ANP contracted the certifier Gaffney, Cline & Associates to estimate the recoverable volumes under the Onerous Assignment Agreement. It is an activity of high complexity. All analyzes are performed in an environment of uncertainties, where information is limited. Reservoir data, which determine engineering designs, are restricted to a small number of samples, if any. As a result, statistical parameters are used which, although calculated with the best technique available, are subject to wide variations. One of the consequences of using these parameters is the great difficulty in specifying a point value for the volumes of oil and gas contained in the reservoirs. As a result, the disclosure of an interval at which volumes are likely to occur is consecrated.

When preparing volumetric estimates for each area evaluated, Gaffney, Cline & Associates used techniques that resulted in a range of volumes comprised between the P90 volume (ninety percent chance of occurrence of equal volume or greater), volume P50 fifty percent chance of occurrence of equal or greater volume) and volume P10 (ten percent chance of occurrence of equal or greater volume). Although the odds are low, the final volume of reserves may fall outside this range.

Under these criteria, the statistically established volumes for the excess of the Onerous Assignment are:

P50: 10,836 million barrels of oil equivalent,

P90: 6.068 million barrels of oil equivalent,

P10: 15,062 million barrels of oil equivalent.

To reach the total volumes must be added the 5 billion barrels of oil equivalent already negotiated with Petrobras under the Agreement on Assignment Onerous.