注蒸汽吞吐井井筒应力的数值计算方法

将注蒸汽吞吐井井筒温度场的计算结果引入井筒应力分析模型中,利用有限元分析软件ANSYS计算了不同约束条件下的井筒应力。计算结果表明,最大热应力都发生在套管内壁,且超过了N80套管的热弹性屈服极限;最大热膨胀都发生在温度变化过渡区,当套管周围掏空时,其热应变达到了2%,远远超过材料弹性极限应变值(0 3%),这是导致热采井套管变形损坏的主要原因。

Numerical calculation method for well bore stress in the steam injection wells

The calculated result of temperature distribution in the steam injection well was introduced into the stress analysis model for the steam injection well. The well bore stresses under different restrictive conditions were calculated by using software package ANSYS. The calculated results indicate that the maximum thermal stress occurs in the internal wall of the casing pipe and is over the thermo-elastic yield ultimate stress of casing pipe made of N80 steel. The maximum thermal expansion occurs in the transition area of temperature changes. When the surrounding area of the casing is empty, the thermal strain rate of the casing can reach 2 per cent, which is much more than the elastic strain limit of 0.3 per cent. The ultra thermal strain is the main reason for deformation and failure of casing in thermal production wells.