- Email: [email protected]
Characterising average permeability in oil and gas formations
292A 925148 Permeability transects of Eolian sands and their use in generating random permeability fields Goggin, D J; Chandler, M A; Kocurek, G; Lake, L W SPE Form Eval V7. N1. March 1992, P7-16 Geological information on permeability of geological media is often nonquantitative and sparse. The application of detailed outcrop data directly to the subsurface has been treated as suspect. Observations from over 10000 permeability measurements on eolian sandstones have been used to generate permeability fields for reservoir simulation input. These were examined to evaluate portability of measurements from outcrop to subsurface and from one formation to another. Results indicate that classification and statistical measures of variability and spatial correlation are portable between outcrop and subsurface, but mean permeability is not.
925149 Pressure-transient analysis of arbitrarily shaped reservoirs with the boundary-element method Kikani, J; Home, R N SPE Form Eval V7. NI, March 1992, P53-60 Two boundary element formulations are presented for solution of pressure-time problems in homogeneous, anisotropic reservoirs. The ease of handling of multiple line sources and sinks and a variety of reservoir geometries and boundary conditions is a major advantage. The analytical nature of the solution is presented and numerical dispersion and grid orientation effects are minimal. The advantages and disadvantages of the convolution and Laplace domain solutions are compared and discussed.
925150 Characterising average permeability in oil and gas formations Rollins, J B; Holditch, S A; Lee, W J SPE Form Eval V7, N1, March 1992, P99-105 Permeability of geological formations frequently follows a unimodal probability distribution. Sedimentary formations generally have permeability distributions similar to log-normal. Theoretical considerations, field data, and a reservoir simulation example are used to demonstrate that the median, rather than arithmetic mean, is the correct value to describe the average value of the permeability distribution of the formation. The relevance of this to statute classification of tight gas sands is illustrated.
925151 Physics and modeling of thermal flow in unconsolidated porous media Settari, A SPE Prod Engng V7, N1, Feb 1992, P47-55 The mechanics of unconsolidated porous media is important to exploitation of oil sands or other poorly consolidated formations. A new formula for nonlinear stress strain behaviour and multiphase fluid flow is presented. Nonlinearity of soil behaviour and its interaction with fluid flow causing shear failure of the soil are the main features. The numerical formulation of the coupled flow/stress solution includes nonlinear compressibility and flow properties as functions of pressure, stress, and temperature; nonlinear thermal poroelastic stress analysis; shear or tensile failure; porosity and stress. A I D example provides new insight into reservoir mechanics in unconsolidated media.
925152 Percolation theory of two-phase relative permeability Helba, A A; Sahimi, M; Scriven, L E; Davis, H T SPE Reservoir Engng V7. N1. Feb 1992, P123-132 The slow concurrent flow of two immiscible fluids, one strongly wetting, through a porous medium is studied using statistical concepts, some borrowed from the percolation theory of disordered media. Relative permeabilities are derived. Input requirements are a network model of the pore space. distribution of the pore throat radii, and functions relating pore throat conductance and volume to the radius. Observed trends in two phase relative permeability of systems with one strongly wetting phase can be predicted. Inputs to the theory can be adjusted to fit experimental data closely.
925153 Limit form of the equations for immiscible displacement in a fractured reservoir Douglas, J; Paes-Leme, P J; Hensley, J L Transport Porous Med V6, N5/6, Oct-Dec 1991, P549-565 Immiscible displacement of one incompressible fluid by another in a naturally fractured petroleum reservoir is modelled. The medium block model is based on three families of equispaced planar fractures and is equivalent to a transformed model for immiscible flow in an unfractured reservoir with a reduced saturation and saturation-dependent porosity. Existence, uniqueness, and regularity of the solutions are established, and numerical results presented and compared to those of a single porosity model.
925154 Characterization of porous media - pore level Dullien, F A L Transport Porous Med V6, N5/6, Oct-Dec 1991, P581-606 Pore size and pore size distribution are defined, considering actual and false pores, dead-end pores, and periodically constricted tubes. ID pore structure models and 2D and 3D network models of pore structures are reviewed. The use of network models to simulate capillary pressures and relative permeability curves is discussed. Methods to determine pore structure based on computer processing of data from serial sections of rocks are described and examples illustrated. Immobilisation and microscopic distribution of wetting and non-wetting phases in immiscible flow are examined.
