Shell Oil's two drilling rigs have left Unalaska on their way to the U.S. Arctic Ocean, where company officials hope to punch into hydrocarbon-bearing zones that haven't been touched in roughly a quarter-century.
The 500-foot Noble Discoverer left Thursday evening. The 400-foot Transocean Polar Pioneer left port at 1 p.m. Friday.
The company is awaiting two federal permits before exploratory drilling can be allowed in the Chukchi Sea about 70 miles off Alaska's northwest coast.
The rigs are moving toward the proposed drilling grounds before the permits are issued because the travel will be a multi-day process, with additional time also needed for the mobile rigs to be locked in place with several pre-staged anchors, said Megan Baldino, a spokeswoman for Shell.
Shell is trying to "maximize the short open water season" in the Arctic, where the federal government allowed Shell to conduct limited top-hole drilling in the summer of 2012 that did not extend into hydrocarbon-bearing zones.
Shell's previous campaign in the Chukchi Sea ended 24 years ago, after the oil giant had drilled four exploratory wells between 1988 and 1991, with each discovering hydrocarbons, though they were not considered commercially viable at the time, according to the U.S. Interior Department.
Shell's latest effort to find oil in the previously explored Burger Prospect has been beset with obstacles and missteps, with the grounding of the drill rig Kulluk near Kodiak Island in late 2012 the most notable.
A more recent mishap -- damage to the hull of a key icebreaker as it was leaving Dutch Harbor earlier this month -- is under investigation by the U.S. Coast Guard.
The Alaska Marine Pilots have said no underwater obstruction to cause the damage was visible on charts. A recently conducted federal hydrographic survey found previously uncharted shoals in the area where the damage reportedly occurred.
The 380-foot Fennica is currently in Dutch Harbor receiving temporary repairs to the 39-inch gash in the hull. Because specialized steel is required and to ensure the damage is permanently fixed, the icebreaker must travel to Portland for repairs, said Baldino.
Baldino said there is no predetermined timeline for how long those repairs will take.
Also uncertain is when drilling can begin.
"We can't do any drilling until we have our applications for permits to drill," she said, referring to approval from the Bureau of Safety and Environmental Enforcement.
"We're waiting for those and we'll comply with the permits," she said.