Attached FPSO vessels
Two options exist for FPSO stationkeeping - the
great majority
of existing FPSO’s employ a fixed mooring system using anchors and anchor
lines; a few rely on dynamically positioned systems that employ
a series of thrusters and positioning technology (satellite, GPS,
etc.). The fixed mooring system can be further described as permanent or disconnectable.
Most FPSO’s deployed to date (and planned) are
permanently moored, that is, they are designed to remain at the
location throughout all anticipated environmental (weather)
situations; there are few that have been designed to be disconnected under severe weather
circumstances such as typhoons and hurricanes, or threat of icebergs.
When FPSO works, it needs
to be attached to the turret with two types-internal or external. Both
types allow the vessel rotates around the turret. It is means that the FPSO
can turn to a certain angle to the storm and the waves when the storm
comes, which can effectively reduce the motion of the vessel. The turret is
also the interim station of the pipe and the vessel. So it does make sense
for the vessel to be attached to the turret.
Nowadays, the force and
relative motion between the turret and the vessel is one of the most
discussed topics in the FPSO field.