925155 Qualitative mathematical analysis of the Richards equation Gilding, B H Transport Porous Med V6, N5/6, Oct-Dec 1991, P651-666 Water flow in unsaturated soils is often modelled by the Richards equation. For the case of one dimensional flow in a homogeneous medium, the equation may be written as a specific nonlinear partial differential equation with a time derivative and one spatial derivative. Progress in pure mathematical analysis of this equation is examined, with emphasis on the interpretation of results. Criteria for description of hydraulic conductivity and pressure head as functions of water content, which characterise the occurrence and behaviour of the wetting front, are identified.
© 1992 Pergamon Press Ltd. Reproduction not permitted
925149 Pressure-transient analysis of arbitrarily shaped reservoirs with the boundary-element method Kikani, J; Home, R N SPE Form Eval V7. NI, March 1992, P53-60 Two boundary element formulations are presented for solution of pressure-time problems in homogeneous, anisotropic reservoirs. The ease of handling of multiple line sources and sinks and a variety of reservoir geometries and boundary conditions is a major advantage. The analytical nature of the solution is presented and numerical dispersion and grid orientation effects are minimal. The advantages and disadvantages of the convolution and Laplace domain solutions are compared and discussed.
925150 Characterising average permeability in oil and gas formations Rollins, J B; Holditch, S A; Lee, W J SPE Form Eval V7, N1, March 1992, P99-105 Permeability of geological formations frequently follows a unimodal probability distribution. Sedimentary formations generally have permeability distributions similar to log-normal. Theoretical considerations, field data, and a reservoir simulation example are used to demonstrate that the median, rather than arithmetic mean, is the correct value to describe the average value of the permeability distribution of the formation. The relevance of this to statute classification of tight gas sands is illustrated.
925151 Physics and modeling of thermal flow in unconsolidated porous media Settari, A SPE Prod Engng V7, N1, Feb 1992, P47-55 The mechanics of unconsolidated porous media is important to exploitation of oil sands or other poorly consolidated formations. A new formula for nonlinear stress strain behaviour and multiphase fluid flow is presented. Nonlinearity of soil behaviour and its interaction with fluid flow causing shear failure of the soil are the main features. The numerical formulation of the coupled flow/stress solution includes nonlinear compressibility and flow properties as functions of pressure, stress, and temperature; nonlinear thermal poroelastic stress analysis; shear or tensile failure; porosity and stress. A I D example provides new insight into reservoir mechanics in unconsolidated media.
925152 Percolation theory of two-phase relative permeability Helba, A A; Sahimi, M; Scriven, L E; Davis, H T SPE Reservoir Engng V7. N1. Feb 1992, P123-132 The slow concurrent flow of two immiscible fluids, one strongly wetting, through a porous medium is studied using statistical concepts, some borrowed from the percolation theory of disordered media. Relative permeabilities are derived. Input requirements are a network model of the pore space. distribution of the pore throat radii, and functions relating pore throat conductance and volume to the radius. Observed trends in two phase relative permeability of systems with one strongly wetting phase can be predicted. Inputs to the theory can be adjusted to fit experimental data closely.
925153 Limit form of the equations for immiscible displacement in a fractured reservoir Douglas, J; Paes-Leme, P J; Hensley, J L Transport Porous Med V6, N5/6, Oct-Dec 1991, P549-565 Immiscible displacement of one incompressible fluid by another in a naturally fractured petroleum reservoir is modelled. The medium block model is based on three families of equispaced planar fractures and is equivalent to a transformed model for immiscible flow in an unfractured reservoir with a reduced saturation and saturation-dependent porosity. Existence, uniqueness, and regularity of the solutions are established, and numerical results presented and compared to those of a single porosity model.
925154 Characterization of porous media - pore level Dullien, F A L Transport Porous Med V6, N5/6, Oct-Dec 1991, P581-606 Pore size and pore size distribution are defined, considering actual and false pores, dead-end pores, and periodically constricted tubes. ID pore structure models and 2D and 3D network models of pore structures are reviewed. The use of network models to simulate capillary pressures and relative permeability curves is discussed. Methods to determine pore structure based on computer processing of data from serial sections of rocks are described and examples illustrated. Immobilisation and microscopic distribution of wetting and non-wetting phases in immiscible flow are examined.
925155 Qualitative mathematical analysis of the Richards equation Gilding, B H Transport Porous Med V6, N5/6, Oct-Dec 1991, P651-666 Water flow in unsaturated soils is often modelled by the Richards equation. For the case of one dimensional flow in a homogeneous medium, the equation may be written as a specific nonlinear partial differential equation with a time derivative and one spatial derivative. Progress in pure mathematical analysis of this equation is examined, with emphasis on the interpretation of results. Criteria for description of hydraulic conductivity and pressure head as functions of water content, which characterise the occurrence and behaviour of the wetting front, are identified.
© 1992 Pergamon Press Ltd. Reproduction not permitted