Source of Gulf of Mexico sheen sought

An unmanned, underwater vehicle was surveying plugged undersea oil wells for seepage as authorities sought the source of a 10-mile oil sheen in the Gulf of Mexico off Louisiana.

The federal Bureau of Safety and Environmental Enforcement said it had instructed operators of pipelines in the area 130 miles southeast of New Orleans to survey their lines.

Royal Dutch Shell, which has two platforms in the area, said the mile-wide sheen didn’t originate from its operations and was dissipating. Shell estimated the spill at six barrels; the Coast Guard said it was too early to tell whether any environmental damage had occurred.