16 Matching Results

Search Results

Advanced search parameters have been applied.

Seismic and Rockphysics Diagnostics of Multiscale Reservoir Textures

Description: As part of our study on ''Relationships between seismic properties and rock microstructure'', we have studied (1) Kerogen-rich shales using Scanning Acoustic Microscopy and ultrasonic wave propagation. We find that an increase in elastic modulus with increasing kerogen maturity can be directly related to the microstructural acoustic impedance changes. A positive relation is established between microstructural changes and velocity variations as functions of kerogen maturity. (2) Elastic properties of clay minerals using Atomic Force Acoustic Microscopy and Scanning Acoustic Microscopy. We show the effect of clay minerals in contact zones as load-bearing constituents of rocks (3) Elastic properties of unconsolidated sediments in an effort to quantify attributes for detection of overpressures from seismic and for effects of stress-induced velocity anisotropy in sediments (4) We have initiated efforts for velocity upscaling to quantify long-wavelength and short-wavelength velocity behavior and the scale-dependent dispersion caused by sediment variability in different depositional environments.
Date: November 1, 2002
Creator: Mavko, Gary
Partner: UNT Libraries Government Documents Department

HEAVY AND THERMAL OIL RECOVERY PRODUCTION MECHANISMS

Description: The Stanford University Petroleum Research Institute (SUPRI-A) conducts a broad spectrum of research intended to help improve the recovery efficiency from difficult to produce reservoirs including heavy oil and fractured low permeability systems. Our scope of work is relevant across near-, mid-, and long-term time frames. The primary functions of the group are to conduct direction-setting research, transfer research results to industry, and educate and train students for careers in industry. Presently, research in SUPRI-A is divided into 5 main project areas. These projects and their goals include: (1) Multiphase flow and rock properties--to develop better understanding of the physics of displacement in porous media through experiment and theory. This category includes work on imbibition, flow in fractured media, and the effect of temperature on relative permeability and capillary pressure. (2) Hot fluid injection--to improve the application of nonconventional wells for enhanced oil recovery and elucidate the mechanisms of steamdrive in low permeability, fractured porous media. (3) Mechanisms of primary heavy oil recovery--to develop a mechanistic understanding of so-called ''foamy oil'' and its associated physical chemistry. (4) In-situ combustion--to evaluate the effect of different reservoir parameters on the insitu combustion process. (5) Reservoir definition--to develop and improve techniques for evaluating formation properties from production information. What follows is a report on activities for the past year. Significant progress was made in all areas.
Date: September 30, 2002
Creator: Kovscek, Anthony R. & Castanier, Louis M.
Partner: UNT Libraries Government Documents Department

HIGH RESOLUTION PREDICTION OF GAS INJECTION PROCESS PERFORMANCE FOR HETEROGENEOUS RESERVOIRS

Description: This report outlines progress in the first quarter of the third year of the DOE project ''High Resolution Prediction of Gas Injection Process Performance for Heterogeneous Reservoirs''. In this report we present an application of compositional streamline simulation in modeling enhanced condensate recovery via gas injection. These processes are inherently compositional and detailed compositional fluid descriptions must be use to represent the flow behavior accurately. Compositional streamline simulation results are compared to those of conventional finite-difference (FD) simulation for evaluation of gas injection schemes in condensate reservoirs. We present and compare streamline and FD results for two-dimensional (2D) and three-dimensional (3D) examples, to show that the compositional streamline method is a way to obtain efficiently estimates of reasonable accuracy for condensate recovery by gas injection.
Date: December 31, 2002
Creator: Franklin M. Orr, Jr.
Partner: UNT Libraries Government Documents Department

