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Two-phase flow in heterogeneous porous media. 2. Model application
20A 921149 Formation damage effects on horizontal-well flow efficiency Renard. G; Dupuy, J M J Pet Technol V43, N7, July 1991, P786-789, 868-869 Wellbore damage is best described using the flow efficiency index. A comparison is presented for flow efficiency for horizontal and vertical wells assuming steady state flow of an incompressible fluid in a homogeneous, anisotropic medium. It is shown that permeability reduction around the wellbore is less detrimental for horizontal wells when vertical permeability is greater than horizontal, and vice versa. Examples of flow efficiency calculations are presented for formation damage or formation collapse around a liner in poorly consolidated formations.
921153 One-dimeusional approximation for infiltration in heterogeneous soils Protopapas, A L; Bras, R L Water Resour Res V27. N6. June 1991. PI019-1027 Analytical solutions to the linearised infiltration equation for unsteady infiltration from a strip source into a soil with hydraulic conductivity varying exponentially in space (Protopapas and Bras, ibid, V27, Pt029-1034) are used to derive a criterion for the conditions under which the onedimensional approximation is valid. Numerical solutions for the Iinearised infiltration equation are developed for general soil conditions. The multidimensional infiltration problem can be simulated by set of independent neighboring soil columns for the case of a sizeable strip source and moderate variation of hydraulic conductivity.
921150 Asymptotic solutions for solute transport in dual velocity media Dykhuizen, R C Math Geol V23, N3, April 1991, P383-401
921154 Analytical solutions for unsteady multidimensional infiltration in heterogeneous soils Protopapas, A L; Bras, R L Water Resour Res V27, Nr, June 1991, P1029-1034
Dual velocity (dual porosity) models have been used to analyse flow and transport in fractured porous media. Current models are reviewed. Asymptotic solutions are obtained in a general form via the analysis of moments of particular solutions. Effective velocity and dispersion coefficients are obtained. The asymptotic solutions are valid at large times. Early time bchaviour can be analysed considering only the faster mechanism, without coupling of the slower. Only at intermediate times are the complex dual porosity models required.
The problem is analysed for a soil whose hydraulic conductivity is an exponential function of matric potential and a linear function of soil moisture. Multidimensional flow equations are linearised and solved using integral transform methods. The resulting equations are shown to be generalised versions of known results for homogeneous soils. The purpose is to obtain quantitative criteria for assessing the validity of the one dimensional approximation commonly used in hydrologic applications.
921151 New method for the rational arrangement of gas drainage boreholes. Technical note Sun, P Min Sci Technol V13. NI, July 1991, P105-111 Borehole size and spacing are two fundamental parameters to be considered when designing borehole drainage patterns. Based on theoretical formulae for gas pressure distribution in a radial flow field, mathematical formulae for rational arrangement of the boreholes are derived. Practical experience in collieries indicates these formulae are easy to use and effective in design of a pre-drainage system for rockburst prevention.
921152 Performance of water infiltrated within infiltration strata and Kanto loam taking into account hysteresis Harada, S; lchikawa, A Natural Disaster Sci VI2, N2. 1990. P21-35 Stormwater is channelled to the natural Kanto loam in Tokyo via infiltration drains, comprising layers of artificial turf, permeable pavement, crushed gravel, and sand. Two columns of such strata were set up outdoors and their response to natural precipitation observed. A model has been developed to describe the infiltration behaviour, based on Richards' equation and Campbell's equation to express soil property functions. Rapid changes in drainage rate in response to rainfall rate are only predicted accurately if hysteresis of the soil property functions is included.
921155 Two-phase flow in heterogeneous porous media. 1. Model development Kueper, B H; Frind, E O Water Resour Res V27, Nr, June 1991, P1049-1057 Simultaneous movement of a dense nonaqueous phase liquid and water in a heterogeneous porous medium is studied using a two-dimensional finite difference model. The two primary variables solved for, pressure and saturation of the wetting phase, are always existent, regardless of the presence of the nonwetting phase. The method is thus well suited to such problems as advance of immiscible liquids into previously uncontaminated groundwater systems. A computationally efficient solution procedure is used. The model is verified against an exact analytical solution, and validated using laboratory physical model data. 921156 Two-phase flow in heterogeneous porous media. 2. Model application Kueper, B H; Frind, E O Water Resour Res V27. N6, June 1991, P1059-1070 The previously developed two-phase flow model (ibid, V27, P1049-1057) is used in numerical simulations to assess the sensitivity of fluid properties on the movement of dense immiscible phase fluids through heterogeneous porous media. Results are characterised by spatial moments to reflect relative degrees of lateral spreading in the presence of lenses of differing permeability. Local scale sensitivity of porous medium and fluid properties is also examined. Migration of nonwetting fluids is seen to be sensitive to variation in capillary properties of the porous medium and strongly influenced by fluid physical properties.
