Effect of crossflow on upgridding geological model under water flooding scenario

The main purpose of upgridding is to reduce the number of grid blocks present in the geological model while preserving the dynamic behavior observed in the geological model. Since the main goal is to preserve the dynamic behavior, the reservoir parameters, which have an impact on dynamic behavior, should be properly calibrated before upgridding. This includes the type of flow process that is under consideration as well as crossflow across the geological layers. In this paper, we examined the effect of mobility ratio in the presence and absence of crossflow under water flooding conditions. We observed that in the case of favorable mobility ratio and crossflow condition, the upgridding error (difference between fine and coarse layer models production) is small and many more layers could be combined without deviating from the fine-scale model result. In contrast, for unfavorable mobility ratio displacements, crossflow does not help homogenize heterogeneous layers. The upgridding error increases very rapidly as the layers are combined. This implies that we need to maintain a much higher level of detail from the fine-scale model if we want to retain the dynamic behavior.