Biodegradation of Chlorinated Solvents: Reactions near DNAPL and Enzyme Function

Description: The anaerobic biodegradation of chlorinated solvents is of great interest both for natural attenuation and for engineered remediation of these hazardous contaminants in groundwater. Compounds to be studied are carbon tetrachloride (CT) and the chlorinated ethenes, tetrachloroethene (PCE), trichloroethene (TCE) cis-1,2-dichloroethene (cDCE), and vinyl chloride (VC). The chlorinated solvents often are present as dense non-aqueous-phase liquids (DNAPLs), which are difficult to remove. Biodegradation of DNAPLs was previously thought not possible because of toxicity, but recent evidence indicates that under the right conditions, biodegradation is possible. Anaerobic biodegradation of DNAPLs is the major subject of this research. The specific objectives of this multi-investigator effort are: (1) Evaluate the potential for chlorinated solvent biodegradation near DNAPLs, (2) Provide a molecular understanding of the biological mechanisms involved, (3) Determine cellular components involved in carbon tetrachloride transformation by Pseudomonas stutzeri strain KC without chloroform formation.
Date: June 1, 2002
Creator: McCarty, Perry L.; Spormann, Alfred M. & Criddle, Craig S.
Partner: UNT Libraries Government Documents Department

The Influence of Calcium Carbonate Grain Coatings on Contaminant Reactivity in Vadose Zone Sediments

Description: The primary objective of this project is to investigate the role of calcium carbonate grain coatings on adsorption and heterogeneous reduction reactions of key chemical and radioactive contaminants in sediments on the Hanford Site. Research will ascertain whether these coatings promote or discourage contaminant reaction with sediment mineral particles, and whether calcium carbonate phases resulting from waste-sediment reaction sequester contaminants through coprecipitation. The research will provide new conceptual models of contaminant reaction/retardation processes in Hanford sediments (for 90Sr2+ and Cr(VI)O4 2- primarily) and improved geochemical models to forecast the future behavior of in-ground contaminants.
Date: June 1, 2002
Creator: Zachar, John M.; Chambers, Scott; Brown Jr, Gordon E. & Eggleston, Carrick M.
Partner: UNT Libraries Government Documents Department

The Role of Biogenic Solids in Thereductive Stabilization of Metal Contaminats: Influences Onmicrobial Versus Chemical Pathways and Reaction Products

Description: In situ stabilization of toxic metals and radionuclides such as chromium and uranium is an attractive approach for remediating many contaminated DOE sites. To enhance in situ remediation, microbiological reductive stabilization of contaminant metals has been, and continues to be, actively explored. It is likely that surface and subsurface microbial activity can alter the redox state of toxic metals and radionuclides so they are rendered immobile. The reaction products and their stability will depend on the specific mechanism by which reduction takes place--the focus of this work. Uranium and Cr exist in more than one oxidation state in the surface- and near-surface environment; different oxidation states of these elements have markedly different properties. The fully oxidized species of Cr and U, both hexavalent forms, have a high solubility in soils and groundwaters, and consequently they tend to be mobile in the environment. Chromate is also subject to biological uptake, a factor that contributes to its toxicity. In contrast, the reduced form of chromium, Cr(III), has a limited hydroxide solubility and forms strong complexes with soil minerals, it is therefore less mobile and has a lower bioavailability than Cr(VI). Similarly, the oxidized forms of U have a greater solubility and hence exhibit greater mobility in soils and subsurface environments than either U(VI) or U(V). They may conclude that oxidized forms of these radionuclides and metals are subject to enhanced migration through surface and subsurface environments. Reductive stabilization is therefore a desirable pathway for these elements.
Date: August 31, 2002
Creator: Fendrof, Scott
Partner: UNT Libraries Government Documents Department

Microbially Mediated Immobilization of Contaminants Through In Situ Biostimulation: Scale up of EMSP project 55267

Description: The overall goal of the proposed research is to provide an improved understanding and predictive capability of the mechanisms that allow metal-reducing bacteria to be effective in the bioremediation of redox sensitive toxic metals and radionuclides. The study is motivated by the likelihood that subsurface metal-reducing bacteria can be stimulated to effectively alter the redox state of contaminants so that they are immobilized in situ for long time periods. The work described in this proposal will advance the technological and scientific needs associated with the long-term management of the enormous inground inventories of Cr, U, Tc, and Co present at numerous DOE installations throughout the country. The objectives of our project are to (1) develop an improved understanding and predictive capability of the rates and mechanisms controlling microbially mediated reduction of toxic metals and radionuclides in heterogeneous field settings, (2) quantify the impacts of hydrological and geochemical processes on the effectiveness of indigenous microorganisms to transform and immobilize radionuclides and metals in situ, (3) provide an improved understanding of the importance of microbial consortia interactions in the bacterial immobilization of radionuclides and toxic metals, and (4) determine intrinsic bioreduction rate parameters to improve our generic predictive capability of in situ microbially metal reduction.
Date: June 28, 2002
Creator: Jardin, Philip M.; Brooks, Scott C. & Fendorf, Scott E.
Partner: UNT Libraries Government Documents Department

