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以高温高压井套管-水泥环-地层为研究对象,建立套管-水泥环-地层组合系统的热固耦合模型,结合边界条件和连续条件,得到相应的应力解析解,并与有限元结果进行对比,验证了解析方法的计算精度.通过分析热固耦合作用下的解析解和不考虑热载荷的解析解,发现热载荷对整体等效应力的影响较大.采用Mises、Drucker-Prager及Mohr-Coulomb屈服准则定义失效系数评价套管-水泥环-地层组合系统的井筒完整性.讨论了水泥环弹性模量、泊松比、非均匀地应力系数、地层温度、套管内压等参数对套管内壁、水泥环内壁及第一、二胶结面失效系数的影响.上述因素对套管内壁、水泥环内壁及第一、二胶结面失效系数均有影响;第一胶结面失效系数较高,对井筒完整性影响较大.
Taking the casing of high temperature and high pressure casing - cement ring - formation as the research object, a thermomechanical coupling model of the casing - cement ring - formation combination system is established, and the corresponding stress analytical solutions are obtained in combination with the boundary conditions and the continuous conditions. The analytical accuracy of the analytical method is verified.Analysis of the analytic solution of the thermal load and the analytic solution without considering the thermal load, we find that the thermal load has a greater impact on the overall equivalent stress.Mises, Drucker-Prager and Mohr-Coulomb yield criterion is used to define the failure coefficient to evaluate the wellbore integrity of the casing-cement ring-formation combination system.Parameters such as elastic modulus, Poisson’s ratio, non-uniform stress coefficient, formation temperature and casing pressure are discussed The inner wall of the casing, the inner wall of the cement sheath and the coefficient of failure of the first and second adhesive surfaces.The above factors have an effect on the failure coefficient of the inner surface of the casing, the inner wall of the cement sheath and the first and second cement surfaces; the coefficient of failure of the first cement surface is relatively high , A greater impact on the integrity of the wellbore.