SBM Offshore is to supply what will be the second operational fpso in the Gulf of Mexico to Shell Offshore. The ?oater capex has been estimated at $1bn.

The fpso for Shell’s Stones development (SEN, 30/5) will be the deepest moored at 2,896m and will feature a number of technological innovations including the ?rst use of steel catenary risers (scrs) in a lazy-wave con?guration (SLWR) deployed from an fpso.

SBM will equip this new unit, based on a suezmax tanker, with its proprietary buoyant turret mooring (BTM) system to make the ?oater ‘disconnectable’ in the event of a hurricane. The turret buoy - ‘the biggest challenge’, SBM told SEN - will be bigger and more robust - although SBM has been vague on the exact details - to accommodate the scrs. There will be at least three in the ?rst instance - one to each of the ?rst two wells plus one for gas export - as well as an umbilical to each well.

Gimme shelter

What seems apparent is that SBM pioneered the ‘disconnectable’ concept back in the late 1980’s and early 1990’s when it equipped two fpso’s with BTM systems for use in the typhoon-prone Chinese sector for Phillips and ACT, although the ?rst will have actually been one of its RTM (riser turret mooring) system supplied for the Jabiru Venture in 1986.

It also equipped Husky Energy’s SeaRose fpso with a similar system for the White Rose development in ‘Iceberg Alley’ off the east coast of Canada.

In addition, it has supplied at least six fpso’s in use in the Australian sector with its external RTM system including at En?eld and, most recently, for the replacement fpso Okha for Woodside. Interestingly, SBM supplied an RTM on the original Cossack fpso and Woodside retained that mooring unit for the new fpso, only replacing the loading arm.

The ?oater contractor has been working with Shell for 18 months on this new concept which follows on from its work for the BC-10 fpso in Brazil (see Floater News) which used scrs, although in a hang-off mode. With that project now four years old, SBM sees that concept as having passed its in-house ‘technology gate’ and is considered mature and commercialised.

This new floater is described in SBM terminology as a ‘generation 2' fpso. A ‘Gen 3' is how it categorises the units being supplied for Petrobras’ pre-salt fields with complex topsides of at least 20,000t featuring considerable gas processing and CO2 recovery and reinjection. This ‘Gen 2' is low complexity - 7,000t topside, 60,000b/d oil processing with no water or gas injection - compared with the mooring system.

The other item of note is the Inline Mooring Connector (ILMC) - called a ‘subsea ratchet’ - which allows the fpso to be moved around on the mooring lines, although this cannot be done from the floater, only with the assistance of a support vessel.

Comments