Since the confining force will increase, the increase in resistance to longitudinal crack propagation ends in a gradual changeover of shale failure manner from longitudinal to inclined shear failure that displays an escalation in rock plasticity. If the confining stress reaches 30 MPa, there are still regional shear microcracks https://livebookmarking.com/story21557452/not-known-factual-statements-about-wellbore-stability