Feds up estimates of BP-spill rate

The national flow-rate technical group pegs likely releases at a minimum of 20,000 barrels per day.

For most of the first month after the catastrophic blowout of the Deepwater Horizon well in the Gulf of Mexico, both BP – the well’s owner – and federal officials offered similar guesstimates of the daily flow of oil into the water: 5,000 barrels, or 210,000 gallons. But in recent weeks, independent research teams have begun conducting their own assessments and coming up with strikingly higher numbers. At a 5 p.m. EDT news briefing on June 10, Marcia McNutt, Director of the U.S. Geological Survey and chair of the National Incident Command’s Flow Rate Technical Group, offered her technical group’s best guess as to the well’s release rate: 20,000 to more than 40,000 barrels per day.

McNutt explained that the number may be revised and tweaked many more times in coming days and weeks as additional teams within her group weigh in using different techniques, or as additional data become available.

The new number reflects estimates only of what was likely jetting into the Gulf prior to June 3, when BP successfully lowered a cap over the well head to systematically collect and bring to the surface some of the spewing oil and gas. Earlier in the day, Coast Guard Admiral Thad Allen reported that BP was recovering 15,800 barrels of oil per day via this new top cap collection system.

Several members of the Flow Rate Technical Group – which is comprised of federal, academic and other scientists – are currently assessing whether and how the well’s release rate might have changed after the new oil-collection system went into operation. They have not yet hazarded guesses as to whether cutting the broken pipe atop the well head and installing the new collection system would be expected to increase or decrease the well’s flow rate.

McNutt noted that part of the responsibility of her flow-rate group includes doing a “mass balance” of the released oil. Essentially, this exercise will assess whether the projected total amount of oil released from the well dovetails with the apparent quantity of oil that has surfaced and become visible to planes and satellites. Any mismatch between the two numbers will offer a rough gauge as to how much of the spilled oil may still reside under the water in diffuse plumes or in particles that may be raining onto the seafloor.

See: BP spill–Gulf is primed to heal, but . . .

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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