缝洞型碳酸盐岩油藏岩溶储集体注氮气提高采收率实验  

Experimental study on enhanced oil recovery by nitrogen injection in fracture-cave carbonate reservoir

作　　者：杨景斌 侯吉瑞[1,2] YANG Jingbin;HOU Jirui(Research Institute of Unconventional Petroleum Science and Technology,China University of Petroleum(Beijing),Beijing City,102249,China;MOE Key Laboratory of Petroleum Engineering,China University of Petroleum(Beijing),Beijing City,102249,China)

机构地区：[1]中国石油大学(北京)非常规油气科学技术研究院,北京102249 [2]中国石油大学(北京)石油工程教育部重点实验室,北京102249

出　　处：《油气地质与采收率》2019年第6期107-114,共8页Petroleum Geology and Recovery Efficiency

基　　金：国家科技重大专项“缝洞型油藏注气提高采收率技术”之“缝洞型碳酸盐岩油藏提高开发效果技术”（2016ZX05014-004-004）和“缝洞型油藏注气提高采收率机理研究“（2016ZX05014-004-001）

摘　　要：缝洞型碳酸盐岩油藏储集空间类型多样,形态复杂,在水驱过程中容易形成阁楼油和绕流油,采用气驱能够有效补充地层能量,提高剩余油的采出程度。为观察缝洞型油藏中注入气体的驱油动态,根据塔河油田实际地质资料和注采特征,依据相似性原则,设计制作二维缝洞型油藏可视化物理模型,开展缝洞型油藏岩溶储集体模型注气提高采收率实验研究。结果表明:以注气速度分别为20和5 mL/min进行驱替,宏观油水界面特征基本相似,在氮气驱替过程中会出现明显的气水同锥现象和气水协同效应;注气速度为20 mL/min下的最终采出程度约为70.5%,注气速度为5 mL/min下的最终采出程度约为78.9%,注气速度高易发生气窜,低注气速度可以延长注氮气时间,防止气体过早发生气窜,但是由于速度低,驱动能量低,氮气只能进入阻力相对较小的溶洞和裂缝中。因此,合理控制注气速度能够充分发挥气驱提高采收率的潜能。The types of reservoir spaces in the fracture-cave carbonate reservoir are various and its shapes are complex. Attic oil and bypassing oil are easily formed during the process of water flooding. Gas flooding can effectively supplement formation energy and improve the recovery of remaining oil. In order to observe the displacement performance of injected gas in the fracture-cave reservoir,a two-dimensional visual physical model of fracture-cave reservoir is designed and made according to the actual geological data and injection-production characteristics of Tahe Oilfield as well as similarity principle.At the same time,the experimental study on enhanced oil recovery by gas injection in the karst-reservoir model of fracturecave reservoir is carried out. The results show that the macroscopic characteristics of oil-water interface are basically similar after displacement at 20 and 5 mL/min of gas injection rate,and there are obvious gas-water coning phenomenon and gas-water synergistic effect during nitrogen flooding. The ultimate recovery is about 70.5% at 20 mL/min of gas injection rate,and it is 78.9% at 5 mL/min of gas injection rate. High gas injection rate easily causes gas breakthrough. Low gas injection rate can prolong the time of nitrogen injection,so that gas breakthrough is not easy to occur prematurely. However,nitrogen can only enter caves and fractures with relatively low resistance due to low injection rate and low driving energy.Therefore,it is found that reasonable gas injection rate can enhance the potential of gas flooding in improving oil recovery.

关 键 词：缝洞型碳酸盐岩油藏 岩溶储集体 可视化物理模型 注气 提高采收率 

分 类 号：T357.7[一般工业技术]