Brazilian naval authorities are investigating yet another oil sheen seen floating near an offshore platform owned by state oil company Petrobras.

Workers returning from work reported seeing a 1-kilometer-long (0.6-mile-long) oil drift near Petrobras' P57 platform, which operates in the Jubarte field 53 miles off Brazil's coast. There is as of yet no estimated size or cause of the spill, Reuters reported Thursday.

The spill is the third since November 2011, when as much as 3,000 barrels leaked from ruptures in the ocean floor caused by Chevron drilling activities.

In March, another sheen was reported floating near other Chevron assets, but was not found to be linked to the first leak.

Brazil could have as much as 100 billion barrels of oil and 400 trillion cubic feet of natural gas locked up in offshore deposits yet to be uncovered, estimates the U.S. Geoological Survey.

The country is in the midst of an energy bonanza which could slingshot it past the United States as the world's third largest oil producer, Reuters reported.

Much of the country's resources, however, are in ultra-deep regions of the ocean, and reside under a thick layer of salt, making drilling and producing the oil a greater technical challenge. Petrobras has previously said it intends to invest close to $200 billion in the next several years to develop the country's energy riches.