We examine how quantitative rock physics models, such as effective medium theories, can improve the interpretation of seismic parameters and material and fluid properties at The Geysers. We use effective medium theories to estimate effects of fractures on velocities for The Geysers rocks. We compare theoretical velocity estimates to laboratory measurements from the literature and our seismic velocity values from 1992 earthquake data. We approximate the reservoir as being homogeneous in mineral composition, with a constant density of fractures whose total void ratio is reduced by lithostatic pressure. Thus, we expect low velocities near the surface, increasing with depth up to the values observed in the lab on intact samples, 5.5 - 5.7 km/sec. We use a one-dimensional inversion of P-waves to obtain an ''expected'' P-wave velocity (Vp) and attenuation (Qp) relation as a function of depth for The Geysers rocks. We then use a three-dimensional Vp and Qp inversion to find anomalous zones within the reservoir. We find portions with ''high'' Vp and Qp, high Vp and low Qp, and low Vp and low Qp. We interpret the regions with high Vp and Qp to be relatively less fractured, and the regions with low Vp and Qp to be …

Hydrothermal alteration and the active vapor-dominated geothermal system at The Geysers, CA are related to a composite hypabyssal granitic pluton emplaced beneath the field 1.1 to 1.2 million years ago. Deep drill holes provide a complete transect across the thermal system and samples of the modem-day steam. The hydrothermal system was liquid-dominated prior to formation of the modem vapor-dominated regime at 0.25 to 0.28 Ma. Maximum temperatures and salinities ranged from 440 C and 44 wt. percent NaCl equivalent in the biotite hornfels adjacent to the pluton to 305 C and 5 wt. percent NaCl equivalent at distances of 1730 m from the intrusive contact. The major, minor, and noble gas compositions of fluid inclusions in the hydrothermally altered rocks were integrated with microthermometric and mineralogic data to determine their sources and the effects of mixing and boiling. Major and minor gaseous species were released from the inclusions by crushing or thermal decrepitation; noble gases were released by crushing. The samples were analyzed by mass spectrometry. The analyses document the presence of magmatic, crustal, and meteoric components in the trapped fluids. Hydrothermal fluids present during the liquid-dominated phase of the system contained gaseous species derived mainly from crustal and magmatic …

A workshop entitled ''Radionuclide Contamination in Water Resources'' was held in Almaty, Kazakhstan from Tuesday 29 May through Friday 1 June. This workshop was co-sponsored by the U.S. Department of Energy, Lawrence Livermore National Laboratory, and three organizations from the Republic of Kazakhstan: the Institute of Nonproliferation, the Institute of Hydrogeology and Hydrophysics, and KazAtomProm. Representatives from the U.S. Department of Energy, three national laboratories, and 13 different organizations from the Republic of Kazakhstan attended the workshop. A complete list of attendees, the workshop program, and information on the background and motivation for this workshop are provided in this report. The objective of the workshop was to identify critical problems, discover what is known about the problems related to radionuclide contamination of groundwater resources, form collaborative teams, and produce a small number proposals that both address further characterization and assess risk via contaminant fate and transport modeling. We plan to present these proposals to U.S. government agencies and international sponsors for funding.

Lowering the costs of front-end processes in the geologic sequestration of CO{sub 2} can dramatically lower the overall costs. One approach is to sequester less-pure CO{sub 2} waste streams that are less expensive or require less energy to separate from flue gas, a coal gasification process, etc. The objective of this research is to evaluate the impacts of an impure CO{sub 2} waste stream on geologic sequestration using both reaction progress and reactive transport simulators. The simulators serve as numerical laboratories within which a series of computational experiments can be designed, carried out, and analyzed to quantify sensitivity of the overall injection/sequestration process to specific compositional, hydrologic, structural, thermodynamic, and kinetic parameters associated with the injection fluid and subsurface environment.

We are creating a new method of combining disparate types of geologic observations and process simulations. Using Bayesian inferencing and an efficient search algorithm, we obtain a consolidated body of knowledge in the form of multiple configurations and parameter values of the system that are consistent with our existing data and process models. In so doing, we effectively estimate the distributions of both individual parameters and system-wide states, and their likelihood of occurrence. This is in contrast with conventional inversion methods, which produce a single deterministic understanding lacking quantitative information about the distribution of uncertainty. We call this combination of probabilistic evaluation and deterministic process simulators the stochastic engine. Our approach allows the investigators to rapidly improve their understanding of system progress, making it particularly valuable for active processes like injection. The Bayesian inferencing is driven by forward process models that predict data values, such as temperature or electrical voltage, for direct comparison to measured field values. We stage the stochastic searches of possible configurations and run the simplest models, such as lithology estimators, at the lower stages. The majority of possible configurations are eliminated from further consideration by the higher stages' more complex models, such as electrical resistance models …

Article wherein James and Virginia Marshall visit Manaccan, England, to explore the site where titanium was first discovered. The area is described, as well as the man who discovered titanium, Reverend William Gregor.

