Based on the Brazilian tests of continental shale with different layer orientations, combined with AE monitoring, the influence of layer orientation on the anisotropy of mechanical properties, fracture mode, and fracture mechanism of continental shale was analyzed. The results show that the tensile strength and deformation at the peak stress decrease with the increase of layer orientation at a constant deformation loading rate of 0.06mm/min, and the splitting modulus decreases first and then increases. The tensile strength was 90° > 60° > 45° > 30° > 0°, and the maximum and minimum tensile strengths were 5.154 MPa and 0.669 MPa, respectively. Under the action of splitting load, the samples with 30°, 45°, and 60° layer orientations mainly undergo shear failure along the layer orientation, while the samples with 0° and 90° layer orientations undergo tensile failure. In addition, the crack propagation in the 0° and 30° samples penetrated the bedding. These characteristics have important reference significance for the study of the mechanism of hydraulic fracture communication, propagation, and activation of structural planes.

In this study, a series of laboratory fracturing experiments were conducted on samples mined from reservoirs of the Guanyinqiao Member shale in Xishui County, Guizhou Province, using a traditional triaxial fracturing simulation system. Based on the experimental results, the breakdown pressure and effective stimulated reservoir volume were obtained for four fracturing fluids (supercritical carbon dioxide, water, NO-sand, and sand). The fracture mechanism was then analyzed using acoustic emission monitoring data. Based on the curves of pressure vs injection time for different fracturing fluids, the breakdown pressure increased with increasing fracturing fluid viscosity. When sands with different viscosities were used as the fracturing fluid, the breakdown pressure first increased and then decreased with an increase in the sand viscosity. The distribution of the tracer or proppant was not only correlated with the fracturing effect, but also promotes the filling crack of the tracer and proppant at a certain viscosity as the best fracturing effect. During sand fracturing, the proppant mainly formed shear cracks. The results provide a valuable technical reference for shale gas mining.

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