Exhibit 99.1
 DeGolyer and MacNaughton  5001 Spring Valley Road  Suite 800 East  Dallas, Texas 75244




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Methodology and Procedures
      Definition of Reserves
  2




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Proved oil and gas reserves 
         3




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Developed oil and gas reserves
   Undeveloped reserves 
    4




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Primary Economic Assumptions
  Oil and Condensate Prices
  Natural Gas Prices
  Operating Expenses and Capital Costs
   5




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Estimated by PetrobrasNet Proved Reserves as ofDecember 31, 2009Oil and
    
    Natural
    
    OilProperties reviewed by
    
    Condensate
    
    Gas
    
    EquivalentDeGolyer and MacNaughton
    
    (MMbbl)
    
    (Bcf)
    
    (MMboe)BrazilProved Developed
    
    
    5,940.4
    
    
    
    4,808.0
    
    
    
    6,741.7Proved Undeveloped
    
    
    3,693.2
    
    
    
    4,371.9
    
    
    
    4,421.9Total Proved
    
    
    9,633.6
    
    
    
    9,179.9
    
    
    
    11,163.6
  . Extractive Industries  Oil and Gas (Topic 932): Oil and Gas Reserve
Estimation and Disclosures
  6




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Submitted,/s/ DeGOLYER and MacNAUGHTONDeGOLYER and MacNAUGHTONTexas Registered Engineering Firm F-716(SEAL)
    /s/ R. M. Shuck, P.E.R. M. Shuck, P.E.Senior Vice President
DeGolyer and MacNaughton 7




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CERTIFICATE of QUALIFICATION
  1.
    
    That I am a Senior Vice President with DeGolyer and MacNaughton, which company did
prepare the report addressed to Petrobras dated February 17, 2010, and that I, as Senior
Vice President, was responsible for the preparation of this report.2.
    
    That I attended University of Houston, and that I graduated with a Bachelor of Science
degree in Chemical Engineering in the year 1977; that I am a Registered Professional
Engineer in the State of Texas; that I am a member of the International Society of
Petroleum Engineers; and that I have in excess of 32 years of experience in the oil and gas
reservoir studies and reserves evaluations.
 (SEAL)
    /s/ R. M. Shuck, P.E.R. M. Shuck, P.E.Senior Vice President
DeGolyer and MacNaughton




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DeGolyer and MacNaughton




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Methodology and Procedures
      Definition of Reserves
  2




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Proved oil and gas reserves Proved oil and gas reserves are those quantities of oil and
gas, which, by analysis of geoscience and engineering data, can be estimated with reasonable
certainty to be economically produciblefrom a given date forward, from known reservoirs,
and under existing economic conditions, operating methods, and government regulationsprior
to the time at which contracts providing the right to operate expire, unless evidence
indicates that renewal is reasonably certain, regardless of whether deterministic or
probabilistic methods are used for the estimation. The project to extract the hydrocarbons
must have commenced or the operator must be reasonably certain that it will commence the
project within a reasonable time.
          3




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Developed oil and gas reserves Developed oil and gas reserves are reserves of any
category that can be expected to be recovered:
   Undeveloped reserves Undeveloped oil and gas reserves are reserves of any category that
are expected to be recovered from new wells on undrilled acreage, or from existing wells
where a relatively major expenditure is required for recompletion.
    Primary Economic Assumptions
  Oil and Condensate Prices
  4




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Natural Gas Prices
  Operating Expenses and Capital Costs
    5




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Net Proved Reservesas ofDecember 31, 2009Oil and
    
    Natural
    
    OilCondensate
    
    Gas
    
    Equivalent(MMbbl)
    
    (MMcf)
    
    (MMboe)North AmericaProved Developed
    
    
    3.890
    
    
    
    28,599
    
    
    
    8.656Proved Undeveloped
    
    
    3.404
    
    
    
    16,575
    
    
    
    6.167Total Proved
    
    
    7.294
    
    
    
    45,174
    
    
    
    14.823South America (outside of Brazil)Proved Developed
    
    
    97.758
    
    
    
    487,746
    
    
    
    179.049Proved Undeveloped
    
    
    61.867
    
    
    
    452,216
    
    
    
    137.236Total Proved
    
    
    159.625
    
    
    
    939,962
    
    
    
    316.285Total Proved
    
    
    166.919
    
    
    
    985,136
    
    
    
    331.108
  1.
    
    Gas is converted to oil equivalent using a factor of 6,000 cubic feet of gas per 1
barrel of oil equivalent.2.
    
    Reserves estimated in Argentina include only PESAs interest. Extractive Industries  Oil and Gas (Topic 932): Oil and Gas Reserve Estimation
and Disclosures
 6




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Submitted,/s/ DeGOLYER and MacNAUGHTONDeGOLYER and MacNAUGHTONTexas Registered Engineering Firm F-716(STAMP)
    /s/ R. M. Shuck, P.E.

R. M. Shuck, P.E. 
Senior Vice President 
DeGolyer and MacNaughton 7




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CERTIFICATE of QUALIFICATION
  1.
    
    That I am a Senior Vice President with DeGolyer and MacNaughton, which company
did prepare the reports addressed to Petrobras dated January 11, 2010, January 15,
2010, and February 17, 2010, and that I, as Senior Vice President, was responsible for
the preparation of this report.2.
    
    That I attended University of Houston, and that I graduated with a Bachelor of
Science degree in Chemical Engineering in the year 1977; that I am a Registered
Professional Engineer in the State of Texas; that I am a member of the International
Society of Petroleum Engineers; and that I have in excess of 32 years of experience in
the oil and gas reservoir studies and reserves evaluations.
 (STAMP)
    
    /s/ R. M. Shuck, P.E.

R. M. Shuck, P.E. 
Senior Vice President 
DeGolyer and MacNaughton