Capillary Effects in Heterogeneous Porous Media: Experiments, Pore Network Simulations, and Continuum Modeling

Abstract

Abstract We investigate effects of capillary heterogeneity induced by variations in permeability in the direction of displacement in heterogeneous porous media. The investigation is three-pronged and uses macroscopic simulation, based on the standard continuum equations, experiments with the use of an acoustic technique and pore network numerical models. It is found that heterogeneity affects significantly the saturation profiles, the effect being stronger at lower rates. For drainage, a good agreement is found between continuum model predictions, experimental results and the pore network numerical models based on which it can be concluded that capillary heterogeneity effects in the direction of displacement act much like a body force (e.g. gravity). The results are interpreted with the use of invasion percolation concepts. For secondary imbibition, a poorer agreement exists between continuum model and experimental results at low capillary numbers, which requires the use of a pore network simulator involving film flow. Numerical simulation results are discussed for 2-D geometries.