Subsidiaries of HRT Participações em Petróleo SA and TNK- BP have signed a $1 billion, farm-in agreement relating to the transfer of a 45% interest in concession rights over 21 blocks located in the Solimões Basin in Brazil covering an area of approximately 48,500 sq km.

Once the Brazilian Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP) approves the assignment of the concession rights from Petra Energia S.A. to HRT O&G Exploração e Produção de Petróleo Ltda. (for which the call option was exercised on May 25, 2011), HRT O&G will affect the transfer and will receive $1 billion from TNK-Brasil Exploração e Produção de Óleo e Gás Natural Ltda. over a two-year period. HRT O&G will remain as operator of the blocks that are subject to the transfer.

HRT O&G will also have the right to additional payments by TNK-Brasil. Those payments would include; reimbursement of past costs and earn-out; and $ 0.73/bbl for every barrel above 500 million barrels of oil equivalent of total 2P reserves, which may reach up to $5 billion, for a 10-year period after approval of the transfer by ANP.

TNK Brasil will have an option (exercisable 30 months after approval by ANP) to acquire an additional 10% interest of HRT O&G´s concession rights in the Solimões blocks, which should be priced based on resources and reserves. Should the call not be exercised, HRT O&G will have the right to sell the same 10% to TNK-Brasil (“put”), on similar terms.

HRT O&G was advised by Vinson & Elkins LLP and Goldman Sachs.