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Seismic imaging of reservoir flow properties: Resolving waterinflux and reservoir permeability

Description: Methods for geophysical model assessment, in particuale thecomputation of model parameter resolution, indicate the value and thelimitations of time-lapse data in estimating reservoir flow properties. Atrajectory-based method for computing sensitivities provides an effectivemeans to compute model parameter resolutions. We examine the commonsituation in which water encroaches into a resrvoir from below, as due tothe upward movement of an oil-water contact. Using straight-forwardtechniques we find that, by inclusing reflections off the top and bottomof a reservoir tens of meters thick, we can infer reservoir permeabilitybased upon time-lapse data. We find that, for the caseof water influxfrom below, using multiple time-lapse 'snapshots' does not necessarilyimprove the resolution of reservoir permeability. An application totime-lapse data from the Norne field illustrates that we can resolve thepermeability near a producing well using reflections from threeinterfaces associated with the reservoir.
Date: November 27, 2006
Creator: Vasco, D.W. & Keers, Henk
Partner: UNT Libraries Government Documents Department

Water Imbibition into Rock as Affected by Sample Shape, Pore, Conductivity, and Antecedent Water Content

Description: Infiltration is often presumed to follow Philip's equation, I = st{sup 1/2}, where I is cumulative infiltration, s is sorptivity, and t is time. This form of the equation is appropriate for short times, and/or for negligible gravitational effects. For a uniform soil, this equation describes a plot of log(mass imbibed) versus log(time), with a slope (imbibition exponent) of 1/2. The equation has also been applied to low-porosity rocks, where the extremely small pores render gravitational forces negligible. Experiments recently performed on a wide variety of rocks produced imbibition exponents from 0.2 to 0.5. Many rock types showed initial imbibition proceeding as I {approx} t{sup 1/4}, then later switched to ''normal'' (t{sup 1/2}) behavior. The distance to the wetting front that corresponds to this cross-over behavior was found to be related to the sample shape: tall thin samples are more likely to exhibit the exponent 1/4, and to cross over to 1/2-type behavior later, while short, squat samples are less likely to display the 1/4-type behavior at all. Additionally, the exponents are sensitive to antecedent water content, with initially wetter samples having smaller values. In this study, we present the experimental data, and provide a consistent and physically-based explanation using percolation theory. The analogy between imbibition and diffusion is used to model imbibition into samples with low pore connectivity, with the exponents and their crossover behavior emerging from a random walk process. All laboratory phenomena--different exponents, crossover behavior, and effects of sample shape and antecedent water content--are reproduced by the model, with similar patterns across experiment and simulation. We conclude both that diffusion is a useful and powerful conceptual model for understanding imbibition, and also that imbibition experiments, being simpler than diffusion measurements, can be used to examine diffusive behavior in rock.
Date: August 29, 2005
Creator: Ewing, R.P.
Partner: UNT Libraries Government Documents Department

Stochastic analysis of well capture zones in heterogeneous porous media

Description: In this study we present a moment-equation-based approach to derive the time-dependent mean capture zones and their associated uncertainties. The flow statistics are obtained by solving the first two moments of flow, and the mean capture zones are determined by reversely tracking the non-reactive particles released at a small circle around each pumping well. The uncertainty associated with the mean capture zones is calculated based on the particle displacement covariance for nonstationary flow fields. For comparison purpose, we also conducted Monte Carlo simulations. It has been found that our model results are in good agreement with Monte Carlo results.
Date: January 1, 2002
Creator: Zhang, D. (Dongxiao) & Lu, Z. (Zhiming)
Partner: UNT Libraries Government Documents Department

Calculation of discrete fracture flow paths in dual-continuum models

Description: Movement of water through fractures plays an important role in performance assessments of the potential high-level nuclear waste repository at Yucca Mountain, Nevada. The magnitude and frequency of water flowing through individual fractures impacts predictions of the near-field environment and waste-package corrosion. Discrete fracture flow paths, referred to as ``weeps``, have been derived from dual continuum models of fracture flow. The required parameters include the geometric fracture spacing, an assumed width of each weep, and a scaling factor that accounts for reduced flow between fracture and matrix elements in dual continuum models. The formulation provides a convenient means to determine discrete weep spacing and flow rates that are mathematically consistent with the dual continuum model. Specific applications and examples related to seepage into drifts are also discussed.
Date: December 1, 1997
Creator: Ho, C.K. & Wilson, M.L.
Partner: UNT Libraries Government Documents Department

