Simulation of Conventional and Cyclic Water Injection Processes in a Heavy-Crude Oil in San Cristobal Field of Venezuela

Abstract

AbstractThis paper compares the performances of conventional water injection versus cyclic water injection in a 15° API heavy oil field of the Oficina Formation in San Cristobal, Venezuela. Cyclic water injection is a secondary oil recovery technique divided into two cycles: injection and shut in of injector wells. In the latter, the depressurization and redistribution of fluids occur because of the hysteresis of capillary forces generated in the fluid-rock system. Some oil molecules move from areas with low properties towards those with better petrophysical characteristics. The latter areas are connected to production wells, which are always kept active, thus allowing greater oil recovery, and reducing water production during the shut-in phase of injector wells. The processes behaviour was obtained through a three-dimensional black oil simulation study (Eclipse 100) with the hysteresis option activated. To compare the two processes, the fluid–rock model is calibrated using the capillary pressure drainage and imbibition curves derived by special core analyses of the reservoir under study. It is concluded that the cyclic water injection has a much better performance in terms of heavy oil recovery from unconsolidated formations with higher heterogeneity in comparison with the conventional water injection process.KeywordsReservoir simulationCyclic water injectionCapillary hysteresis