裂缝性低渗油藏二氧化碳驱注入方式实验

Injection experiment of carbon dioxide flooding in low-permeability fissure reservoirs

邹积瑞 岳湘安 孔艳军 张俊彬 张丽娟 赵决顺

中国石油大学（北京）石油工程教育部重点实验室，北京 102249

MOE Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing 102249, China

低渗透油藏一般都伴有裂缝发育，由于裂缝具有较高的导流能力，致使注入的CO₂沿裂缝发生气窜，严重影响CO₂驱效果。针对这一问题，提出了将裂缝作为注气通道，在裂缝两侧布井采油的方法。运用岩心驱替物理模拟实验，研究了沿裂缝注CO₂的速度对波及效率和采收率的影响，以及缝注侧采后关闭气窜井和焖井措施对采收率的影响。结果表明：沿裂缝注CO₂能够有效地消除裂缝气窜的不利影响，提高采收率17.72百分点；驱替速度越小，岩心的波及效率和采出程度越高；关停气窜井是有效抑制气窜的措施，焖井后驱替能够进一步挖掘剩余油，提高采收率7.52百分点。

In low-permeability reservoir, fractures are generally initiated during the injection. Subsequently, the efficiency of CO2 injection is significantly affected by the gas channeling along fractures due to the high conductivity of fractures. In this paper, we employ the fractures as the injection gas channel and place the injection wells at the both wings of the fracture to deal with the above problems. The core flooding experiments are conducted to physically simulate the velocity of CO2 along the fracture and the impacts on sweep efficiency, ultimate recovery of CO2 injection, and ultimate recovery after the shut-in of the gas channeling wells. As a result, CO2 injection along fractures can efficiently counter the detrimental impact by gas channeling in fractures, which leads to 17.72% increase in ultimate recovery. The sweep efficiency and ultimate recovery increase with decreasing flooding velocity. Shut-in of gas channeling well can greatly hinder the gas channeling and thereby enhance the recovery of remaining oil, which leads to 7.52% increase in ultimate recovery.

10.6056/dkyqt201606024