(CNN) -- A Royal Dutch Shell oil drilling barge remained grounded Tuesday on an island off southern Alaska amid a fierce winter storm that hindered recovery efforts, Coast Guard and Alaskan authorities reported.
The Shell-owned rig Kulluk was being towed to Seattle when it began encountering trouble Sunday, the Coast Guard said. One tug needed help after its engines failed; a replacement had to cut the rig loose Monday night during a storm that whipped up 24-foot waves in the Gulf of Alaska.
The 266-foot rig ran aground off Sitkalidak Island, about 200 miles south of Anchorage, on Monday night. A joint command was set up to head off any possible environmental damage, but crews had not been able to confirm the Kulluk's condition Tuesday morning, those authorities reported.
The Kulluk had 139,000 gallons (4,400 barrels) of diesel fuel and 12,000 gallons of combined lube oil and hydraulic fluid on board; no leaks had been detected early Tuesday.
Weather conditions were expected to improve through the rest of the week, with seas subsiding from 24 feet Tuesday to 11 feet by Friday, according to the National Weather Service.
Susan Childs, Shell's incident commander, said more than 250 people were working on the response. The rig grounded in an area of Ocean Bay, where water depth is 32 feet to 48 feet, according to a release from the response team.
The Kulluk is part of Shell's controversial effort to drill for oil in the remote Arctic, a project that caused widespread concern among environmentalists and was held up after BP's Deepwater Horizon disaster in the Gulf of Mexico. It finished drilling operations in October, and its 18-person crew was evacuated Saturday.
The rig was being used to drill in the Beaufort Sea, off Alaska's North Slope. Shell says it's working at far less depth and lower pressures than the BP well that erupted off Louisiana, killing 11 men aboard and unleashing an undersea gusher that took three months to cap.
The U.S. Geological Survey estimates more than 90 billion barrels of oil and nearly 1,700 trillion cubic feet of natural gas may be recoverable by drilling. And the shrinking of the region's sea ice -- which hit record lows in 2012 -- has created new opportunities for energy exploration in the region.
Climate researchers say that a decrease in sea ice is a symptom of a warming climate, caused largely by the combustion of carbon-rich fossil fuels. The science is politically controversial but generally accepted as fact by most scientists.