New method for estimating characteristic relative permeability from coreflooding data

Determining relative permeability of reservoir rocks is essential for modeling multi-phase flow. A common method for estimating relative permeability curves is coreflooding experiments conducted on samples extracted from the formation. Since cores are heterogeneous the measured curves are in fact effective, i.e., they characterize flow over the entire sample. These effective curves are known to be dependent on the rate of fluid injection chosen for the experiment. At sufficiently high flow rates, i.e., under viscosity dominated conditions, the measured curves become independent of flow rate and these are known as characteristic curves (kr). Estimating kr of rocks is extremely important for many reservoir modeling applications. In this work a new and simplified method for calculating kr is developed. Given properties measured in experiments, i.e., effective relative permeability, effective permeability, sub-core permeability, overall capillary pressure and steady state saturation from CT imaging, we history match single-phase flow simulations to obtain kr. The simplified equations (single phase) are obtained by substituting steady state saturation in the general two-phase flow equations. The method is fast and efficient allowing to bypass difficulties, such as numerical errors and capillary end effects, encountered in full two-phase flow simulations of coreflooding.