A Semi-Analytical Solution for Steady Infiltration in Unsaturated Fractured Rock

Description: A semi-analytical solution is developed for one-dimensional steady infiltration in unsaturated fractured rock. The differential form of the mass conservation equation is integrated to yield an analytical expression relating elevation to a function of capillary pressure and relative permeability of the fracture and rock matrix. Constitutive relationships for unsaturated flow in this analysis are taken from van Genuchten [1980] and Mualem [1976], but alternative relations can also be implemented in the integral solution. Expressions are presented for the liquid saturations and pore velocities in the fracture, matrix, and effective continuum materials as a function of capillary pressure and elevation. Results of the analytical solution are applied to examples of infiltration in fractured rock consisting of both homogeneous and composite (layered) domains. The analytical results are also compared to numerical simulations to demonstrate the use of the analytical solution as a benchmarking tool to address computational issues such as grid refinement.
Date: December 19, 2000
Creator: HO,CLIFFORD K.
Partner: UNT Libraries Government Documents Department

Electrical resistance tomography for monitoring the infiltration of water into a pavement section

Description: Electrical resistance tomography (ERT) was used to follow the infiltration of water into pavement section at the UC Berkeley Richmond Field Station. A volume of pavement 1m square and 1.29 m deep was sampled by an ERT array consisting of electrodes in 9 drilled holes plus 8 surface electrodes. The data were collected using a computer controlled data acquisition system capable of collecting a full data set in under 1 hour, allowing for nearly real time sampling of the infiltration. The infiltration was conducted in two phases. During the first phase, water was introduced into the asphalt-concrete (AC) layers at a slow rate of about 8 ml per hour for a period of about 6 days. In the second phase, water was introduced into the asphalt-treated-permeable base (ATPB) layer at a more rapid rate of about 100 ml/h for about 2 days. The ERT images show that water introduced into the upper AC layers shows up as a decrease in resistivity which grows with time. The images also appear to show that when water moves into the layers below the ATPB, the resistivity increases; an unexpected result. There are some indications that the water moved laterally as well as down into the deeper ATPB and the aggregate base. The images also show that when water is introduced directly into the ATPB and aggregate layer, the water moves into the the underlying materials much more quickly.
Date: July 3, 1997
Creator: Buettner, M.; Daily, B. & Ramirez, A.
Partner: UNT Libraries Government Documents Department

Effects of inflow on NuMI groundwater concentrations

Description: Recent discussions of the NuMI groundwater problem have been concerned with the effect of inflow of water into the tunnel on the overall groundwater concentration. The purpose of this note is to document calculations of these effects using simple mathematical models. These results can, then, be compared with the results obtained using more elaborate methods such as computer modeling techniques. At Fermilab, a concentration model has been developed to address groundwater activation concerns. While this model has evolved to some degree over time, the main features have remained stable.
Date: September 8, 1999
Creator: Cossairt, J. Donald
Partner: UNT Libraries Government Documents Department

Water Influx, and Its Effect on Oil Recovery: Part 1. Aquifer Flow, SUPRI TR-103

Description: Natural water encroachment is commonly seen in many oil and gas reservoirs. In fact, overall, there is more water than oil produced from oil reservoirs worldwide. Thus it is clear that an understanding of reservoir/aquifer interaction can be an important aspect of reservoir management to optimize recovery of hydrocarbons. Although the mathematics of these processes are difficult, they are often amenable to analytical solution and diagnosis. Thus this will be the ultimate goal of a series of reports on this subject. This first report deals only with aquifer behavior, so it does not address these important reservoir/aquifer issues. However, it is an important prelude to them, for the insight gained gives important clues on how to address reservoir/aquifer problems. In general when looking at aquifer flow, there are two convenient inner boundary conditions that can be considered; constant pressure or constant flow rate. There are three outer boundary conditions that are convenient to consider; infinite, closed and constant pressure. And there are three geometries that can be solved reasonably easily; linear, radial and spherical. Thus there are a total of eighteen different solutions that can be analyzed.
Date: August 9, 1999
Creator: Brigham, William E.
Partner: UNT Libraries Government Documents Department

