A New Method for the Scale Up of Displacement Processes in Heterogeneous Reservoirs

Abstract

A general method for the scale up of highly detailed, heterogeneous reservoir cross sections to coarser scales, for the purposes of flow simulation of displacement processes, is developed and applied. The technique involves the nonuniform coarsening of the fine scale description, with fine resolution introduced in regions of potentially high fluid velocities (typically regions of connected, high permeability) and coarse, homogenized descriptions applied to the remainder of the reservoir. The method is designed to capture both average behavior as well as some important behaviors which are due to the extremes of the permeability field, such as the breakthrough time of the displacing fluid. The method is applied to several example problems, including two actual field examples, and is shown to provide coarsened models (~ 25 x 25) which give simulation results for fractional flows and saturations in close agreement with fine scale (~ 100 x 100) results. These examples demonstrate the ability of the method to capture a wide variety of flow behavior without the need for specific knowledge of the global flow field, indicating that the coarsened reservoir description is to a large degree process independent.