ANCHORAGE - State regulators have accepted BP Exploration (Alaska) Inc.'s plan to improve the failure rate of wellhead safety valves at the Prudhoe Bay oil field.
The valves sit atop more than 1,000 Prudhoe oil wells, acting as a first line of defense to stop big oil leaks. They're designed to automatically shut down oil production from a well if pressure drops because of a pipeline rupture. If they don't close or the pressure-detection system doesn't work, a larger oil spill could occur.
BP had problems with valves on the western side of Prudhoe Bay in 2000 and early 2001. The commission found high failure rates on wellhead valves at six of the 24 production pads, with four pads failing consecutive tests, according to Alaska Oil and Gas Conservation Commission officials.
The commission said multiple retesting of problem well valves from April through December of last year found only one Prudhoe Bay pad with a failure rate above 10 percent.
In response to the problems, BP leaders said they developed a new valve management system.
The plan calls for improved preventive maintenance, more vigilance to find the causes of valve failures, increased documentation of repairs, creation of a new database of test results, and worker accountability.
"We're still encountering problems in the field, but we are managing the system a lot more than before," said BP spokesman Ronnie Chappell.
BP will be required to submit quarterly updates to the commission so regulators can monitor the progress. Regulators also will continue the standard practice of random inspections and testing.
The action comes nearly a year after the commission said the oil company had problems with some valves. BP workers criticized the company for not keeping up with maintenance.
BP had faced state fines. But Cammy Oechsli Taylor, the commission's chairwoman, said BP leaders have been "very proactive and made a good-faith effort to address the problems."
Although the valves are common in offshore oil fields, Alaska is among the few places in the country that require oil companies to install them at onshore wells, according to the commission.
Alaska oil companies must test the valve systems every six months. But if a group of safety valves on a well production pad is found to have an average failure rate of more than 10 percent, the state requires more frequent testing.
Prudhoe is not the only oil field that has had problems with such valves. At Kuparuk, the Slope's second-biggest field, 13 of 44 pads tested had failure rates above 10 percent in tests last year. High failure rates also were found at well pads at the smaller Badami, Milne Point and Lisburne oil fields.
Phillips Alaska Inc., which operates Kuparuk, fixed the problems and does not face enforcement action, regulators said.