Designation Of Mooring System For FPSO And Motion Analysis Of Cargo Transfer Vessel

FPSO long-term operates in the changing ocean environment,in order to ensure safe and effective work,the research of mooring system is necessary.The oil and gas need to be transferred after preliminary working,so choosing the export tanker(such as shuttle tanker,etc)might be a good way.Ocean complex wind and waves environment will lead to hydrodynamic mutual interference between the FPSO and transfer oil tankers,therefore,it is difficult to transfer oil and gas stably and safely.So it's significance to study the coupling motion of floating bodies in mooring condition.This paper is based on the theory of potential flow,AQWA is used to simulate the FPSO and the VLCC.The wave motions and loads of the FPSO are predicted,including the additional mass coefficient,the radiation damping coefficient,the F-k diffraction forces,the steady drift forces and the free floating raos,which provide the data basis for the design of the mooring system and the response analysis of the multi-body system.The mooring system of FPSO has been degisned,and the advantages and disadvantages of the arrangement of mooring lines of different numbers,different angles and different lengths are compared and analyzed.The results show that the FPSO locating capability under 1000 m working depth is better when the number of mooring lines is 16,the angle between the mooring lines is 3 degrees,and the length of the mooring line is 1960 m,which can meet the safety and economic requirements.The research of FPSO motion time curves and the tension of each mooring line under different wind directions and wave directions in the Brazil Sea and the South China Sea is conduct.Under the conditions of the FPSO in tandem configuration with the VLCC,the differences of F-k+diffraction forces and free floating raos between the single FPSO and the FPSO connected with VLCC are compared.The results show that the values of F-k+diffraction forces and free floating raos are smaller when the FPSO is connected with the VLCC.The F-k+diffraction forces,the steady drift forces and the free floating raos of the two vessels are compared and analyzed at three different distances.The results show that the distances have little effect on the F-k+diffraction forces and the free floating raos of the two vessels.With the increase of the distances,the amplitudes of the steady drift forces decrease.Overall,the distances have more effects on the VLCC than the FPSO because of the shielding effect in the condition of head sea.The lacating ability is studied by the motion responses of the multi-body system and the tensions of hawser at three different distances.When the distances get farther,the relative swing responses are smaller and the tensions of the hawser are bigger.In this paper,design of FPSO's mooring system and research of operational security of multi-body system composed of VLCC is carried out.It makes great difference and has practical reference value to real engineerings.