Investigation On Hydrodynamics Of A Side-by-Side Offloading FING System With LNGC And Sloshing Effect

With growing demands for offshore natural gas exploration,Floating Liquefied Natural Gas System(FLNG)attracts much more attentions as a new platform for offshore natural gas production.FLNG can liquefy the natural gas and transfer it to the Liquefied Natural Gas Carrier(LNGC)during the side-by-side operation.As FLNG and LNGC have large displacements,and they are close to each other,there are complex hydrodynamic performance and evident coupled motions.Furthermore,they have LNG cargo in their compartments so that sloshing has a crucial impact on the hydrodynamic performance.Coupled motions and sloshing effect directly affect the state of relative motion which is crucial to security and efficiency of offloading.This research focuses on the hydrodynamic performance of FLNG and LNGC during side-by-side operation,the relative motions of the offloading arms and the sloshing effect through the model test method and the numerical method.A series of model tests has been conducted in Deepwater Offshore Basin in Shanghai Jiao Tong University.The model tests include decay tests in still water,white noise irregular wave tests and irregular wave tests.Based on the three-dimensional potential theory,SESAM code is used to analyze the hydrodynamic performance of FLNG and LNGC in frequency domain and in time domain.It’s concluded that during the side-by-side operation,the LNGC has more severe motions than the FLNG does,which also affects the relative motions of the vessels.When the displacement of the LNGC is the smallest or when the wind,current and waves come from the LNGC side or when the significant height of the waves increases,the relative motions of the vessels and the offloading arms increase.Sloshing effect on the roll motion is the most evident.Under this certain loading condition,sloshing effect can decrease the amplitude and the wave-frequency part of the relative motions.