井眼破坏与钻井液密度关系的三维有限元模型

建立了井壁围岩剪切破坏的三维弹塑性有限元模型，根据Drucker—Prager破坏准则，模拟了在三向地应力和钻井液压力作用下井壁剪切破坏的连续过程，井壁围岩破坏尺寸与钻井液密度的关系在弹塑性条件下为二次曲线，不同于弹性条件下的线性关系。模拟规律与现场观测和实验室试验结果基本一致，为更真实地分析钻井液密度对井壁围岩破坏区域的影响提供了定量依据。

Three-Dimensional Finite Element Model for Relationship between Wellbore Failure and Mud Density

Three-dimensional elasto-plastic finite element model for the relationship between wellbore failure and mud density is established, based on Drucker-Prage failure criterion, to simulate the continuous shear failure of rock around wellbore under the three principal underground stresses and mud pressure. The main conclusions are that the relationship between well-bore failure region and mud density is parabolic under elasto-plastic condition, which is different from that of linear shape under elastic condition. And the conclusions are consistent with practical observations and laboratory experiments, providing quantitative basis for analyzing the influence of mud density on wellbore failure region.