应用弹塑性力学相关理论分析套管射孔后剩余强度

Analysis of Casing Strength after Perforation Using Plasto-Elasticity Theory

针对采用试验和ANSYS建模方法工作量大、周期长的缺点,应用圆柱壳体开小孔弹塑性力学理论建立了套管射孔后单孔应力分布理论力学模型,推导出了理论应力集中系数表达式,计算出整个圆孔周围应力分布,找到了应力集中最大点。在此基础上,考虑多孔影响(如孔密、相位角等),结合材料和应用环境的敏感系数建议值,进一步推导出了有效应力集中系数计算公式,利用该公式计算了几种不同射孔参数下的套管剩余强度,并和ANSYS的分析结果进行了对比,结果表明,该公式可以替代ANSYS软件用于计算套管剩余强度,且具有计算简便,速度快,易于现场应用等特点。

The single hole stress distribution theoretical model after casing perforation was created based on cylinder open hole plasto-elasticity theory considering the disadvantages of the experiment and ANSYS methods which require more work and longer time period. The expression for the theoretical stress concentration factor was obtained. The stress distribution along the hole was calculated and the maximum stress concentration point was identified. Based on this, the equation to calculate the effective stress concentration factor was derived considering the effects of multiple holes （perforation density, Phase Angle etc. ）, material and the suggested sensitivity coefficients in the applied conditions. Casing residual strength for different perforation conditions were calculated using this equation and compared with the results using ANSYS. The results indicate that this equation can replace ANSYS to calculate the casing residual strength. This method is simple, fast and easy application in field.