Immiscible Displacements in Porous Media: Testing Network Simulators by Micromodel Experiments

Abstract

ABSTRACT In the past, many network simulators have been presented to describe transport processes through porous media, such as deep filtration, immiscible or miscible displacements, blob mobilization, acidizing, etc. In this paper we compare the results of physical and stochastic network simulators with experiments in micromodels. We first describe the patterns obtained by displacing a wetting fluid by a non-wetting fluid in a 2-dimensional porous medium, when both viscosity ratio (M) and capillary number (Ca) are varied independently over many orders of magnitude. The main result is the good agreement between experimental and simulated patterns (trapping, fingering, connectivity…) even for extreme values of M and Ca (high viscosity contrast or very strong capillary effects, for instance). In the second part, both experiments and simulations are compared to the results of stochastic models. The classical models of "invasion percolation" and "diffusion limited aggregation" are shown to represent the limiting cases when the dimensionless numbers Ca (for I.P.) and 1/M (for DLA) tend to zero. Finally, some comments are presented on a recent model based on fluid compressibility and particle diffusion.