved the way for increasingly sophisticated suites of geophysical and geochemical tools and methodologies. The efforts to characterize and assess known geothermal fields and find new, previously unknown resources has been aided by the advent of higher spatial resolution airborne geophysics (e.g. aeromagnetics), development of new seismic processing techniques, and the genesis of modern multi-dimensional fluid flow and structural modeling algorithms, just to name a few. One of the newest techniques on the scene, is hyperspectral imaging. Really an optical analytical geochemical tool, hyperspectral imagers (or imaging spectrometers as they are also called), are generally flown at medium to high altitudes aboard mid-sized aircraft and much in the same way more familiar geophysics are flown. The hyperspectral data records a continuous spatial record of the earth's surface, as well as measuring a continuous spectral record of reflected sunlight or emitted thermal radiation. This high fidelity, uninterrupted spatial and spectral record allows for accurate material distribution mapping and quantitative identification at the pixel to sub-pixel level. In volcanic/geothermal regions, this capability translates to synoptic, high spatial resolution, large-area mineral maps generated at time scales conducive to both the faster pace of …

Critical instrumentation needs for borehole-oriented, geoscience research were identified in a program consisting of formal presentations, psoter sessions and a workshop. The proceedings include results of the workshops, abstracts of the papers and poster sessions, and the attendance list. Details of any of the presentations should be obtained from the individual authors. Separate entries were prepared for individual presentations.

This report summarizes the presentations and discussions of a workshop on lost circulation technology. The workshop identified and defined lost circulation problem areas in field operations, materials, mud effects, and standards. Problem solution needs were also categorized as requiring analytical evaluation and procedure, instrument, and material development.

The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant art of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Falls in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studies we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated with …

The Na/K ratio in geothermal well waters provides a better estimate of the relative stability of low albite and potash feldspar than do predictions from calorimetry and high temperature phase equilibria. The calculated saturation indices from field data for low albite, potash feldspar suggest that [Delta]G[sub f,298][sup o] for the latter should be revised to [minus]3748.6[plus minus]3.7 kJ.mol[sup [minus]1].

As was stated by the first presenter, the Long Valley Exploratory Well represents a vital linking of geothermal theory, technology and applications. The five presenters take us through that linking to the extent the current progress at the well makes that possible. The site is, of course, a geothermally rich resource, a ''recently active'' caldera. In many ways, the site has a wealth of data preceding the present work. It is a site which has excited the interest of the geothermal community for a long time. As is often the case in geothermal work, the prior data has raised as many questions as were answered. It is on this basis that the further exploration of a probable high temperature resource is being explored to great depths. The first presentation represents the cooperation and coordination maintained between similar elements of the Basic Energy Sciences programs and those in the Geothermal programs of DOE's Conservation and Renewable Energy activities. Similarly, the work exemplifies the close coordination of the DOE work with the U. S. Geological Survey, the National Science Foundation, and the U. S. Continental Scientific Drilling Program. The first presentation also represents the theoretical and modeling portion of the session. Appropriate …

The Na/K ratio in geothermal well waters provides a better estimate of the relative stability of low albite and potash feldspar than do predictions from calorimetry and high temperature phase equilibria. The calculated saturation indices from field data for low albite, potash feldspar suggest that {Delta}G{sub f,298}{sup o} for the latter should be revised to {minus}3748.6{plus_minus}3.7 kJ.mol{sup {minus}1}.

