影响连续油管疲劳寿命的因素分析

疲劳寿命是衡量连续油管质量好坏的关键 ,分析影响连续油管疲劳寿命的因素 ,对提高连续油管寿命 ,指导其选择引进和应用管理 ,以及连续油管作业技术的推广应用都具有重要意义。通过对连续油管应力和最终拉伸强度的计算 ,建立了连续油管疲劳寿命预测模型。利用图表法分析得知 ,连续油管的疲劳寿命随内部压力的增加而急剧降低 ;外径尺寸越大的连续油管 ,疲劳寿命越低 ;其疲劳寿命随卷筒直径和导向拱弯曲半径的增大而增大 ;随连续油管材料抗拉强度的提高 ,其疲劳寿命明显增加。并据此提出建议 :( 1 )优先选用抗拉强度高的连续油管材料 ;( 2 )应尽量增大卷筒直径和导向拱的弯曲半径 ;( 3)应尽量增加大直径连续油管的壁厚 ;( 4 )在满足使用要求的前提下 ,应优先选用小直径连续油管。

Main factors influencing fatigue life of coiled tubing

Fatigue life is one of the key factors evaluating the quality of coiled tubing. By calculating the stress and ultimate tensile strength of coiled tubing, the model for predicting the fatigue life of the coiled tubing is set up. Analysis shows that the larger the OD of the coiled tubing is, the longer its fatigue life will be, and the fatigue life increases with the increase of the drum's diameter and the bending radius of the guide arc. The fatigue life of the coiled tubing also increases with the improvement of its tensile strength. Thereby suggestions are put forward as follows: (1) selecting material with high tensile strength first for coiled tubing; (2) increasing the diameters of the drum and guide arc as large as possible; (3) thickening the wall of large-diameter coiled tubing; (4) selecting small-diameter coiled tubing as far as possible.