Correcting Oil/Water Relative Permeability Data for Capillary End Effect in Displacement Experiments

Abstract

ABSTRACT Capillary effects in low flow rate displacement experiments cause error in relative permeability values calculated by JBN or Jones and Roszelle methods. The results from a series of displacement and capillary pressure experiments were used along with a history matching package to quantify the changes in relative permeabilities with rate. The experiments were conducted with different rates on short and long cores. The history matching procedure was developed using a one-dimensional, two phase finite difference simulator, and the Levenberg-Marquardt optimization algorithm. Exponential form for relative permeability functions were used and the change of function parameters with rate was investigated. The results show that for the case of drainage the relative permeability parameters (i.e., end-point relative permeability and saturation exponent) have functional relationships with rate. The saturation exponent in non-wetting phase and the end-point nonwetting relative permeability increase with rate. However, the end-point relative permeability to wetting phase did not show any significant change but the saturation exponent in the wetting phase decreased with increase in rate. Regression equations of these changes were developed. In the case of imbibition, these parameters did not indicate any meaningful trend with rate.