A second exploration oil well at Brazil's Libra field will be drilled this month, the managing director for Total SA in Brazil told Reuters on Monday.

Drilling on the first well began in August.

"We need to drill more wells to confirm the actual nature and size of the field," Denis Besset, managing director of Total Brazil, told Reuters on the sidelines of a conference in Rio de Janeiro.

The Libra consortium is led by state-run oil firm Petroleo Brasileiro SA, or Petrobras, with a 40 percent stake. Total and Royal Dutch Shell Plc both have 20 percent while China's National Petroleum Corp and CNOOC have 10 percent each.

Brazil oil agency ANP has said Libra is the biggest oil reserve discovered in the South American country, holding an estimated 8 billion to 12 billion barrels of crude oil.

(Reporting by Jeb Blount and Marta Nogueira; Writing by Stephen Eisenhammer; Editing by Tom Brown)