深水条件下高温气井井口抬升的螺旋屈曲效应

Effect of Helical Buckling on Wellhead Height Growth of High Temperature Gas Well under Deepwater Condition

井口抬升高度对深水高温油气井安全生产具有重大影响,传统预测模型只考虑了温度效应和鼓胀效应对井口抬升高度的影响,未充分考虑螺旋屈曲效应对井口抬升高度的影响。鉴于此,借助井筒温度模型,在考虑温度效应和鼓胀效应的基础上,加入螺旋屈曲效应,建立了井口抬升高度预测模型并进行求解,得到较为准确的井口抬升高度。实例计算结果表明:随着时间的延长和产量的增加,螺旋屈曲效应引起的各层管柱屈曲段长度、井口抬升力以及抬升高度都将增加,但增加的幅度逐渐减小,最后趋于稳定;生产过程中生产套管和技术套管始终处于受压状态,对井口抬升起主要作用;表层套管和隔水导管处于受拉状态,管柱不发生屈曲现象。研究结果对井口抬升高度预测及油气井安全生产具有重要的指导意义。

Wellhead growth has a significant impact on the safe production of deepwater high temperature oil and gas wells. The traditional prediction model only take into account of the effect of temperature effect and expansion effect on wellhead growth but neglects the helical buckling. In view of this,based on the wellbore temperature model,besides considering the temperature effect and the expansion effect,the helical buckling effect is added to establish the wellhead growth prediction model in order to obtain more accurate wellhead growth. The calculation results of case study show that,with the extension of service time and the increase of production,the length of the buckling section,the wellhead growth force and height of each pipe string increases. The increase will gradually decrease and finally stabilize. During the production process,the production casing and the intermediate casing are always under pressure,which plays a major role in the wellhead growth. The surface casing and the riser are in the tension state,which does not buckle. The study results could provide guidance for the prediction of wellhead growth and the safe production of oil and gas wells.