Upscaling of Nonlinear Forchheimer Flows
This work addresses the need for efficient upscaling of nonlinear flows in heterogeneous porous media, which is important for reservoir simulation and groundwater modeling.
The authors propose an upscaling method for nonlinear Forchheimer flow in heterogeneous porous media, achieving coarse-scale parameters that yield close volumetric average velocities between fine and coarse scales. Analytical formulas for stratified domains correlate with numerical results with high accuracy.
In this work we propose upscaling method for nonlinear Forchheimer flow in highly heterogeneous porous media. The generalized Forchheimer law is considered for incompressible and slightly-compressible single-phase flows. We use recently developed analytical results Aulisa et al. (2009) and write the resulting system in terms of a degenerate nonlinear flow equation for the pressure with the nonlinearity that depends on the pressure gradient. The coarse scale parameters for the steady state problem are determined so that the volumetric average of velocity of the flow in the domain on fine scale and on coarse scale are close enough. A flow-based coarsening approach is used, where the equivalent permeability tensor is first evaluated following the streamline of the existing linear cases, and successively modified in order to take into account the nonlinear effects. Compared to previous works Durlofsky and Karimi-Fard (2009) and Peszynska et al. (2009), our approach relies on recent analytical results of Aulisa et al. (2009) and combines it with rigorous mathematical upscaling theory for monotone operators. The developed upscaling algorithm for nonlinear steady state problems is effectively used for variety of heterogeneities in the domain of computation. Direct numerical computations for average velocity and productivity index justify the usage of the coarse scale parameters obtained for the special steady state case in the fully transient problem. Analytical upscaling formulas in stratified domain are obtained for the nonlinear case. They correlate with high accuracy with numerical results.