1,501 Matching Results

Search Results

Advanced search parameters have been applied.

Distinguishing Sedimentary Depositional Environments on Mars Using In-Situ Luminescence Measurements and Neural Network Analysis.

Description: Although not recognized as a true geologic period on Mars, the term 'Martian Quaternary' emerged at the 2001 LPSC. The phrase helps focus attention on the fact that Mars does indeed exhibit dynamic surface processes andd geomorphic features active on time scales less than 10{sup 6} years. As on earth evolving landscapes can serve as important storehouses for paltoclimatic and paIeoenvironmental records. However, deciphering the 'Quaternary' history of Mars will require the development of 4 new set of tools that are uniquely suited to examining youthful sediments and geomorphic features.
Date: January 1, 2001
Creator: Lepper, K. E. (Kenneth E.) & Whitley, V. H. (Von H.)
Partner: UNT Libraries Government Documents Department

Estimation of hydrologic properties of heterogeneous geologic media with an inverse method based on iterated function systems

Description: The hydrologic properties of heterogeneous geologic media are estimated by simultaneously inverting multiple observations from well-test data. A set of pressure transients observed during one or more interference tests is compared to the corresponding values obtained by numerically simulating the tests using a mathematical model. The parameters of the mathematical model are varied and the simulation repeated until a satisfactory match to the observed pressure transients is obtained, at which point the model parameters are accepted as providing a possible representation of the hydrologic property distribution. Restricting the search to parameters that represent fractal hydrologic property distributions can improve the inversion process. Far fewer parameters are needed to describe heterogeneity with a fractal geometry, improving the efficiency and robustness of the inversion. Additionally, each parameter set produces a hydrologic property distribution with a hierarchical structure, which mimics the multiple scales of heterogeneity often seen in natural geological media. Application of the IFS inverse method to synthetic interference-test data shows that the method reproduces the synthetic heterogeneity successfully for idealized heterogeneities, for geologically-realistic heterogeneities, and when the pressure data includes noise.
Date: May 1, 1996
Creator: Doughty, C.A.
Partner: UNT Libraries Government Documents Department

Establishing the Relationship between Fracture-Related Dolomite and Primary Rock Fabric on the Distribution of Reservoirs in the Michigan Basin

Description: This topical report covers the year 2 of the subject 3-year grant, evaluating the relationship between fracture-related dolomite and dolomite constrained by primary rock fabric in the 3 most prolific reservoir intervals in the Michigan Basin (Ordovician Trenton-Black River Formations; Silurian Niagara Group; and the Devonian Dundee Formation). The characterization of select dolomite reservoirs has been the major focus of our efforts in Phase II/Year 2. Fields have been prioritized based upon the availability of rock data for interpretation of depositional environments, fracture density and distribution as well as thin section, geochemical, and petrophysical analyses. Structural mapping and log analysis in the Dundee (Devonian) and Trenton/Black River (Ordovician) suggest a close spatial relationship among gross dolomite distribution and regional-scale, wrench fault related NW-SE and NE-SW structural trends. A high temperature origin for much of the dolomite in the 3 studied intervals (based upon initial fluid inclusion homogenization temperatures and stable isotopic analyses,) coupled with persistent association of this dolomite in reservoirs coincident with wrench fault-related features, is strong evidence for these reservoirs being influenced by hydrothermal dolomitization. For the Niagaran (Silurian), a comprehensive high resolution sequence stratigraphic framework has been developed for a pinnacle reef in the northern reef trend where we had 100% core coverage throughout the reef section. Major findings to date are that facies types, when analyzed at a detailed level, have direct links to reservoir porosity and permeability in these dolomites. This pattern is consistent with our original hypothesis of primary facies control on dolomitization and resulting reservoir quality at some level. The identification of distinct and predictable vertical stacking patterns within a hierarchical sequence and cycle framework provides a high degree of confidence at this point that results will be exportable throughout the basin. Ten petrophysically significant facies have been described in the northern reef ...
Date: September 30, 2006
Creator: Grammer, G. Michael
Partner: UNT Libraries Government Documents Department


Description: Work during this reporting period focused primarily on data processing in support of creation of the broadband transform function. Project participants processed seismic data and calculated attributes on that data, performed log clustering, produced a rock physics model, and completed the creation of the engineering model relating well logs and core data. These elements are essential input for the creation of the broadband transform function.
Date: January 1, 2003
Creator: Reeves, Scott R.
Partner: UNT Libraries Government Documents Department

Audio-magnetotelluric data collected in the area of Beatty, Nevada

Description: In the summer of 1997, electrical geophysical data was collected north of Beatty, Nevada. Audio-magnetotellurics (AMT) was the geophysical method used to collect 16 stations along two profiles. The purpose of this data collection was to determine the depth to the alluvial basement, based upon the needs of the geologists requesting the data.
Date: November 1, 1998
Creator: Williams, J.M.
Partner: UNT Libraries Government Documents Department