The Use of Radar Methods to Determine Moisture Content in the Vadose Zone

Description: Moisture content is a critical parameter affecting both liquid-phase and vapor-phase contaminant transport in the vadose zone. The objective of our three-year research project is to determine the optimal way to use radar methods as a non-invasive means of determining in situ moisture content.
Date: June 1, 2002
Creator: Knight, Rosemary
Partner: UNT Libraries Government Documents Department

HIGH RESOLUTION PREDICTION OF GAS INJECTION PROCESS PERFORMANCE FOR HETEROGENEOUS RESERVOIRS

Description: This report outlines progress in the third quarter of the second year of the DOE project ''High Resolution Prediction of Gas Injection Process Performance for Heterogeneous Reservoirs''. High order finite difference schemes for one-dimensional, two-phase, multicomponent displacements are investigated. Numerical tests are run using a three component fluid description for a case when the interaction between phase behavior and flow is strong. Some currently used total variation diminishing (TVD) methods produce unstable results. A third order essentially non-oscillatory (ENO) method captures the effects of phase behavior for this test case. Possible modifications to ensure stability are discussed along with plans to incorporate higher order schemes into the 3DSL streamline simulator.
Date: June 30, 2002
Creator: Franklin M. Orr, Jr.
Partner: UNT Libraries Government Documents Department

HIGH RESOLUTION PREDICTION OF GAS INJECTION PROCESS PERFORMANCE FOR HETEROGENEOUS RESERVOIRS

Description: This report outlines progress in the second quarter of the second year of the DOE project ''High Resolution Prediction of Gas Injection Process Performance for Heterogeneous Reservoirs''. A three-dimensional streamline simulator, developed at Stanford University, has been modified in order to use analytical one-dimensional dispersion-free solutions to multicomponent gas injection processes. The use of analytical one-dimensional solutions in combination with streamline simulation is demonstrated to speedup compositional simulations of miscible gas injection processes by orders of magnitude compared to a conventional finite difference simulator. Two-dimensional and three-dimensional examples are reported to demonstrate the potential of this technology. Finally, the assumptions of the approach and possible extensions to include the effects of gravity are discussed.
Date: March 31, 2002
Creator: Franklin M. Orr, Jr.
Partner: UNT Libraries Government Documents Department

SEISMIC AND ROCK PHYSICS DIAGNOSTICS OF MULTISCALE RESERVOIR TEXTURES

Description: As part of our study on ''Relationships between seismic properties and rock microstructure'', we have studied (1) How to quantify elastic properties of clay minerals using Atomic Force Acoustic Microscopy. We show how bulk modulus of clay can be measured using atomic force acoustic microscopy (AFAM) (2) We have successfully measured elastic properties of unconsolidated sediments in an effort to quantify attributes for detection of overpressures from seismic (3) We have initiated efforts for velocity upscaling to quantify long-wavelength and short-wavelength velocity behavior and the scale-dependent dispersion caused by sediment variability in different depositional environments.
Date: May 1, 2002
Creator: Mavko, Gary
Partner: UNT Libraries Government Documents Department

