Shell drilling unit runs aground on Sitkalidak Island, Alas.

Royal Dutch Shell PLC confirmed its conical drilling unit, the Kulluk, broke free while being towed in heavy seas and ran aground on the southeast shoreline of Sitkalidak Island, Alas., on Dec. 31, 2012, while on its way to Seattle. Shell owns the unit, which is managed by Noble Corp.

“The grounding of the Kulluk is a maritime transportation incident and not a drilling incident,” Shell said. The company is posting updates on the response online. The US Coast Guard is leading a unified response team, which includes federal, state, and local government representatives.

Shell said workers are facing “fierce winds and high seas.” The company is reviewing the sequence of events, including the failure of multiple engines on the towing vessel MV Aiviq.

“We intend to use lessons from that review to strengthen our maritime fleet operations, globally,” Shell said. “The incident did not involve our drilling operations, nor does it involve any possibility of crude oil release.”

A USCG aircraft flew over the Kulluk on Jan. 1, and observers reported no signs of leaking fuel. Plans were under way to get salvage crews aboard. The Kulluk has 139,000 gal of diesel on board. Equipment on the Kulluk is estimated to have 12,000 gal of combined lube oil and hydraulic fluid.

At the time of the incident, USCG and another tow ship hired by Shell went to the Kulluk, but tow cables repeatedly slipped in waves of 35-45 ft and 50-knot winds.

Gulf Canada Resources Inc. built the Kulluk conical drilling unit in 1982, and Amoco Production Co. bought Gulf Canada's drilling assets in 1992. Arco Alaska Inc. used the Kulluk to drill the Kuvlum wells about 16 miles offshore in 1992-93. Shell Offshore bought the Kulluk in 2005 and upgraded it for use in its arctic drilling program (OGJ, Oct. 1, 2007, p. 40).