Download or read book Comparison of Field-Scale Effective Properties of Two-Phase Flow in Heterogeneous Porous Media Obtained by Stochastic Analysis and Numerical Experiments written by and published by . This book was released on 2002 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of subsurface heterogeneity on two-phase flow can be observed from the characterization functions of field-scale effective relative permeability and capillary pressure with respect to mean saturation. Numerical experiments were used to evaluate such effective properties of two-phase flow in a heterogeneous medium with properties representing the Borden Aquifer, and compared with the results of stochastic analysis developed using a spectral perturbation technique that employs a stationary, stochastic representation of the spatial variability of soil properties. Arbitrary forms of the relative permeability and capillary pressure characteristic functions with respect to saturation can be used in the theoretical analysis and numerical code. A statistical scaling procedure, which is a generalization of Leverett scaling, was developed for the relationship between intrinsic permeability and two capillary parameters. The procedure for estimating the effective properties of two-phase flow using numerical simulation consists of three-steps. Firstly, a local-scale heterogeneous system with random fields of intrinsic permeability and two capillary parameters was generated. Secondly, numerical simulation of single-phase flow in the system, with different sets of flow boundary conditions for different directions, was performed; the field-scale effective saturated hydraulic conductivity tensor was calculated on the basis of the mean Darcy law. The tensor obtained numerically is very close to that determined using the generalized spectral-perturbation approximation. Finally, a number of numerical experiments on two-phase flow in the system were conducted with different infiltration rates of DNAPL; the field-scale effective relative permeability and capillary pressure functions were obtained. In each experiment, a highly heterogeneous saturation field was obtained, leading to large variations of actual nonwetting phase permeability (combination of intrinsic permeability and its positively correlated relative permeability). Both stochastic and numerical analyses produced very similar results of effective properties of multiphase flow. The vertical effective relative permeability is significantly lower than the homogeneous one found using mean capillary parameters, particularly at low mean DNAPL saturation (low mean capillary pressure). On the other hand, the effective capillary pressure function differs only slightly from the homogeneous case. Various statistical properties of local-scale NAPL saturation, capillary pressure and relative permeability and their relationships with intrinsic permeability and capillary parameters were analyzed in detail.