Petrobras Strikes Oil Beneath a Field Discovered in 1987

A Petrobras pre-salt discovery in the Campos Basin has added to the evidence that Brazil’s oldest offshore oil province still holds significant untapped reserves beneath its original producing layers. The Rio Times, the Latin American financial news outlet, reports that the state oil company confirmed “excellent quality” crude in an exploratory well at the Marlim Sul field — a find that comes as elevated global oil prices make deepwater exploration more economically attractive than at any point in the past decade.

The well, designated 3-BRSA-1397-RJS, sits 113 kilometers off the coast of Campos dos Goytacazes in Rio de Janeiro state at a water depth of 1,178 meters. Oil was confirmed through electrical profiles, gas indicators, and fluid sampling, with laboratory analysis now underway to characterize the reservoir and estimate commercial potential.

Why This Petrobras Pre-Salt Find Matters

Marlim Sul was originally discovered in 1987, making it one of the legacy fields that built Brazil’s offshore industry. Petrobras operates it with 100 percent ownership. The new discovery sits in the pre-salt layer — geological formations beneath thick salt deposits containing some of the world’s highest-quality light crude — beneath a field that has been producing from shallower reservoirs for decades.

This is the second significant Campos Basin find in five months. In November 2025, Petrobras announced a high-quality oil discovery at the Tartaruga Verde block, just 108 kilometers from the same coastline. Together, the discoveries suggest the basin — once thought to be in terminal decline — has a second productive life in its deeper pre-salt formations.

Campos Basin in Context

The Campos Basin currently accounts for roughly 7 percent of Brazil’s pre-salt production, a modest share compared to the Santos Basin’s dominant 78 percent. But Campos was the foundation of Brazil’s offshore oil industry and still hosts major fields including Marlim, Marlim Leste, and Roncador. Renewing reserves in these mature areas is central to Petrobras’ strategy of sustaining output without relying solely on new frontier blocks.

The timing strengthens Brazil’s position as a net oil exporter during the Iran conflict, with Brent above $100 and the Strait of Hormuz disrupting roughly 20 percent of global oil transit. Petrobras set production records in 2025, and Goldman Sachs recently named Brazil its top emerging market pick partly because of the country’s energy-exporter advantage.

Petrobras said drilling was completed safely and in compliance with environmental regulations. Samples will undergo laboratory analysis to determine whether the discovery justifies commercial development — a process that typically takes several months before any investment decision is made.