Speaking at a teleconferenced news briefing Thursday in Anchorage, Shell Alaska operations manager Dean Crutchfield outlined problems inspectors discovered in a 3-hour inspection of the rig Wednesday.
The rig's emergency and service generators were damaged and watertight doors were breached, Crutchfield said.
It is too early to ascertain if the rig is seaworthy and can be be moved, he said.
U.S. Coast Guard Capt. Paul Mehler said he ordered a "marine casualty investigation" of the grounding
The rig ran ashore near Sitkalidak Island, about 10 miles south of Kodiak Island, the Anchorage Daily News reported.
There was no sign of a fuel leak, the report said.