深水钻井隔水管-井口系统涡激疲劳详细分析  

Detailed analysis of vortex induced fatigue for deep-water drilling riser-wellhead system

作　　者：畅元江 杨焕丽 刘秀全 刘康 

机构地区：[1]中国石油大学海洋油气装备与安全技术研究中心,山东青岛266580

出　　处：《石油学报》2014年第1期146-151,共6页Acta Petrolei Sinica

基　　金：国家重大科技专项"深水油气田开发钻完井工程配套技术"(2011ZX05026-001-05);教育部长江学者和创新团队发展计划项目(No.RT1086);中央高校基本科研业务费专项资金项目(11CX05009A)资助

摘　　要：提出基于威布尔分布的隔水管一井口系统涡激疲劳详细分析方法，根据海洋环境条件的长期统计分布特征，采用随机变量的威布尔分布理论划分涡激疲劳详细分析的工况，得到具有不同超越概率的流剖面。在此基础上，应用涡激振动疲劳分析程序SHEAR7计算各个流剖面对应的涡激疲劳损伤，按照其发生概率折算得出隔水管系统总的疲劳损伤。算例结合南海某油井隔水管系统设计和具体海况参数，给出了上述方法的具体应用。研究表明，采用常规三种单一流剖面计算得到的涡激疲劳寿命分别为1．95年、0．039年和0．012年，而采用基于威布尔分布的涡激疲劳详细分析得到的疲劳寿命约为40年。两种方法相比，由于后者更符合实际的海洋环境条件，预测隔水管-井口涡激疲劳损伤更为合理，从而可以避免过于保守的隔水管钻前设计。推荐涡激疲劳详细分析工况数量为20-28个。A method is detailed for fatigue analysis of vortex-induced vibration （VIV） in deep-water drilling riser-wellhead systems based on the Weibull distribution. According to the long-term statistical distribution of marine environmental conditions, the load ca- ses of detailed VIV fatigue analysis are divided by using the Weibull distribution theory of random variables, and current profiles with different probabilities of exceedance are obtained. Further, VIV fatigue damage corresponding to each current profile is calculat- ed by using the VIV fatigue analysis program SHEAR7, and the total fatigue damage of the riser system is estimated according to the occurrence probability. A case study is then conducted for a specific application of the proposed method by combining the design of riser system and the parameters of sea conditions in an oil well in South China Sea. The results show that VIV-induced fatigue lives calculated from the three single conventional current profiles are only 1.95, 0. 039, and 0. 012 years, respectively, whereas that ob- tained by detailed fatigue analysis based on the Weibull distribution is approximately 40 years. Compared with the conventional meth- od, the proposed method is more suitable for predicting VlV-induced fatigue damage in riser-wellhead system as it complies more with the real marine environmental conditions and avoids over-conservative riser pre-drilling design. The number of load cases recom- mended for detailed fatigue analysis of VIV is 20-28.

关 键 词：深水钻井 隔水管-井口系统 涡激疲劳 威布尔分布 超越概率 

分 类 号：TE22[石油与天然气工程—油气井工程]