连续管与夹持块干涉的应力应变分析

Stress-strain Analysis on the Interference between Coiled Tubing and Grip Blocks

连续管的损伤是连续管疲劳失效的重要原因。在连续管作业时,注入头链条传动的夹持块在切出过程中将与连续管发生干涉现象,在连续管中产生较大的应变。应用有限元计算分析了最大应变与各个几何参数之间的关系。研究结果表明,连续管最大应变受切出角和夹持块端部距转动中心的轴线方向距离h的影响较大,切出角越大,应力越大;h越大,应力越大。因此尽量采用单节距夹持块,若采用双节距夹持块时,切入切出角应不大于1°。

The damage of coiled tubing was an important reason for the fatigue failure.During its operation,grip blocks driven by chain in injector head would interfere with coiled tubing in the entering or exiting contact with coiled tubing,and it would produce large strain.In this paper,the relationship between the maximum strain and each geometric parameter was analyzed by FEM.Results show that the maximum strain of the coiled tubing is greatly affected by the exit angle and the distance h between the end of the grip block and the axis of the center of rotation.The larger the exit angle is,the larger the stress is;the larger the h is,the larger the stress is.The paper suggests that it prefers using single pitch grip blocks,if a double pitch grip block is used,the entering and exiting angles should not be larger than 1°.