Predicting relative permeability from experimental capillary pressure porous plate test for two phase flow

Abstract

Relative permeabilities relationships as a function of fluids saturation are one of the most important parameters for describing multiphase flow processes in reservoir rocks. When direct laboratory tests are not available for investigating oil-water multi-phase flow in rocks, then indirect prediction techniques using relative permeability functions are widely used, e.g. from capillary pressure test. In this study the measurement of capillary pressure was performed on rocks plugs with different characteristics at reservoir conditions using porous plate method. During measurement semi-permeable membrane was used with 15 bar threshold pressure, what allowed to register formation water saturation, at changing differential pressures steps. Desaturation at each pressure stage was continued until no more produced liquid was observed. Water saturation point at maximum capillary pressure applied is assumed to be final irreducible water saturation. Application of porous plate method provides sufficient stabilization time, allowing to achieve uniform saturation distribution. In this research, Brook–Corey model was used to predict relative permeability from experimental measured capillary pressure data for oil-water phase flow in porous media. As a result, it is possible to obtain more accurate capillary pressure outcomes, and relative permeability curves for the two-phase system, than other methods used in practice. Performing capillary pressure measurements at reservoir conditions, allows to restore the processes occurring in the reservoir.