基于尖点位移突变模型的井壁稳定性分析

引入基于广义Hoek-Brown准则的有限元强度折减法，考虑井壁不同位置的水平方向位移与强度折减系数的非唯一相关性，以及井壁失稳破坏时岩体变形的瞬时突变性，建立了井壁最大水平方向位移与强度折减系数的井壁稳定性尖点位移突变模型。利用上述模型研究了井眼直径与井筒压力对井壁稳定性影响规律，结果表明，随着井眼直径的增加，井壁稳定性安全系数降低速度越快；随着井筒压力的增大，井壁稳定性安全系数增加速度越快。

Wellbore Stability Analysis Based on Cusp Catastrophe Model of Displacement

The strength reduction method based on generalized Hoek-Brown criteria is introduced. Considering the non-unique correlation between horizontal displacements of different parts of borehole wall and strength reduction factors, and the instantaneous mutation of wellbore instability, the cusp catastrophe model of displacement under the maximum horizontal displacement and reduction factor is set up. The influence law of hole size and internal pressure to wellbore stability in coal seam is studied. The result indicates that the mutability of wellbore failure process can be reflected when this model is employed as wellbore instability criterion. And the safety factor of wellbore stability decreases with the increase of hole size, and increases with the increase of internal pressure.