连续管水平井钻磨作业力学分析

Mechanical Analysis of Coiled Tubing in Horizontal Well Drilling and Milling

连续管在水平井钻磨作业时,易发生屈曲变形而使轴向力传递效率降低,严重时可能由于轴向力降为0而发生自锁。在充分考虑屈曲、摩擦、弯矩、内外液体阻力等因素的影响下,建立了连续管在水平井钻磨作业过程中的力学模型,并分别推导出直段和弯曲段有效轴向力、接触力和摩阻力的数学模型。由所得的理论模型计算可知,连续管失稳屈曲类型主要是螺旋屈曲;改变连续管初始端的注入力大小对最大注入深度和增加钻压几乎没有影响,而不同管柱尺寸对等效轴向力分布影响很大。研究结果对连续管现场作业有借鉴意义。

During horizontal well drilling and milling operations, the coiled tubing is prone to buckling deformation due to low stiffness, leaving reduced axial force transfer efficiency. At severe conditions, the axial force may be reduced to zero and result in the self-locking that may cause accident. A mechanical model of coiled tubing in horizontal well drilling and milling is established, which considers the effects of factors like buckling, friction, bending, internal and external fluid resistance. The mathematical model of effective axial force, contact force and friction of straight section and curved section are also deduced. The calculation results by the theoretical model show that the main buckling type of coiled tubing is helical buckling. The injection force of the coiled tubing end has little effect on maximum injection depth and increase of weight on bit. But the tubing size has a great influence on the distribution of effective axial force. The study results could provide references for the coiled tubing operation.