不同工况下的水下井口油管悬挂器有限元分析

Finite Element Analysis of Tubing Hanger at Subsea Wellhead under Different Working Conditions

在水下油气开采过程中,油管悬挂器是水下井口核心的承压部件,其性能高低决定开采系统能否持续安全可靠运行。对处于500 m水深的油管悬挂器在下放过程、密封激励建立过程和工作过程3种复杂工况下进行强度及疲劳寿命分析。分析结果表明:油管悬挂器在密封激励建立过程中,最大等效应力为427.01 MPa,最大变形量为0.27226 mm,最小疲劳寿命为12174 d,确定其为最危险工况。对处于密封激励建立过程的油管悬挂器主体分别进行模态及可靠性分析,以全面评估其安全性能;运用Modal模块分析得到油管悬挂器的6阶固有频率都较高,远远高于水下井口涡轮转动频率,不存在共振风险;运用6σ模块分析得到油管悬挂器的可靠性为98.61%,并发现材料的许用应力和外界载荷对油管悬挂器的可靠性影响最大。研究结果可为油管悬挂器的优化设计提供参考。

In the process of subsea oil and gas exploitation, the tubing hanger is the core pressure bearing component at subsea wellhead, and its performance determines whether the exploitation system can continue to operate safely and reliably.Under three complex working conditions such as the lowering process, the sealing excitation establishment process and the working process respectively. The study results show that in the process of sealing excitation establishment, the maximum equivalent stress of tubing hanger is 427.01 MPa, the maximum deformation is 0.272 26 mm, and the minimum fatigue life is 12 174 d, therefore, this process is determined as the most dangerous working condition. Moreover, the modality and reliability analyses were conducted on the main body of tubing hanger in the process of sealing excitation establishment respectively to comprehensively evaluate its safety performance;the modal module analysis was conducted to show that the six-order inherent frequency of the tubing hanger is high, which is far higher than the dynamic frequency of turbodrill at subsea wellhead, and there is no resonance risk;the 6σ module analysis was conducted to show that the reliability of tubing hanger is 98.61%, and the allowable stress of material and external load have the greatest influence on the reliability of the tubing hanger. The study results provide references for the optimum design of tubing hanger.