The Impacts of Reservoir Heterogeneities on the CO 2 -Enhanced Oil Recovery Process—A Case Study of Daqingzijing Block in Jilin Oilfield, China

With the exploitation of oilfields, the oil production efficiency of traditional water flooding has been very low, and CO 2 -enhanced oil recovery (EOR) has become an inevitable trend of development. CO 2 -EOR is affected by many factors, among which the heterogeneity of reservoirs is one of the main influencing factors. In order to understand the impact of different reservoir conditions on the production of oil from CO 2 and the reasons behind it, and on the basis of researching the heterogeneity of reservoir porosity and permeability and its influence on the CO 2 -enhanced oil recovery process, this study has altogether established three different reservoir characteristics for comparative analysis. Under the homogeneous and heterogeneous porosity and permeability conditions of a reservoir, the displacement characteristics during a CO 2 –oil displacement process were analyzed. The layered heterogenous model had the best oil displacement effect, with its oil displacement amount reaching 8.46 × 10 4 kg, while the homogeneous model and the spatially heterogenous model had lower values; they were 1.51 × 10 4 and 1.42 × 10 4 , respectively. The results indicate that the heterogeneous conditions overall improved the flooding effect of CO 2 . Under the same injection volume and other reservoir conditions, the cumulative oil flooding effect of the layered heterogenous model was the best compared to the homogeneous and spatially heterogeneous models. Good permeability promotes the accumulation of oil, leading to a higher saturation of the oleic phase. This work provides an in-depth analysis of the effect of the non-uniform distribution of formation permeability on CO 2 -enhanced oil recovery and can help to improve carbon sequestration efficiency and oil recovery in CO 2 –oil recovery projects.