Origin, diagnostics, and mitigation of a salt dissolution sinkhole at the US Strategic Petroleum Reserve storage site, Weeks Island, Louisiana

Description: A sinkhole was first observed in May 1992 over the edge of the two-level former salt mine that was converted for oil storage by the US Strategic Petroleum Reserve (SPR). Diagnostic studies that included geophysical, geochemical, drilling, and hydrological methods suggest a direct connection exists between the surface collapse area and the underground mine as shown by correlative measurements of sediment slump rates and brine influx into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which served as hydrologic flowpaths. Modeling studies of mine stresses show that years may be required before tensional cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater, very slowly initially, but gradually enlarging as undersaturated groundwater dissolves salt on the sides of the crack. Mitigation measures include increasing the mine pressurization, slowing the dissolution by injecting brine into the sinkhole throat, and freeze grouting to restrict hydrologic flowpaths.
Date: January 27, 1995
Creator: Neal, J.T. & Myers, R.E.
Partner: UNT Libraries Government Documents Department

Carbon Sequestration in Reclaimed Mined Soils of Ohio

Description: This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites, owned and maintained by the American Electrical Power, are located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites, characterized by age chronosequences, were reclaimed with and without topsoil application and are under continuous grass or forest cover. Among the three sites chosen for this study one was reclaimed in 1978 (Cumberland), one in 1987 (Switch Grass) and one site was reclaimed in 1994 (Tilton's Run). All three sites were reclaimed with topsoil application and were under continuous grass cover. Eighteen experimental plots were developed on each site. Five fertilization treatments were applied in triplicate on each experimental site. During this quarter, water infiltration tests were performed on the soil surface in the experimental plots. Soil samples were analyzed for soil moisture characteristics. This report presents the data on infiltration rates, volume of transport and storage pores, and available water capacity (AWC) of soil. The infiltration rates after 5 min (i{sub 5}) showed high statistical variability (CV > 0.62) among the three sites. Both steady state infiltration rate and cumulative infiltration showed moderate to high variability (CV > 0.35). The mean values for the infiltration rate after 5 min, steady state infiltration rate, and cumulative infiltration were higher for Switch Grass (2.93 {+-} 2.05 cm min{sup -1}; 0.63 {+-} 0.34 cm min{sup -1}; 113.07 {+-} 39.37 cm) than for Tilton's Run (1.76 {+-} 1.42 cm min{sup -1}; 0.40 {+-} 0.18 cm min{sup -1}; 73.68 {+-} 25.94 cm), and lowest for Cumberland (0.63 {+-} 0.34 cm min{sup -1}; 0.27 {+-} 0.19 cm min{sup -1}; 57.89 {+-} 31.00 cm). The AWC for 0-15 cm soil was highest at Tilton's Run (4.21 {+-} 1.75 cm) followed by Cumberland (3.83 {+-} ...
Date: October 1, 2005
Creator: Shukla, M.K.; Lorenz, K. & Lal, R.
Partner: UNT Libraries Government Documents Department

Field Validation of Toxicity Tests to Evaluate the Potential for Beneficial Use of Produced Water

