海上低渗油田CO_(2)气水交替驱可行性实验研究

Experimental study on feasibility of CO_(2)‑WAG flooding in offshore low permeability oilfield

海上L油田属于特低渗透断块油藏,常规水驱开发难度大、注入压力高且储层能量亏空。为有效提高油田开发效果,以海上L油田特低渗透断块油藏为研究对象,开展靶区CO_(2)驱油机制、CO_(2)气水交替驱注入参数优化和CO_(2)气水交替驱效果评价研究,为目标油田CO_(2)驱可行性提供依据。结果表明,气水交替驱较水驱可提高采收率6.48%,CO_(2)气水交替驱最佳气液比为1∶1,最佳注气速度为1.0 mL/min,交替段塞大小为0.3 PV。该研究对海上L特低渗油田开发具有重要的指导意义。

The offshore L oilfield belongs to an ultra-low permeability fault block reservoir,which is difficult to develop by conventional water flooding and has high injection pressure.In order to effectively improve the oilfield development effect,the offshore L ultra-low permeability fault block reservoir was studied,the CO_(2)displacement mechanism and the effect of CO_(2)-WAG flooding,the changes in the phase behavior characteristics of crude oil before and after CO_(2)injection were evaluated.The injection parameters of CO_(2)-WAG flooding were optimized to provide a basis for the feasibility of CO_(2)flooding in the target oilfield.Compared with water flooding,the oil displacement efficiency of WAG flooding could be increased by 6.48%.The optimal gas-liquid ratio of CO_(2)-WAG flooding was 1∶1,the optimal gas injection rate was 1.0 mL/min,and the size of the alternative slug was 0.3 PV.The feasibility experimental study of CO_(2)-WAG flooding has important guiding significance for the development of offshore L ultra-low permeability oilfield.