Borehole breakouts in berea sandstone: two porosity-dependent distinct shapes and mechanisms of formation

摘要

We conducted laboratory-drilling experiments in Berea sandstone blocks of two different porosities inwhich borehole breakouts were induced under several truly triaxial far-field stress conditions. We used a petrographic microscope to study thin sections of the drilledboreholes and observed the mechanism of failure that ultimately resulted in breakout formation. In lower porosity Berea sandstone (17