Numerical Simulation Study on Recovery Factor of Different Development Methods

Numerical simulation of oil reservoirs can be applied at various stages of reservoir development. The numerical simulation method is considered the most accurate approach for predicting reservoir recovery factors. However, in practice, the recovery factor predicted by numerical simulation for depletion development is often overestimated and even close to that of waterflooding. This study employs a multi-factor sensitivity analysis method to investigate the impacts of rock pore compressibility, waterflood residual oil saturation, gas-flood residual oil saturation, and bottom-hole flowing pressure on the recovery factor during depletion development. The results indicate that gas-flood residual oil saturation and bottom-hole flowing pressure have the most significant influence. After appropriately adjusting these two parameters, a reasonable recovery factor can be obtained. Furthermore, the recovery factors for waterflooding, CO2 flooding, and N2 flooding were analyzed. For the target reservoir, CO2 flooding achieves miscible displacement, resulting in the highest recovery factor (34%), followed by water-flooding (22%), and N2 flooding (18%).