Waste package for a repository located in tuff

Description: The development of waste packages for emplacement in a tuff repository has been proceeding during the past year on a broad front. Experimental work has been focused on determination of important package environment parameters and testing the response of waste forms and package materials to the anticipated environment. Conceptual designs have been selected with alternatives to accommodate present uncertainties in the environment and material performance. Computational capabilities are being adapted to provide analyses of anticipated package performance, and plans are being developed for in-situ testing. The waste package activities have been integrated into the overall NNWSI project to assure timely completion consistent with the statutory and regulatory requirements leading to repository site selection around the end of the decade. 7 references.
Date: November 1, 1983
Creator: Ballou, L.B.
Partner: UNT Libraries Government Documents Department

Final Technical Report. Origins of subsurface microorganisms: Relating laboratory microcosm studies to a geologic time scale

Description: This project was conducted as part of the Department of Energy's Deep Subsurface Science Program. It was part of a larger effort to determine the origins of subsurface microorganisms. Two hypotheses have been suggested for the origins of subsurface microorganisms: (1) microorganisms were deposited at the time of (or shortly after) geologic deposition of rocks and sediments (the in situ survival hypothesis), and (2) microorganisms have been transported from surface environments to subsurface rocks and sediments since the time of geologic deposition (transport hypothesis). These two hypotheses are not mutually exclusive. Depending on the geological setting, either one or both of these hypotheses may best explain microbial origins. Our project focused on the in situ survival hypothesis. We tested the hypothesis that microorganisms (individuals populations and communities) can survive long-term sequestration within subsurface sediments. Other objectives were to identify geologic conditions that favor long-term survival, identify physiological traits of microorganisms that favor long-term survival, and determine which groups of microorganisms are most likely to survive long-term sequestration in subsurface sediments. We tested this hypothesis using a combination of pure culture techniques in laboratory microcosms under controlled conditions and field experiments with buried subsurface sediments.
Date: December 1, 1998
Creator: Kieft, Thomas; Amy, Penny S. & Phillips, Fred M.
Partner: UNT Libraries Government Documents Department

Heterogeneity, permeability patterns, and permeability upscaling: Physical characterization of a block of Massillon sandstone exhibiting nested scales of heterogeneity

Description: Over 75,000 permeability measurements were collected from a meter-scale block of Massillon sandstone, characterized by conspicuous cross bedding that forms two distinct nested-scales of heterogeneity. With the aid of a gas minipermeameter, spatially exhaustive fields of permeability data were acquired at each of five different sample supports (i.e. sample volumes) from each block face. These data provide a unique opportunity to physically investigate the relationship between the multi-scale cross-stratified attributes of the sandstone and the corresponding statistical characteristics of the permeability. These data also provide quantitative physical information concerning the permeability upscaling of a complex heterogeneous medium. Here, a portion of the data taken from a single block face cut normal to stratification is analyzed. Results indicate a strong relationship between the calculated summary statistics and the cross-stratified structural features visible evident in the sandstone sample. Specifically, the permeability fields and semivariograms are characterized by two nested scales of heterogeneity, including a large-scale structure defined by the cross-stratified sets (delineated by distinct bounding surfaces) and a small-scale structure defined by the low-angle cross-stratification within each set. The permeability data also provide clear evidence of upscaling. That is, each calculated summary statistic exhibits distinct and consistent trends with increasing sample support. Among these trends are an increasing mean, decreasing variance, and an increasing semivariogram range. Results also clearly indicate that the different scales of heterogeneity upscale differently, with the small-scale structure being preferentially filtered from the data while the large-scale structure is preserved. Finally, the statistical and upscaling characteristics of individual cross-stratified sets were found to be very similar owing to their shared depositional environment; however, some differences were noted that are likely the result of minor variations in the sediment load and/or flow conditions between depositional events.
Date: April 20, 2000
Partner: UNT Libraries Government Documents Department


Description: RSI has access to two synthetic seismic programs: Osiris seismic modeling system provided by Odegaard (Osiris) and synthetic seismic program, developed by SRB, implementing the Kennett method for normal incidence. Achieving virtually identical synthetic seismic traces from these different programs serves as cross-validation for both. The subsequent experiments have been performed with the Kennett normal incidence code because: We have access to the source code, which allowed us to easily control computational parameters and integrate the synthetics computations with our graphical and I/O systems. This code allows to perform computations and displays on a PC in MatLab or Octave environment, which is faster and more convenient. The normal incidence model allows us to exclude from the synthetic traces some of the physical effects that take place in 3-D models (like inhomogeneous waves) but have no relevance to the topic of our investigation, which is attenuation effects on seismic reflection and transmission.
Date: October 1, 2002
Creator: Walls, Joel; Taner, M.T.; Derzhi, Naum; Mavko, Gary & Dvorkin, Jack
Partner: UNT Libraries Government Documents Department


