Given that the confining strain raises, the increase in resistance to longitudinal crack propagation ends in a gradual changeover of shale failure manner from longitudinal to inclined shear failure that reflects an escalation in rock plasticity. When the confining force reaches 30 MPa, there remain nearby shear microcracks around https://vertechs21.wixsite.com/vertechs21/post/innovations-in-mpd-drilling-revolutionizing-well-control