缝洞型碳酸盐岩储层压裂效果评价方法试验研究

An Experimental Study on Evaluation Methods for Fracturing Effect of Fractured-Vuggy Carbonate Reservoir

李新勇 耿宇迪 刘志远 汪文智 周舟

LI Xinyong GENG Yudi LIU Zhiyuan WANG Wenzhi ZHOU Zhou

中国石化西北油田分公司工程技术研究院，新疆乌鲁木齐 831000 油气资源与探测国家重点实验室（中国石油大学（北京）），北京 102249 中国石油大学（北京）石油工程学院，北京 102249

Research Institute of Petroleum Engineering, Sinopec Northwest Oilfield Company, Urumqi, Xinjiang, 831000, China State Key Laboratory of Petroleum Resources and Prospecting(China University of Petroleum (Beijing)), Beijing, 102249, China College of Petroleum Engineering, China University of Petroleum(Beijing), Beijing, 102249, China

目前，由于缺乏缝洞型碳酸盐岩储层压裂裂缝沟通效果评价体系，无法实现压裂改造效果量化评价，因而需要针对缝洞型碳酸盐岩特征建立压裂改造效果评价方法。利用人造缝洞型碳酸盐岩岩心进行了水力压裂物理模拟试验，基于试验结果建立了符合缝洞型碳酸盐岩压裂特征的评价标准，提出了“缝洞沟通系数”的概念，然后利用该系数定量分析了地应力差对缝洞型碳酸盐岩压裂效果的影响。试验发现：用以评价压裂效果的SRV系数无法准确评价缝洞型碳酸盐岩压裂效果，而缝洞沟通系数可以针对此类缝、洞发育的岩石情况作出准确的压裂效果评价；利用缝洞沟通系数评价了水平地应力差对缝洞碳酸盐岩压裂效果的影响，发现随着地应力差增大缝洞沟通系数先降低后升高。研究结果表明，缝洞型碳酸盐岩储层中各因素对压裂改造效果的影响规律与常规储层不同，利用缝洞沟通系数分析压裂裂缝扩展沟通情况针对性更强、评价缝洞碳酸盐岩储层压裂改造效果更有效。

The lack of evaluation system for evaluating communication of fractures in vuggy carbonate reservoirs makes it impossible to quantitatively analyze post frac treatment. Therefore, it is necessary to establish an evaluation method for post frac according to the characteristics of abundant natural fractures and karst caves in carbonate reservoirs. A physical experiment simulated hydraulic fracturing on artificial fractured-vuggy carbonate cores was conducted, the evaluation criteria that meets the fracturing characteristics of fractured-vuggy carbonate reservoirs were proposed based on the experimental results, and the concept of fractured-vuggy communication coefficient was proposed. Then, the proposed coefficient was used to quantitatively analyze the influence of in-situ differential stress on vuggy carbonate fracturing effect. The experimental results show that the SRV coefficient used to evaluate fracturing effect cannot accurately evaluate the effect of fractured-vuggy carbonate fracturing, while the fractured-vuggy communication coefficient can make a more accurate evaluation. The influence of horizontal in-situ differential stress on fractured-vuggy carbonate fracturing effect was evaluated with the proposed coefficient. It is found that the coefficient decreases first then increases with the increase of in-situ differential stress. The results demonstrate that the influence of various factors on fracturing effect of fractured-vuggy carbonate reservoirs are different from that of conventional ones, and the proposed fractured-vuggy communication coefficient can be used to more precisely analyze the fracture propagation and communication conditions, and to more effectively evaluate such reservoirs.

国家科技重大专项“缝洞型油藏堵调及靶向酸压工艺技术”（编号：2016ZX05014-005-003）、国家自然科学基金青年科学基金项目“碳酸盐岩储层孔洞与水力裂缝扩展相互作用的力学机理研究”（编号：51704306）资助

https://doi.org/10.11911/syztjs.2020074