Federal officials Thursday gave Royal Dutch Shell approval for limited site work in the Beaufort Sea off Alaska's northern coast.
The decision was widely expected. A Shell drill ship, the Kulluk, is positioned in the Beaufort waiting for the whaling season to end.
The Bureau of Safety and Environmental Enforcement earlier gave Shell approval for similar work in the Chukchi Sea.
The company can't drill into petroleum zones until its spill response barge is in place. A containment dome on the barge was damaged in tests last weekend.
Shell says it will drill only pilot holes and mud-line cellars this year.
Shell hopes to tap into an estimated 26 billion barrels of recoverable oil and 130 trillion cubic feet of natural gas in U.S. Arctic waters.