不压井作业过程中管柱力学分析

为解决不压井作业过程中下压力的确定问题,提出了一种不压井管柱进行力学分析方法.该方法考虑油管与套管内壁的初始间隙和随机接触摩擦力,利用有限元法建立不压井管柱非线性力学分析模型,并运用梁单元和间隙元进行求解,最终得出管柱内力、应力以及接触状态结果.结果表明,下压力过大会增加油管与套管内壁接触位置的个数,还会使管柱发生屈曲,过小则影响施工安全.采用该方法计算得出的参数进行作业,能保证作业安全,并且减少管柱磨损和屈曲现象的发生.

The mechanical analysis of drillstring in snubbing

To determine the downward pressure in snubbing,a mechanical analysis method for snubbing string is proposed.This method considered the initial gap and the random contact friction between oil tube and inside wall of casing.The noliner mechanical analysis model of snubbing string was established by using finite element method.It was solved by beam elements and interstitial elements.The result of internal force,stress and contact condition was obtained.The results show that high downward pressure could increase the number of contact position between oil tube and inside wall of casing,cause string buckled,but low downward pressure could affect operation safety.The result parameters could ensure operation safe,reduce string wornout and buckling.