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Pore-scale modeling of nonwetting-phase residual in porous medi
60A
HYDROGEOLOGY:FLUID FLOW
Doping the fluids with property-selective fluorophores allows planar areas of the system to be successively excited with a shaped laser light to reveal the structure of the system. The resulting illumination is recorded by a high-resolution, cooled, slow scan charged-coupled device (CCD) camera. (from Authors) 962089 Pore-scale modeling of nonwetting-phnse residual in porous media M. I. Lowry & C. T. Miller, Water Resources Research, 31(3), 1995, pp 455-473. This work investigates factors affecting residual in strongly wet, capillary-dominated systems. Porous media are modeled as three-dimensional networks of pore bodies and throats. A random network approach is developed, which provides stochastic geometry and variable conductivity. Immiscible displacement occurs via piston-displacement and film-fow mechanisms. Residual ganglia become trapped during imbibition. Wetting-phase continuity is maintained during drainage, disallowing the entrapment of wetting-phase ganglia. Results show that pore-scale geometric parameters significantly affect residual saturation, the ganglia-volume distribution, and nonwetting-wetting-phase interracial area. (from Authors) 962090 Prediction of log-transmissivity 1. Using specific capacity S. Christensen, Nordic Hydrology, 26(1), 1995, pp 1-20. The log-transmissivity may in many cases be predicted from the log-transformed specific capacity of wells by applying a linear statistical model. The coefficients of the linear equation can be estimated by the least-square method. It is shown that if the estimated slope of the line differs from unity then it may indicate that the specific capacity is correlated with the well efficiency. The above prediction method is applied to case studies of aquifers in three different formations. If the predictor values are taken from the drillers log then the standard error of prediction in all the cases is 0.35. This seems to be unacceptable in most practical applications. (from Author) 962091 Prediction of log-transmissivity 2. Using lithology and specific capacity S. Christensen, Nordic Hydrology, 26(0, 1995, pp 21-36. Two physically based models are derived that can be used to predict the log-transmissivity from the lithology, e.g. as logged in boreholes. The first model uses the lithology as the only predictor, whereas the second model uses the lithology and the specific capacity as simultaneous predictors. The model parameters can be estimated by statistical methods from actual observations. The methods are applied to three case studies. In two cases the joint model improves the prediction considerably when compared with the single predictor models; in the third case the joint model is at least as good as the single predictor models. (from Author) 962092 Pilot point methodology for automated calibration of an ensemble of conditionally simulated transmissivity fields 1. Theory and computational experiments B. S. Rama Ran, A. M. La Venue, G. De Marsily & M. G. Marietta, Water Resources Research, 31(3), 1995, pp 475493. A new methodology for solution of the inverse problem in groundwater hydrology is proposed and applied to a site in southeastern New Mexico with extensive hydrogeologlc data. The methodology addresses the issue of nonuniqueness of the inverse solutions by generating an ensemble of transmissivity fields considered to be equally likely, each of which is in agreement with the measured transmissivity and pressure data. It consists of generatiing a selected number of conditionally simulated transmissivity fields and then calibrating each of the fields to match the measured steady state or transient pressures, in a least squares sense. The method
has been applied to the Waste Isolation Pilot Plant (WIPP) site, in southeastern New Mexico, where the US Department of Energy is conducting probabifistic system assessment for the permanent disposal of transurauic nuclear waste. The resulting calibrated transmissivity fields are input to a Monte Carlo analysis of the total system performance. The present paper describes the methodology. (from Authors) 962093 Pilot point methodology for automated calibration of n ensemble of conditionally simulated transmissivity fields 2. Application A. M. LaVenue, B. S. Ramagao, G. De Marsily & M. G. Marietta, Water Resources Research, 31_(3), 1995, pp 495516. This paper presents the application of a methodology to assess spatial variability of the transmissivities within a regional aquifer in the vicinity of the Waste Isolation Pilot Plant (WIPP), the Culebra dolomite. A fully automated inverse algorithm using pilot points as parameters of calibration was employed. The application of this new methodology to the Culebra dolomite flow system produced 70 conditional simulations which were consistent with all the