嵌入非线性黏弹性材料弹性尖楔尖端的应力、应变场

套管损坏是石油工程研究中的重要问题之一,引起套管损坏发生的主要原因是在采油过程中油藏结构变化改变了原地应力场的分布以及不同岩层间界面的相对滑动.建立了以油藏隆起为尖楔嵌入非线性黏弹性材料的界面断裂力学模型.在平面应变条件下,通过奇异量级分析、运动方程和协调方程,推导出在尖楔尖端的非线性黏弹性材料中的控制方程.根据问题的边界条件和连续条件,通过数值计算得到了尖楔尖端连续的分离变量形式的应力、应变和位移场.数值计算表明,尖楔尖端场分布主要受材料的力学特性、地层倾角和摩擦系数的影响.模型阐明了套管剪切损坏力学机理,研究的结果为解决套管损坏问题提供了理论上的参考依据.

Stress and strain fields of the near tip of an elastic wedge embedded in nonlinear viscoelastic material

The study of well casings failures is important in oil engineering.The main reasons for casing failure are the change of construction of reservoir compaction in oil-extraction, which leads to the change of the crust stress fields, and the relative gliding of the interface between different rock layers. Here,an idealized interface fracture model was established in which the reservoir hunch as an elastic wedge was embedded in nonlinear viscoelastic material. Under condition of plane strain,through analysis of the singularity of the stress and strain and combining the movement and compatibility equations, the governing equation in the nonlinear viscoelastic material of the near tip of the elastic wedge was deduced. Through numerical calculations and with boundary conditions and continuous conditions, the asymptotic solution of the fully continuous separate variable formal of stress, strain and displacement of the near tip of the elastic wedge was obtained.Numerical results show that the field distribution is mainly influenced by the mechanic characteristics for materials, the angle of inclination and the coefficient of friction. The mode illustrates reasons for the mechanical mechanism of casing shear failure and the research results can serve as reference for solving casing failure in oil fields.