特殊螺纹接头是高温高压井油套管柱连接的重要部件,管内流体压力、流速的变化诱发管柱振动,引起特殊螺纹接头密封面发生微滑,表现为力与位移的刚度软化与滞回等非线性特征,进而导致接头密封性能下降.为查明密封面的微滑机制,基于离散Iwan模型本构关系,建立某锥面-锥面Φ88.9 mm×6.45 mm P110 特殊螺纹接头有限元分析模型,得到不同循环位移载荷下密封面处的力-位移滞回曲线,通过滞回曲线离散化分析,识别出离散Iwan模型的4 组参数;构建该特殊螺纹接头等效Iwan模型,分析密封面间的微滑状态;对比分析两种模型滞回曲线的相似度,验证等效Iwan模型的准确性.结果表明:构建的特殊螺纹接头等效Iwan模型与有限元分析模型的综合相似度较高,滞回曲线面积重合度大于92%,位置误差小于2%;利用特殊螺纹接头等效Iwan模型得到的滞回曲线,能够准确描述密封面间黏着、滑移、宏观滑移之间的转化过程,从而为特殊螺纹接头滞回曲线分析提供一种新方法.
Hysteresis curve of premium connection sealing surface of oil tubing strings based on Iwan model
Premium connections are important components for tubing strings used in high-temperature and high-pressure oil and gas wells.During production,vibration of the tubing strings can be induced because of fluid pressure and velocity varia-tions inside the oil tube,resulting in micro slips between the sealing surfaces of the premium connections.Stiffness softening and hysteresis of the force and displacement can also appear due to the vibration.In this paper,a finite element analysis model(FEAM)for a cone to cone(Φ88.9 mm×6.45 mm P110)premium connection was established,and the force dis-placement hysteresis curves at the sealing surface under different cyclic loads were obtained using the model.The hysteresis curves were discretized and four sets of parameters for a discrete Iwan model were obtained,and then an equivalent Iwan model of the premium connection was constructed using the identified parameters,and the characteristics of the micro slips between the sealing surfaces were analyzed.Finally,the similarity of the hysteresis curves between the two models was com-pared and analyzed,verifying the accuracy of the equivalent Iwan model.The results demonstrate that the similarity of the ar-ea of the hysteresis curves between the two models is greater than 92%,with an error in position less than 2%.The transfor-mation processes of stick,micro slip and gross slip between the sealing surfaces can be described accurately by the force dis-placement curves obtained using the equivalent Iwan model.
万方数据
维普
