A Shell deepwater drilling site off the Nigerian coast that the company reported leaking on Wednesday may have spilled up to 2.4 million gallons, according to nonprofit environmental satellite monitoring group SkyTruth.
If so, that’s far worse than indicated in statements made so far by Royal Dutch Shell, which has put the amount of oil leaked at the Bonga offshore site at “less than 40,000 barrels,” (1.7 million gallons).
“That could mean anything from 1 gallon to 1.7 million gallons,” John Amos, founder and president of satellite-imaging nonprofit SkyTruth told TPM.
Oil must be at least 1 micron (1/1000th of a millimeter) thick to be seen from a satellite, according to Amos. The visible rainbow sheen, he says, means that the oil could be anywhere from .3 to 10 microns thick, depending on two different sets of guidelines.
Amos used an image from a European Space Agency radar satellite (the ASAR instrument) to determine that as of mid-week, the spill covered an area of 923 square kilometers (356 square miles).
So if the spill is 5 microns thick—the estimate where the two sets of guidelines intersect—the oil would add up to around 1.2 million gallons, Amos said.
Shell has stated that the spill’s thickness is mostly less than 1/100th of a millimeter, or 10 microns, a statement which leaves a big data gap as well.
“If the whole slick is, on average, 10 microns thick, that’s 2.4 million gallons,” Amos said.
Reached for comment, Shell did not acknowledge SkyTruth’s estimate, and and would only reiterate the 40,000 barrel figure.
On Saturday, Shell released an updated, upbeat statement assuring observers that the spill had been contained and was shrinking thanks to the use of dispersals. As the company’s statement reads: “Current estimates based on over flights indicate less than 10,000 barrels of oil remain on the surface of the water.”
The Bonga spill took place Tuesday, December 20, when oil was being transferred between storage ships. The ordinary production capacity of the field was 200,000 barrels a day, and 10 percent of Nigeria’s overall monthly oil production, according to Reuters.
Presumably, Shell would know how much oil it started with on the day of the spill compared to how much remains, according to Amos.
“We have a lot more to hear from Shell about what actually happened at this site,” Amos told TPM.
Shell has been using floating production and storage offloading, or FPSO technology at the Bonga oilfield, “in which crude oil is piped to floating, mobile tanks, usually converted supertankers, rather than fixed platforms. Shuttle tankers collect oil from the FPSO and carry it to market,” as Wired reported earlier this week.
FPSO is a much cheaper way for an oil company to drill offshore, compared to setting up a drilling platform.
In addition, Shell has reported several oil spills off the coast of Nigeria since it began operating there in 2002, which it blames on sabotage and theft.
Amos believes Shell has a big incentive to be more transparent about the Bonga spill: the company recently received the Obama adminstration’s conditional approval to drill in the Arctic.
“If they weren’t honest [about the Bonga oil spill] and it was discovered they weren’t, I think that would make our government less likely to ease up on drilling restrictions in the Arctic,” he says.
Another recent Shell update states that “survelliance and aerial photos” show the spill breaking up, and that it has not reached the Nigerian coast. SkyTruth hasn’t been able to confirm or debunk this statement so far.
Amos believes Shell has caught on that groups like SkyTruth are using remote sensing to monitor its operations and vet its public statements.
For proof he points to a statement on Shell’s web site, posted after Amos blogged about the size of the Bonga oil slick, stating that while the spill’s extent, “as seen on satellite images, is very large, it’s also very thin.”
Says Amos, “The days when this stuff was so expensive and techie that only oil companies had access to it are over.”