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A Temperature-Profile Method for Estimating Flow Processes inGeologic Heat Pipes

Description: Above-boiling temperature conditions, as encountered, forexample, in geothermal reservoirs and in geologic repositories for thestorage of heat-producing nuclear wastes, may give rise to stronglyaltered liquid and gas flow processes in porous subsurface environments.The magnitude of such flow perturbation is extremely hard to measure inthe field. We therefore propose a simple temperature-profile method thatuses high-resolution temperature data for deriving such information. Theenergy that is transmitted with the vapor and water flow creates a nearlyisothermal zone maintained at about the boiling temperature, referred toas a heat pipe. Characteristic features of measured temperature profiles,such as the differences in the gradients inside and outside of the heatpipe regions, are used to derive the approximate magnitude of the liquidand gas fluxes in the subsurface, for both steady-state and transientconditions.
Date: December 6, 2004
Creator: Birkholzer, Jens T.
Partner: UNT Libraries Government Documents Department

Annual Hanford Seismic Report for Fiscal Year 1998

Description: Seismic monitoring at the Hanford Site was established in 1969 by the United States Geological Survey (USGS) under a contract with theJ.J.S. Atomic Energy Commission. In 1975, the University of Washington (UW) assumed responsibility for the network and subsequently expanded it. In 1979, the Basalt Waste o Isolation Program (13WIP) became responsible for collecting seismic data for the Hdord Site as part of site " characterization activities. Rockwell Htiord Operations, followed by Westinghouse Ha&ord Company . (WHC), operated the local network and were the contract technical advisors for the Eastern Washington Regional Network @wRN) operated and maintained by the UW. Funding for BWIP ended in December 1988. Seismic Monitoring and responsibility for the University of Washington contract were then trans- ferred to WHC'S Environmental Division. Maintenance responsibilities for the EWRN were also Assigned to WHC, who made major upgrades to EWRN sites. Effective October 1,1996, Seismic Monitoring was transfemed to the Pacific Northwest National Laboratory (PI@lL*). Seismic Monitoring is part of PNNL's Applied Geology and Geochemistry Group, Energy Technology Division. The Hanford Strong Motion Accelerometer network was constructed during 1997 and came online in May 1997. It operated continuously until September 30, 1997, when it was mothballed due to can- . cellation of fimding. Funding was restored on October 1, 1998, by joint agreement between the U.S. Department of Energy (DOE) and PNNL. Operation of the free-field sites resumed on November 20, 1998.
Date: December 22, 1998
Creator: Hartshorn, DC; Reidel, SP & Rohay, AC
Partner: UNT Libraries Government Documents Department

Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments

Description: In this project we have sought to explain the co-existence of gas and hydrate phases in sediments within the gas hydrate stability zone. We have focused on the gas/brine interface at the scale of individual grains in the sediment. The capillary forces associated with a gas/brine interface play a dominant role in many processes that occur in the pores of sediments and sedimentary rocks. The mechanical forces associated with the same interface can lead to fracture initiation and propagation in hydrate-bearing sediments. Thus the unifying theme of the research reported here is that pore scale phenomena are key to understanding large scale phenomena in hydrate-bearing sediments whenever a free gas phase is present. Our analysis of pore-scale phenomena in this project has delineated three regimes that govern processes in which the gas phase pressure is increasing: fracturing, capillary fingering and viscous fingering. These regimes are characterized by different morphology of the region invaded by the gas. On the other hand when the gas phase pressure is decreasing, the corresponding regimes are capillary fingering and compaction. In this project, we studied all these regimes except compaction. Many processes of interest in hydrate-bearing sediments can be better understood when placed in the context of the appropriate regime. For example, hydrate formation in sub-permafrost sediments falls in the capillary fingering regime, whereas gas invasion into ocean sediments is likely to fall into the fracturing regime. Our research provides insight into the mechanisms by which gas reservoirs are converted to hydrate as the base of the gas hydrate stability zone descends through the reservoir. If the reservoir was no longer being charged, then variation in grain size distribution within the reservoir explain hydrate saturation profiles such as that at Mt. Elbert, where sand-rich intervals containing little hydrate are interspersed between intervals containing large hydrate ...
Date: December 31, 2011
Creator: Bryant, Steven & Juanes, Ruben
Partner: UNT Libraries Government Documents Department

Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments

Description: In this project we have sought to explain the co-existence of gas and hydrate phases in sediments within the gas hydrate stability zone. We have focused on the gas/brine interface at the scale of individual grains in the sediment. The capillary forces associated with a gas/brine interface play a dominant role in many processes that occur in the pores of sediments and sedimentary rocks. The mechanical forces associated with the same interface can lead to fracture initiation and propagation in hydrate-bearing sediments. Thus the unifying theme of the research reported here is that pore scale phenomena are key to understanding large scale phenomena in hydrate-bearing sediments whenever a free gas phase is present. Our analysis of pore-scale phenomena in this project has delineated three regimes that govern processes in which the gas phase pressure is increasing: fracturing, capillary fingering and viscous fingering. These regimes are characterized by different morphology of the region invaded by the gas. On the other hand when the gas phase pressure is decreasing, the corresponding regimes are capillary fingering and compaction. In this project, we studied all these regimes except compaction. Many processes of interest in hydrate-bearing sediments can be better understood when placed in the context of the appropriate regime. For example, hydrate formation in sub-permafrost sediments falls in the capillary fingering regime, whereas gas invasion into ocean sediments is likely to fall into the fracturing regime. Our research provides insight into the mechanisms by which gas reservoirs are converted to hydrate as the base of the gas hydrate stability zone descends through the reservoir. If the reservoir was no longer being charged, then variation in grain size distribution within the reservoir explain hydrate saturation profiles such as that at Mt. Elbert, where sand-rich intervals containing little hydrate are interspersed between intervals containing large hydrate ...
Date: December 31, 2011
Creator: Bryant, Steven & Juanes, Ruben
Partner: UNT Libraries Government Documents Department

Use of ARM Products in Reanalysis Applications and IPCC Model Assessment

Description: Year-3 of the project was spent developing an observed cloud climatology for Barrow, AK and relating the observed cloud fractions to the surface circulation patterns and locally observed winds. Armed with this information, we identified errors and sources of errors of cloud fraction simulations by numerical models in the Arctic. Specifically, we compared the cloud simulations output by the North American Regional Reanalysis (NARR) to corresponding observed cloud fractions obtained by the Department of Energy’s Atmospheric Radiation Measurement (ARM) program for four mid-season months: (January, April, July, and October). Reanalyses are obtained from numerical weather prediction models that are not run in real-time. Instead, a reanalysis model ingests a wide variety of historical observations for the purpose of producing a gridded dataset of many model-derived quantities that are as temporally homogeneous as possible. Therefore, reanalysis output can be used as a proxy for observations, although some biases and other errors are inevitable because of model parameterizations and observational gaps. In the observational analysis we documented the seasonality of cloudiness at the north slope including cloud base height and dependence on synoptic regime. We followed this with an evaluation of the associations of wind-speed and direction and cloud amounts in both the observational record and the reanalysis model. The Barrow cloud fraction data show that clear conditions are most often associated with anomalous high pressure to the north of Barrow, especially in spring and early summer. Overcast skies are most commonly associated with anomalous low pressure to the south. The observational analysis shows that low, boundary layer clouds are the most common type of cloud observed North Slope ARM observing site. However, these near-surface clouds are a major source of errors in the NARR simulations. When compared to observations, the NARR over-simulates the fraction of low clouds during the winter months, ...
Date: September 30, 2011
Creator: Walsh, John E. & Chapman, William L.
Partner: UNT Libraries Government Documents Department

Collaborative Research: Robust Climate Projections and Stochastic Stability of Dynamical Systems

