A Renormalisation-Based Upscaling Technique for WAG Floods in Heterogeneous Reservoirs

A novel and rapid upscaling procedure is described in which: (1) pseudo-functions are generated for each block in a coarse grid; (2) a renormalization method is used to calculate the pseudo-functions; (3) an empirical viscous fingering model is used to allow for fluid instabilities in unfavorable mobility ratio displacements. Oil recovery predictions are shown to agree well with conventional simulations made on the fine (geological model) grid for unstable, first-contact miscible WAG floods with a range of permeability distributions. In all cases, the result is an improvement (usually a substantial one) over a conventional coarse grid model in which only the absolute permeability of each block is upscaled.