BP Plc’s Macondo well released 4.1 million barrels of oil in the waters of the Gulf of Mexico before it was capped, a team of scientists said today.
An additional 800,000 barrels that flowed from the well after it started leaking were captured by BP, the U.S. government-appointed group said in its most specific estimate yet of the magnitude of the worst oil spill in U.S. history.
At 4.1 million barrels, the spill would be about 16 times the amount leaked by the Exxon Valdez, which released an estimated 257,000 barrels in a 1989 accident.
The well was gushing about 62,000 barrels a day when it started leaking and about 53,000 barrels when it was capped on July 15, according to an e-mailed statement from the U.S. government’s joint information center. The estimate, made using pressure readings and oil reservoir modeling, is an update from the group’s earlier range of 35,000 to 60,000 barrels a day.
During the 87 days that the well was leaking, the flow rate decreased as the reservoir became depleted, according to the researchers.
The spill was triggered April 20 when the Deepwater Horizon drilling rig, which BP leased from Transocean Ltd., caught fire and sank, killing 11 workers.
“The revised estimates are part of this administration’s ongoing commitment to ensuring that we have the most accurate information possible,” U.S. Energy Secretary Steven Chu said in the statement.
‘Static Kill’ Delayed
The new numbers could be used to help determine how much London-based BP is penalized because federal law requires that companies that spill oil into the ocean pay a per-barrel fine.
BP continues to work on a permanent plug for the well. A pumping test and a “static kill” at the site will be delayed until tomorrow after a small hydraulic leak was discovered in the capping stack hydraulic control system, BP said in an e- mailed statement.
The test will determine whether oil and gas trapped in the sealed well can be pushed back into the reservoir, BP Senior Vice President Kent Wells said today on a conference call with reporters.
After the test, the company will begin injecting drilling mud with the goal of clogging the oil and gas reservoir. Static kill work may extend into Aug. 4, Wells said.
The static kill will help BP determine whether to try to plug the well from the top with cement this week, or inject cement from the bottom via a relief well that may intercept the damaged hole between Aug. 11 and Aug. 13.
Regardless of the result of the test, BP will continue drilling the relief well it began in May to intercept the damaged bore, Wells said.