This article discusses the use of creased-plastic permeameters as an inexpensive way for students to estimate the hydraulic conductivity of local rock aquifers.

Program and abstracts for the second international nitrogen conference

Pleistocene ground-water discharge deposits approximately 20 km southwest of Yucca Mountain were previously thought to represent pluvial water-table rises of 80 to 120 m. Data from new boreholes at two of the three discharge sites indicate that the modern water-table is at depths of only 17 to 30 m and that this shallow water is part of the regional ground-water flow system rather than being perched. Calcite in equilibrium with this modern ground water would have isotopic compositions similar to those in Pleistocene calcite associated with the discharge deposits. Carbon and uranium isotopes in both ground water and discharge deposits imply that past discharge consisted of a mixture of both shallow and deep ground water. These data limit Pleistocene water-table fluctuations at the specified Amargosa Desert discharge sites to between 17 and 30 m and eliminate the need to invoke large water-table rises.

A 3-D hydrostratigraphic framework model has been built for the use of hydrologic modelers who are tasked with developing a model to determine how contaminants are transported by groundwater flow in an area of complex geology. The area of interest includes Pahute Mesa, a former nuclear testing area at the Nevada Test Site (NTS), and Oasis Valley, a groundwater discharge area down-gradient from contaminant source areas on Pahute Mesa. To build the framework model, the NTS hydrogeologic framework was integrated with an extensive collection of drill-hole data (stratigraphic, lithologic, and alteration data); a structural model; and several recent geophysical, geological, and hydrological studies to formulate a hydrostratigraphic system. The authors organized the Tertiary volcanic units in the study area into 40 hydrostratigraphic units that include 16 aquifers, 13 confining units, and 11 composite units. The underlying pre-Tertiary rocks were divided into six hydrostratigraphic units, including two aquifers and four confining units. The model depicts the thickness, extent, and geometric relationships of these hydrostratigraphic units (''layers'' in the model) along with all the major structural features that control them, including calderas and faults. The complexity of the model area and the non-uniqueness of some of the interpretations incorporated into the base …

The broad range of activities on radioactive waste isolation that are summarized in Table 1.1 provides a comprehensive picture of the operations that must be carried out in working with this problem. A comparison of these activities with those published in the two previous reviews shows the important progress that is being made in developing and applying the various technologies that have evolved over the past 20 years. There are two basic challenges in perfecting a system of radioactive waste isolation: choosing an appropriate geologic barrier and designing an effective engineered barrier. One of the most important developments that is evident in a large number of the reports in this review is the recognition that a URL provides an excellent facility for investigating and characterizing a rock mass. Moreover, a URL, once developed, provides a convenient facility for two or more countries to conduct joint investigations. This review describes a number of cooperative projects that have been organized in Europe to take advantage of this kind of a facility in conducting research underground. Another critical development is the design of the waste canister (and its accessory equipment) for the engineered barrier. This design problem has been given considerable attention in …

Osmosis has been cited as a mechanism for explaining anomalously high fluid pressures in the subsurface. Clays and shales act as membranes, and osmotic flux across these units may result in pressures sufficiently high to explain these anomalies. The theoretical osmotic pressures as calculated solely from solution properties can be quite large; however, it is not yet resolved whether these geologic membranes are sufficiently ideal to generate such pressures.

The capacity of fluvial brine-bearing formations to sequester CO{sub 2} is investigated using numerical simulations of CO{sub 2} injection and storage. Capacity is defined as the volume fraction of the subsurface available for CO{sub 2} storage and is conceptualized as a product of factors that account for two-phase flow and transport processes, formation geometry, formation heterogeneity, and formation porosity. The space and time domains used to define capacity must be chosen with care to obtain meaningful results, especially when comparing different authors' work. Physical factors that impact capacity include permeability anisotropy and relative permeability to CO{sub 2}, brine/CO{sub 2} density and viscosity ratios, the shape of the trapping structure, formation porosity and the presence of low-permeability layering.

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The purpose of this study is to compare elemental analyses of river waters from the southeastern US with existing data on elemental concentrations within the river drainage basins to determine how uranium and lanthanide elements are transported.

These proceedings contain papers prepared for the 23rd Seismic Research Review: Worldwide Monitoring of Nuclear Explosions, held 2-5 October, 2001 in Jackson Hole, Wyoming. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Defense Threat Reduction Agency (DTRA), Air Force Technical Applications Center (AFTAC), the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

The 2001 Proceedings include various papers regarding different areas of hydrogen-related research.