Norway’s Standlifter has developed a decommissioning jackup concept. The concept, shown during Norway’s Subsea Valley conference in April, is a jackup equipped for plugging and abandonment (P&A) and decommissioning operations in up to 300ft water depth.

The facility could be used for plugging wells, removing topsides, removing jackets, cutting piles and sea floor clean-up.

The unit has one 30-tonne capacity via a 50m-reach crane and two knuckle boom-based demolition arms fitted with hydraulic cutters, designed for cutting and lifting 5-tonne sections at 50m maximum reach. It would also have a subsea station serving three purposes — one for a bottom crawler for seabed clean up during P&A, one for marine growth removal and one for jacket cutting using two ROVs and Standlifter’s own patented design subsea lifting yoke, for lifting subsea infrastructure and jacket sections via the crane. The jackup could accommodate up to 150 people, which would allow for spare capacity, according to Standlifter.

The firm’s founder, Leif Salthaug, says by removing facilities either in single lifts or smaller lifts to shore for decommissioning, the environmental risk is simply being moved from offshore to onshore.

“One of the large benefits with this concept is the material handling,” he says. “By separating hazardous materials offshore, the material handling is much easier. Marine growth is left where it belongs, in the sea and not drying out next to receiving plant neighbors. And by using the piecemeal method, transport to shore can be by normal supply vessels. Safety is also improved, as the topsides to be removed can be unmanned during cutting operations.”

The procedure also enables parallel operations and independence from weather concerns and heavy lift vessel availability, he says.

Source: www.oedigital.com

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