裂缝性碳酸盐岩油藏可视化模型水驱油实验

为了更好地认识裂缝性碳酸盐岩油藏的渗流机理,结合油藏实际地质特征,利用真实岩心设计制作了可视化网络裂缝模型,考察了注入速度、模型倾斜角度等因素对注水效果的影响,以及水驱油过程中的油水运动分布特征。观测到由于受裂缝性油藏非均质性的影响,水驱后残余油存在形式主要有孤滴状、角隅状及膜状等,每种残余油的形成机理也不同。实验结果表明:水驱油时,驱替速度与采出程度不成正比,而是存在一个最佳驱替速度,即临界驱替速度;剩余油的形成和分布主要受岩石表面润湿性、裂缝连通性和重力分异的影响;水驱油效率与裂缝地层倾斜角度有关,地层倾斜角度越小,采出程度越高。裂缝性油层较厚时,水驱后油层顶部可能会有大量剩余油,仍具有较大开发潜力。

Experiment on water-oil displacing for visible model of fractured carbonate reservoir

This paper focuses on the research of flow mechanism in the fractured carbonate reservoir. Based on the actual geologic characteristics and core, it designs a visible network fracture model to simulate the water flooding mechanism and analyzes the influence of different injection velocities and inclination angles of model on the water flooding effect. The oil and water distribution in process of water flooding is understood. Because of reservoir heterogeneity, residual oil is mainly in the fi）rm of isolated droplet, cant and membrane, etc. The formation mechanism of residual oil is different. The experiment results indicate that when water-oil displacing, the displacing velocity is not proportional to recovery degree, but there is an optimum displacing velocity in water flooding, that is the critical displacing velocity. The formation and distribution of remaining oil is mainly affected by wettability of rock, connectivity of fracture and differentiation of gravity. The water-oil displacing efficiency is related to the inclination angle of fractured reservoir. The smaller the fractured layer dip is, the higher the degree of recovery is. If the oil-bearing layer is thick, there is a great potential for development on the top of oil-bearing layer.