Abstract:

This presentation shows that for primary recovery, the oil production is relatively high at the initial stage of production and declined rapidly in the first two years. After one year of production, the oil rate is 10% of the original oil rate. The primary recovery of Bakken formation is 9.11%, while the primary recovery of the study area is only 5.15%, which means that the primary recovery is inefficient for oil recovery from the study area. The MMP for CH4, CO2 and separator gas are 32, 26 and 25MPa, respectively. The oil production with gas injection is better than with water injection. Compared with primary recovery, the incremental after CH4, CO2 and separator gas injections are 56.89%, 36.31% and 50.49%, respectively. CH4 and the separator gas are more suitable than CO2 for enhancing oil recovery in the study area. As reservoir heterogeneity increased, oil recovery decreased. However, compared with primary recovery, gas injection can still increase the oil recovery. Gas injection is beneficial for production in low and medium heterogeneous reservoirs.