Royal Dutch Shell has officially relinquished the majority of its leases in Alaska’s Chukchi Sea.
A company spokesperson told the AP on Tuesday that the company has formally relinquished all but one of its offshore leases in northwest Alaska.
The decision was prompted in part by the increasing costs tied to operating in the U.S. Arctic.
“While we support regulations that enforce high safety and environmental standards, the unpredictable federal regulatory environment for the Alaska Outer Continental Shelf also made it difficult to operate efficiently,” the Shell spokesperson told the AP.
The company will be separately evaluating its leases in Alaska’s Beaufort Sea.
The move comes less than a year after Shell announced it would cease further exploration activity in offshore Alaska for the “foreseeable future” following its disappointing drilling campaign in the Burger prospect.
The company announced in late September that the Burger J well in the Chukchi Sea found indications of oil and gas, but those indications were not sufficient to warrant further exploration in the prospect.
The balance sheet carrying value of Shell’s Alaska position was $3 billion at the time of announcement, with a further $1.1 billion of future contractual commitments.
Shell told the AP that it will keep the lease where the Burger J well was drilled because the company believes “there is value in the data gathered during our exploration efforts there.”
Shell has spent about $7 billion on its Arctic efforts.
The Arctic campaign was plagued by legal issues, protests and equipment delays.
The company won the rights to its offshore Alaska leases in 2008 but a January 2014 federal court decision had suspended the leases until the Bureau of Ocean Energy Management conditionally approved its plan in May 2015.
The relinquishment was discovered by environmental organization Oceana after the group filed a Freedom of Information Act request.
Oceana said on Monday that its FOIA request shows that Shell has relinquished more than 150 of its Chukchi Sea leases.
Oceana added that those documents also show that ConocoPhillips, Eni and Iona Energy have relinquished all of their leases in the Chukchi Sea.
ConocoPhillips formally relinquished its 61 leases on April 26, according to Bloomberg.
A ConocoPhillips spokesperson told Bloomberg that company will end its proceedings with the Interior Board of Land Appeal to extend the leases.
Italy’s Eni and UK-based Iona Energy have not commented on the relinquishments.
In November, Norway’s Statoil exited its 16 operated leases and its stake in 50 leases operated by ConocoPhillips in the Chukchi Sea.