Friday, February 4, 2011

February 4, 2011, 7:47 am Oil Spill, Redux: Revisiting a Mystery By JUSTIN GILLIS

Agence France-Presse — Getty Images An image from a live video feed shows oil gushing from BP’s Macondo well on May 28.
I attended a symposium last week at the University of Georgia on the Deepwater Horizon oil spill, with panelists (I was one) revisiting many of the issues that came up during that disaster last summer. As I chatted him up, one of the scientists in attendance, Ian MacDonald, pointed me toward a recent article of his that tries again to get at one of the central mysteries of the spill.

The question is: What was the origin of the 5,000-barrel-per-day flow rate that the government and BP promulgated in the early weeks of the spill?

Remember that this claimed rate was questioned by scientists, especially Dr. MacDonald, and by advocacy groups, notably a small environmental organization called SkyTruth. Eventually their concerns were proven correct, the 5,000-barrel estimate was discredited, and a government-appointed scientific panel produced an estimate of the flow rate from the broken oil well that was more than 10 times greater. The bad estimate was a big blow to the Obama administration’s credibility, and it heightened public suspicion of virtually everything else the government said about the spill.

Dr. MacDonald, of Florida State University, worked with the office of a congressman who investigated the spill, Edward J. Markey of Massachusetts, to obtain and analyze worksheets and other background documents that went into the original estimate. He found that, as reported in this newspaper at the time, the first version of the bad estimate was created by the National Oceanic and Atmospheric Administration. Shortly thereafter, BP did its own calculations.

The NOAA number, based on aerial and satellite surveillance, was roughly 5,000 barrels per day, and BP’s analysis of similar data seemed to confirm it. A second BP approach produced a remarkably wide range: a possible flow rate of 5,000 to 60,000 barrels per day.

It’s unclear to what extent the people doing those analyses were talking to each other. But on the surface, at least, it looks like the NOAA estimate was firmly supported by one independent BP calculation and at least weakly supported by the other. “Without knowing the background, a manager presented with this would probably be inclined to say that 5,000 barrels of oil per day was a pretty good number,” Dr. MacDonald told me.

But Dr. MacDonald, in his research, ferreted out critical flaws in some of the calculations supporting that number. For instance, the unidentified NOAA technician or scientist who made that agency’s quick one-page analysis apparently failed to follow procedures laid out in NOAA’s own field manual for how to estimate the volume of an oil slick.

According to Dr. MacDonald’s research, the technician probably misinterpreted satellite photos of the slick and also made unsupported assumptions that tended to lower the estimate.

In its calculations, BP appeared to follow the procedures prescribed in its “Regional Oil Spill Response Plan” for the Gulf of Mexico, Dr. MacDonald found — but the fundamental assumptions incorporated into those calculations were nonetheless flawed. BP apparently converted visual analysis of the oil slick’s thickness into estimates of oil volume using a table of numbers from the response plan.

But the numbers in the table were far too low, failing to match up with the accepted international standards for how to do this sort of thing, Dr. MacDonald discovered in his research.

Dr. MacDonald pointed out that the authorities all along had cameras trained on the gushing well — producing video feeds that, when finally made public after pressure from Congress, heightened suspicions about the 5,000-barrel estimate.

“In choosing to believe this rate, the authorities ignored the strongly contradictory evidence offered by videos of jetting oil and refused to consult independent experts who could have provided better analyses,” Dr. MacDonald wrote in his article.

The bottom line is that, in the early weeks of the spill, the single most important piece of information needed in the response was badly off base. The haunting question is whether engineers, had they known the true rate of flow from the outset, would have skipped many of the failed efforts to cap the well in those first weeks, cutting straight to the aggressive approach that eventually worked — after some 4.9 million barrels, or 206 million gallons, of oil had flowed into the Gulf of Mexico.

We may never know the answer. But this much is clear: If another large oil spill happens in American waters, government and industry are going to be under enormous pressure to come up with credible estimates from the outset, not only as a matter of principle but also to guide the response to the spill.

One hopes that federal agencies are doing some hard thinking now about who would make such estimates, by what methods, and how the work would be vetted before any calculation is released to the public.