热采井中偏梯形套管螺纹有限元分析

Finite element analysis of buttress casing thread in thermal well

采用有限元方法分析了热采井中的偏梯形套管螺纹接头在不同载荷工况下的力学特性。结果认为,套管在承受轴向拉伸载荷的工况下,最大等效应力的发生区域集中在套管螺纹和接箍螺纹的两端;在套管温度升至300℃的工况下,螺纹接头已发生塑性屈服,并且塑性区域有从接头两端向接头中部发展的趋势;套管温度降至地层原始温度30℃的工况下,塑性屈服区域减小,仅局限在接头两端。在轴向拉伸载荷的工况下,最大接触压力发生在套管螺纹的第1圈,并且每圈上的接触压力分布并不是均匀的;高温载荷下,螺纹间的接触压力值和接触位置发生了改变;恢复至初始温度时,套管螺纹接触面上的接触压力增大。

The mechanical properties of buttress casing thread are analyzed with finite element method under different loading behaviors in thermal well.The results show: peak value range of equivalent stress locates the two ends of joint under axial tensile load.When casing temperature increases to 300 ℃,thread has generated plastic yielding in part,and plastic range has expanded from the ends to middle part of joint.When casing temperature declines to initial temperature 30 ℃,plastic range reduces and only locates the two ends of casing.The maximal contact pressure locates the first thread of casing under axial tensile load,and the pressure on each thread is non-uniform.Under the high casing temperature,the contact pressure value and contact location have changed.Returning to initial temperature 30 ℃,contact pressure on contact surface of thread increases.