Extending the drilling season beyond the open water period in the Arctic is the primary driver behind a new jackup concept designed to operate in light ice conditions. The defining feature of the Arctic jackup is its telescopic leg that protects the drillstring from ice loads and is adjustable for depths down to approximately 50 m.
Developed at the University of Stavanger in Norway as part of a graduate thesis and presented in a technical paper at the 2014 Arctic Offshore Technology Conference in Houston, the hull of the jackup is ship-shaped and borrows from icebreaker technology to withstand hits from drift ice as it is transported to an Arctic drilling location.
The design of the Arctic jackup’s other supporting legs are also unique and key to enabling the system to remain in ice conditions for more than a month after the open water season has ended. The design seeks to provide operators with an extra 30 to 40 days on the back end of the season—enough time, the designers say, to drill and test a new well in the same season. Because conventional jackup rigs are vulnerable to ice loading, they must begin mobilizing out of the Arctic well before any ice has formed, which tightens an already very narrow operating window. “The legs (on a conventional jackup) are traditionally open trusses,” said Maria Urycheva, a codeveloper of the concept and now a pipeline engineer at Ramboll Oil and Gas in Norway. “But we suggest using a tubular shape because it is more resistant to ice impact and will result in less ice accumulation around the legs.”
Additionally, once ice is present in the area, conical collars are to be lowered to the water line to break up the ice without impacting the legs directly and this also prevents the ice from accumulating on the structure. The jackup could also serve as an oil spill response system in the event of an emergency, and through ice management provided by an icebreaker, the rig would be able to remain on location for the length of time needed to drill a relief well.
Like many new Arctic drilling concepts, the cost of building such a system also sets it apart from other jackups. “This could be 20–30% more expensive than the most expensive jackups because of the hull configuration and the icebreaking capabilities,” said Ove Gudmestad, a University of Stavanger professor and a codeveloper of the concept. “But the question is: Is it suitable for the industry to be able to drill in Arctic areas?” To answer that question, more research and modeling will need to be done with a naval engineering firm or jackup contractor, he added.
