The U.S. Coast Guard said on Nov. 28 that about 3% of the Gulf of Mexico's daily oil production remained shut in after a million-gallon oil spill, as it continued surveying Third Coast Infrastructure's pipeline to find the source of the leak.

The pipeline was closed by Third Coast's Main Pass Oil Gathering Co. (MPOG) on Nov. 16 after crude oil was spotted around 19 miles (30 km) offshore the Mississippi River delta, near Plaquemines Parish, southeast of New Orleans.

The Coast Guard had not yet identified the source of the leak after surveying around 40 miles (64 km) of the 67-mile-long (108 km) underwater pipeline, as remote-controlled devices and divers scanned the rest along with other surrounding pipelines.

No new oil had been spotted since Nov. 20 from the suspected release, the Coast Guard said while leading clean-up efforts.

Initial calculations placed the volume of the leak at 1.1 million gallons, or 26,190 barrels, with the Bureau of Safety and Environmental Enforcement estimating that around 61,165 barrels of daily oil output from at least six producers was shut in.

Operators whose facilities are impacted include W&T Energy VI, Occidental Petroleum, Walter Oil and Gas, Cantium, Arena Offshore and Talos Energy Ventures.