Abstract: For most of the anticlinal, fault nose, salt dome and buried hill reservoirs in China, attic oil is easy to form during the waterflooding exploiting process, which reduces the oil recovery efficiency. The top gas injection gravity immiscible displacement process can push oil⁃water interface to the bottom of production wells and improve the final recovery efficiency. An experimental study on the gravity immiscible displacement process of top gas injection is carried out. The horizontal gas injection and top gas injection displacement processes are compared. The results show that the recovery efficiency of the top gas injection is higher than that of horizontal gas injection. Besides, four groups of the gravity immiscible displacement processes of top gas injections are compared. The results show that the final recovery efficiency can increase to a certain extent with the decreasing of gas injection rate, but the duration of the whole displacement process increases sharply. The research indicates that gravity differentiation can increase the final recovery efficiency. At the same time, in consideration of the cost of time, there is a limited gas injection rate, for which the calibration value is 2 mL/h.

Key words: Carbonate, Top gas injection, Gravitational differentiation, Improving recovery efficiency

摘要： 针对我国大部分背斜构造、断鼻构造、盐丘构造和潜山构造油藏，注水开发过程中容易形成“阁楼油”，降低最终采收率的问题，采用顶部注气重力非混相驱替过程能够推移油水界面至生产井底之下，提高最终采收率。对顶部注气重力非混相驱替过程进行实验研究，对比分析水平注气和顶部注气驱替过程，结果显示顶部注气驱替过程采出程度均高于水平注气驱替过程，同时对比分析四组顶部注气重力非混相驱替过程，结果显示降低注气速率能在一定程度上增大最终采收率，但驱替全过程持续时间增幅剧烈。研究表明，重力分异作用能增大最终采收率；同时在考虑时间的成本上，顶部注气非混相驱替过程存在极限注气速率，标定值为2 mL/h。

关键词: 碳酸盐岩, 顶部注气, 重力分异, 提高采收率