Comparative Evaluation on the Coupled Fracture Characteristics for Longmaxi Anisotropic Shale

Abstract The shale fracture characteristics are important for realizing the complex hydraulic network, predicting wellbore pressure, and optimizing trajectory rock fragmentation efficiency. Through a three-point bending test of notched semicircular specimens Longmaxi shale, coupled relationship mode-I toughness (Kic), peak force (Pmax), energy release rate (GI), applied work (W), loading was studied by using kernel density analysis method. results showed that dynamic force-displacement curve exhibited obvious angle dependence, including two types “deformation accumulation-brittleness” accumulation-brittleness-plasticity.” Kic GI increased linearly with Pmax increasing. With increasing angle, dispersion degree Pmax, Kic, GI, W all increased. nonlinearly Kic. rate, basically linearly. under static quasistatic conditions had strong anisotropy. At high anisotropy index gradually decreased as have significant implications design fracturing exact control shale.