Comparative Simulation Study of Waterflooding and CO2 Injection in Sandstone Reservoirs: Asphaltene Stability Considerations

This comparative simulation study investigates the impact of asphaltene stability on oil recovery in sandstone reservoirs using waterflooding and CO2 injection.Asphaltene precipitation poses significant risks to reservoir performance, particularly in high-risk scenarios.The simulation study utilized a range of reservoir properties, including permeability, porosity, viscosity, temperature, pressure, and salinity.The asphaltene stability index was varied from 0.4 (high precipitation risk) to 0.6 (moderate precipitation risk) and 0.8 (low precipitation risk).Waterflooding and CO2 injection methods were simulated, and oil recovery rates were evaluated.The study evaluates the effects of varying asphaltene stability indices (0.4, 0.6, and 0.8) on oil recovery using both waterflooding and CO2 injection methods.The results indicate that waterflooding consistently outperforms CO2 injection across all asphaltene stability indices, with recovery rates ranging from 20-22% at high precipitation risk (0.4) to 25-28% at low precipitation risk (0.8).In contrast, CO2 injection yields lower recovery rates, ranging from 15-18% at high precipitation risk to 22-28% at low precipitation risk.The findings suggest that waterflooding is a more effective method for oil recovery in sandstone reservoirs with high asphaltene content, while CO2 injection may be more suitable for reservoirs with lower asphaltene precipitation risks.