Given that the confining tension improves, the increase in resistance to longitudinal crack propagation brings about a gradual transition of shale failure method from longitudinal to inclined shear failure that reflects an escalation in rock plasticity. When the confining tension reaches 30 MPa, there are still regional shear microcracks https://thesocialvibes.com/story7132219/the-2-minute-rule-for-wellbore-stability-issues