高温高压高产气井油管柱三维非线性流致振动模型

3D nonlinear flow-induced vibration model of tubing string in high-pressure,high-temperature and high-yield gas wells

针对高温高压高产(三高)气井流体诱发油管柱振动失效问题,采用微元法、能量法结合哈密顿原理,考虑了油管自重、井眼轨迹变化、井筒温度压力变化、油套管接触碰撞等因素,建立了三高气井油管柱三维非线性流致振动模型。采用拉格朗日和三次埃尔米特函数离散控制方程,并使用增量形式的Newmark‑β和Newton‑Raphson联合迭代求解离散后的控制方程。根据中国南海三高气井参数,采用相似原理,设计了油管柱流致振动模拟试验装置,测得油管柱振动响应数据,与理论模型计算结果对比,验证了振动模型的正确性。采用实例井参数,分析了油管柱振动特性,结果表明,上部油管三维空间横向振动明显,而中下部油管长时间紧靠于套管壁上发生振动,导致下部油管易发生纵向和横向的磨损,同时油管纵向振动出现混沌现象,且中下部位置油管混沌现象最明显,因此,现场设计人员需重点关注下部油管柱的安全性。

In view of the failure of tubing string by flow-induced nonlinear vibration(FINV)in high-temperature,high-pressure and high-yield(3H)gas wells,the 3D FINV model of tubing string is established by using the element method,energy method and Hamilton variational principle,which takes into account the self-weight changes of wellbore trajectory,wellbore temperature/pressure,and contact/collision of tubing-casing.The Lagrange and cubic Hermite functions are used to discretize the governing equations,and the incremental form of Newmark and Newton-Raphson are used to solve the FINV model of tubing string.According to the parameters of 3H gas wells in the South China Sea and the similarity principle,a flow induced vibration simulation test device for tubing string is designed.The vibration response data of the tubing string is measured and compared with the calculation results of the theoretical model,and the correctness of the vibration model is verified.Meanwhile,the vibration characteristics of the tubing string are analyzed by using well parameters.The results show that the transverse vibration of the upper tubing is obvious,while the vibration of the middle and lower tubing is close to the casing wall for a long time,which leads to the longitudinal and transverse wear of the lower tubing.At the same time,the longitudinal vibration of the tubing is chaotic,and the chaos phenomenon of the middle and lower tubing string is the most obvious.Therefore,the field designers should pay attention to the safety of the lower tubing string.