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| Study on the influence of meso-mineral bands on macroscopic failure modes of shale |
| DUAN Yongting1，FENG Xiating1，LI Xiao2，3，4 |
(1. Key Laboratory of Ministry of Education for Safe Mining of Deep Metal Mines，Northeastern University，Shenyang，Liaoning 110819，China；2. Key Laboratory of Shale Gas and Geoengineering，Institute of Geology and Geophysics，Chinese Academy of Sciences，Beijing 100029，China；3. Innovation Academy of Earth Science，Chinese Academy of Sciences，Beijing 100029，China；4. College of Earth Science，University of Chinese Academy of Sciences，Beijing 100049，China)
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Abstract It is crucial for shale gas reservoir reconstruction to clarify the initial structure characteristics，the fracturing evolution rule and the formation mechanism of failure modes for shale. In view of this，in this paper，the in-situ micro-CT tests of shale under uniaxial compression condition are carried out，and the internal structure characteristics of shale and the its influence on shale fracturing evolution and failure mode are studied. Based on the test results，the internal structure change of shale under uniaxial compression condition is described，the fracturing evolution stage of shale based on the crack volume is analyzed，and the development degree and connectivity of 3-D cracks in failure shale are quantified. On this basis，two failure modes of shale under uniaxial compression condition are summarized，and the distribution characteristics of meso-scale minerals and their influence on failure modes of shale are analysed. In addition，according to the mineral distribution identified by CT images，the uniaxial compression simulation tests of numerical samples containing mineral bands are carried out，and the influence mechanism of mineral bands on shale failure modes are revealed. Relevant research results have important reference value for study of shale fracturing mechanism and mineral permeability-increasing mechanism of reservoir shale，and have clear guiding significance for the scheme optimal design of shale gas exploitation.
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2021, Vol. 40 
