Engineering news
An innovative submersible decommissioning system for North Sea oil and gas platforms could be developed outside the UK after failing to attract investment.
Joe Glass, managing director of Seaways Engineering International, needs £2 million to develop his Novel Extended Semi-Submersible (Nessie) design, which he said will lift redundant topsides and jackets and deliver them to a dry-dock facility at a fraction of the cost of the current methods. According to Glass Nessie can be built at less than 10% of the cost of a ship and operated at a correspondingly lower day-rate.
The semi-submersible has six columns and a gate at the aft end, like a giant floating dry-dock. Once the vessel approaches the structure, it ballasts down, opens the gate and moves over the structure. Using accurate laser positioning, the topside unit is lifted clear and secured at the forward end. Nessie then positions itself until the jacket is located amidships, rigging is attached and the jacket is rotated underwater to the horizontal position, where it is secured for transport to shore.
The full-size version of Nessie, at 220m x 120m, could handle the largest North Sea structures, while a 60m x 60m version would handle the smaller structures, commonly located in the southern North Sea, in a single lift.
“Nessie uses its buoyancy to lift the topsides and jackets, effectively eliminating the floating crane and increasing safety. For larger jackets, the lifting is done underwater to further increase safety,” said Glass.
Seaways has been approved by the Oil and Gas Innovation Centre for 50% funding of further research at Strathclyde University. But the company needs a further £2 million to complete the detailed engineering, build a full-scale prototype, and carry out marketing.
“We have been refused help by a major oil company, and prime contractors are expressing minimal interest. We have also approached local government offices without success,” said Glass.
The company is now looking to the US, where it has received a serious expression of commercial interest.
Decommissioning more than 400 oil platforms in the North Sea could cost up to £70 billion over the next 20 years, according to the latest estimates.