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Brazil's state oil company Petrobras is buying deeper into the Gulf of Guinea, acquiring a 75% operating stake in Block 3 offshore São Tomé and Príncipe from Nigerian billionaire Arthur Eze's Oranto Petroleum in its latest African expansion move.
The agreement, announced on April 17, will see Petrobras assume operatorship of the block from Oranto, which currently holds a 90% working interest and serves as operator. The National Petroleum Agency of São Tomé and Príncipe (ANP-STP) holds the remaining 10%. Upon completion, the consortium will consist of Petrobras as operator with 75%, Oranto retaining 15%, and ANP-STP at 10%. The transaction is subject to governmental and regulatory approvals in São Tomé and Príncipe.
Petrobras described the deal as a portfolio diversification move aligned squarely with its 2026-2030 Business Plan. "This transaction strengthens exploratory activities on the African continent, with the purpose of portfolio diversification, and is aligned with the company's long-term strategy, aiming to replenish oil and gas reserves through exploration of new frontiers and partnership operations," the company said in a statement.
Petrobras is building fast in Africa
The Block 3 transaction is the latest in a rapid sequence of African acquisitions for Petrobras since the company resumed continental operations in 2024 after years of withdrawal. The Brazilian state giant had retreated from its overseas portfolio in the early 2010s under the weight of debt and the fallout from the Lava Jato corruption investigation, which implicated dozens of company executives and contractors. Its return to Africa has been methodical and accelerating.
In February 2024, Petrobras completed the acquisition of interests in 3 blocks in São Tomé and Príncipe from Shell — a 45% stake each in Blocks 10 and 13, and a 25% stake in Block 11. In September 2025, it added a 27.5% stake in Block 4 in the same archipelago, joining a consortium led by Shell with Galp also participating. In October 2024, the company's board approved a 10% stake in the Deep Western Orange Basin block in South Africa, through a competitive process led by TotalEnergies. In February 2026, Petrobras acquired a 42.5% stake in a Namibian offshore block, deepening its presence on the continent's Atlantic margin.
Block 3 is therefore at least the 6th African block in which Petrobras holds or is acquiring an interest since 2024, with São Tomé and Príncipe now hosting the company's largest concentration of African exposure.
The geological rationale is consistent across all these moves. Petrobras executives have repeatedly noted that the deepwater basins along Africa's west coast share structural characteristics with Brazil's pre-salt formations — the massive deepwater deposits that transformed Brazil into a significant global oil producer over the past two decades. Sylvia dos Anjos, Petrobras' head of exploration and production, has said the company sees the west coast of Africa as a region of "good opportunities" with geological characteristics "largely analogous to our sedimentary basins."
Petrobras' international exploration allocation stands at approximately $1.3 billion over 5 years as part of its current strategic plan. Its total proved reserves reached 11.4 billion barrels of oil equivalent in 2024, with production at 3 million boepd at the end of 2025. Those figures are expected to come under pressure after 2030 as existing fields mature, making reserve replenishment through new frontier exploration a strategic priority.
The counterparty: Arthur Eze and Oranto
The interest Petrobras is acquiring comes from Oranto Petroleum, a company founded by Prince Arthur Eze, the Nigerian billionaire and one of Africa's most prolific private oil concession holders.
Eze founded Atlas Petroleum International and Oranto Petroleum in the early 1990s, building what has become the Atlas Oranto Group — now operating across 22 African countries and marketed as the continent's largest indigenous exploration group by acreage. The group holds licences across Equatorial Guinea, Senegal, South Sudan, Uganda, Zambia, Liberia and São Tomé and Príncipe, among others, and in August 2024 extended its reach to Venezuela with a prospecting agreement signed in the presence of President Nicolás Maduro.
Oranto has held interests in São Tomé and Príncipe for years, with Block 3 among its established positions in the archipelago. By farming down to 15% and ceding operatorship to Petrobras, Eze's company is following the standard independent explorer playbook: acquire acreage early, retain a carried or promoted interest, and bring in a larger operator with the technical capacity and capital to drive the programme to the drill bit.
The sale mirrors a pattern Eze has previously executed in other markets. In Liberia, he secured 4 blocks in September 2025 valued at approximately $800 million in planned investment, and earlier acquired and sold Liberian blocks to Chevron for a reported $250 million profit. He has built his empire through a combination of early entry, political access and the ability to attract major partners — and the Petrobras deal is a further validation of that model in São Tomé and Príncipe specifically.
For Petrobras, inheriting operatorship of Block 3 from a well-connected indigenous operator and bringing it under a technically sophisticated programme consistent with its broader west coast strategy is precisely the kind of transaction its Business Plan is designed to execute.
