连续管伸长量分析

连续管在作业过程中因受残余应力等多种因素的作用，容易发生塑性变形伸长。在分析连续管残余应力的形成及塑性伸长原理的基础上，重点讨论了轴向载荷引起的伸长、热伸长、内外压差引起的伸长及螺旋弯曲引起的缩短等4种变形问题，研究了相应的理论计算公式和计算方法，并通过实例计算绘制关系曲线，阐明了连续管变形伸长的基本特点:连续管在起下作业中的塑性变形伸长比常规油管复杂，其变形伸长量比较明显；连续管轴向伸长量和螺旋屈曲缩短量都比较大，在作业中应重点考虑；热伸长和内外压差引起的伸长比较小，在作业中可不作为重点考虑；在实际作业中连续管总的变形伸长量是上述4种变形的不同组合，由于伸长与缩短相互抵消，故总的变形伸长量并不大。

Elongation analysis of coiled tubing

It is easy for Coiled Tubing(CT) to deform a plastic elongation because of many factors,such as the residual stress etc,in the process of coiled tubing service.The paper analyses the cause of coiled tubing plastic elongation and explains the principle of the same elongation.Coiled tubing plastic elongation has four mainly reasons: axial load causes plastic elongation,thermal causes plastic elongation,pressure difference causes plastic elongation,helical buckling causes elongation.The theoretical calculation formula and calculation method for CT plastic elongation are summarized.Calculation examples about CT plastic elongation give some basic CT plastic elongation conclusions by comparative analysis of relation curve on calculated value.The CT plastic elongation is more complicated and more obvious than conventional tube.The elongation caused by axial load and the shortening caused by helical buckling are larger than others and should be focused on the need to consider in the progress of coiled tubing service.The thermal expansion and the elongation caused by pressure difference are smaller than above all and should be given due consideration in the progress of coiled tubing service.Total elongation deformation is made up of four parts: the plastic elongation caused by axial load,thermal expansion,plastic elongation caused by pressure difference and the shortening caused by helical buckling.The four elongations may cancel partially each other,so the total elongation deformation generally is smaller than every single elongation.