含磨损缺陷套管抗内压强度数值计算研究

NUMERICAL CALCULATION OF BURST STRENGTH FOR CASINGS WITH WEARING DEFECTS

由弹性力学变分原理引入有限单元法基本方程,进而给出了磨损区域边界上任意点法向量解析解和数值解的方法。假设磨损缺陷模型为圆弧状,并认为是平面问题,采用Serendipity等参单元变结点有限单元格式,分别按照平面应力和平面应变问题进行分析研究,阐明了考虑磨损深度、磨损区域半径和套管壁厚影响时的套管抗内压强度定量变化规律,分析了在不同磨损量及其相应抗内压强度下套管内应力强度分布规律,并依据等效内压设计套管柱的可行性及安全性进行定量分析,编制计算机程序。

The basic FEM equation is introduced from the variation principle of elastic mechanics. The numerical and analytical solutions of the vector are derived at any point of the wearing zone boundary on the inner wall. Assuming the shape of the wearing defect is regarded as arc-like and the wearing defect is considered as plane issue, with the limited node-changing element format of Serendipity isoparametric elements, the issue is analyzed by the plane stress and the plane strain respectively. The quantitative changing law of casing burst strength is described considering the influence of the wearing depth, the wearing zone radius and the casing wall thickness. The distribution law of the stress strength in the casing is analyzed under the different wear and the corresponding burst strength. The feasibility and security of casing string designed by the equivalent inner pressure are analyzed quantitatively. The computer program is made.