An accurate multiphase upscaling for flow and transport in heterogeneous porous media

Subgrid effects can have a strong influence on flow and transport in oil reservoirs. In this work a new model for the representation of subgrid terms is introduced and applied to two-phase reservoir flows. The model entails a construction of pseudo relative permeabilities using accurate inlet boundary conditions for the saturation field. Motivation for the form of the model is provided through a consideration of asymptotic techniques for two-phase flow. The numerical computation of the subgrid terms and the implementation of the overall method are described. The accuracy of the new subgrid representation is compared to that of coarse scale models with no subgrid treatment and to coarse models based on traditional pseudo relative permeabilities. In essentially all cases the new model provides more accurate coarse scale predictions relative to reference fine scale results. These are preliminary results.