Characterization of 3D pore nanostructure and stress-dependent permeability of organic-rich shales in northern Guizhou Depression,China

作     者：Xiaofang Jiang Shouchun Deng Haibo Li Hong Zuo Xiaofang Jiang;Shouchun Deng;Haibo Li;Hong Zuo

作者机构：State Key Laboratory of Geomechanics and Geotechnical EngineeringInstitute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of SciencesBeijing100049China 

出 版 物：《Journal of Rock Mechanics and Geotechnical Engineering》 (岩石力学与岩土工程学报（英文版）)

年 卷 期：2022年第14卷第2期

页      面：407-422页

核心收录：

学科分类：08[工学] 0818[工学-地质资源与地质工程] 080104[工学-工程力学] 0815[工学-水利工程] 0801[工学-力学（可授工学、理学学位）] 

基　　金：supported by the National Key R&D Program of China(Grant No.2020YFA0711802) the Strategic Program of Chinese Academy of Sciences(Grant No.XDB10030400) 

主　　题：Focused ion beam scanning electron microscopy(FIB-SEM) Three-dimensional(3D)reconstruction Pulse decay permeability(PDP) Stress sensitivity Wufeng-Longmaxi formation 

摘      要：The three-dimensional(3D)pore structures and permeability of shale are critical for forecasting gas production capacity and guiding pressure differential control in practical reservoir ***,few investigations have analyzed the effects of microscopic organic matter(OM)morphology and 3D pore nanostructures on the stress sensitivity,which are precisely the most unique and controlling factors of reservoir quality in *** this study,ultra-high nanoscale-resolution imaging experiments,*** ion beam-scanning electron microscopy(FIB-SEMs),were conducted on two organic-rich shale samples from Longmaxi and Wufeng Formations in northern Guizhou Depression,*** morphology,porosity of 3D pore nanostructures,pore size distribution,and connectivity of the six selected regions of interest(including clump-shaped OMs,interstitial OMs,framboidal pyrite,and microfractures)were qualitatively and quantitatively *** decay permeability(PDP)measurement was used to investigate the variation patterns of stress-dependent permeability and stress sensitivity of shales under different confining pressures and pore pressures,and the results were then used to calculate the Biot coefficients for the two shale *** results showed that the samples have high OM porosity and 85%of the OM pores have the radius of less than 40 *** OM morphology and pore structure characteristics of the Longmaxi and Wufeng Formations were distinctly *** particular,the OM in the Wufeng Formation samples developed some OM pores with radius larger than500 nm,which significantly improved the *** macroscopic permeability strongly depends on the permeability of OM *** stress sensitivity of permeability of Wufeng Formation was significantly lower than that of Longmaxi Formation,due to the differences in OM morphology and pore *** Biot coefficients of 0.729 and 0.697 were obtained for the Longmaxi and Wufeng Formations,respectively.