Description: During the third quarter a suitable test site was obtained, data acquired, and the process of data loading and data QC/QA begun. Preliminary data analysis was done in log clustering, seismic interpretation, and engineering model construction. These analysis tasks were continuing at the conclusion of the quarter.
Date: October 1, 2002
Creator: Reeves, Scott R.
Partner: UNT Libraries Government Documents Department


Description: The ''Seismic Evaluation of Hydrocarbon Saturation in Deep-Water Reservoirs'' (Grant/Cooperative Agreement DE-FC26-02NT15342) began September 1, 2002. During this second quarter: A Direct Hydrocarbon Indicator (DHI) symposium was held at UH; Current DHI methods were presented and forecasts made on future techniques; Dr. Han moved his laboratory from HARC to the University of Houston; Subcontracts were re-initiated with UH and TAMU; Theoretical and numerical modeling work began at TAMU; Geophysical Development Corp. agreed to provide petrophysical data; Negotiations were begun with Veritas GDC to obtain limited seismic data; Software licensing and training schedules were arranged with Paradigm; and Data selection and acquisition continues. The broad industry symposium on Direct Hydrocarbon Indicators was held at the University of Houston as part of this project. This meeting was well attended and well received. A large amount of information was presented, not only on application of the current state of the art, but also on expected future trends. Although acquisition of appropriate seismic data was expected to be a significant problem, progress has been made. A 3-D seismic data set from the shelf has been installed at Texas A&M University and analysis begun. Veritas GDC has expressed a willingness to provide data in the deep Gulf of Mexico. Data may also be available from TGS.
Date: March 20, 2003
Creator: Batzle, M.; Han, D-h; Gibson, R. & Djordjevic, O.
Partner: UNT Libraries Government Documents Department

Geochemical variation of Columbia River basalts beneath the Hanford Reservation, Washington

Description: Major element and trace element analyses of Columbia River basalts have been compiled to indicate where geochemical changes occur in the stratigraphy of the basalts. The analyses were averaged and plotted on petrologic variation diagrams to elucidate geochemical trends and correlations. This report is concerned mainly with the major elements. (auth)
Date: September 30, 1972
Creator: Tatman, J.B.
Partner: UNT Libraries Government Documents Department

Status of evaluation of tuff in southern Nevada for geologic disposal of high level nuclear wastes

Description: Siliceous tuff in southern Nevada occurs in a complex and locally active geological environment. Regional thrust faulting, Basin and Range faulting, and present-day seismicity complicate exploration and site characterization activities. The inherent variability of tuff and the complexity of caldera complexes also complicate siting efforts, but may serve to enhance long-term containment. Time--space trends of silicic volcanism are moderately well-established, while those of recent basaltic volcanism are not. At present, the final consequences for repository siting of the geologic complexities described in this paper are not known. Evidence from laboratory cation exchange measurements indicate that tuff and tuffaceous alluvium can serve as effective natural barriers to migration of radionuclides. This fact, coupled with multiple hydrologic barriers and long flow paths, as in the vicinity of the Nevada Test Site, might well result in tuff being a suitable medium for the safe long-term geologic disposal of nuclear wastes. Preliminary thermal modeling indicates the strong influence of varying assumptions regarding in situ fluid pressures and geothermal heat flux on acceptable initial areal power loadings.
Date: December 31, 1979
Creator: Lappin, A. R. & Crowe, B. M.
Partner: UNT Libraries Government Documents Department

Ground reaction curve based upon block theory

Description: Discontinuities in a rock mass can intersect an excavation surface to form discrete blocks (keyblocks) which can be unstable. Once a potentially unstable block is identified, the forces affecting it can be calculated to assess its stability. The normal and shear stresses on each block face before displacement are calculated using elastic theory and are modified in a nonlinear way by discontinuity deformations as the keyblock displaces. The stresses are summed into resultant forces to evaluate block stability. Since the resultant forces change with displacement, successive increments of block movement are examined to see whether the block ultimately becomes stable or fails. Two-dimensional (2D) and three-dimensional (3D) analytic models for the stability of simple pyramidal keyblocks were evaluated. Calculated stability is greater for 3D analyses than for 2D analyses. Calculated keyblock stability increases with larger in situ stress magnitudes, larger lateral stress ratios, and larger shear strengths. Discontinuity stiffness controls blocks displacement more strongly than it does stability itself. Large keyblocks are less stable than small ones, and stability increases as blocks become more slender.
Date: September 1, 1985
Creator: Yow, J.L. Jr. & Goodman, R.E.
Partner: UNT Libraries Government Documents Department

