As being the confining stress boosts, the rise in resistance to longitudinal crack propagation ends in a gradual changeover of shale failure mode from longitudinal to inclined shear failure that reflects an escalation in rock plasticity. If the confining strain reaches thirty MPa, there are still community shear microcracks https://directorypixels.com/listings13660196/the-2-minute-rule-for-wellbore-stability-issues