腐蚀套管剩余强度数值模拟分析

Numerical Simulation Analysis on Corroded Casing Residual Strength

套管腐蚀损坏是油气田开发过程中的重要问题之一。国内外研究主要集中在套管腐蚀速率预测及防护技术方面,对于腐蚀套管剩余强度的分析研究较少。采用数值模拟的方法对圆弧形和半月形这两种套管腐蚀后的主要形态进行分析。结果表明:套管剩余抗拉强度随圆弧形腐蚀缺陷长度的增加而增加,剩余抗挤、抗内压强度随圆弧形腐蚀缺陷长度的增加而减小;套管剩余抗拉强度随半月形腐蚀缺陷长度增加而增加,剩余抗挤强度随缺陷长度增加而减小,套管剩余抗内压、抗拉强度随缺半月形腐蚀陷深度的增加而线性减小,套管剩余抗拉、抗挤和抗内压强度都随套管壁厚的增加而增加,与圆弧形腐蚀缺陷规律相同。

Corrosion failure of casing is one of key problems in oil and gas field development.Current researches at home and abroad focus on casing corrosion rate and control.Less analytical investigation is conducted on corroded casing residual strength.Adopted is the numerical simulation to analyze circular arc and semilune forms after casing corrosion and analysis results show that residual tension strength increases when circular arc corrosion defect length increases,residual collapsing strength and residual internal pressure strength decrease when circular arc corrosion defect length increases,residual tension strength increases when semilune corrosion defect length increases,residual collapsing strength decrease when circular arc corrosion defect length increases,residual internal pressure strength and residual tension strength decreases linearly when semilune corrosion defect length increases and residual tension strength,residual collapsing strength and residual internal pressure strength increase when casing wall thickness increases.