Coupled processes in single fractures, double fractures and fractured porous media

Description: The emplacement of a nuclear waste repository in a fractured porous medium provides a heat source of large dimensions over an extended period of time. It also creates a large cavity in the rock mass, changing significantly the stress field. Such major changes induce various coupled thermohydraulic, hydromechanic and hydrochemical transport processes in the environment around a nuclear waste repository. The present paper gives, first, a general overview of the coupled processes involving thermal, mechanical, hydrological and chemical effects. Then investigations of a number of specific coupled processes are described in the context of fluid flow and transport in a single fracture, two intersecting fractures and a fractured porous medium near a nuclear waste repository. The results are presented and discussed.
Date: December 1, 1986
Creator: Tsang, C.F.
Partner: UNT Libraries Government Documents Department

Evaluation of tuff as a medium for a nuclear waste repository: interim status report on the properties of tuff

Description: This report is the second in a series of summary briefings to the National Academy of Science`s (NAS) Committee on Radioactive Waste Management dealing with feasibility of disposal of heat-producing radioactive waste in silicic tuff. The interim status of studies of tuff properties determined on samples obtained from Yucca Mountain and Rainier Mesa (G-tunnel) located on the Nevada Test Site (NTS) are discussed. In particular, progress is described on resolving issues identified during the first briefing to the NAS which include behavior of water in tuff when heated, the effect of the presence or absence of water and joints on the thermal/physical properties of tuff and the detailed/complex sorptive properties of highly altered and unaltered tuff. Initial correlations of thermal/physical and sorptive properties with the highly variable porosity and mineralogy are described. Three in-situ, at-depth field experiments, one nearly completed and two just getting underway are described. In particular, the current status of mineralogy and petrology, geochemistry, thermal and mechanical, radiation effects and water behavior studies are described. The goals and initial results of a Mine Design Working Group are discussed. Regional factors such as seismicity, volcanism and hydrology are not discussed.
Date: July 1, 1980
Creator: Johnstone, J.K. & Wolfsberg, K. (eds.)
Partner: UNT Libraries Government Documents Department

Mechanical modeling of nuclear waste disposal in argillite at the Nevada Test Site

Description: Numerical calculations for a near surface heater experiment in argillite conducted at the Nevada Test Site were performed using the finite element code ADINA assuming a two-dimensional axisymmetric geometry. The existence and extent of the region of tensional opening of joints surrounding the heater, predicted by the mechanical model, were confirmed by posttest borehole inspection, permeability measurements, and drillback. Exrapolation of near surface heater model to repository depths reveals the necessity for prior knowledge of the mechanical properties and state of stress in-situ. The extent of the joint opening zone, for example, is not altered by changes in the elastic modulus at the near surface, but is significantly decreased beyond certain depths depending upon the in-situ elastic modulus. Results of these calculations are presented. To further define the behavior at depth, and place bounds on the joint opening zone, far-field calculations were performed for a generic repository in argillite. Both spent fuel and high level waste heat sources were considered at different burial densities and depths. Results of a parametric study are presented in which the mechanical properties, in-situ stresses, and waste heat sources were varied.
Date: December 31, 1979
Creator: Thomas, R.K. & Lappin, A.R.
Partner: UNT Libraries Government Documents Department

Modeling of strongly heat-driven flow in partially saturated fractured porous media

Description: We have performed modeling studies on the simultaneous transport of heat, liquid water, vapor, and air in partially saturated fractured porous media, with particular emphasis on strongly heat-driven flow. The presence of fractures makes the transport problem very complex, both in terms of flow geometry and physics. The numerical simulator used for our flow calculations takes into account most of the physical effects which are important in multi-phase fluid and heat flow. It has provisions to handle the extreme non-linearities which arise in phase transitions, component disappearances, and capillary discontinuities at fracture faces. We model a region around an infinite linear string of nuclear waste canisters, taking into account both the discrete fractures and the porous matrix. From an analysis of the results obtained with explicit fractures, we develop equivalent continuum models which can reproduce the temperature, saturation, and pressure variation, and gas and liquid flow rates of the discrete fracture-porous matrix calculations. The equivalent continuum approach makes use of a generalized relative permeability concept to take into account for fracture effects. This results in a substantial simplification of the flow problem which makes larger scale modeling of complicated unsaturated fractured porous systems feasible. Potential applications for regional scale simulations and limitations of the continuum approach are discussed. 27 references, 13 figures, 2 tables.
Date: October 1, 1984
Creator: Pruess, K.; Tsang, Y.W. & Wang, J.S.Y.
Partner: UNT Libraries Government Documents Department