Improved Capillary Desaturation Model for Carbonate Reservoirs

Abstract

Abstract This paper presents a modified Capillary Desaturation Curve (CDC) model to capture the effect of the capillary number (Nc) on residual oil saturation (Sor) for carbonate reservoirs during water- and polymer flooding. The proposed model is implemented in a multicomponent, multiphase chemical reservoir simulator. Several simulation test cases are presented to illustrate the impact of the modified CDC model. Experimental and literature data for CDC were used to show that the modified model was needed to make accurate forecasts of a proposed polymer flood in a carbonate reservoir. The simulation results and experimental CDC data show that the decrease in Sor at relatively lower capillary numbers (10 -7<Nc<10 -5) often makes polymer flooding more attractive for carbonate reservoirs. Simulation results also show that the original CDC model underestimates the incremental recovery during water- and polymer flooding. Also, a sensitivity study shows the proposed model yields better forecasts of the oil recovery at various trapping-number exponent, injection rate, and permeability.