新型立柱储油式半潜平台水动力特性频域分析

Frequency domain analysis of hydrodynamic characteristics of a new type of column oil storage semi-submersible platform

近年来,海上油气工业的远海化与超深水化对半潜平台的响应性能与储送油能力提出了新的考验。为适应更高的工作要求,我国设计生产了世界上首座具有凝析油储存和动力定位穿梭油轮外输功能的立柱储油式半潜生产平台,其运行时储油量的大幅度变化会对平台水动力特性产生影响。本文建立了考虑储油量变化的储油式半潜平台水动力模型并对其进行了频域水动力分析。结果表明:储油量越大,垂荡与横摇一阶波浪力越小,横荡一阶波浪力越大;横摇与垂荡方向的辐射效应受储油量影响大,辐射阻尼随储油量增多而减小,满载状态下最多分别减小22%与42%,附加质量变化规律类似;垂荡RAOs随储油量的增多而减小,最大差值约1 m/m,横摇RAOs在储油量6000 t时达到最大值1.45°/m;储油量变化使垂荡和横摇方向的自然频率发生偏移。

In recent years, the seaward and ultra-deep water production in offshore oil & gas industry has put forward new challenges to the response performance and oil storage and transportation capability of semi-submersible platforms. China has developed the first column oil storage semi-submersible production platform with condensate storage and power positioning shuttle tanker export function in the world. The changes in oil storage capacity will have impact on the hydrodynamic characteristics of the platform during operation. Considering the change of oil storage, the hydrodynamic model of an oil storage semi-submersible platform was established. The frequency domain hydrodynamic analysis was carried out according to this model. The results show that the greater the oil storage is, the smaller the roll and heave first-order wave forces are. The sway first-order wave force increases with the increase of oil storage. The radiation effects of roll and heave directions are greatly affected by the amount of oil storage. The radiation damping decreases with the increase of oil storage.The maximum decreases in heave and roll radiation damping are 22% and 42% respectively under full load condition. The law of additional mass change is similar. The heave RAO decreases with the increase of oil storage, its maximum difference is about 1m/m. The maximum value of sway RAO is 1.45 °/m when the oil storage is 6000 t. The natural frequency shift of heave and roll directions occurs due to the change of oil storage.