RIO DE JANEIRO (Dow Jones) -- Brazil's oil industry regulator ANP said tests on samples collected from an oil spill at Roncador field in Brazil's Campos Basin indicate the oil didn't originate in any Campos oil reservoir.
Results of the tests indicate the fluid collected is drilling oil or another type of oil commonly used in well operations, ANP said in a statement Wednesday. The regulator said it continues to analyze the incident and the oil's origin.
ANP had said Monday that oil was discovered seeping from cracks near the Roncador field, about 120 kilometers off the coast of Rio de Janeiro state. The Campos Basin produces more than 90% of Brazil's crude oil.
The seep was near the border between Roncador and the Frade field operated by U.S. oil major Chevron Corp. (CVX). In November, a drilling accident caused an estimated 2,400 to 3,000 barrels of oil to spill into the Atlantic Ocean from similar seeps at Frade, where production was halted.
Brazilian state-energy company Petroleo Brasileiro SA (PBR, PETR4.BR), or Petrobras, said earlier Wednesday that the oil seep discovered is not related to the company's nearby Roncador field.
"The drops collected have characteristics similar to a type of fluid used during well-drilling operations," Petrobras said in a statement. Petrobras said that no recent drilling operations had been conducted near the area, nor had the company registered any oil slicks on the ocean's surface.
Petrobras also said that evaluation of the Roncador wells showed cement casings to be sound. "The origin of this fluid is being analyzed by the company's technical team," Petrobras said.
-By Diana Kinch, Dow Jones Newswires, Tel: 55 21 2586 6086, firstname.lastname@example.org
--Jeff Fick contributed to this article