Description: This study investigated potential biological effects of produced water contamination derived from occasional surface overflow and possible subsurface intrusion at an oil production site along the shore of Skiatook Lake, Oklahoma. We monitored basic chemistry and acute toxicity to a suite of standard aquatic test species (fathead minnow-Pimephales promelas, Daphnia pulex, Daphnia magna, and Ceriodaphnia dubia) in produced water and in samples taken from shallow groundwater wells on the site. Toxicity identification evaluations and ion toxicity modeling were used to identify toxic constituents in the samples. Lake sediment at the oil production site and at a reference site were also analyzed for brine intrusion chemically and by testing sediment toxicity using the benthic invertebrates, Chironomus dilutus, and Hyallela azteca. Sediment quality was also assessed with in situ survival and growth studies with H. azteca and the Asian clam, Corbicula fluminea, and by benthic macroinvertebrate community sampling. The produced water was acutely toxic to the aquatic test organisms at concentrations ranging from 1% to 10% of the whole produced water sample. Toxicity identification evaluation and ion toxicity modeling indicated major ion salts and hydrocarbons were the primary mixture toxicants. The standardized test species used in the laboratory bioassays exhibited differences in sensitivity to these two general classes of contaminants, which underscores the importance of using multiple species when evaluating produced water toxicity. Toxicity of groundwater was greater in samples from wells near a produced water injection well and an evaporation pond. Principle component analyses (PCA) of chemical data derived from the groundwater wells indicated dilution by lake water and possible biogeochemical reactions as factors that ameliorated groundwater toxicity. Elevated concentrations of major ions were found in pore water from lake sediments, but toxicity from these ions was limited to sediment depths of 10 cm or greater, which is outside of the ...
Date: March 31, 2008
Creator: Bidwell, Joseph; Fisher, Jonathan & Cooper, Naomi
Partner: UNT Libraries Government Documents Department

Technology Review of Nondestructive Methods for Examination of Water Intrusion Areas on Hanford’s Double-Shell Waste Tanks

Description: Under a contract with CH2M Hill Hanford Group, Inc., PNNL has performed a review of the NDE technology and methods for examination of the concrete dome structure of Hanford’s double-shell tanks. The objective was to provide a matrix of methodologies that could be evaluated based on applicability, ease of deployment, and results that could provide information that could be used in the ongoing structural analysis of the tank dome. PNNL performed a technology evaluation with the objective of providing a critical literature review for all applicable technologies based on constraints provided by CH2M HILL. These constraints were not mandatory, but were desired. These constraints included performing the evaluation without removing any soil from the top of the tank, or if necessary, requesting that the hole diameter needed to gain access to evaluate the top of the tank structure to be no greater than approximately 12-in. in diameter. PNNL did not address the details of statistical sampling requirements as they depend on an unspecified risk tolerance. PNNL considered these during the technology evaluation and have reported the results in the remainder of this document. Many of the basic approaches to concrete inspection that were reviewed in previous efforts are still in use. These include electromagnetic, acoustic, radiographic, etc. The primary improvements in these tools have focused on providing quantitative image reconstruction, thus providing inspectors and analysts with three-dimensional data sets that allow for operator visualization of relevant abnormalities and analytical integration into structural performance models. Available instruments, such as radar used for bridge deck inspections, rely on post-processing algorithms and do not provide real-time visualization. Commercially available equipment only provides qualitative indications of relative concrete damage. It cannot be used as direct input for structural analysis to assess fitness for use and if necessary to de-rate critical components. There are currently ...
Date: May 9, 2008
Creator: Watkins, Michael L. & Pardini, Allan F.
Partner: UNT Libraries Government Documents Department

