缝洞型油藏泡沫驱效果及缝洞结构动用机理

缝洞型碳酸盐岩油藏储集空间主要以裂缝和溶洞为主，非均质性极强，注水和注气开发过程中储集空间内残余大量剩余油。本文根据塔河油田缝洞型碳酸盐岩油藏的地质特点设计制作了能够表征不同缝洞结构特征的二维可视化物理模型，并基于可视化模型开展了的泡沫驱物理模拟实验，揭示了泡沫驱对不同缝洞结构的驱油效果及不同缝洞结构的动用机理，并明确了泡沫对不同驱替阶段剩余油的动用效果。研究表明泡沫具有极好的流度控制能力和高渗通道封堵能力，对于水平方向、垂直方向和高角度的裂缝都具有很好的驱替效果，能够有效的提高缝洞型碳酸盐岩油藏不同开发阶段后的原油采收率。充填介质的存在有利于扩大泡沫波及体积提高微观驱油效率；增强泡沫的强度和稳定性，能够增强泡沫调流转向的能力；减小泡沫的密度，降低界面张力，提高泡沫在缝洞油藏中的采收率。室内研究结果可为缝洞型碳酸盐岩油藏泡沫驱矿场应用提供理论基础。

Study on foam flooding effect and displacement mechanism of fracture-vuggy structure in fracture-vuugy reservoir

The fracture-vuggy carbonate reservoir possess strong heterogeneity, and the reservoir space of it is mainly composed of fractures and vugs. After water injection and gas injection development, there is a large amount of remaining oil in the reservoir space. In this paper, a two-dimensional visual physical model which can characterize the structural characteristics of different fractures and vugs is designed and made according to the geological characteristics of fracture-vuggy carbonate reservoirs in Tahe Oilfield. The physical experiments of foam flooding are carried out based on these visualization model. The foam flooding effect and the production mechanism of different fracture-vuggy structures are revealed, and the foam production effect on remaining oil in different displacement stages is clarified. The study shows that foam has excellent mobility control ability and high permeability channel plugging ability. It has a good displacement effect for horizontal, vertical and high-angle fractures, and can effectively improve the oil recovery of fracture-vuggy carbonate reservoirs at different development stages. The existence of filling medium is beneficial to enlarge the foam sweep volume and improve the microscopic oil displacement efficiency. Enhancing the strength and stability of the foam can enhance the ability of the foam to change fluid flow direction. Reduce the density of foam and reduce the interfacial tension can improve the foam flooding recovery in fracture-cave reservoir. The results of laboratory research can provide a theoretical basis for the field application of foam flooding in fracture-vuggy carbonate reservoirs.