When I first wrote about Brazilian emerging market giant Petroleo Brasileiro (NYSE: PBR) a year and a half ago, I was bullish on the company for three reasons: Petrobras was far and away the dominant player in Brazil's booming energy market, it boasted the second-largest amount of proven reserves in Latin America, and it traded at an attractive valuation.

Since then, shares of the Brazilian energy giant have soared 144% compared to the not-too-shabby 30% gain posted by PetroChina (NYSE: PTR), the 20% gain at ExxonMobil (NYSE: XOM), and the light-years-ahead 3% advance at Total (NYSE: TOT). While I'd like to think the factors I mentioned above contributed to the stellar run, the real reason was the company's huge oil discovery back in November in the deepwater Santos Basin.

Dubbed the Tupi field, this find was initially estimated to contain between 5 billion to 8 billion barrels of oil and equivalents (BOE). Just last week, however, Petrobras' partner in the field, U.K.-based BG Group (OTC: BRGYY), upped its estimate of the field to between 12 billion and 30 billion barrels. To put the magnitude of this find in perspective, as of the end of 2006, Petrobras had total proven reserves of roughly 12 billion barrels.

Pretty impressive stuff, eh?

Well, as they say, "that's not all, folks." The Tupi field is located in an area that seems likely to yield further riches. Indeed, the whole area is expected to hold close to 60 billion barrels, a fact that was obviously uppermost in the Brazilian government's mind when it pulled from auction 41 oil exploration blocks that abutted the field. Last but not least, let's not forget that the oil discovered at Tupi is light, sweet crude, which is much less expensive to refine than heavy oil.

In simple terms, Petrobras' find will enable Brazil to join the ranks of the world's major oil exporters. Indeed, Brazilian President Luiz de Silva has suggested that Brazil would join OPEC when the Tupi field starts production oil in 2011.

I don't know about you folks, but I'd sure like to be along for this ride. If you're looking for a long-term emerging-market giant that's moving up in the ranks of the oil industry, Petrobras should make a great oil play in your portfolio.

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Fool contributor Will Frankenhoff does not own shares in any of the companies mentioned above. Total and Petrobras are Income Investor selections. The Fool has a disclosure policy.