New estimate: Up to 40,000 barrels a day was coming from BP well

(CNN) — Scientists now estimate the leaking BP oil well in the Gulf of Mexico was releasing 20,000 to 40,000 barrels — or 840,000 to 1.7 million gallons — per day through last week, the head of the U.S. Geological Survey said Thursday.

The scientists’ previous estimate was 12,000 to 19,000 barrels per day.

The new estimate is of the well’s flow rate prior to BP’s cutting of the damaged riser pipe extending from the well’s blowout preventer last week, U.S. Geological Survey Director Marcia McNutt said. After BP cut the riser on June 3, it placed a containment cap over the preventer’s lower marine riser package to capture some of the leaking oil.

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