Description: The project was completed along the lines of the original proposal, with additional elements arising as new results were obtained. The originally proposed three thrusts were expanded to include an additional, fourth one. (i) The e#11;ffects of stochastic perturbations on climate models have been examined at the fundamental level by using the theory of deterministic and random dynamical systems, in both #12;nite and in#12;nite dimensions. (ii) The theoretical results have been implemented #12;first on a delay-diff#11;erential equation (DDE) model of the El-Nino/Southern-Oscillation (ENSO) phenomenon. (iii) More detailed, physical aspects of model robustness have been considered, as proposed, within the stripped-down ICTP-AGCM (formerly SPEEDY) climate model. This aspect of the research has been complemented by both observational and intermediate-model aspects of mid-latitude and tropical climate. (iv) An additional thrust of the research relied on new and unexpected results of (i) and involved reduced-modeling strategies and associated prediction aspects have been tested within the team's empirical model reduction (EMR) framework. Finally, more detailed, physical aspects have been considered within the stripped-down SPEEDY climate model. The results of each of these four complementary e#11;fforts are presented in the next four sections, organized by topic and by the team members concentrating on the topic under discussion.
Date: October 13, 2011
Creator: Ghil, Michael; McWilliams, James; Neelin, J. David; Zaliapin, Ilya; Chekroun, Mickael; Kondrashov, Dmitri et al.
Partner: UNT Libraries Government Documents Department

ON""GENERAL CONSERVATION EQUATIONS FOR MULTIPHASE SYSTEMS: 1. AVERAGING PROCEDURE"" BY M. HASSANIZADEH AND W.G. GRAY.

Description: The author comments upon a point made in the referenced paper on general conservation equations. The author directs attention to the fact that the referenced paper's authors correctly point out that when an averaging operation involves integration, the integrand multiplied by the infinitesimal volume must be an additive quantity. The importance of this requirement is emphasized.
Date: December 1, 1979
Creator: Narasimhan, T.N.
Partner: UNT Libraries Government Documents Department

World Surface Currents From Ship's Drift Observations

Description: Over 4 million observations of ship's drift are on file at the U.S. National Oceanographic Data Centre, in Washington, D. C., representing a vast amount of information on ocean surface currents. The observed drift speeds are dependent on the frequency of occurence of the particular current speeds and the frequency of observation. By comparing frequency of observation with the drift speeds observed it is possible to confirm known current patterns and detect singularities in surface currents.
Date: November 1, 1980
Creator: Duncan, C. P. & Schladow, S. G.
Partner: UNT Libraries Government Documents Department

Probabilistic Simulation of Subsurface Fluid Flow: A Study Using a Numerical Scheme

Description: There has been an increasing interest in probabilistic modeling of hydrogeologic systems. The classical approach to groundwater modeling has been deterministic in nature, where individual layers and formations are assumed to be uniformly homogeneous. Even in the case of complex heterogeneous systems, the heterogeneities describe the differences in parameter values between various layers, but not within any individual layer. In a deterministic model a single-number is assigned to each hydrogeologic parameter, given a particular scale of interest. However, physically there is no such entity as a truly uniform and homogeneous unit. Single-number representations or deterministic predictions are subject to uncertainties. The approach used in this work models such uncertainties with probabilistic parameters. The resulting statistical distributions of output variables are analyzed. A numerical algorithm, based on axiomatic principles of probability theory, performs arithmetic operations between probability distributions. Two subroutines are developed from the algorithm and incorporated into the computer program TERZAGI, which solves groundwater flow problems in saturated, multi-dimensional systems. The probabilistic computer program is given the name, PROGRES. The algorithm has been applied to study the following problems: one-dimensional flow through homogeneous media, steady-state and transient flow conditions, one-dimensional flow through heterogeneous media, steady-state and transient flow conditions, and two-dimensional steady-stte flow through heterogeneous media. The results are compared with those available in the literature.
Date: March 1, 1980
Creator: Buscheck, Timothy Eric
Partner: UNT Libraries Government Documents Department