储气库采–关作业油管气相波动压力分析

Analysis of Gas Phase Fluctuation Pressure in Oil Pipes During Production and Shutdown Operations of Gas Storage

  • 摘要: 为优化储气库采–关作业,降低油管气相波动压力,减少冲击载荷导致的阀芯和油管疲劳失效,考虑气相压缩性、流动速度、压力波速等因素,基于质量及动量守恒方程,建立了储气库采–关作业油管气相波动压力数学模型,并采用特征线法编程求解。以呼图壁储气库H2井为例,分析了储气井日产气量、油管深度、油管内径、关阀时间和气体流量等因素对油管波动压力的影响。随着阀门关闭时间延长,波动压力峰值减小,达到峰值的时间增长;随着油管内径减小、日产气量增大、关阀时间缩短,波动压力呈增大趋势。日产气量从50×104 m3/d增至600×104 m3/d,井口波动压力最大峰值减小10.05 MPa,井底波动压力最大峰值减小4.01 MPa。研究表明,油管气相波动压力数学模型具有较高精度,可以为储气库采–关作业提供指导。

     

    Abstract: To optimize the production and shutdown operations of gas storage, reduce the gas phase fluctuation pressure of oil pipes and avoid fatigue failure of valve cores and oil pipes caused by impact loads, a mathematical model of gas phase fluctuation pressure in the oil pipes for production and shutdown operations of gas storage was established by considering the gas phase compressibility, flow velocity, pressure wave velocity, and other factors. The model was established based on the conservation equation of mass and momentum, and the model was solved by the method of characteristics programming. With Well H2 of Hutubi gas storage as an example, the effects of factors such as daily gas production, depth and inner diameter of oil pipe, shutdown time, and gas volume of gas storage well on the fluctuation pressure of oil pipe were analyzed. As the shutdown time prolonged, the peak fluctuation pressure decreased, and the time to reach the peak increased. As the inner diameter of the oil pipe decreased, the daily production increased, and the shutdown time decreased. The fluctuation pressure showed an increasing trend. Compared with a daily production of 50×104 m3/d and 600×104 m3/d, the maximum peak fluctuation pressure at the wellhead decreased by 10.05 MPa, and the maximum fluctuation pressure at the bottom of the well decreased by 4.01 MPa. The research shows that the mathematical model for the gas phase fluctuation pressure of the oil pipe has high accuracy, it can provide assistance for the production and shutdown operations of gas storage.

     

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