Gene probe hybridization was used to determine distribution and expression of co-metabolic genes at a contaminated site as it underwent in situ methanotrophic bioremediation of trichloroethylene (TCE). The bioremediation strategies tested included a series of air, air:methane, and air:methane:nutrient pulses of the test plot using horizontal injection wells. During the test period, the levels of TCE reduced drastically in almost all test samples. Sediment core samples (n = 367) taken from 0 m (surface)-43 m depth were probed for gene coding for methanotrophic soluble methane monooxygenase (sMMO) and heterotrophic toluene dioxygenase (TOD), which are known to co-metabolize TCE. The same sediment samples were also probed for genes coding for methanol dehydrogenase (MDH) (catalyzing the oxidation of methanol to formaldehyde) to assess specifically changes in methylotrophic bacterial populations in the site. Gene hybridization results showed that the frequency of detection of sMMO genes were stimulated approximately 250% following 1% methane:air (v/v) injection. Subsequent injection of 4% methane:air (v/v) resulted in an 85% decline probably due to nutrient limitations, since addition of nutrients (gaseous nitrogen and phosphorus) thereafter caused an increase in the frequency of detection of sMMO genes. Detection of TOD genes declined during the process, and eventually they were non-detectable …

The agenda, list of participants, and minutes of the meeting are presented. Included in the appendices are figures, data, outlines, etc. from the following presentations: 500 kW Direct-Contact Heat Exchanger Pilot Plant; LBL/EPRI Heat Exchanger Field Test, Critical Temperature and Pressure Comparisons for n-Butane/n-Pentane Mixtures; Second Law Techniques in the Correlation of Cost-Optimized Binary Power Plants; Outline of Chapter on Geothermal Well Logging; Outline and Highlights from Geothermal Drilling and Completion Technology Development Program Annual Progress: October 1979-September 1980; Geothermal Well Stimulation; World Update on Installed Geothermal Power Plants; Baca No. 1 Demonstration Flask Plant: Technical and Cost Data; Heber Binary Project; 45 mw Demonstration Plant; Raft River 5 mw Geothermal Dual-Boiling-Cycle Plant; Materials Considerations in the Design of Geothermal Power Plants; Raft River Brine Treatment for Tower Make-up; and Site Photographs of Raft River Valley.

For many enhanced recovery methods propagating fronts arise that may be steep or discontinuous. One example is the waterflooding of a petroleum reservoir, in which there is forced out residual oil that remains after outflow by decompression has declined. In this paper high-resolution numerical methods to solve porous flow problems having propagating discontinuities are discussed. The random choice method can track solution discontinuities sharply and accurately for one space dimension. The first phase of this study adapted this method for solving the Buckley-Leverett equation for immiscible displacement in one space dimension. Extensions to more than one space dimension for the random choice method were carried out subsequently by means of fractional splitting. Because inaccuracies could be introduced for some problems at dicontinuity fronts propagating obliquely to the splitting directions, efforts are currently being directed at investigating alternatives for multidimensional cases.

As a deep well in the center of a major Quaternary caldera, the Long Valley Exploratory Well (LVEW) provides a new perspective on the relationship between hydrothermal circulation and a large crustal magma chamber. It also provides an important test of models for the subsurface structure of active continental calderas. Results will impact geothermal exploration, assessment, and management of the Long Valley resource and should be applicable to other igneous-related geothermal systems. Our task is to use the cuttings and core from LVEW to interpret the evolution of the central caldera region, with emphasis on evidence of current hydrothermal conditions and circulation. LVEW has reached a depth of 2313 m, passing through post-caldera extrusives and the intracaldera Bishop Tuff to bottom in the Mt. Morrison roof pendant of the Sierran basement. The base of the section of Quaternary volcanic rocks related to Long Valley Caldera was encountered at 1800 m of which 1178 m is Bishop Tuff. The lithologies sampled generally support the classic view of large intercontinental calderas as piston-cylinder-like structures. In this model, the roof of the huge magma chamber, like an ill-fitting piston, broke and sank 2 km along a ring fracture system that simultaneously and explosively …

Papers presented at the conference can be broadly classified into five categories: reviews, instrumentation, field applications, theory and techniques, and drilling and related activities. A separate abstract was prepared for each of the fourteen papers compiled. (JSR)

