根据弹塑性力学和岩石力学理论分析了井眼周围和井壁上岩石的受力状态、破坏机理和破坏形式,阐述了防止泥页岩地层、砂质和粉砂质泥页岩地层、裂缝性发育地层的井眼坍塌破坏的条件和判断方法,同时,也介绍了针对不同的破坏形式选用相应临界泥浆比重的方法。 Based on the theory of elasto-plasticity and rock mechanics, the stress state, failure mechanism and failure mode of rock around the borehole and on the shaft wall are analyzed. The measures to prevent the shale formation, sandy and silty shale formation, The conditions and judging methods of wellbore collapse in developing stratum, and the method of selecting the corresponding specific gravity of critical mud for different types of damage are also introduced.