HEAVY AND THERMAL OIL RECOVERY PRODUCTION MECHANISMS

Description: This technical progress report describes work performed from April 1 through June 30, 2002, for the project ''Heavy and Thermal Oil Recovery Production Mechanisms.'' We investigate a broad spectrum of topics related to thermal and heavy-oil recovery. Significant results were obtained in the areas of multiphase flow and rock properties, hot-fluid injection, improved primary heavy oil recovery, and reservoir definition. The research tools and techniques used are varied and span from pore-level imaging of multiphase fluid flow to definition of reservoir-scale features through streamline-based history-matching techniques. Briefly, experiments were conducted to image at the pore level matrix-to-fracture production of oil from a fractured porous medium. This project is ongoing. A simulation studied was completed in the area of recovery processes during steam injection into fractured porous media. We continued to study experimentally heavy-oil production mechanisms from relatively low permeability rocks under conditions of high pressure and high temperature. High temperature significantly increased oil recovery rate and decreased residual oil saturation. Also in the area of imaging production processes in laboratory-scale cores, we use CT to study the process of gas-phase formation during solution gas drive in viscous oils. Results from recent experiments are reported here. Finally, a project was completed that uses the producing water-oil ratio to define reservoir heterogeneity and integrate production history into a reservoir model using streamline properties.
Date: July 1, 2002
Creator: Kovscek, Anthony R.
Partner: UNT Libraries Government Documents Department

MECHANISMS OF PYRITE OXIDATION TO NON-SLAGGING SPECIES

Description: A project was undertaken to characterize the oxidation of iron pyrite to the non-slagging species magnetite during pulverized coal combustion. The work was aimed at defining the pyrite transformations responsible for the higher slagging propensity of staged, low-NO{sub x} pulverized coal combustor burners. With such burners, coal is injected into a reducing environment. Consequently, the products of pyrite combustion become shifted from non-depositing, oxidized species such as Fe{sub 3}O{sub 4} to highly-depositing, reduced species such as FeO and Fe{sub 1-x}S, where x ranges from 0 to 0.125. The propensity for slagging can be minimized by the judicious redistribution of furnace air to maximize the oxide formation rate. This must be accomplished with minimal degradation of other aspects of boiler performance. To effect this, an understanding of the rate-limiting mechanisms of pyrite oxidation is required. The overall objectives of this project were to characterize the various mechanisms that control overall pyrite combustion rates and to synthesize the mechanisms into a pyrite combustion model. These objectives were achieved. The model produced has the capability of being incorporated into numerical codes developed to predict phenomena occurring in coal-fired boilers and furnaces. Such comprehensive codes can be used to formulate and test strategies for enhancing pyrite transformation rates that involve the minor adjustment of firing conditions. Ultimately, the benefit of this research project is intended to be an increase in the range of coals compatible with staged, low-NO{sub x} combustor retrofits. Project activities were aimed at identifying the mechanisms of pyrite combustion and quantifying their effects on the overall oxidation rate in order to formulate a model for pyrite conversion during coal combustion. Chemical and physical processes requiring characterization included pyrite intraparticle kinetics and mass transfer, gas-phase kinetics and mass transfer, and carbon matrix kinetics and mass transfer.
Date: September 1, 2002
Creator: Mitchell, Professor Reginald E.
Partner: UNT Libraries Government Documents Department

Relative Permeability of Fractured Rock

Description: Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.
Date: June 30, 2002
Creator: Habana, Mark D.
Partner: UNT Libraries Government Documents Department

Fate and Transport of Radionuclides Beneath the Hanford Tank Farms: Unraveling Coupled Geochemical and Hydrological Processes in the Vadose Zone

Description: The overall goal of this research is to provide an improved understanding and predictive capability of coupled hydrological and geochemical mechanisms that are responsible for the accelerated migration of radionuclides in the vadose zone beneath the Hanford Tank Farms. The study is motivated by the technological and scientific needs associated with the long-term management of the enormous in-ground inventories of multiple contaminants at the Hanford site. Our objectives are to (1) provide an improved understanding of how lithological discontinuities within the sediments influence the propensity for preferential flow and matrix diffusion at different water contents, (2) quantify the significance of downward vertical advection, lateral spreading, and physical nonequilibrium processes on radionuclide transport under variable hydrologic conditions, and (3) quantify the rates and mechanisms of {sup 137}Cs, {sup 235/238}U, and {sup 99}Tc interaction with the solid phase under various hydrodynamic conditions and to determine how physical heterogeneities (i.e. stratification, pore regime connectivity) influence the retardation and degree of geochemical nonequilibrium during contaminant transport.
Date: June 1, 2002
Creator: Jardine, Philip M.; Ainsworth, Calvin C. & Fendorf, Scott
Partner: UNT Libraries Government Documents Department