NEW ORLEANS — A new federally led study of oil seeping from a platform toppled off Louisiana’s coast 14½ years ago found releases lower than other recent estimates, but it contradicts the well owner’s assertions about the amount and source of oil.
Oil and gas have been leaking into the Gulf of Mexico since a subsea mudslide caused by Hurricane Ivan on Sept. 15, 2004, knocked over a Taylor Energy Co. production platform, which dragged and broke a bundle of well pipes. Taylor capped nine wells but said it couldn’t cap 16.
The company contends oil sheens on the water’s surface indicate there’s only a dribble of 2.4 to 4 gallons of oil and gas a day. Taylor Energy, which is fighting a federal order to stop the seepage, also says any oil rising from the site is from oil-soaked sediment and any gas is produced by living organisms.
“The results of this study contradict these conclusions,” said the report paid for by the federal Bureau of Safety and Environmental Enforcement, which oversees offshore drilling, and written by two National Oceanic and Atmospheric Administration scientists and one from Florida State University.
Taylor said in an emailed statement that it wants verifiable scientific data about the leak and a scientifically and environmentally sound solution. The company has said remaining pipes are buried under so much oily and treacherous silt that stopping any leaks would do more environmental damage than letting them be.
No coastal environmental damage has been reported from the ongoing seepage, unlike the 2010 Deepwater Horizon oil spill, an outside scientist said.
The study’s authors figure that the total released each day from the Taylor site could have been as much as 4,500 gallons a day. They used sonar and a newly developed “bubblometer” to measure oil and gas bubbles rising through the water.
These are based on direct measurements, while previous estimates have relied on satellite and remote sensing of the sheen of oil resulting from the seep, Chris Taylor, of NOAA’s National Centers for Coastal Ocean Science in Beaufort, N.C., said Friday.
The figure is a conservative one, the report said.
The team’s methods look reasonable, said Ed Overton, a professor of environmental studies at Louisiana State University who was not part of the study.
“There are no standard methods for this type of work,” because the amounts of oil involved are relatively small, he said.
NOAA reported two possible ranges: one using sonar from a boat and an underwater robot; the other using their bubblometer — a box with a video camera to get pictures of the bubbles, topped by a funnel to collect the oil and gas.
The sonar showed releases of 378 to 1,974 gallons a day; the bubblometer data indicated 798 to 4,536 gallons daily.
A 2015 investigation by The Associated Press revealed evidence that the leak was worse than the company or government had publicly reported.