© 1992 Pergamon Press plc. Reproduction not permitted
921153 One-dimeusional approximation for infiltration in heterogeneous soils Protopapas, A L; Bras, R L Water Resour Res V27. N6. June 1991. PI019-1027 Analytical solutions to the linearised infiltration equation for unsteady infiltration from a strip source into a soil with hydraulic conductivity varying exponentially in space (Protopapas and Bras, ibid, V27, Pt029-1034) are used to derive a criterion for the conditions under which the onedimensional approximation is valid. Numerical solutions for the Iinearised infiltration equation are developed for general soil conditions. The multidimensional infiltration problem can be simulated by set of independent neighboring soil columns for the case of a sizeable strip source and moderate variation of hydraulic conductivity.
921150 Asymptotic solutions for solute transport in dual velocity media Dykhuizen, R C Math Geol V23, N3, April 1991, P383-401
921154 Analytical solutions for unsteady multidimensional infiltration in heterogeneous soils Protopapas, A L; Bras, R L Water Resour Res V27, Nr, June 1991, P1029-1034
Dual velocity (dual porosity) models have been used to analyse flow and transport in fractured porous media. Current models are reviewed. Asymptotic solutions are obtained in a general form via the analysis of moments of particular solutions. Effective velocity and dispersion coefficients are obtained. The asymptotic solutions are valid at large times. Early time bchaviour can be analysed considering only the faster mechanism, without coupling of the slower. Only at intermediate times are the complex dual porosity models required.
The problem is analysed for a soil whose hydraulic conductivity is an exponential function of matric potential and a linear function of soil moisture. Multidimensional flow equations are linearised and solved using integral transform methods. The resulting equations are shown to be generalised versions of known results for homogeneous soils. The purpose is to obtain quantitative criteria for assessing the validity of the one dimensional approximation commonly used in hydrologic applications.
921151 New method for the rational arrangement of gas drainage boreholes. Technical note Sun, P Min Sci Technol V13. NI, July 1991, P105-111 Borehole size and spacing are two fundamental parameters to be considered when designing borehole drainage patterns. Based on theoretical formulae for gas pressure distribution in a radial flow field, mathematical formulae for rational arrangement of the boreholes are derived. Practical experience in collieries indicates these formulae are easy to use and effective in design of a pre-drainage system for rockburst prevention.
921152 Performance of water infiltrated within infiltration strata and Kanto loam taking into account hysteresis Harada, S; lchikawa, A Natural Disaster Sci VI2, N2. 1990. P21-35 Stormwater is channelled to the natural Kanto loam in Tokyo via infiltration drains, comprising layers of artificial turf, permeable pavement, crushed gravel, and sand. Two columns of such strata were set up outdoors and their response to natural precipitation observed. A model has been developed to describe the infiltration behaviour, based on Richards' equation and Campbell's equation to express soil property functions. Rapid changes in drainage rate in response to rainfall rate are only predicted accurately if hysteresis of the soil property functions is included.
921155 Two-phase flow in heterogeneous porous media. 1. Model development Kueper, B H; Frind, E O Water Resour Res V27, Nr, June 1991, P1049-1057 Simultaneous movement of a dense nonaqueous phase liquid and water in a heterogeneous porous medium is studied using a two-dimensional finite difference model. The two primary variables solved for, pressure and saturation of the wetting phase, are always existent, regardless of the presence of the nonwetting phase. The method is thus well suited to such problems as advance of immiscible liquids into previously uncontaminated groundwater systems. A computationally efficient solution procedure is used. The model is verified against an exact analytical solution, and validated using laboratory physical model data. 921156 Two-phase flow in heterogeneous porous media. 2. Model application Kueper, B H; Frind, E O Water Resour Res V27. N6, June 1991, P1059-1070 The previously developed two-phase flow model (ibid, V27, P1049-1057) is used in numerical simulations to assess the sensitivity of fluid properties on the movement of dense immiscible phase fluids through heterogeneous porous media. Results are characterised by spatial moments to reflect relative degrees of lateral spreading in the presence of lenses of differing permeability. Local scale sensitivity of porous medium and fluid properties is also examined. Migration of nonwetting fluids is seen to be sensitive to variation in capillary properties of the porous medium and strongly influenced by fluid physical properties.
© 1992 Pergamon Press plc. Reproduction not permitted