Technical safety requirements for the South Tank Farm remediation project, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Description: The South Tank Farm (STF) is a series of six, 170,000-gal underground, domed storage tanks that were placed into service in 1943. The tanks were constructed of a concrete mixture known as gunite. They were used as a portion of the Liquid LOW-LEVEL WASTE (LLW) System for the collection, neutralization, storage, and transfer of the aqueous portion of the radioactive and/or hazardous chemical wastes produced as part of normal facility operations at Oak Ridge National Laboratory (ORNL). Although the last of the tanks was taken out of service in 1986, they have been shown by structural analysis to continue to be structurally sound. An attempt was made in 1983 to empty the tanks; however, removal of all the sludge from the tanks was not possible with the equipment and schedule available. Since removal of the liquid waste in 1983, liquid continues to accumulate within the tanks. The in-leakage is believed to be the result of groundwater dripping into the tanks around penetrations in the domes. The tanks are currently being maintained under a Surveillance and Maintenance Program, which includes activities such as level monitoring, vegetation control, High Efficiency Particulate Air filter leakage requirement testing/replacement, sign erection/repair, pump-out of excess liquids, and instrument calibration/maintenance. A technique known as confined sluicing, which uses a high-pressure, low-volume water jet integrated with a jet pump, will be used to remove the sludge. The Technical Safety Requirements (TSRs) are those operational requirements that specify the operating limits and surveillance requirements, the basis thereof, safety boundaries, and the management of administrative controls necessary to ensure the safe operation of the STF remediation project. Effective implementation of TSRs will limit to acceptable levels the risks to the public and workers from uncontrolled releases of radioactive or other hazardous material.
Date: January 1999
Creator: Platfoot, J. H.
Partner: UNT Libraries Government Documents Department

Distribution of fast hydrologic paths in the unsaturated zone at Yucca Mountain

Description: Development and testing of conceptual flow and transport models for hydrologic systems are strengthened when natural environmental tracers are incorporated into the process. One such tracer is chlorine-36 ({sup 36}Cl, half-life, 301,000 years), a radioactive isotope produced in the atmosphere and carried underground with percolating groundwater. High concentrations of this isotope were also added to meteoric water during a period of global fallout from atmospheric testing of nuclear devices, primarily in the 1950s. This bomb-pulse signal has been used to test for the presence of fast transport paths in the unsaturated zone at Yucca Mountain and to provide the basis for a conceptual model for their distribution. Yucca Mountain is under investigation by the US Department of Energy as a potential site at which to host an underground high-level radioactive waste repository. Under wetter climatic conditions, fast-flow pathways will respond quickly to increases in infiltration and have the potential to become seeps in the tunnel drifts. The {sup 36}Cl data are also being used in numerical flow and transport models to establish lower bounds on infiltration rates, estimate ground water ages, and establish bounding values for hydrologic flow parameters governing fracture transport.
Date: December 31, 1998
Creator: Fabryka-Martin, J.T.; Wolfsberg, A.V.; Levy, S.S.; Roach, J.L.; Winters, S.T.; Wolfsberg, L.E. et al.
Partner: UNT Libraries Government Documents Department

Microbial characterization for the Source-Term Waste Test Program (STTP) at Los Alamos

Description: The effects of microbial activity on the performance of the proposed underground nuclear waste repository, the Waste Isolation Pilot Plant (WIPP) at Carlsbad, New Mexico are being studied at Los Alamos National Laboratory (LANL) as part of an ex situ large-scale experiment. Actual actinide-containing waste is being used to predict the effect of potential brine inundation in the repository in the distant future. The study conditions are meant to simulate what might exist should the underground repository be flooded hundreds of years after closure as a result of inadvertent drilling into brine pockets below the repository. The Department of Energy (DOE) selected LANL to conduct the Actinide Source-Term Waste Test Program (STTP) to confirm the predictive capability of computer models being developed at Sandia National Laboratory.
Date: April 1, 1999
Creator: Leonard, P.A.; Strietelmeier, B.A.; Pansoy-Hjelvik, M.E. & Villarreal, R.
Partner: UNT Libraries Government Documents Department

