BP Exploration Alaska (BPXA) employees discovered an uncontrolled gas release from the top of a well house on Friday morning. By Sunday, the crude was no longer spraying, and workers were able to activate a safety valve that reduced the pressure of the gas.
According to Alaska Department of Environmental Conservation spokeswoman Candice Bressler, the well is back under control.
The agency says the initial oil release may have affected an area of about one hectare and there were no reports of damage to wildlife.
Based on aerial pictures, the release appeared to be confined to the gravel pad surrounding the well head and had not reached the surrounding tundra, BP said.
The state department also said that the exact volume of the leak is yet to be determined.
But the release of vented natural gas means that the well is still leaking methane, a potent greenhouse gas that traps heat 86 times more effectively than carbon dioxide over a 20-year period, into the atmosphere.
The spray of crude onto the pad of the well, which occurred when the well in the bay area of Greater Prudhoe was leaking gas, stopped by afternoon on Sunday. It wasn't until Monday, however, that BP announced that the well had been killed and the oil had stopped flowing.
BP set up a unified command with state and federal regulators to address the leaking gas and oil. BP and other groups were still working on a response plan for the leak on Sunday, according to the report. Output there rose to 565,000 bpd in March, its highest level since December 2013. There is no estimation of the volume of oil spilled or the amount of natural gas that is still coming from the wellhead.
BP did not immediately respond to questions about how much oil the well typically produces. In 2006, a corroded pipeline released almost 5,000 barrels of crude oil, the largest oil spill in the North Slope at the time.