页岩储层自发渗吸实验及润湿性研究

Spontaneous imbibition experiment and wettability of shale reservoir

叶洪涛 宁正福 王庆 程志林 黄亮 穆代峰 2

中国石油大学（北京）油气资源与探测国家重点实验室，北京 102249 中国石油大学（北京）石油工程学院，北京 102249

State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing 102249, China School of Petroleum Engineering, China University of Petroleum, Beijing 102249, China

页岩储层一般需要水力压裂技术进行开发，压裂液在储层中的自发渗吸是页岩气藏开发的重要机理。文中利用页岩粉末装置分别在页岩油气系统和气水系统开展自发渗吸实验研究，对页岩储层的渗吸特征取得了进一步的认知。实验结果表明：页岩粉末渗吸油量高于渗吸水量，但渗吸水的速率高于渗吸油的速率。其结论与常规渗吸实验相反，主要是由于页岩中有机质纳米孔数量较多，粉末化后疏水网络能有效连接，比表面积增大，引起页岩粉末渗吸油量大于渗吸水量；同时由于有机纳米孔孔径较小，摩擦阻力较大，引起渗吸油速率降低，平衡时间延长。通过应用液￣液萃取（LLE）润湿性实验和润湿性指数法进一步表明，实验页岩粉末的润湿性为弱油湿。

To increase the shale gas productivity, hydraulic fracturing is a common technique. The spontaneous imbibition of fracturing fluids in reservoirs is an important mechanism for the development of shale gas reservoirs. In this paper, the experiment is conducted by using a shale powder device under the air-oil and the air-water system, and the imbibition characteristics of shale reservoirs are further recognized. The experimental results show that the oil uptake is higher than the water uptake, but the rate of water imbibition is higher than the rate of oil imbibition. The conclusion is inconsistent with conventional imbibitions. Due to the high content of organic nanopores in the shale, the hydrophobic network can be effectively connected after powdering, and the specific surface area increases, causing the oil uptake higher than the water uptake. At the same time, the organic nanopore pore size is smaller, which enhanced greater frictional resistance, resulting in lower oil imbibition rate and longer equilibration times. The LLE method and wettability index were used to further demonstrate that the experimental shale powders are oil-wet.

10.6056/dkyqt201901019