Preserving vorticity improves the accuracy of multiscale solvers

Within reservoir management, there is a growing demand for highly accurate and fast reservoir simulators. So-called multiscale methods are designed to preserve fine-scale information accurately in an accelerated coarse-scale computation of fluid flow. In many cases, this requires that coarse partitions are meticulously adapted to prominent geological features that determine flow paths. Partitions that seek to preserve the vorticity from a representative fine-scale flow simulation can be particularly effective to this end. We describe how to incorporate such partitions in the state-of-the-art multiscale restriction-smoothed basis (MsRSB) method, and present a series of two-phase test cases to validate and demonstrate the effectiveness of the resulting method. Our results show that using a nonuniform vorticity-based partition improves the accuracy of the MsRSB solver compared with uniform partitions and nonuniform partitions with a similar number of coarse blocks that adapt to permeability or velocity.