Posted on behalf of Mark Schrope
Within weeks of the 2010 Deepwater Horizon blowout in the Gulf of Mexico, scientists from the National Oceanic and Atmospheric Administration (NOAA) were taking air samples near the spill via one of the agency’s Hurricane Hunter aircraft (pictured). At a time when official estimates said the spill was about 5,000 barrels a day, the group’s measurements suggested that number was many times higher, as it proved to be.
But the team was doing something new and there was no way to vouch for accuracy. The group has since proved its case, and at this week’s Gulf of Mexico Oil Spill and Ecosystem Science Conference in New Orleans, the group’s leader Tom Ryerson, a NOAA atmospheric chemist, explained how the researchers applied their lessons during the 2012 Elgin platform natural-gas blowout in the North Sea. The team helped British scientists estimate the spill’s size, allowing them to answer a key question that shaved expensive months off the capping process.
“The first time was a learning experience,” says Ryerson, “The second time we could do it very quickly and we did, and if there’s going to be a third time we’re there.”
Many of the hydrocarbon compounds in oil and natural gas evaporate rapidly at the ocean surface during a spill. Running back and forth through the chemical cloud, the team measures a cross section of this virtual pipe of evaporating gas. Combining these data with basic details about oil or gas composition, along with wind speeds, allows the researchers to work out the size of the spill.
The compounds that work best vary. With Deepwater Horizon, for instance, several chemicals dissolved before the oil reached the surface, knocking them out of the running. Elgin was a spill that offered more options. Researchers at the National Centre for Atmospheric Science in Leeds, UK, who had asked Ryerson’s team for advice, settled on methane, which is easily measured.
At Elgin, knowing the size of the spill was crucial in helping officials respond. If the gas flow had been large, the platform would have been at risk of an explosion, and a direct capping effort would have been prevented. Officials would have been forced to wait months until a relief well was drilled. But the airborne data showed the flow to be relatively small, and officials sent workers back to the evacuated platform, probably saving billions of dollars.
“There’s this horrible thing going on,” says Ryerson. “We were able to offer what seems to be a simple solution. Science doesn’t get any better than that.”