LOS ANGELES – BP’s outlaw well released more than 200 million gallons of oil before it was capped, government officials said Monday, as the company prepared to stuff the well with dense mud in preparation for a final seal later this month.
The new figures, described as the most accurate to date, place the size of the BP spill in the upper range of earlier estimates, affirming the disaster’s ranking as by far the worst offshore oil spill in U.S. history.
Based on pressure measurements from the capped well and new modeling, science teams believe that the deep sea leak initially poured 62,000 barrels of oil a day into the Gulf. As the leak depleted the well’s underlying oil reservoir, the rate fell to a daily flow of 53,000 barrels just before the well was corked with a mechanical cap in mid-July.
All told, experts say about 4.9 million barrels of oil, or 205.8 million gallons, gushed from the well. Not all of that tainted the Gulf, as containment efforts captured about 33 million gallons and funneled them to oil ships.
With the cap in place, BP is embarking on a series of carefully calibrated steps this week to plug the well in advance of permanently sealing the well with cement.
After detecting a small leak in the capping system, engineers postponed until today the start of a “static kill” procedure that involves pumping heavy drilling mud through the well top. If it works as planned, the dense material will shove the oil down the well’s pipe system into the reservoir miles beneath the seabed.
Expected to take several days to complete, the process will fill the well with mud. But federal officials continued to say Monday that even then, they will probably not write the well’s obituary.
“I don’t think we can see this as the end-all, be-all, until we actually get the relief wells done,” said retired Adm. Thad Allen, who is overseeing the federal response effort.
In the first phase of the static kill, now slated for today, BP will run “an injectivity test” to see how the well holds up when material is pumped into it. Pressure at the top of the well will be carefully monitored to avoid dangerous pressure levels.
In the meantime, controversy continues over one of the tools BP used to keep the oil offshore. Especially in the early stages of the three-month leak, the company made extensive use of chemical dispersants to break the oil into smaller bits that would rapidly dissolve and degrade.
But that raised questions about the dispersant’s toxicity and the degree to which it would speed the uptake of oil into the Gulf’s ecological webs.
Monday, the U.S. Environmental Protection Agency released a second round of test results that the agency said showed that oil treated with dispersants was no more toxic than untreated oil.
“I think that probably shows us … the oil itself is the hazard we’re concerned about,” Paul Anastas, the EPA’s assistant administrator for research and development, said in a news briefing.