二维类圆形腐蚀孔应力集中对套管强度的影响

油气水井套管由于长期处于充满流体的环境中,极易受到腐蚀。套管遭严重腐蚀后所形成的类圆形腐蚀孔分浅半圆形孔、半圆形孔和深半圆形孔3种情况。分析了3种几何形状的腐蚀孔情况,下孔边应力和应力集中系数的分布情况,讨论了孔边应力集中对套管抗内压强度和抗挤强度的影响,提出了相应的修正公式。研究得出,在孔开口直径一定的情况下,应力集中系数随孔深增加而增大,套管强度的降低程度也随孔深增加而增大。

Effect of Two-Dimensional Corrosion Cavity on Casing Strength

Casing string placed in the environment filled with fluid for a long time is prone to be corroded.Such cavities have various types including shallow-circular cavity,half-circular cavity and deep-circular cavity.Stress distributions and stress concentration factor(SCF) around those cavities are discussed.The effects of SCF on casing burst strength and casing collapse strength are analyzed and modified formulae are presented accordingly.The conclusion is that,with a constant open diameter,with the increase of cavity depth,the SCF increases and the casing strength decreases.