Modeling brine inflow to Room Q: A numerical investigation of flow mechanisms

Description: A hydrologic modeling study was performed to gain insight into the flow mechanisms around Room Q. A summary of hydrologic and structural data and of predictive fluid flow models from Room Q are provided. Six years of measured data are available from the time of excavation. No brine accumulation in Room Q was measured in the first two years following excavation. However, there is considerable uncertainty associated with this early-time data due to inadequate sealing of the room. Brine may have been lost to evaporation or it may have flowed into newly created disturbed rock zone (DRZ) porosity resulting from excavation. Non-zero brine accumulation rates were measured from 2--5 years, but brine accumulation within the room dropped to zero after 5.5 years. A conceptual model for brine inflow to Room Q was developed which assumes far-field Darcy flow combined with an increasing DRZ pore volume. Numerical simulations employed TOUGH28W and used predictive DRZ porosity increase with time from SPECTROM-32 rock deformation simulations. Simulated brine inflow showed good agreement with measured brine accumulation rates for the first five years. Two important conclusions were drawn from the simulation results: (1) early-time brine inflow to the room can be reduced to zero if the DRZ pore volume increases with time, and (2) brine accumulation (inflow) rates from 2 to 5 years suggest a far-field permeability of 5 {times} 10{sup {minus}22} m{sup 2} with a bulk rock compressibility of 5.4 {times} 10{sup {minus}12} Pa{sup {minus}1}.
Date: April 1, 1997
Creator: Freeze, G.A.; Christian-Frear, T.L. & Webb, S.W.
Partner: UNT Libraries Government Documents Department

Using TOUGH2 to model capillary barriers

Description: Ross (1990) developed an analytical relationship to calculate the diversion length of a tilted fine-over-coarse capillary barrier. Oldenburg and Pruess compared TOUGH2 simulation results to the diversion length predicted by Ross` formula using upstream and harmonic weighting. The results were mixed. The qualitative agreement is reasonable but the quantitative comparison is poor, especially for upstream weighting. The proximity of the water table to the fine-coarse interface at breakthrough has been proposed as a possible reason for the poor agreement. In the present study, the Oldenburg and Pruess problem is extended to address the water table issue. When the water table is sufficiently far away from the interface at breakthrough, good qualitative and quantitative agreement is obtained using upstream weighting.
Date: September 1, 1998
Creator: Webb, S.W.
Partner: UNT Libraries Government Documents Department

In situ permeability modification using gelled polymer systems. Annual report, April 11, 1997--April 10, 1998

Description: Results from a research program on the application of gelled polymer technology for in situ permeability modification are presented in this report. The objective of this technology when used with displacement processes such as waterflooding is to reduce the permeability in fractures and/or high permeability matrix zones to improve volumetric sweep efficiency of the displacement process. In production wells, the objective is to reduce water influx. The research program focused on five areas: Gel treatment in fractured systems; Gel treatment in carbonate rocks; In-depth placement of gels; Gel systems for application in carbon dioxide flooding; and Gel treatment in production wells. The research program is primarily an experimental program directed toward improving the understanding of gelled polymer systems and how these systems can be used to increase oil recovery from petroleum reservoirs. A summary of progress for research conducted in the second 12 month period of a 28 month program is described.
Date: September 1, 1998
Creator: Green, D.W.; Willhite, G.P.; McCool, C.S.; Heppert, J.A.; Vossoughi, S. & Michnick, M.J.
Partner: UNT Libraries Government Documents Department

Information on Hydrologic Conceptual Models, Parameters, Uncertainty Analysis, and Data Sources for Dose Assessments at Decommissioning Sites

Description: This report addresses issues related to the analysis of uncertainty in dose assessments conducted as part of decommissioning analyses. The analysis is limited to the hydrologic aspects of the exposure pathway involving infiltration of water at the ground surface, leaching of contaminants, and transport of contaminants through the groundwater to a point of exposure. The basic conceptual models and mathematical implementations of three dose assessment codes are outlined along with the site-specific conditions under which the codes may provide inaccurate, potentially nonconservative results. In addition, the hydrologic parameters of the codes are identified and compared. A methodology for parameter uncertainty assessment is outlined that considers the potential data limitations and modeling needs of decommissioning analyses. This methodology uses generic parameter distributions based on national or regional databases, sensitivity analysis, probabilistic modeling, and Bayesian updating to incorporate site-specific information. Data sources for best-estimate parameter values and parameter uncertainty information are also reviewed. A follow-on report will illustrate the uncertainty assessment methodology using decommissioning test cases.
Date: February 28, 2000
Creator: Meyer, Philip D. & Gee, Glendon W.
Partner: UNT Libraries Government Documents Department

