FPSO串靠外输系缆方案优化

Optimization of Mooring Hawser Scheme for FPSO Tandem Offloading System

对某单点系泊浮式成产储油卸油船(FPSO)与穿梭油轮组成的串靠外输系统进行时域耦合分析。针对系泊缆绳两组式的布置形式,通过改变每组系泊缆绳长度及数量,分析不同方案下的系缆张力和两船运动响应,确定最优串靠外输系统设计方案,并对该方案下FPSO的单点系泊系统进行校核。在FPSO串靠外输系统中,由于浪流的联合作用,穿梭油轮的运动响应出现所谓的“鱼尾效应”。研究发现:当维持系缆长度不变而增加每组缆绳数量时,缆绳的弹性并联效应不仅会导致缆绳张力呈非线性减小,还会改善系统的运动稳定性,致使“甩尾”发生时间延迟。双缆方案可有效增加系统刚度,对两船相对水平运动有更好的控制效果。

In this study,a coupled analysis of tandem offloading system composed of a SPM(single point mooring)FPSO and a shuttle tanker is performed in time domain.In view of the two-group layout of mooring hawsers,the scheme design of offloading system is carried out by changing the length of hawsers and the number of each group.According to the statistical value of hawser tension and the motion response of two ships under different schemes,the optimal design scheme of tandem offloading system is determined through comparative analysis,and the safety of FPSO’s SPM system is also checked.In the FPSO tandem offloading system,the motion response of shuttle tanker appears the so-called"fishtail effect"due to the combination of waves and currents.It is found that when the number of each group of hawsers is increased,the parallel effect of the hawsers’elasticity not only leads to the nonlinear reduction of the tensions,but also improves the motion stability.The double-hawser scheme is better on the control of relative horizontal motion between the two ships due to the increased system stiffness.