Integrated Simulation of CO2 Injection in Heavy Oil Reservoirs with Asphaltene Precipitation Effects

Abstract

The results of core flooding experiments can guide the formulation of development plans for similar oil reservoirs. However, for cores from heavy oil reservoirs, asphaltene deposition often occurs during flooding due to changes in pressure, temperature, and petroleum composition, affecting the determination of injection parameters. Taking core samples from the Xia 018 well block as the research object, this study determined that the crude oil sample exhibits normal CO2 sensitivity based on PVT experiments and core flooding results. A corresponding asphaltene precipitation model was established and coupled with core-scale numerical simulation, forming an integrated core-scale numerical simulation method considering asphaltene precipitation. Through orthogonal experimental design, the optimized fracturing production parameters for Well Y were determined as follows: fracturing stage length of 1000 m, CO2 injection volume of 100 m3 per stage, fluid volume per stage of 1000 m3, proppant volume of 1000 m3, and injection rate of 14 m3/min. Finally, the optimized parameters were applied to simulate a case well, where the asphaltene deposition model combined with pressure nephograms during production provided effective guidance on unplugging timing. Compared with results without using the asphaltene deposition model, cumulative production decreased by 1300 m3 when the model was applied. These findings can provide a reference for the development of similar reservoirs.