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First Subsea is supplying the mooring connections for the disconnectable STP Buoy to be used by the FPSO, supplied and operated by BW Offshore, in the Chinook Cascade field in the Gulf of Mexico.
 The Cascade Chinook field development will be the first FPSO in the Gulf of Mexico. Moored in 2,600 metres of water, it will be the deepest mooring for a Submerged Turret Production (STP) buoy supplied by Advanced Production and Loading (APL) so far.
Ballgrab Mooring Connections
First Subsea is supplying 11 Series II ball and taper Ballgrab mooring connections with a minimum breaking load (MBL) of 6,600kN. The buoy will feature Ballgrab female uni-joint connectors on its underside.
All risers, umbilicals and monitoring systems transceivers are integrated within the turret buoy which can be disconnected from the FPSO, allowing it to move off-station should the need arise.
Safer Mooring Connection
Once the STP buoy has been positioned in the field, all the male mooring line connections, linked by polyester rope to the sea bed, are connected to the female connectors subsea by ROV, avoiding the need for divers. This is a safer connection technique than traditional surface connection methods.
Pre-installing the Ballgrab female connectors on the buoy will also make it easier to lift the buoy from the installation vessel into the water, without the need to support mooring lines.
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| Mooring the Chinook Cascade STP in this depth of water can present significant technical challenges. By using the Ballgrad connectors we're able to avoid many of the practical problems at the tow out and mooring line connection stages. |
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| Knut Ola Kirkass, project manager, APL AS |
World Record Polyester Mooring Depth
To reduce the size of the STL buoy, the primary mooring lines are synthetic polyester tethers. Petrobras selected Quintas & Quintas Offshore (QQO) to manufacture the 12 (11+1 spare) lengths x 2.5km long x 800 tonne MBL Polyester Tethers. This is a new world record for continuous lengths of polyester mooring tether.
Our mooring system partners, Offspring International, were the project managers on behalf of QQO.
Final delivery of APL’s STP buoy system for the Chinook Cascade field is expected in April 2009, and the installation campaign will commence soon after.
For the latest news on the Chinook Cascade STL buoy visit the First Subsea blog.
For more information on First Subsea's mooring systems contact Brian Green.
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