Royal Dutch Shell Plc, Europe’s largest oil company, said an oil sheen between two of its platforms in the Gulf of Mexico is dissipating, and the company is trying to determine where it came from.
The sheen, estimated at about six barrels that covered 10 square miles, has broken up, the Hague-based company said in an e-mailed statement. Shell said in an earlier statement that an inspection found “no sign of leaks” and “no well control issues” from its operations in the area.
“It is well-studied and documented that the Gulf of Mexico has a long history of natural occurring seeps, which can on occasion produce sheens,” Kelly op de Weegh, a company spokeswoman in Houston, said in the e-mailed statement. “Shell’s subsea surveillance today and tomorrow will continue to determine if there is a connection between natural seeps and this orphan sheen.”
The company’s Mars and Ursa platforms off the coast of Louisiana are still operating, op de Weegh said. The platforms handle the equivalent of about 60,000 barrels of oil a day for Shell, about 1.8 percent of the company’s output, according to research company Sanford C. Bernstein & Co.
The sheen’s appearance comes almost two years after an April 20, 2010, explosion at BP Plc’s Macondo well caused the biggest offshore oil spill in U.S. history. London-based BP holds a stake in both platforms. Exxon Mobil Corp. and ConocoPhillips are partners in Ursa.
“Given the location of the sheen, we expect sensitivities to be high,” said Peter Hutton, an RBC Capital Markets analyst.
A U.S. Coast Guard helicopter was sent to fly over the area to get “a feel for the size and composition and hopefully where it’s coming from,” Petty Officer Steve Lehmann said in an interview today.
The federal Bureau of Safety and Environmental Enforcement, established after the Macondo spill, directed Shell to use a remote-operated vehicle to survey the seafloor for leaks. It also asked pipeline operators near the sheen to check their lines, according to a statement issued today.
Shell’s Class A shares declined 0.8 percent to 2,125 pence at the close in London. Shell’s American depositary receipts, which represent two ordinary shares, rose 0.2 percent to $67.86 at the close in New York.
The company’s credit-default swaps, which protect against losses on its debt, jumped 18 basis points to 85, the highest since Jan. 10, according to CMA prices at 3 p.m. in London. The contracts are up from 57 basis points March 27.
Shell planned to shut Mars in the second quarter for maintenance and to conduct work related to a second platform it’s building in the field, the company said on April 3. Production from its Olympus platform, capable of handling about 100,000 barrels a day, is expected to begin in 2015, the company said when announcing the project in 2010.
Shell produced an average of 180,000 barrels of oil equivalent a day in the Gulf last year, according to its annual report. The Mars platform is about 100 miles (160 kilometers) south of New Orleans and Ursa is about 130 miles.
The company reported several leaks in the North Sea and Nigeria since August, including the worst for the regions in at least a decade.
Total SA, Europe’s third-largest oil producer, is fighting a natural-gas leak at its Elgin platform in the U.K. North Sea, which also contains light liquids. A sheen of condensate spread to an area 22 kilometers by 4.5 kilometers, U.K. Department of Energy and Climate Change estimates from March 29 show.
Separately, Shell said operational spills of oil and oil products doubled to 6,000 metric tons last year, from 2,900 tons in 2010, according to a sustainability report published on its website today. The Bonga field spill in Nigeria accounted for about 80 percent of the total volume in 2011, it said.