The company and the Obama administration cautioned that 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" that tips the scales at 13.2 pounds per gallon to muscle
oil and gas back down its ancient reservoir — about
"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."
The company also said it was possible that it would have to pump more mud into the well during a monitoring period. It could take several days to assess whether the operations permanently plugged the well, which spewed nearly 5 million barrels of crude oil into the Gulf, some 20 times more 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.
"And there should be no ambiguity about that," Allen said. "I'm the national incident commander, and that's the way this will end."
Although a massive 75-ton "stacking cap" sealed the well in July, Allen said it remained unclear where the flow was coming from inside a well running some two and a half miles below the seafloor. A static kill 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 usually carries oil and gas and the larger bore hole that surrounds it.
Earlier in the week, Wells had suggested that the static kill alone might be enough to finish off the well.
Allen, however, supported by a team of federal scientists led by Energy Secretary
"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."
Allen said earlier that BP had completed cementing in casing for its primary relief well, which is 100 feet from its target some two miles down.
The oil giant estimated that it would take another week or more to finish drilling the well and start the final bottom kill.———
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