Highlights of the meeting were discussions on the problem of waste heat rejection including the effects of noncondensable gases in geothermal power plants, a review of the state of the art in binary fluid geothermal power plants, and progress reports on the preparation of chapters and sections of the ''Sourcebook on the Production of Electricity from Geothermal Energy.'' Appendices are included with information on: the dry cooling enhancement program; condenser effects on Rankine cycle performance; waste heat rejection systems; effect on seasonal variations of ambient temperatures on the performance of low temperature power cycles; geothermal loop experimental facility fact sheet; Heber geothermal demonstration plant fact sheet; geothermal energy conversion systems using geofluids with high levels of noncondensable gases; analysis of East Mesa 16-29 well flow data; site-specific sub- and super-critical hybrid power cycles; novel hybrid fossil-geothermal power plants; total flow comparative cost studies; and, fact sheets on the geothermal component test facility, Magmamax dual binary power plant, and Cerro Prieto geothermal field and power plant. (JGB)

The main objective of the DOE/GD-funded Geothermal Reservoir Technology Program at Lawrence Berkeley Laboratory is the development and testing of new and improved methods and tools needed by industry in its effort to delineate, characterize, evaluate, and exploit hydrothermal systems for geothermal energy. This paper summarizes the recent and ongoing field, laboratory, and theoretical research activities being conducted as part of the Geothermal Reservoir Technology Program. 28 refs., 4 figs.

The testing of low permeability rocks is common to waste disposal, fossil energy resource development, underground excavation, and geothermal energy development. This document includes twenty-six papers and abstracts, divided into the following sessions: opening session, case histories and related phenomena, well test design in low permeability formations, analysis and interpretation of well test data, and instrumentation for well tests. Separate abstracts were prepared for 15 of the 16 papers; the remaining paper has been previously abstracted. (DLC)

Rising atmospheric concentrations of CO2, and their role inglobal warming, have prompted efforts to reduce emissions of CO2 fromburning of fossil fuels. An attractive mitigation option underconsideration in many countries is the injection of CO2 from stationarysources, such as fossil-fueled power plants, into deep, stable geologicformations, where it would be stored and kept out of the atmosphere fortime periods of hundreds to thousands of years or more. Potentialgeologic storage reservoirs include depleted or depleting oil and gasreservoirs, unmineable coal seams, and saline formations. While oil andgas reservoirs may provide some attractive early targets for CO2 storage,estimates for geographic regions worldwide have suggested that onlysaline formations would provide sufficient storage capacity tosubstantially impact atmospheric releases. This paper will focus on CO2storage in saline formations.Injection of CO2 into a saline aquifer willgive rise to immiscible displacement of brine by the advancing CO2. Thelower viscosity of CO2 relative to aqueous fluids provides a potentialfor hydrodynamic instabilities during the displacement process. Attypical subsurface conditions of temperature and pressure, CO2 is lessdense than aqueous fluids and is subject to upward buoyancy force inenvironments where pressures are controlled by an ambient aqueous phase.Thus CO2 would tend to rise towards the top of a permeable formation andaccumulate …

In the unlikely event that CO2 leakage from deep geologic CO2 sequestration sites reaches the vadose zone, remediation measures for removing the CO2 gas plume may have to be undertaken. Carbon dioxide leakage plumes are similar in many ways to volatile organic compound (VOC) vapor plumes, and the same remediation approaches are applicable. We present here numerical simulation results of passive and active remediation strategies for CO2 leakage plumes in the vadose zone. The starting time for the remediation scenarios is assumed to be after a steady-state CO2 leakage plume is established in the vadose zone, and the source of this plume has been cut off. We consider first passive remediation, both with and without barometric pumping. Next, we consider active methods involving extraction wells in both vertical and horizontal configurations. To compare the effectiveness of the various remediation strategies, we define a half-life of the CO2 plume as a convenient measure of the CO2 removal rate. For CO2 removal by passive remediation approaches such as barometric pumping, thicker vadose zones generally require longer remediation times. However, for the case of a thin vadose zone where a significant fraction of the CO2 plume mass resides within the high liquid saturation …

