页岩气井返排规律实验与微观力学机制分析

Flowback rule experiment and micromechanical mechanism analysis for shale gas wells

阎续 孙敬 刘德华

YAN Xu SUN Jing LIU Dehua

中石化江汉石油工程有限公司页岩气开采技术服务公司 长江大学 湖北省油气钻采工程重点实验室 湖北省页岩气工程研究中心

Shale Gas Exploitation Technology Service Company, SINOPEC Jianghan Petroleum Engineering Co., Ltd., Wuhan 430043, Hubei, China Yangtze University, Wuhan 434023, Hubei, China Hubei Key Laboratory of Oil & Gas Drilling and Production Engineering, Wuhan 434023, Hubei, China Hubei Shale Gas Engineering Research Center, Wuhan 434023, Hubei, China

针对页岩气井压裂液返排规律认识不清，影响实际页岩气生产井工作制度优化的问题，采用岩心流动实验和气、水与储层岩石的微观作用力分析等方法，研究了压裂液返排规律和机制。研究结果表明，储层矿物成分差异是影响压裂液返排速度、返排率的主要因素，黏土矿物含量高的储层返排速度慢、返排率低，而返排压差大小只影响初始返排速度；通过分析压裂液在储层有机孔和无机孔的微观分子作用力，给出不同孔径对应的返排压差，进而可依据总孔隙分布折算不同类型储层合理返排压差；最后建立了基于单孔模型的累积返排量的计算方法。研究成果对分析压裂液返排规律和确定合理生产制度具有实际意义。

In view of problems that the understanding on the flowback law of fracturing fluid from shale gas wells is unclear, as well as that the unclear understanding affects optimizing the working system of actual shale gas production wells, by using the core flow experiments and the analysis on microcosmic force among gas, water, and reservoir rocks, the flowback rules and mechanisms of fracturing fluids were studied. The research results show that the differences in reservoir mineral composition are the main factors affecting the flowback speed and flowback rate of fracturing fluids. Reservoirs with high clay mineral content have slow flowback speed and low flowback rate, while the flowback pressure difference only affects the initial flowback speed. By analyzing the microscopic molecular force of the fracturing fluid in the organic and inorganic pores in the reservoir, the flowback pressure difference corresponding to different pore diameters was given, and then reasonable flowback pressure difference can be calculated according to the total pore size distribution. Finally, the method for calculating cumulative flowback volume based on single-pore model was established. The research results have practical significance for analyzing the flowback rule of fracturing fluid and determining a reasonable production system.

10.13639/j.odpt.2022.04.009