Western Hemisphere's largest find in three decades.

Exxon Mobil Corp.’s oil discovery off the coast of Brazil may hold enough crude to rival the nearby Tupi prospect as the Western Hemisphere’s largest find in three decades.

Exxon Mobil’s Azulao-1 well in an offshore region designated BM-S-22 tapped a reservoir that could contain 8 billion barrels of recoverable oil, A floating drilling rig began boring a second well, called Guarani, into the reservoir in BM-S-22 earlier this week.

“We have no idea how big it is,” McGinn said “We’re nowhere near that yet.

Petrobras triggered a flood of interest in Brazil’s offshore crude deposits with the November 2007 announcement that Tupi may hold the equivalent of 8 billion barrels of recoverable oil. That would make it the largest find in the Americas since Mexico’s Cantarell field was discovered in 1976.

Domestic oil production is expected to increase this year over last, for the first time since 1991. That swing is attributable in part to increased production in the Gulf of Mexico from two giant new platforms that were years in the making. Domestic natural gas output rose by almost 8 percent last year from 2007, the biggest annual jump in more than a generation.