MIAMI — Pumping a barrel of mud a minute, then two, then five, then seven, BP on Tuesday finally began slowly strangling its blown-out well at the bottom of the Gulf of Mexico.
The company and the Obama administration cautioned that it would take another step and a week or more to officially pronounce the monstrous gusher dead, but a successful "hydrostatic kill" operation would drive one huge nail in the coffin.
Early on, the signs from a mile below the Gulf's surface were encouraging. BP said it 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, around 3 p.m. CDT. The process followed what BP vice president Kent Wells called some "textbook" tests.
The Associated Press reported that well site leader Bobby Bolton estimated the job — also known as bullheading — could be done by day's end.
But Wells, in an earlier teleconference, and federal officials estimated it would take several days to assess whether the operations had permanently plugged a well that spewed nearly 5 million barrels of crude into the Gulf, a volume some 20 times larger than the nation's previous largest offshore oil spill.
Thad Allen, the retired Coast Guard admiral who leads the federal response task force, and Robert Gibbs, President 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."
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 open space between the casing that normally carries oil and gas and the larger bore hole surrounding it, and pump in more mud and cement.