Disconnectable
FPSO vessels
Depending on location, climate and the expected
lifetime of the oil or gas field it might be preferable to have a
disconnectable instead of a permanent FPSO. FPSO’s in the North
Sea are normally permanent and designed for 100 year storm
conditions. Offshore facilities in the in the Golf of Mexico (GOM) are also
mainly permanent but are generally evacuated in advance of a hurricane. A
detailed operation contingency plan with predesignated weather conditions,
determines when operations should be suspended. Continuing work during
storms is of course more effective than evacuating but requires more of the
facility because it should remain a safe work environment during storms.
Evacuation is not always safe either. Distance to shore can constrain the
evacuation and brings increased risk of loss of life because of accidents
during the evacuation.
A solution is found in disconnectable mooring systems.
These systems offer an operator the ability to evacuate personnel and
assets to avoid damage during harsh environmental conditions, such as
hurricanes, typhoons and icebergs. After the weather has subsided
sufficiently the FPSO can return and reconnect.
Turrets
Turrets
are generally used to create a disconnectable system. The installation will
take place in two phases: First the installation of the turret and its
mooring legs. The second phase is the establishment of the connection
between the vessel and the turret. By rising and lowering the buoy the
turret can easily be connected to the vessel.
Hawsers
between tower and vessel