Statoil is postponing its plans to explore for oil in the American Arctic, citing the high costs of operating in the region, regulatory uncertainty and the continued delays that Royal Dutch Shell PLC has encountered this summer as it attempts to sink wells in the region.

Officials with the Dutch company said they're pushing back operations at 16 leases in the company's Amundsen prospect until 2015, at the earliest. The company had previously set 2014 as its starting date and predicted that commercial production could begin in 2020.

ConocoPhillips is sticking with its proposal to begin exploration in 2014 at one or two sites in the company's Devil's Paw leases in the Chukchi Sea. Statoil owns a 25 percent share in those 50 leases.

The three companies were among the successful bidders in the Interior Department's 2008 lease sale for lands in the Chukchi Sea. Since then, Shell has taken the lead in pushing forward with oil exploration, although delays continue to dog the company.

The Interior Department has estimated that the Chukchi could hold 12 billion barrels of recoverable oil. However, developing those resources is expected to cost tens of billions of dollars.

Shell's problems have had a sobering effect on Statoil, a Norwegian energy company with operations in the Barents and North seas.

"In light of the significant uncertainty regarding Alaska offshore exploration, we've decided to take the prudent step of observing the outcome of Shell's efforts before finalizing our own exploration decision time frame," Statoil spokesman Jim Schwartz said.

"We believe it's important to observe the timing and outcome of obtaining all necessary permits, securing regulatory approvals, and -- this is the key part -- demonstrating that exploration operations can be reliably and cost-effectively conducted in the field," Schwartz said.

The company is continuing scientific work and other studies that would be needed to submit an environmental impact assessment and exploration plan in mid-2013. Last month, Statoil's Alaska team shared the revised drilling schedule with residents of Barrow, Kotzebue, Nome, Wainwright and other Native villages in northern Alaska that would be most directly affected by the oil development.

The company is calling on the Interior Department to establish firm regulations, rather than imposing drilling restrictions through individual "notices to lessees and operators." Those notices are formal documents that provide guidelines for energy development.

But Schwartz said the notices may not be enforceable and could change over time. "Arctic exploration is very expensive," he said. "The issue is, there has to be some predictability and certainty with regard to the regulatory process, and Shell is obviously working its way through it. But it's new ground for everyone."

Shell was recently given the green light to begin preparatory work at its Chukchi Sea lease about 70 miles from Wainwright. As of Tuesday, the company's Noble Discoverer drillship was about 10 miles south of the Burger lease site and waiting for the sea state to settle before refueling and moving on to the site, said Shell spokesman Curtis Smith (Greenwire, Sept. 5).

The final drilling permits won't be released until the Coast Guard certifies the Arctic Challenger oil spill response vessel. Shell last Thursday told Interior it expected certification of the vessel to be completed within five days. The company isn't allowed to drill into the hydrocarbon zone until the Challenger completes its two-week trip to the Chukchi Sea.