油管与接箍的螺纹联接部分是保证油管正常工作的关键纽带.基于弹塑性力学理论,利用ABAQUS有限元软件建立了N80油管接箍的轴对称模型,对油管接箍的上扣过程进行了数值模拟,并结合实际工况分析了不同井深条件下油管接箍螺纹的应力状况,得到了油管与接箍螺纹的失效特征.结果表明:上扣过程中油管和接箍螺纹的Mises应力呈两端高中间低的形式分布,过盈上扣3圈时接箍两端的螺纹已经进入塑性状态;实际工况下,油管螺纹的Mises应力随着井深的增加呈下降趋势,井口处油管两端的螺纹已经超过屈服强度,而接箍螺纹的Mises应力随着井深的增加而增大,3 000 m井深时接箍两端的螺纹均已进入塑性状态,易发生粘扣而导致密封失效.%The threaded connection between tubing and collar is a key link to guarantee the normal operation of tubing.An axisymmetric model of N80 tubing and collar was established by using the ABAQUS finite element software based on the theory of elastic-plastic mechanics.The make-up process of tubing and collar was simulated, and the stress state of tubing and collar threads under different well depths was analyzed combining with the actual conditions, then the failure characteristics of tubing and collar threads were obtained.The results showed that during the make-up process, the Mises stress of tubing and collar threads presented the form distribution of high at both ends and low at the middle, and the threads at both ends of collar got into the plastic state after three circles of make-up.Under the actual conditions, the Mises stress of tubing threads decreased with the increase of well depth, and the threads at both ends of tubing in wellhead exceeded their yield strength.While the Mises stress of collar threads increased with the increase of well depth, and the threads at both ends of collar got into the plastic state when the well depth reached 3000 meters, so the thread gluing is much more likely to occur and lead to seal failure.
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