Assessing seal performance and parameter sensitivity with a full-shaft model

Description: The Waste Isolation Pilot Plant (WIPP) is a planned geologic repository for permanent disposal of transuranic waste generated by US government defense programs. Located near Carlsbad in southeastern New Mexico, the facility`s disposal regions are mined from the bedded salt of the Salado Formation at a depth of approximately 652 m. Four shafts service the operational needs of the facility for air intake, exhaust, waste handling and salt handling. These shafts range in diameter from 3.5 to 6.1 m and extend from the ground surface to the repository. During repository closure, following an operational life of approximately 50 years, these shafts will be sealed in accordance with an acceptable design. Under contract to the US Department of Energy (DOE), the Repository Isolation Systems Department (RISD) of Sandia National Laboratories has developed a design for the WIPP shaft sealing system. This design has been reviewed by the US Environmental Protection Agency (EPA) as part of the 1996 WIPP Compliance Certification Application (CCA). An effective shaft sealing system for the WIPP will limit liquid and gas flows, and permanently prevent the migration of radiological or other hazardous constituents through the sealed shafts from repository to accessible environment. Because of these performance objectives, a significant effort has been directed toward evaluation of the seal design. Whereas RISD (1996) provides a comprehensive discussion, this paper focuses on only one aspect of the evaluation effort, namely a full shaft, fluid flow model.
Date: May 1998
Creator: Reeves, M.; Fryar, D. G.; Statham, W. H. & Knowles, M. K.
Partner: UNT Libraries Government Documents Department

Modeling unsaturated-zone flow at Rainier Mesa as a possible analog for a future Yucca Mountain

Description: Rainier Mesa is structurally similar to Yucca Mountain, and receives precipitation similar to the estimated long-term average for Yucca Mountain. Tunnels through the unsaturated zone at Rainier Mesa have encountered perched water and, after the perched water was drained, flow in fractures and faults. Although flow observations have been primarily qualitative, Rainier Mesa hydrology is a potential analog for Yucca Mountain hydrology in a wetter climate. In this paper, a groundwater flow model that has been used in the performance assessment of Yucca Mountain--the weeps model--is applied to Rainier Mesa. The intent is to gain insight in both Rainier Mesa and the weeps flow model.
Date: January 1998
Creator: Gauthier, J. H.
Partner: UNT Libraries Government Documents Department

High temperature water adsorption on The Geysers rocks

Description: In order to measure water retention by geothermal reservoir rocks at the actual reservoir temperature, the ORNL high temperature isopiestic apparatus was adapted for adsorption measurements. The quality of water retained by rock samples taken from three different wells of The Geysers geothermal reservoir was measured at 150{sup degree}C, 200{sup degree}C, and 250{sup degree}C as a function of pressure in the range 0.00 {<=}p/p{sub degree} {<=} 0.98, where p{sub degree} is the saturated water vapor pressure. Both adsorption (increasing pressure) and desorption (decreasing pressure) runs were made in order to investigate the nature and the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were performed on the same rock samples. Nitrogen or krypton adsorption and desorption isotherms at 77 K were used to obtain BET specific surface areas, pore volumes and their distributions with respect to pore sizes. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A correlation is sought between water adsorption, the surface properties, and the mineralogical and petrological characteristics of the solids.
Date: August 1, 1997
Creator: Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M. & Mesmer, R.E.
Partner: UNT Libraries Government Documents Department

Research on oil recovery mechanisms in heavy oil reservoirs

Description: The research described here was directed toward improved understanding of thermal and heavy-oil production mechanisms and is categorized into: (1) flow and rock properties, (2) in-situ combustion, (3) additives to improve mobility control, (4) reservoir definition, and (5) support services. The scope of activities extended over a three-year period. Significant work was accomplished in the area of flow properties of steam, water, and oil in consolidated and unconsolidated porous media, transport in fractured porous media, foam generation and flow in homogeneous and heterogeneous porous media, the effects of displacement pattern geometry and mobility ratio on oil recovery, and analytical representation of water influx.
Date: March 16, 2000
Creator: Kovscek, Anthony R. & Brigham, William E., Castanier, Louis M.
Partner: UNT Libraries Government Documents Department