缝洞型油藏注水驱油可视化物理模拟研究

采用可视化物理模拟方法直观研究了缝洞油藏的注水驱油机理，考察了不同注入流体、注入方向、注入角度等多方面因素对注水效果的影响，直观了解了缝洞油藏注水驱油前后的油水分布，并进行了注气提高采收率实验。结果表明：缝洞位置对水驱效果产生明显的影响；重力分异在缝洞模型中具有重要的作用；对于缝洞型油藏，剩余油的形成和分布主要受缝洞通道不规则性和重力捕集的影响，水驱后剩余油主要分布在上部溶洞和下部溶洞顶部难以驱替的“阁楼空间”内，这部分剩余油也是注气驱替的主要驱替空间；实验发现，水驱油过程中一旦形成水流通道，孔洞中的剩余油就难以被驱替，改变注水方式或注入介质（如注气）等，有可能进一步驱替孔洞中的剩余油，提高采出程度。后续注气实验证明通过改变注气方式可以明显驱出“阁楼空间”中的剩余油。

STUDY ON THE VISUAL MODELING OF WATER FLOODING IN CARBONATE FRAC-TURE-CAVITY RESERVOIR

This paper focuses on the research of water flooding mechanism in fracture-cavern reservoirs by visualized physical simulation. The effects of different injection fluids, injection directions and injection angles on flooding, and the oil and water distributions before and after water injection are obtained directly. The experiment of gas injection to enhance oil recovery has also been conducted. The results indicate that the location of fractures and caverns has a significant impact on water flooding, and gravity differentiation plays an important role in the fracture-cavern model. The formation and distribution of remaining oil is mainly affected by channel irregularity and gravitational capture. Residual oil mainly distributes in the“attic storey”, in which the top caves and head of bottom caves the residual oil is difficult to flood. They are also the main displacement space of gas injection. Once the water channel was formed during the displacement, remaining oil in caves would be difficult to displace. Changing the way of water injection or injection media, such as gas injection, is possible to further displace the remaining oil in caves, so that to enhance the recovery. Sequent gas injection experiments demonstrate that remaining oil in the attic storey can be driven obviously by changing the way of gas injection.