ANCHORAGE - BP has begun putting dozens of Prudhoe Bay oil wells back into production after testing to see whether they presented a danger to workers.
The company had shut down 137 wells after an explosion and fire on Aug. 16 that seriously injured oil field worker Don Shugak.
Steve Marshall, president of BP Exploration (Alaska) Inc., said Monday that tests so far on the wells have not revealed significant problems. Each was under abnormally high pressure but operated under special waivers.
The well that exploded was under excessive pressure. BP investigators believe a casing 17 feet underground ruptured and caused a natural gas explosion inside a wellhead building.
Shugak, who had gone to the newly restarted well to bleed off pressure, was hit by the blast and suffered burns and multiple broken bones. He remains in a Seattle hospital.
The 137 wells together produce about 45,000 barrels of oil a day. Prudhoe, the largest North American oil field, has about 1,600 wells in all and produces most of the North Slope's total daily output of more than 1 million barrels.
Restarting the idled wells could take days or weeks, Marshall said. Meanwhile, BP plans to dismantle the ruptured well to gain more clues about why it failed.
BP has worked closely with unionized Prudhoe workers to come up with some new safety procedures, Marshall added.
George Blankenship, greater Prudhoe Bay field manager, outlined these changes:
Wells must pass a tougher pressure test. Normally the casings or steel pipes that line a well are tested at 100 percent of their maximum operating pressure rating. Now it will be 120 percent to provide an extra level of confidence.
Wells that receive a common waiver to operate at an abnormally high pressure level will never be allowed to spike above that level. This was tolerated in the past, Blankenship said.
Wells restarted from a cold state must be "continuously monitored" by an oil field worker. In the past, workers could leave well pads even though pressure buildup often occurs as temperature rises in restarted wells.
Pressure must be bled off wells before start-up as an extra safety measure. Historically, that was not done, Blankenship said.