垂直井段连续管屈曲锁死的判定与预防

Determination and Prevention of Buckling and Locking of Coiled Tubing in Vertical Section

为了防止连续管在井下作业过程中的屈曲锁死甚至损坏现象,建立了一个判断连续管锁死的临界准则,以指导连续管注入操作,保护连续管。通过对垂直井段连续管屈曲的理论分析和试验研究,连续管屈曲后,连续管与井壁接触力随轴向力的平方增加,如进一步增加注入力,可能很快发生锁死现象。因此得出评价连续管锁死的临界准则,即根据注入头载荷为零判别或根据输出力和注入力的增加比例进行判别。同时,结合现场实际施工垂直井屈曲锁死后断裂的案例,验证了判据的准确性,并提出了避免或减小连续管屈曲锁死的措施。

In order to prevent the occurrence of buckling and damage during the downhole operation of the coiled tubing,a critical criterion for judging the coiled tubing lock is established to guide the coiled tubing injection operation and protect the coiled tubing.Through the theoretical analysis and experimental research on the buckling of the coiled tubing in the vertical section,the contact force between the coiled tubing and the well wall increases rapidly with the increase of the axial force after the buckling of the coiled tubing.When the coiled tubing is buckled,with the injection force is further increased,the locking will occur very quickly.Therefore,an evaluation criterion for coiled tubing locking is obtained.The critical evaluation criterion can be determined based on the zero of the injection head load or based on the increase ratio of the output force and the injection force.At the same time,combined with the case of vertical well buckling and locking fracture in the field of oilfield application,the accuracy of the criterion was verified,and the measures to avoid or reduce the buckling of the continuous tube were proposed.