Pore-scale simulations of disproportionate permeability reducing gels

The purpose of this paper is to investigate, by simulation, how a gel affects the two-phase flow (oil and water) in a uniform pore-space geometry under various wettability conditions (neutrally wet, water-wet, oil-wet and fractional-wet). The (aqueous) gelant is assumed to be attracted to water-wet walls and the gel itself is assumed water-wet. It is of practical interest that the gel reduces the water phase permeability more than it reduces the oil phase permeability. This disproportionate permeability reduction (DPR) is measured at steady state flow using the same driving force before and after gel. The wanted DPR is found in neutrally wet, water-wet and fractional-wet systems, but depends on the capillary number. The DPR is next tried optimized for the most promising case of fractional wettability. The optimal DPR is found when using a relative low gelant fraction (∼0.2) and a relative high capillary number (∼0.1) when placing the gel. Also, the simulations indicate that the gelant/oil viscosity ratio is not a critical parameter for the gel-placement.