measured transmissivity and head data at the site. Based on an analysis of the calibrated transmissivity fields, the spatial variability of the transmissivity fields was increased as a result of the calibration process. This increase is in part due to the addition of a high-transmissivity feature to each of the transmissivity fields which is needed to match both steady state and transient state head data. (from Authors) 962094 Field-senie solute transport in n heavy clay soil J. J. B. Bronswijk, W. Hamminga & K. Oustindie, Water Resources Research, 31(3), 1995, pp 517-526. The transport of a bromide tracer was studied in a heavy clay soil. Solute transport occurred in three domains: large continuous macropores, smaller more tortuous mesopores, and the pores inside the soil aggregates. Quantitatively, the most important solute transport occurred through the mesopores. This transport was characterized by high spatial variability, significant lateral transport, and low mobile water volumes. At the field scale this resulted in the rapid leaching of solute in comparison with earlier experiments on sand and loam soils. (from Authors) 962095 Uncoupling of coupled flows in soil - a finite element method Daichao Sheng & K. Axelsson, International Journal for Numerical & Analytical Methods in Geomechanics, 19(8), 1995, pp 537-553. In this paper, a general expression is presented that can be used to represent various types of coupled flows in soil. A finite element method is then proposed to solve the generalized coupled flows of convection - conduction pattern. The proposed technique can be used for solving multi-dimensional, transient, coupled or simultaneous flows of convection - conduction type. Application to a flow example shows that the technique exhibits optimality in convergence and in stability. (from Authors) 962096 Fundamental formulation of eleetrukinetie extraction of contaminants from soil A. T. Yeung & S. Datla, Canadian Geotechnical Journal, 32(4), 1995, pp 569-583. An attempt is made to formulate the coupled flows of ionic contaminants and the resulting change o f p H in the pore fluid during the electrokinetic extraction process. The coupled flows of contaminants are formulated by the formalism of nonequilibrium thermodynamics. The pH is determined as a function of time and space by maintaining electrical neutrality throughout the system all the times. A numerical model NEUTRAL is developed to simulate the processes. Resutls indicate that the approach is a valid step toward a better
HYDROGEOLOGY:FLUID FLOW
Doping the fluids with property-selective fluorophores allows planar areas of the system to be successively excited with a shaped laser light to reveal the structure of the system. The resulting illumination is recorded by a high-resolution, cooled, slow scan charged-coupled device (CCD) camera. (from Authors) 962089 Pore-scale modeling of nonwetting-phnse residual in porous media M. I. Lowry & C. T. Miller, Water Resources Research, 31(3), 1995, pp 455-473. This work investigates factors affecting residual in strongly wet, capillary-dominated systems. Porous media are modeled as three-dimensional networks of pore bodies and throats. A random network approach is developed, which provides stochastic geometry and variable conductivity. Immiscible displacement occurs via piston-displacement and film-fow mechanisms. Residual ganglia become trapped during imbibition. Wetting-phase continuity is maintained during drainage, disallowing the entrapment of wetting-phase ganglia. Results show that pore-scale geometric parameters significantly affect residual saturation, the ganglia-volume distribution, and nonwetting-wetting-phase interracial area. (from Authors) 962090 Prediction of log-transmissivity 1. Using specific capacity S. Christensen, Nordic Hydrology, 26(1), 1995, pp 1-20. The log-transmissivity may in many cases be predicted from the log-transformed specific capacity of wells by applying a linear statistical model. The coefficients of the linear equation can be estimated by the least-square method. It is shown that if the estimated slope of the line differs from unity then it may indicate that the specific capacity is correlated with the well efficiency. The above prediction method is applied to case studies of aquifers in three different formations. If the predictor values are taken from the drillers log then the standard error of prediction in all the cases is 0.35. This seems to be unacceptable in most practical applications. (from Author) 962091 Prediction of log-transmissivity 2. Using lithology and specific capacity S. Christensen, Nordic Hydrology, 26(0, 1995, pp 21-36. Two physically based models are derived that can be used to predict the log-transmissivity from the lithology, e.g. as logged in boreholes. The first model uses the lithology as the only predictor, whereas the second model uses the lithology and the specific capacity as