The investigation on anisotropy of shale in mechanical and psychical characteristics is of great significance to successful implementation of hydraulic fracturing in gas shale exploitation. In this paper, the effect of shale anisotropy on tensile strength was studied via Brazilian splitting tests (BD) at different loading angles (the angle between loading axis and the stratification). The specimens were prepared along different angles (0°, 30°, 45°, 60°, 90°) with respect to the stratification of black shale (BS). The results indicate that the tensile strength for samples with different loading angles exhibits obvious anisotropy. It was noted that complex tensile fractures can be formed under larger loading angels. Studying the tensile strength anisotropy of shale can provide some theoretical guidance for optimization of fracturing scheme and fracture evaluation.
Black shale Failure pattern Tensile strength anisotropy Brazilian test Loading angle
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The research reported in this paper was supported by the National Natural Science Foundation of China, study of Rock Fracture under Hydraulic External Force Disturbance (No. 41172270), and supported by the Strategic Priority Research Program of Chinese Academy of Sciences, Research and Development of Test Equipment about Fracture, Seepage and Microseisms (No. XDB10050200) and Science Foundation for Youths (No. 41602330).
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