Decommissioning and abandonment

Decommissioning and abandonment

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ALLSEAS PIONEERING SPIRIT

ƒ New build for 2014 ƒ 48 000 tonne topside ƒ 25 000 tonne jacket

ƒ S-lay capability ƒ Planned Work

ƒ Brent Delta in 2015/16

Allseas is constructing a new-build heavy lift vessel to remove topsides and jacket legs in two operations (as on right). It has been commissioned to meet the expected boom in North Sea decommissioning work. It may be thought of as a linked catamaran that can dock on either side of the platform. It is designed to handle topsides lifts up to 48 000 tonnef (105 000 kip) and jacket lifts over half this, operating in significant wave heights of 3 m (10 ft). The photograph is of a model showing the original concept of adapting a pair of tankers. The new-build has a strengthened central section which limits the transit speed to 11 knots (5.7 m/s). The slot and eight lifting beams are retained. The tilting beams are designed to accommodate any wind and wave movement. However, it can also accommodate a full curve S-lay stinger to lay pipe vertically. Its 1361 tonnef (3000 kip) tensioning capacity will far outstrip anything currently available in the global fleet. The 170 m (558 ft) stinger and seven welding stations will be able to lay up to 1524 mm (60 in) pipe. Vessel length by breadth: 477 m (1,565 ft) by 124 m (407 ft) Slot width by length: 559 m (194 ft) by 122 m (400 ft) Dynamic positioning: LR DP (AAA), fully redundant Kongsberg K-Pos DP-22 and 2 x cJoy system Other heavy lift vessels are available, such as Saipem’s S7000 and Heerema’s Thialf and Balder. They may be used in combination with submersible transport vessels such as the Mighty Servant 3.

LEGISLATIONSUMMARY