Quasi-steady two-equation models for diffusive transport in fractured porous media: large-scale properties for densely fractured systems

When dealing with the macroscopic behavior of a fractured porous medium, on e is faced with the problem of computing the large-scale parameters from th e fracture network properties. In particular, when the retained model is th e quasi-steady two-equation model, three effective coefficients have to be estimated. This upscaling problem has been reviewed using a volume averagin g method by Quintard and Whitaker. As a result, a closed form of the macros copic model was obtained with associate closure problems that can be used f or the determination of the required parameters. In this paper, we use the corresponding problems to study and discuss the behavior of the effective p roperties of 2D densely fractured systems. First, the emphasis is put on th e large-scale fracture permeability tensor, which is related to the degree of interconnection of the fractures combined to the effect of matrix diffus ion. Secondly, the exchange coefficient is considered, in particular, its d ependence on the matrix blocks geometry. Finally, we compare our approach w ith numerous techniques currently proposed in the literature. (C) 2001 Else vier Science Ltd. All rights reserved.