MPSO, mono-column hull type FPSO, is attracting the interest as a floating production system which has high performance for motion and large tank capacity in recent years.
The authors had performed a mooring system safety evaluation of a MPSO named ‘MONOBR’ which was assumed to be installed at the Gulf of Mexico in the international collaborative research and development project between PETROBRAS and JOGMEC.
There exists a strong current called the Loop current in the Gulf of Mexico. It is known that cylindrical floaters like SPARs or MPSOs sway with the long period and large amplitude in the transverse direction of the current. The motion is called Vortex Induced Motion (VIM), and is caused by vortex shedding from the sidewall of the floater. VIM is one of the important issues in the safety evaluation of mooring system of MPSO.
Generally, the combined environmental conditions in which wind, waves and current exist are concerned for the safety evaluation of mooring systems. Therefore, it needs to estimate VIM in waves and current. The authors had performed the VIM measurement tests in order to investigate the estimation method of VIM in waves and current. The results of the VIM measurement test in waves and current and the results of the mooring safety evaluation method using the estimation method of VIM in waves and current are described in this paper.