Videos of the oil leak 5,000 feet down in the Gulf of Mexico are coming out, and according to some scientists, the news is even worse than we thought. If you remember back a few weeks to the outset of the BP oil spill, the official estimate was that 1,000 barrels of oil (42,000 gallons) was leaking into the Gulf of Mexico. While that's nothing to sneeze at, the total wasn't catastrophic compared to historic spills like the Exxon Valdez. Then, more than a week after the Deepwater Horizon exploded and sank, scientists at the National Oceanic and Atmospheric Administration did their own quick calculation and quintupled the estimate to 5,000 barrels per day.
BP later acknowledged to Congress that the worst case, if the leak accelerated, would be 60,000 barrels a day, a flow rate that would dump a plume the size of the Exxon Valdez spill into the gulf every four days. BP’s chief executive, Tony Hayward, has estimated that the reservoir tapped by the out-of-control well holds at least 50 million barrels of oil [The New York Times].
Now, according to an independent analysis done by Purdue's Steve Werely with video footage of the leak, that worst-case figure by BP is close to what's actually happening, and the true total might be even higher. Werely estimates the leak at 70,000 barrels per day, and with a 20% uncertainty in the numbers, that gives a range of 56,000 to 84,000.
Werely told The Guardian he based his estimate on techniques which track the speed of objects travelling in the flow stream."You can see in the video lots of swirls and vortices pumping out of the end of the pipe, and I used a computer code to track those swirls and come up with the speed at which the oils is shooting out of the pipe," he said. "From there it is a very simple calculation to figure out what is the volume flow" [The Guardian].
A second estimate by Eugene Chiang of UC-Berkeley provided a window of 20,000 to 100,000 barrels a day. Though the margin is wider, the estimate roughly coincides with Werely's. But, if these guys are right, then how the heck did initial estimates miss the mark so badly?
The 5,000-barrel-a-day estimate was produced in Seattle by a NOAA unit that responds to oil spills. It was calculated with a protocol known as the Bonn convention that calls for measuring the extent of an oil spill, using its color to judge the thickness of oil atop the water, and then multiplying [The New York Times].
But according to other experts, that method isn't especially accurate for large spills, especially one like this with large quantities of oil below the surface, unable to be seen from above. There's another alternative way to measure this, too. Researchers can use ultrasound to measure the flow rate; they do it under happier circumstances to measure how much oil or gas a well is providing. But two researchers who were going to take these measurements were turned away because BP was about to commence its now-failed attempt to install a containment box
over the leak. They haven't been invited back yet. It's one thing to be wrong, but the troubling development in measuring the spill is that neither BP nor NOAA appears terribly interested in getting the right number. When asked about the varying estimates of the leak total, BP leaders have deflected the question and said that it doesn't really matter how big the spill is because their response would be the same. The government has responded in much the same way:
“I think the estimate at the time was, and remains, a reasonable estimate,” said Dr. Lubchenco, the NOAA administrator. “Having greater precision about the flow rate would not really help in any way. We would be doing the same things" [The New York Times].
For immediate response that may be true. But what about after the spill is finally, someday, stopped? Just as one example, it came out this week that the Deepwater Horizon, like many other rigs in the Gulf, was given the go-ahead to drill
without receiving permits for assessing potential dangers to endangered species in the area. Now that responders are playing catch-up after the fact, it might be nice to know whether the leak amounts to 5,000 barrels a day or an entire order of magnitude higher than that. In any case, the Coast Guard is beginning to treat the spill as a major disaster, according to Commandant Thad Allen.
"It has the potential to be catastrophic ... I am going to act as if it is," Allen told reporters in a briefing [Reuters].
Previous posts on the Gulf Oil Spill: 80beats: Testimony Highlights 3 Major Failures That Caused Gulf Spill
Image: U.S. Coast Guard