Pore network modelling of two-phase flow in porous rock: the effect of correlated heterogeneity

Using large scale computer simulations and pore network models of porous ro ck, we investigate the effect of correlated heterogeneity on two-phase flow through porous media. First, we review and discuss the experimental eviden ce for correlated heterogeneity. We then employ the invasion percolation mo del of two-phase flow in porous media to study the effect of correlated het erogeneity on rate-controlled mercury porosimetry, the breakthrough and res idual saturations, and the size distribution of clusters of trapped fluids that are formed during invasion of a porous medium by a fluid. For all the cases we compare the results with those for random (uncorrelated) systems, and show that the simulation results are consistent with the experimental d ata only if the heterogeneity of the pore space is correlated. In addition, we also describe a highly efficient algorithm for simulation of two-phase flow and invasion percolation that makes it possible to consider very large networks. (C) 2001 Elsevier Science Ltd. All rights reserved.