Petrobras (PBR)

STANDBY PURCHASE AGREEMENT

Dated as of November 1, 2007

Between

PETRÓLEO BRASILEIRO S.A.–PETROBRAS,

as Standby Purchaser,

and

THE BANK OF NEW YORK, as

Trustee for the Noteholders

Referred to Herein

1

(k)          

STANDBY PURCHASE AGREEMENT

Dated as of November 1, 2007

Between

PETRÓLEO BRASILEIRO S.A.—PETROBRAS,

as Standby Purchaser,

and

THE BANK OF NEW YORK, as

Trustee for the Noteholders

Referred to Herein

(k)          

For the purposes of giving this opinion, we have examined and relied upon the originals, copies or certified translations of the documents listed in Schedule 1.

In giving this opinion we have relied upon the assumptions set out in Schedule 2, which we have not independently verified.

We are Attorneys at Law in the Cayman Islands and express no opinion as to any laws other than the laws of the Cayman Islands in force and as interpreted at the date of this opinion. We have not, for the purposes of this opinion, made any investigation of the laws, rules or regulations of any other jurisdiction. Except as explicitly stated herein, we express no opinion in relation to any representation or warranty contained in the Documents nor upon the

31 October 2007

commercial terms of the transactions contemplated by the Documents.

Based upon the foregoing examinations and assumptions and upon such searches as we have conducted and having regard to legal considerations which we deem relevant, and subject to the qualifications set out in Schedule 3, and under the laws of the Cayman Islands, we give the following opinions in relation to the matters set out below.

This opinion is limited to the matters referred to herein and shall not be construed as extending to any other matter or document not referred to herein. This opinion is given solely for your benefit and the benefit of your legal advisers acting in that capacity in relation to this transaction and may not be relied upon by any other person without our prior written consent.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to this firm in the prospectus constituting a part of the Registration Statement, and in the prospectus supplement related to the offering of the Notes, under the heading “Legal Matters” as counsel for the Company who have passed on the validity of the

31 October 2007

Securities being registered by the Registration Statement. In giving such consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission thereunder.

This opinion shall be construed in accordance with the laws of the Cayman Islands.

Yours faithfully

STANDBY PURCHASE AGREEMENT

Dated as of October 6, 2006

Between

PETRÓLEO BRASILEIRO S.A.—PETROBRAS,

as Standby Purchaser,

and

THE BANK OF NEW YORK, as

Trustee for the Noteholders

Referred to Herein

 i

(j)           

For the purposes of giving this opinion, we have examined and relied upon the originals, copies or certified translations of the documents listed in Schedule 1.

In giving this opinion we have relied upon the assumptions set out in Schedule 2, which we have not independently verified.

We are Attorneys at Law in the Cayman Islands and express no opinion as to any laws other than the laws of the Cayman Islands in force and as interpreted at the date of this opinion. We have not, for the purposes of this opinion, made any investigation of the laws, rules or regulations of any other jurisdiction. Except as explicitly stated herein, we express no opinion in relation to any representation or warranty contained in the Documents nor upon the

3 October 2006

commercial terms of the transactions contemplated by the Documents.

Based upon the foregoing examinations and assumptions and upon such searches as we have conducted and having regard to legal considerations which we deem relevant, and subject to the qualifications set out in Schedule 3, and under the laws of the Cayman Islands, we give the following opinions in relation to the matters set out below.

This opinion is limited to the matters referred to herein and shall not be construed as extending to any other matter or document not referred to herein. This opinion is given solely for your benefit and the benefit of your legal advisers acting in that capacity in relation to this transaction and may not be relied upon by any other person without our prior written consent.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to this firm in the prospectus constituting a part of the Registration Statement, and in the prospectus supplement related to the offering of the Notes, under the heading “Legal Matters” as counsel for the Company who have passed on the validity of the

3 October 2006

Securities being registered by the Registration Statement. In giving such consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission thereunder.

This opinion shall be construed in accordance with the laws of the Cayman Islands.

Yours faithfully

Standby Purchase Agreement

On this 15th day of September, 2004, before me personally came Joseph Vieira to me known, who, being by me duly sworn, did depose and say that he is the Assistant Financial Manager – New York Office of Petróleo Brasileiro S.A. – Petrobras, a corporation described in and which executed the foregoing instrument and acknowledges said instrument to be the free act and deed of said entity.

On this 15th day of September, 2004, before me personally came Michael Fruchter and Gavin Lee Parrish to me personally known, who being by me sworn, did depose and say that they signed their names to the foregoing instrument as witnesses.

[Notarial Seal]

On this 15th day of September, 2004, before me personally came Susy P. Pestana to me known, who, being by me duly sworn, did depose and say that she is the Assistant Vice President of JPMorgan Chase Bank described in and which executed the foregoing instrument and acknowledges said instrument to be the free act and deed of said entity.

On this 15th day of September, 2004, before me personally came Michael Fruchter and Gavin Lee Parrish to me personally known, who being by me sworn, did depose and say that they signed their names to the foregoing instrument as witnesses.

[Notarial Seal]

EXHIBIT A

FORM OF PARTIAL NON-PAYMENT NOTICE

Standby Purchase Agreement

PIFCo’s Global Notes have the benefit of credit support from us in the form of a standby purchase agreement under which we are obligated to make certain payments to the trustee in the event PIFCo fails to make required payments of principal, interest and other amounts due under the senior Global Notes and the indenture. Subject to certain limitations, we are required to purchase from the holders of the notes and pay to the trustee amounts in respect of the noteholders’ right to receive:

Obligations under the standby purchase agreement constitute direct and general senior unsecured and unsubordinated obligations of ours and rank pari passu with other senior, unsecured obligations of ours that are not, by their terms, expressly subordinated in right of payment to our obligations under the standby purchase agreement.

The Global Notes did not include a letter of credit or political risk insurance.