水平井连续油管下放速度对下入深度影响规律分析

Influence of Velocity on the Limit Depth of the Input in Coiled Tubing Horizontal Wells

连续油管在水平井作业中,特别是水平段下放过程中,由于连续油管质量轻、弯曲刚度低、环空间隙大等因素,使得连续油管轴向力传递效率下降,水平段下放深度受到限制,由此而产生的作业失效时有发生。连续油管在下放过程中不仅受到自重力和屈曲变形引起的接触摩阻力,还受到液体摩阻力、键槽或台阶产生的局部机械阻力。在现场作业中,通常采用变化下放速度来克服局部机械阻力,从而提高连续油管的下放速度。但过大的下放速度会增加流体阻力,导致油管屈曲;另一方面,遇阻时产生的冲击载荷会导致连续油管损坏和作业失效。采用间隙元理论,考虑了连续油管与套管的接触摩阻力、管内外液体阻力、环空间隙以及下放速度等因素,建立了水平井连续油管下放过程的力学模型,分析了油管下放速度及环空间隙对管柱的受力变形影响,得出常规连续油管可下放的水平段极限深度,为确保连续油管在各种作业中的顺利下放提供理论依据。

The coiled tubing downhole operation has become a hot technology in petroleum engineering,in horizontal wells,especially during the process of horizontal section.Because of the low weight,low bending stiffness and large space gap of the ring,the axial force transfer efficiency of the coiled tubing is decreased,also the depth of the horizontal section is limited,which result failure of the operation at times.There is not only the contact friction caused by the gravity and buckling deformation of coiled tubing,but also the liquid friction and the local mechanical friction generated by keyway or steps.In the field operation,it is usually used to increase the velocity of the local mechanical friction,so as to improve the continuity of coiled tubing.But excessive decentralization velocity will increase fluid friction causing the tubing buckling,on the other hand,blocked the impact load will result in the invalidation of the coiled tubing damage and operation.For this purpose,the paper considers the contact resistance of the coiled tubing and casing,the liquid friction,the annular space of the pipe and the velocity of the decentralization,using gap element method,a mechanical model of the continuous process of horizontal well is established,and the influence of the velocity of the tube on the deformation of the cylinder is analyzed.The limit depth of the coiled tubing can be obtained by the calculation of the velocity,which provides a theoretical basis to ensure the smooth operation of coiled tubing in a variety of operations.