硬悬挂钻井隔水管涡激振动特性研究

Study on the Vortex-Induced Vibration Characteristics for Drilling Risers Evacuated from Typhoon in the Hard Hang-Off Mode

针对深水钻井过程中遭遇强台风,基于安全性考虑要求钻井平台悬挂隔水管提前撤离的问题,采用软件SHEAR7针对HYSY981钻井平台硬悬挂隔水管系统避台风撤离作业过程中,受南海一年一遇海流作用时诱发涡激振动(VIV)的情况,研究航速与悬挂长度对VIV特性的影响。研究表明,浮力块覆盖率越高,隔水管系统张力越小;浮力块分布对隔水管系统VIV响应影响较大,25%交错布置方案VIV响应最弱。隔水管并非越短越好,要综合考虑洋流剖面、隔水管配置和平台航行的影响;在不同悬挂长度及航行条件下的VIV响应,在撤离作业前应尽量避免在高流速区布置浮力单根,撤离作业时应尽量采用顺流而避免平台逆流航向。

For safety considerations, drilling platform is needed to be evacuated with the risers hung off in advance of encountering severe typhoons during drilling operations. There exists a security risk due to vortex-induced vibration （VIV） under the interaction of ocean currents and the navigation of the platform. In this paper, the SHEAR7 software is used to study the VIV characteristics of the drilling risers of the HYSY981, a deepwater semi-submersible drilling platform, under the hard hang-off mode when evacuating platform with risers under the current speed in once-in-a-year environmental conditions in the South China Sea. The study shows that the tension of risers lowers with higher coverage rate of buoyancy modules. Moreover, the distribution of buoyancy modules has considerable impact on VIV response which is weakest in the alternative arrangement scheme of 25% coverage. However, shorter risers are not necessarily better, it is needed to analyze the combined effects of ocean currents, configuration of risers and the navigation conditions of the platform. The computing results indicate that it is necessary to avoid the layout of buoyancy modules in high current velocity areas as well as avoid sailing the platform upstream.