Reprint from CNN:

link: http://news.blogs.cnn.com/2010/06/15/how-the-oil-disaster-flow-estimates-have-evolved/?hpt=T1

 

U.S. government officials on Tuesday said they now estimate the ruptured BP well in the Gulf of Mexico is spewing 35,000 and 60,000 barrels (1.5 million gallons to 2.5 million gallons) per day; that's significantly more than the first estimate of 1,000 barrels per day in late April.

Below is a recap of the different estimates that officials have made, and when they made them, since the disaster began with the explosion of the Deepwater Horizon oil rig on April 20.

April 23: Three days after the explosion of the Deepwater Horizon rig, and one day after the rig sank, Coast Guard Rear Adm. Mary Landry said crews were cleaning up a 1- by 12-mile-long oil slick spreading through Gulf waters. She said crude oil did not appear to be leaking out of the wellhead but that remote vehicles would survey the scene. BP officials had said a day earlier that BP they did not know whether oil or fuel was leaking from the rig. But BP Vice President David Rainey said: "It certainly has the potential to be a major spill."

April 24: Landry said oil was leaking from two places - later to be clarified as two places on the riser pipe extending from the well's blowout preventer - at a preliminary estimate of about 1,000 barrels (42,000 gallons) a day. Officials later said that the two leaks were found within 36 hours of the April 20 explosion.

April 28: Landry said the estimated amount of oil spilling into the Gulf of Mexico has increased to 5,000 barrels (210,000 gallons) a day, five times the initial estimate. The new estimate was based on analysis from the federal National Oceanic and Atmospheric Administration, she says. Also, BP official Doug Suttles said the company has found a third leak in the riser pipe.

May 2: Coast Guard Commandant Adm. Thad Allen said it was impossible so far to know how much oil will eventually leak.

"We lost a total well head; it could be 100,000 barrels [4.2 million gallons] or more a day," Allen told CNN's "State of the Union." The official estimate, though, remained at 5,000 barrels (210,000 gallons) a day.

"This spill, at this point in my view, is indeterminate," Allen said. "That makes it asymmetrical, anomalous and one of the most complex things we've ever dealt with."

May 13: After BP released underwater video footage of the leak, independent experts such as Purdue University associate professor Steve Wereley said the flow rate is probably much higher than the official estimate.

Wereley estimated that about 70,000 barrels (2.94 million gallons) of oil were leaking each day, based on an analysis of video of the spill. "You can't say with precision, but you can see there's definitely more coming out of that pipe than people thought," he said. "It's definitely not 5,000 barrels a day."

May 27: A panel of government experts estimated the well is spewing oil at a rate of 12,000 to 19,000 barrels (504,000 to 798,000 gallons) a day, U.S. Geological Survey chief Marcia McNutt said.

June 10: The panel of government experts, called the Flow Rate Technical Group, estimated the well was leaking 20,000 to 40,000 barrels (840,000 to 1.7 million gallons) per day through June 3. The figure was calculated in part by using high-definition video that BP released after demands from members of Congress.

The new estimate was of the well's flow rate before BP's cutting of the damaged riser pipe extending from the well's blowout preventer on June 3, McNutt said. After BP cut the riser that day, it placed a containment cap over the preventer's lower marine riser package to capture some of the leaking oil.

Scientists estimated that the spill's flow rate increased by 4 to 5 percent after the well's riser pipe was cut last week in order to place the cap atop the well.

BP said that with the cap, it was capturing about 16,000 barrels daily and sending it to a ship on the surface. Before that, BP was capturing some oil through a siphon inserted into the well riser.

June 15: Government officials increased the estimate to between 35,000 and 60,000 barrels (1.5 million gallons to 2.5 million gallons) per day.

The change was "based on updated information and scientific assessments," the Deepwater Horizon Incident Joint Information Center said.

"The improved estimate is based on more and better data that is now available and that helps increase the scientific confidence in the accuracy of the estimate," it said.

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