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New discovery reinforces potential of pre-salt in the Campos Basin and expands Petrobras’ strategy in mature areas with high-quality oil identified in Marlim South.
Petrobras announced on March 26, 2026 the identification of “excellent quality” oil in an exploratory well drilled in the Marlim South field, in the pre-salt of the Campos Basin, off the coast of Rio de Janeiro.
According to the company, well 3-BRSA-1397-RJS is located 113 kilometers from the coast of Campos dos Goytacazes, in a water depth of 1,178 meters, and opens a new phase of evaluation of the area’s potential.
Discovery in the pre-salt in Marlim South
According to the state-owned company, the presence of oil was confirmed through electrical profiles, indications of gas, and fluid sampling.
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Subsequently, the collected material will undergo laboratory analyses, a procedure that should allow for a more precise characterization of the reservoirs and the fluids found before the next steps of the exploratory campaign.
In the official statement, Petrobras reported that “the oil-bearing interval was confirmed through electrical profiles, indications of gas, and fluid sampling.”
The company added that the samples “will subsequently be sent for laboratory analyses, which will allow for the characterization of the conditions of the reservoirs and fluids found, enabling the continuation of the evaluation of the area’s potential.”
The drilling, according to the company, was completed safely and with respect for the environment and people.
Petrobras also confirmed that it acts as the sole operator of the Marlim South field, with 100% participation in the asset.
Importance of the Campos Basin in Brazilian production
The new discovery puts Marlim South back at the center of the company’s exploratory strategy in a basin that has had significant weight in the country’s oil and gas industry for decades.
The Campos Basin, located between the coasts of Rio de Janeiro and Espírito Santo, has historically established itself as one of the most important areas of Brazilian production and continues to be treated by the state-owned company as a key front for the recomposition of reserves in mature areas.
This movement occurs amid Petrobras’ attempt to expand geological knowledge of already known assets while simultaneously identifying new accumulations with commercial potential.
In the case of Marlim South, the company has not yet disclosed estimates of recoverable volume, nor detailed a timeline for any potential development of the discovery.
So far, the official information is limited to confirming the presence of oil and the start of the technical analysis phase of the collected material.
Recent history of discoveries in the region
The most recent discovery reinforces a sequence of announcements from the state-owned company in the same oil province.
On November 17, 2025, Petrobras reported finding excellent quality oil in the post-salt layer of the Southwest Tartaruga Verde block, also in the Campos Basin.
At that time, well 4-BRSA-1403D-RJS was described as located 108 kilometers from the coast of Campos dos Goytacazes, in a water depth of 734 meters.
The comparison between the two announcements helps to gauge the geological diversity of the region.
While the previous discovery occurred in the post-salt, at a shallower depth, the new find is in the pre-salt, below the thick layer of salt that characterizes a significant part of Brazil’s most productive reserves.
In practice, this means that Petrobras is once again recording positive results in two distinct environments within the same basin, as it increases technical interest in the remaining potential of the area.
This interpretation arises from the location and the official description of the two discoveries, without the company having disclosed, for now, a direct comparison between the projects.
Marlim South field and reserve strategy
Marlim South, in turn, is not a new field in the company’s portfolio.
Petrobras itself reports that the original discovery of the area occurred in November 1987, through well 4-RJS-382.
This historical data helps explain why the state-owned company associates its current operations in the Campos Basin with the recomposition of reserves in mature fields, a strategy that combines already known infrastructure with new geological evaluation campaigns.
Although the announcement has resonated in the market and in international media, the current phase is essentially technical.
The laboratory results of the samples should indicate more precisely the characteristics of the oil and the reservoir, in addition to guiding the decision on the continuity of the studies.
Until this stage is completed, Petrobras has not informed whether the identified accumulation will be incorporated into a development project nor what the potential impact of the discovery on the company’s future production in the Campos Basin may be.
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