simultaneous predictors. The model parameters can be estimated by statistical methods from actual observations. The methods are applied to three case studies. In two cases the joint model improves the prediction considerably when compared with the single predictor models; in the third case the joint model is at least as good as the single predictor models. (from Author) 962092 Pilot point methodology for automated calibration of an ensemble of conditionally simulated transmissivity fields 1. Theory and computational experiments B. S. Rama Ran, A. M. La Venue, G. De Marsily & M. G. Marietta, Water Resources Research, 31(3), 1995, pp 475493. A new methodology for solution of the inverse problem in groundwater hydrology is proposed and applied to a site in southeastern New Mexico with extensive hydrogeologlc data. The methodology addresses the issue of nonuniqueness of the inverse solutions by generating an ensemble of transmissivity fields considered to be equally likely, each of which is in agreement with the measured transmissivity and pressure data. It consists of generatiing a selected number of conditionally simulated transmissivity fields and then calibrating each of the fields to match the measured steady state or transient pressures, in a least squares sense. The method
has been applied to the Waste Isolation Pilot Plant (WIPP) site, in southeastern New Mexico, where the US Department of Energy is conducting probabifistic system assessment for the permanent disposal of transurauic nuclear waste. The resulting calibrated transmissivity fields are input to a Monte Carlo analysis of the total system performance. The present paper describes the methodology. (from Authors) 962093 Pilot point methodology for automated calibration of n ensemble of conditionally simulated transmissivity fields 2. Application A. M. LaVenue, B. S. Ramagao, G. De Marsily & M. G. Marietta, Water Resources Research, 31_(3), 1995, pp 495516. This paper presents the application of a methodology to assess spatial variability of the transmissivities within a regional aquifer in the vicinity of the Waste Isolation Pilot Plant (WIPP), the Culebra dolomite. A fully automated inverse algorithm using pilot points as parameters of calibration was employed. The application of this new methodology to the Culebra dolomite flow system produced 70 conditional simulations which were consistent with all the measured transmissivity and head data at the site. Based on an analysis of the calibrated transmissivity fields, the spatial variability of the transmissivity fields was increased as a result of the calibration process. This increase is in part due to the addition of a high-transmissivity feature to each of the transmissivity fields which is needed to match both steady state and transient state head data. (from Authors) 962094 Field-senie solute transport in n heavy clay soil J. J. B. Bronswijk, W. Hamminga & K. Oustindie, Water Resources Research, 31(3), 1995, pp 517-526. The transport of a bromide tracer was studied in a heavy clay soil. Solute transport occurred in three domains: large continuous macropores, smaller more tortuous mesopores, and the pores inside the soil aggregates. Quantitatively, the most important solute transport occurred through the mesopores. This transport was characterized by high spatial variability, significant lateral transport, and low mobile water volumes. At the field scale this resulted in the rapid leaching of solute in comparison with earlier experiments on sand and loam soils. (from Authors) 962095 Uncoupling of coupled flows in soil - a finite element method Daichao Sheng & K. Axelsson, International Journal for Numerical & Analytical Methods in Geomechanics, 19(8), 1995, pp 537-553. In this paper, a general expression is presented that can be used to represent various types of coupled flows in soil. A finite element method is then proposed to solve the generalized coupled flows of convection - conduction pattern. The proposed technique can be used for solving multi-dimensional, transient, coupled or simultaneous flows of convection - conduction type. Application to a flow example shows that the technique exhibits optimality in convergence and in stability. (from Authors) 962096 Fundamental formulation of eleetrukinetie extraction of contaminants from soil A. T. Yeung & S. Datla, Canadian Geotechnical Journal, 32(4), 1995, pp 569-583. An attempt is made to formulate the coupled flows of ionic contaminants and the resulting change o f p H in the pore fluid during the electrokinetic extraction process. The coupled flows of contaminants are formulated by the formalism of nonequilibrium thermodynamics. The pH is determined as a function of time and space by maintaining electrical neutrality throughout the system all the times. A numerical model NEUTRAL is developed to simulate the processes. Resutls indicate that the approach is a valid step toward a better