根据硬脆性地层破碎前只产生弹性变形而无塑性变形的特征,基于线弹性理论,推导了直井井周应力模型,建立了剪切破坏程度(塌块厚度和坍塌角)与地应力、孔隙压力、岩石力学性质、钻井液柱压力之间的定量关系。理论模型计算结果与实测数据十分吻合,具有较高精度。 According to the linear elastic theory, the circumferential stress model of straight shaft is deduced according to the characteristics that only elastic deformation and no plastic deformation occur before the hard and brittle formation crushing, and the shear stress of the vertical well is established. The degree of shear failure (collapse thickness and collapse angle) , The mechanical properties of rock and the pressure of drilling fluid column. Theoretical model calculation results are in good agreement with the measured data, with high accuracy.