Scientists working at Columbia University have offered revised estimates of how much oil was split during the Deepwater Horizon disaster.
Using a technique called optical plume velocimetry to study the oil escaping through the failed blowout preventer, geophysicists Timothy Crone and Maya Tolstoy found about 4.4 million barrels of crude escaped into the Gulf.
The federal government’s Flow Rate Technical Group has previously estimated some 4.9 million barrels of oil were released by the well following an explosion in April, with BP capturing 800,000 barrels.
“Our estimate should be viewed as preliminary,” explained Dr Crone.
“It was based on two short clips. It’s sort of a proof of concept. What we’d like to do in the future is apply this technique to more videos - if they can be made available - to get a better estimate of how the flow rate changed over time.
“This will help us narrow the uncertainties.”
The Deepwater Horizon oil rig exploded on April 20th, with the loss of 11 lives
Gulf of Mexico
For the study the United States team assessed two 20-30-second, high-resolution videos released by BP of the Deepwater Horizon oil plume.
The first was taken while the collapsed riser pipe was still connected to the well’s blowout preventer, while the second shows the well after this riser pipe was cut and removed.
Analysis suggests the average flow rate of oil from the well between April 22nd, when the Deepwater Horizon rig sank and June 3rd was 56,000 barrels per day.
After the riser pipe was removed, the researchers say some 68,000 barrels of oil was flowing into the ocean each day.
The well was finally capped on July 15th.
In total, therefore, Deepwater Horizon spilled is 4.4 million barrels.
This number assumes constant flow rate and the subtraction of the 800,000 barrels BP managed to recover at the disaster site.
The scientists also recognised not all the plume seen in the video comprises oil. It is thought only 40 per cent is oil, while the rest is composed of gas and water.