Crews trying to contain a leak at an old Prudhoe Bay production well that released crude oil and natural gas stopped the leak Sunday night, officials said Monday morning.
"Overnight the Unified Command achieved source control and killed the well," said Dawn Patience, a spokeswoman with BP, the operator at the giant North Slope fields.
Oil and gas were discovered spraying from outside a well house on Friday morning. The oil leak was later stopped but the natural gas leak continued through the weekend. The well produces both oil and gas, but without a pipeline to deliver gas off the North Slope, most of it is injected back into the ground to increase pressure in oil-bearing formations.
Response operations were continuing as investigators tried to learn more about the cause of the leak and other questions, officials said. A heavy, seawater-like fluid was forced down the well to stop the leak.
The well was drilled in the 1970s. It produced about 500 barrels of crude oil daily, BP said.
It also produced a high volume of gas. The oil and gas production were shut down Friday but the leak continued.
Patience said Monday the sprayed crude oil was contained to the gravel drilling pad and didn't reach the surrounding, snow-covered tundra. The gravel pad supports heavy rigs and other hardware atop the tundra.
The source of the release, Well 3, is at Drill Site 2 gravel pad at Flow Station 1, about 5 miles from Deadhorse Airport. Deadhorse is an industrial hub for the Prudhoe Bay oil fields.
Officials have said there were no reported injuries to people or wildlife.
The estimated volume of leaked gas and oil has not been reported.
Cathy Foerster, head of the Alaska Oil and Gas Conservation Commission, said her agency, which regulates oil wells, has sent an inspector to the command center overseeing the response. The command center is at an operating center at Prudhoe Bay and consists of BP, the Alaska Department of Environmental Conservation, North Slope Borough and the Environmental Protection Agency.
DEC is coordinating with BP and AOGCC to investigate the cause of the release.
Foerster said the agency is pleased the well is killed and is anxiously awaiting more information.
"We're still concerned that we don't know what caused this," she said.