The Decomposition of Volumetric Sweep Efficiency and Its Utility in EOR Simulations

The traditional definition of volumetric sweep efficiency sums the effects of both fingering (arising due to contrasts in mobility) and channeling (arising due to contrasts in permeability). Accordingly, we cannot quantitatively attribute poor sweep to either channeling or fingering. Similarly, in EOR, the incremental recovery cannot be quantitatively associated with the reduction of those effects. For such purposes, we rely on visualization of saturation profiles that is both subjective and illusive especially for complex models. In this work, we demonstrate the decomposition of those two effects and its utility. We first redefine recovery factors such that we decouple channeling and fingering effects. We then validate those redefined sweep indicators by examining a 5-spot waterflood and two idealistic polymer floods. Later, we demonstrate the possible utility of those redefined sweep indicators through different examples. In one example, we compare the performance of a shear-thinning polymer to a recovery-equivalent Newtonian polymer. Using fingering and channeling sweep indicators, we immediately conclude that the shear-thinning polymer exacerbates channeling. Accordingly, we recommend the adoption of our redefined sweep indicators in any simulation suite. They provide both instant and better understanding of sweep and hence assess in making decisions that are more informed.