Dissolved CO{sub 2} in groundwater is frequently supersaturated relative to its equilibrium with atmospheric partial pressure and will degas when it is conveyed to the surface. Estimates of dissolved CO{sub 2} concentrations can vary widely between different hydrochemical facies because they have different sources of error (e.g., rapid degassing, low alkalinity, non-carbonate alkalinity). We sampled 60 natural spring and mine waters using a beverage industry carbonation meter, which measures dissolved CO{sub 2} based on temperature and pressure changes as the sample volume is expanded. Using a modified field protocol, the meter was found to be highly accurate in the range 0.2–35 mMCO{sub 2}. The meter provided rapid, accurate and precise measurements of dissolved CO{sub 2} in natural waters for a range of hydrochemical facies. Dissolved CO{sub 2} concentrations measured in the field with the carbonation meter were similar to CO{sub 2} determined using the pH-alkalinity approach, but provided immediate results and avoided errors from alkalinity and pH determination. The portability and ease of use of the carbonation meter in the field made it well-suited to sampling in difficult terrain. The carbonation meter has proven useful in the study of aquatic systems where CO{sub 2} degassing drives geochemical changes that result …

The microbial catalysis of Mn(II) oxidation is believed to be a dominant source of abundant sorption- and redox-active Mn oxides in marine, freshwater, and subsurface aquatic environments. In spite of their importance, environmental oxides of known biogenic origin have generally not been characterized in detail from a structural perspective. Hyporheic zone Mn oxide grain coatings at Pinal Creek, Arizona, a metals-contaminated stream, have been identified as being dominantly microbial in origin and are well studied from bulk chemistry and contaminant hydrology perspectives. This site thus presents an excellent opportunity to study the structures of terrestrial microbial Mn oxides in detail. XRD and EXAFS measurements performed in this study indicate that the hydrated Pinal Creek Mn oxide grain coatings are layer-type Mn oxides with dominantly hexagonal or pseudo-hexagonal layer symmetry. XRD and TEM measurements suggest the oxides to be nanoparticulate plates with average dimensions on the order of 11 nm thick x 35 nm diameter, but with individual particles exhibiting thickness as small as a single layer and sheets as wide as 500 nm. The hydrated oxides exhibit a 10-A basal-plane spacing and turbostratic disorder. EXAFS analyses suggest the oxides contain layer Mn(IV) site vacancy defects, and layer Mn(III) is inferred …

Soils from many industrial sites in southeastern USA arecontaminated with As because of the application of herbicide containingAs2O3. Among those contaminated sites, two industrial sites, FW and BH,which are currently active and of most serious environmental concerns,were selected to characterize the occurrence of As in the contaminatedsoils and to evaluate its environmental leachability. The soils are bothsandy loams with varying mineralogical and organic matter contents.Microwave-assisted acid digestion (EPA method 3051) of the contaminatedsoils indicated As levels of up to 325 mg/kg and 900 mg/kg (dry weightbasis) for FW and BH soils, respectively. However, bulk X-ray powderdiffraction (XRD) analysis failed to find any detectable As-bearingphases in either of the studied soil samples. Most of the soil As wasobserved by scanning electron microscopy, coupled with energy dispersiveX-ray spectroscopy (SEM/EDX), to be disseminated on the surfaces offine-grained soil particles in close association with Al and Fe. A fewAs-bearing particles were detected in BH soil using electron microprobeanalysis (EMPA). Synchrotron micro-XRD and X-ray absorption near-edgestructure (XANES) analyses indicated that these As-rich particles werepossibly phaunouxite, a mineral similar to calcium arsenate, which couldhave been formed by natural weathering after the application of As2O3.However, the scarcity of those particles eliminated them from playing anyimportant role in …