Conceptual Darcy-Scale Model of Oil Displacement with Macroemulsion

Experiments have shown that injection of oil-in-water macroemulsions can be used as an effective enhanced-oil recovery (EOR) method, with potential increase in the volume of oil recovered. As emulsion drops move through the pore space, they give rise to rnultiscale flow effects that are commonly associated with mobilization of residual oil and macroscale mobility control or conformance. Compared to water injection, emulsion flooding can improve the macroscopic reservoir sweep as well as reduce the residual oil saturation. Prediction of reservoir flooding scenarios requires a physically meaningful two-phase flow model that accounts for the presence of emulsion drops in the aqueous phase. Conceptually in this work, we describe emulsions as an aqueous phase containing a certain concentration of oil drops. The aqueous-phase dynamic properties depend on the emulsions and porous media characteristics. Here, we propose to represent emulsion injection effects in a simplified fashion through changes in the relative permeability curves of both the aqueous and oil phases. Steady-state two-phase flow experiments were conducted to evaluate these relative permeability curves with and without the presence of oil drops dispersed in the aqueous phase. The effect of the relative permeability curves on Darcy-scale or continuum oil displacement was evaluated by comparing numerical reservoir-scale predictions of oil recovery for water and emulsion flooding using the experimentally determined relative permeabilities.