Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F. 

Form 20-F ___X___ Form 40-F _______

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

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Third well indicates Tupi potential

(Rio de Janeiro, June 4, 2009). – PETRÓLEO BRASILEIRO S/A - PETROBRAS, [Bovespa: PETR3/PETR4, NYSE: PBR/PBRA, Latibex: XPBR/XPBRA, BCBA: APBR/APBRA], a Brazilian international energy company, announces that the drilling of an additional well in the Tupi area has further confirmed estimates of a potential of 5 to 8 billion barrels of recoverable light oil and natural gas in the pre-salt layers of that field. Drilling is still underway seeking for other objectives at greater depths.

The third well, 4-BRSA-711-RJS (4-RJS-647), is located 33 km to the Northeast of Tupi first well, 1-RJS-628, and indicated similar oil type and quality reservoirs, supporting the original estimations for the area.

Informally known as Iracema, this well is located about 250 km off the coast of the state of Rio de Janeiro at a water depth of 2,210 meters, following the Tupi Evaluation Plan.

The discovery was proved from light oil samples (about 30º API) through cable testing in reservoirs located at a depth of about 5,000 meters and having been notified to the National Petroleum Agency (ANP) today.

Following the conclusion of the drilling, the Consortium composed by Petrobras (65% - Operator), BG Group (25%) and Galp (10%), jointly responsible for the exploration of the BM-S-11 Block, will continue activities and investments forecasted in the Evaluation Plan approved by ANP, which also considers the drilling of other wells in the area.

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This document may contain forecasts that merely reflect the expectations of the Company’s management. Such terms as “anticipate”, “believe”, “expect”, “forecast”, “intend”, “plan”, “project”, “seek”, “should”, along with similar or analogous expressions, are used to identify such forecasts. These predictions evidently involve risks and uncertainties, whether foreseen or not by the Company. Therefore, the future results of operations may differ from current expectations, and readers must not base their expectations exclusively on the information presented herein.

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This press release may contain forward-looking statements. These statements are statements that are not historical facts, and are based on management's current view and estimates offuture economic circumstances, industry conditions, company performance and financial results. The words "anticipates", "believes", "estimates", "expects", "plans" and similar expressions, as they relate to the company, are intended to identify forward-looking statements. Statements regarding the declaration or payment of dividends, the implementation of principal operating and financing strategies and capital expenditure plans, the direction of future operations and the factors or trends affecting financial condition, liquidity or results of operations are examples of forward-looking statements. Such statements reflect the current views of management and are subject to a number of risks and uncertainties. There is no guarantee that the expected events, trends or results will actually occur. The statements are based on many assumptions and factors, including general economic and market conditions, industry conditions, and operating factors. Any changes in such assumptions or factors could cause actual results to differ materially from current expectations.

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