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Propagation mechanism of hydraulic fracture of perforation in laminated slate |
WANG Haiyang, LU Yiyu, XIA Binwei, GONG Tao, ZHANG Rui1,2,3
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1. State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400030, China;2. School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China;3. China Coal Technology Engineering Group Chongqing Research Institute, Chongqing 400037, China
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Abstract: |
On the basis of the elasticity and fracture mechanics, the propagation mechanism of hydraulic fracture of perforation intersecting with shale bedding plane was studied. The stress analysis model of hydraulic turning fracture in laminated slate was built and the deflecting angle, critical internal pressure of deflecting fracture in shale and bedding plane were analyzed. Then the factors of deflecting fracture intersecting with shale bedding plane were studied combined with numerical simulation. The results show that propagation mechanism of deflecting fracture depends on principal stress difference, perforation angle, bedding plane angle, mechanical properties of shale and cohesion of bedding plane. If the angle between the maximum horizontal principal stress and bedding plane is not large, with the increasing of principal stress difference, the propagation mode of deflecting fracture changes gradually from crossing the bedding plane to extending along the bedding plane. However, the change of propagation mode is opposite with the increasing of perforation angle, angle and cohesion of bedding plane. The closer to 90° of the angle between perforation and bedding plane, the higher tendency of crossing the bedding plane and extending along the bedding plane simultaneously and the map cracking is easier to form. |
Key words: perforation hydraulic fracturing deflecting fracture propagation mechanism laminated slate |
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