As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect a...As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.展开更多
超深水打桩锤系统的性能直接影响大型海洋油气平台的建设进度。为深入研究超深水打桩锤系统的故障机理,对系统进行可靠性分析与分配研究。首先,对超深水打桩锤系统进行故障模式与影响分析(failure mode and effect analysis,FMEA),并基...超深水打桩锤系统的性能直接影响大型海洋油气平台的建设进度。为深入研究超深水打桩锤系统的故障机理,对系统进行可靠性分析与分配研究。首先,对超深水打桩锤系统进行故障模式与影响分析(failure mode and effect analysis,FMEA),并基于FMEA结果提出了一种改进的危害性分析(criticality analysis,CA)方法。然后,运用改进的AGREE(advisory group on reliability of electronic equipment,电子设备可靠性咨询组)分配法及基于FMECA(failure mode,effect and criticality analysis,故障模式、影响与危害性分析)的可靠性分配方法,对超深水打桩锤系统的子系统和零部件依次进行可靠性分配研究。最后,在MATLAB App Designer开发环境下对超深水打桩锤系统的CA及可靠性分配过程进行可视化界面设计。结果表明,超深水打桩锤系统共有27种故障模式,钢桩等9个零部件为系统薄弱环节;经一、二次可靠性分配后,系统可靠度分别为0.99906322,0.99906327。超深水打桩锤系统的可靠性研究识别了系统的薄弱环节,为其国产化设计提供了一定的理论指导。展开更多
基金Supported by National Science and Technology Major Project of the Ministry of Science and Technology of China(2016ZX05026-002,2016ZX05028-001,2016ZX05024-005)
文摘As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.
文摘超深水打桩锤系统的性能直接影响大型海洋油气平台的建设进度。为深入研究超深水打桩锤系统的故障机理,对系统进行可靠性分析与分配研究。首先,对超深水打桩锤系统进行故障模式与影响分析(failure mode and effect analysis,FMEA),并基于FMEA结果提出了一种改进的危害性分析(criticality analysis,CA)方法。然后,运用改进的AGREE(advisory group on reliability of electronic equipment,电子设备可靠性咨询组)分配法及基于FMECA(failure mode,effect and criticality analysis,故障模式、影响与危害性分析)的可靠性分配方法,对超深水打桩锤系统的子系统和零部件依次进行可靠性分配研究。最后,在MATLAB App Designer开发环境下对超深水打桩锤系统的CA及可靠性分配过程进行可视化界面设计。结果表明,超深水打桩锤系统共有27种故障模式,钢桩等9个零部件为系统薄弱环节;经一、二次可靠性分配后,系统可靠度分别为0.99906322,0.99906327。超深水打桩锤系统的可靠性研究识别了系统的薄弱环节,为其国产化设计提供了一定的理论指导。
