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Abstract In order to investigate the interaction of the hydraulic fractures and the bedding planes of shale in hydraulic fracturing，the hydraulic fracturing experiments under triaxial conditions were carried out with the acoustic emission system monitoring the process of hydraulic fracturing and the CT scanning system scanning the sections of rock samples before and after hydraulic fracturing for capturing the distribution of fractures. The initiation and propagation of the hydraulic fracture was captured experimentally. At the situation of small difference of stresses，the critical pressure for initiation was found to be differed little in different angels，the fracture grew along the direction of after initiation. The critical pressure for the propagation of major hydraulic fractures was related to the length of fracture and . The small sections of the bedding planes in shale were opened up when the major hydraulic fracture approached. The passage was created at the intersection of the hydraulic fracture and the bedding plane due to shearing tension. The shear zone was larger than opened one，with a ratio of 13 at maximum，functioning as the major passage for fluid flow. The length of the shear zone is sensitive to the cohesion of bedding planes, and the angle of intersection of hydraulic fracture and bedding plane.
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Received: 17 January 2014
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2015, Vol. 34 
