A new upscaling method of relative permeability curves for reservoir simulation Conference Paper uri icon

abstract

  • Relative permeability is one of the most important factors in numerical reservoir simulation. Although the relative permeability curves may be available on a very fine level of detail, their direct use to estimate the amount of uncertainty, which requires thousands of reservoir simulation runs, is generally not practical because of the excessive computer time and memory that would be required. Despite the extensive research that has been performed in the past few decades, effective upscaling to reduce computation times in highly heterogeneous reservoir still remains a challenging procedure. In this paper, we demonstrate how conventional upscaling approaches may lead to large errors. To overcome the inaccuracy, we investigated and developed a new relative permeability upscaling technique for the coarse scale modeling for heterogeneous reservoirs. In our new method, single-phase upscaling was applied at the beginning to set up the base case for optimization. The regression runs were conducted by non-linear optimization. The decision variables in a standard Corey and logistic form were used to check the errors between the coarse and fine models. After the procedure converged, a new relative permeability curve for the coarse model was generated. The match for the breakthrough time and post-breakthrough performance was very accurate using the new relative permeability curves. Predictability with the new curves also appeared to be substantially improved; the newly generated relative permeability curves can be used over periods beyond that of the original match. The new method was verified by using three-phase, 3D, and highly heterogeneous reservoir models. These verifications were performed on large models approaching one million cells with black oil and composition fluids with waterflooding and water-alternating-gas (WAG) recovery processes. The ultimate goal of the work has been to use the upscaled models with modified relative permeabilities to investigate how uncertainty is affected by upscaling. The fine scale results indicate that more reasonable results can be obtained for estimating the effect of uncertainty with the new upscaling technique as compared to conventional methods, with computation time orders of magnitude faster than previously available. Copyright 2009. Society of Petroleum Engineers.

author list (cited authors)

  • Wang, K., Killough, J. E., & Sepehrnoori, K.

publication date

  • December 2009