Shell has secured its Prelude floating liquefied natural gas (FLNG) facility to the seabed offshore Western Australia, after completing the installation of eight of the 16 mooring lines.
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Illustration of Prelude's turret mooring system. From SBM Offshore. |
In a video released by the supermajor, Shell showcases the mooring of leg number eight on the largest floating facility ever built, which has made the FLNG storm safe.
The Prelude is situated 200km off the coast of north-western Australia in the Prelude field, an area known for extreme weather conditions.
The Prelude FLNG facility has been designed to produce 3.6 MTPA of LNG, 1.3 MTPA of condensate and 0.4 MTPA of LPG. Prelude is 488m long and 74m wide, and weighs 660,000-tonne when fully loaded.
“The need for this mooring system to work is critical. We could hit the cyclones and this mooring system will hold us in place,” says Damian Wake, Shell offshore installation lead.
To keep the Prelude in place, Shell says that its Prelude project team created one of the strongest mooring systems ever built.
According to the company, deep inside Prelude is a turret that allows the facility to rotate or weathervane. Beneath Prelude, is one of the largest chains in the world with nearly 25,000 links attached to mooring piles drilled deep into the ocean floor.
As the video shows, the connecting of chain number eight of 16 to the seabed for the next 25 years, has made Prelude officially storm safe.
The operation to moor Prelude began with the rigging team making the steep descent into the bowels of the turret. Outside, three tugs held the Prelude in position. A crew on the Deep Orient constructon vessel retrieved the mooring line, while on the Prelude, a giant winch stood by to haul in the chain.
According to SBM Offshore, the turret mooring system’s primary function is to keep the Prelude facility on station, and limit excursions to protect its riser-system, which receives gas from the subsea architecture. Four groups of four mooring lines secure the Prelude FLNG to anchor points at water depths of 250m. The turret mooring system is designed to withstand category 5 cyclonic conditions.
The Prelude FLNG facility is operated by Shell (67.5%) in joint venture with INPEX (17.5%), KOGAS (10%) and OPIC (5%).
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