MIAMI — After pumping heavy drilling mud for eight hours, BP early Wednesday pronounced it had finally brought its blown-out well at the bottom of the Gulf of Mexico under control.
The company and the Obama administration cautioned it would take another step — completion of a relief well later this month — to officially pronounce the monstrous gusher dead, but the apparently successful "hydrostatic kill" operation drove one huge nail in the coffin.
BP began the process -- which injects a dense "drilling mud" tipping the scales at 13.2 pounds a gallon to muscle oil and gas back down its ancient reservoir -- about 4 p.m. after what BP Vice President Kent Wells called some "textbook" tests. Just under 12 hours later, the oil giant issued a release saying the job was done on a well known as Macondo 252.
"The MC252 well appears to have reached a static condition -- a significant milestone," BP said in its release. "The well pressure is now being controlled by the hydrostatic pressure of the drilling mud."
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The company also said there was a possibility it would have to pump more mud into the well during a monitoring period. It could take several days to assess whether the operations had permanently plugged a well that spewed nearly five million barrels of crude into the Gulf, a volume some 20 times larger than the nation's previous largest offshore oil spill.
The company also will decide, in consultation with federal officials, whether to pump cement into the well before it completes a relief well.
Thad Allen, the retired Coast Guard admiral who leads the federal response task force, and Robert Gibbs, President Barack Obama's press secretary, stressed that there would be no declaring victory until BP completes a relief well and delivers a final "bottom kill."
"And there should be no ambiguity about that," Allen said. "I'm the National Incident Commander, and that's the way this will end."
Though a massive 75-top "stacking cap" sealed the well in July, Allen said it remained unclear where the flow was coming from inside a well running some 2 1/2 miles below the sea floor. Bullheading can plug in the well's inner casing, he said, but an internal rupture also might be allowing oil or gas up the annulus, the open space between the casing that normally carries oil and gas and the larger bore hole surrounding it.
Earlier in the week, Wells had suggested that the static kill alone might be enough to finish off the well.
But Allen, supported by a team of federal scientists led by Energy Secretary Steven Chu, have argued that the only assured permanent plug is for the relief well to penetrate the annulus and pump in more mud and cement.
"We need to go into the bottom to make sure we fill the annulus, the casing, and any drill pipe there and then follow that with cement," Allen said. "This thing won't truly be sealed until those relief wells are done."
Earlier in the day, Allen said BP had completed cementing in casing for its primary relief well, which is just 100 feet from its target some two miles down.
The oil giant estimated it would take another week or more to finish drilling the well and start the final bottom kill.
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