半潜钻井平台气隙频域分析

Frequency Domain Analysis on Air-gap of the Semisubmersible Drilling Platform

以两座半潜钻井式平台为研究对象,基于线性波浪绕射/辐射理论,利用频域方法预报平台气隙,引入不对称因子α考虑实际波浪的不对称现象和非线性绕射效应,并进行相应的敏感性分析,分析α对半潜钻井平台气隙结果的影响,计算平台在一系列不规则海况中的气隙,不规则海况波浪能量与平台运动的关系,结果表明,α对半潜平台气隙预报有很大影响,当考虑波浪不对称现象和非绕射现象时,平台气隙将变得危险;当不规则海况的波浪能量集中区域接近于平台垂向相对运动的共振区域时,即使海况的有义波高不是很大,平台也会发生危险气隙。

The air gap of two semi-submersible drilling platforms was simulated based on a linear radiation/diffraction analysis in frequency domain.An asymmetry factor was adopted to account for the asymmetry of the waves and the effect of non-linear diffraction.Sensitivity analysis was made to know the influence of asymmetry factor on the air gap of semi-submersible drilling platforms.When predicting air gap,a series of irregular sea states were considered to study the relation between the platform motion and irregular wave energy.The results showed that the asymmetry factor has a significant influence upon the air gap prediction,when the asymmetry of the waves and the effect of non-linear diffraction was considered,air gap of platforms will become worse.Even though the significant wave heights were not too high,the platforms may experience dangerous negative air gap when irregular wave energy was closed to the natural frequency of platform vertical relative motion.