Effects of a polyamine inhibitor on the microstructure and macromechanical properties of hydrated shale  

作　　者：Yunlei Hu Xiangchao Shi Qingling Li Leiyu Gao Feng Wu Gang Xie 

机构地区：[1]State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,610500,China

出　　处：《Petroleum》2022年第4期538-545,共8页油气（英文）

基　　金：We gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant No.51774248,U20A20266);the International Science&Technology Cooperation and Exchange Program of Sichuan(Grant No.2019YFH0166)。

摘　　要：China is rich in shale gas resources,however,wellbores in shale gas reservoirs are frequently unstable.This has a serious impact on the shale gas drilling cycle.Polyamine,a common additive in water-based shale drilling fluids,can effectively inhibit shale hydration.However,there is a lack of quantitative research on the effect of polyamine inhibitors on the microstructure and macromechanical properties of shale.Therefore,this study investigated those issues via a systematic hydration experiment carried out on shale from the Longmaxi Formation.The results show that microfractures are created and expand during shale hydration,that they also connect to form a complex microfracture network,and that 3%polyamine inhibitors(polyamine solution with volume fraction of 3%)can effectively inhibit their evolution.The ultrasonic velocities and UCS of the Longmaxi shale are significantly anisotropic;the former first increases and then decreases with the laminae angle,reaching its maximum when the laminae angle is 30°.The UCS of the shale is highest and lowest,respectively,when the laminae angles are 0°or 90°and 30°.In general,these UCS appear as a"U"pattern,high on two sides with a dip in the center.Polyamines can effectively inhibit both the expansion of shale and the reduction of P-wave and S-wave velocities,the UCS,and elastic modulus.The UCS of a shale sample was reduced by 28%e40%after immersion for 96 h in water,compared to 2%e20%after immersion in a 3%polyamine inhibitor for the same amount of time.The inhibiting effect of the polyamine was remarkable.

关 键 词：POLYAMINE MICROFRACTURE Macromechanical properties HYDRATION Anisotropy 

分 类 号：P61[天文地球—矿床学]