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Vol. 232 No. 4 |
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| DAYSE ABRANTES, CONTRIBUTING EDITOR, LATIN AMERICA |
Guilherme Estrella
A presalt pioneer
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Image by Stéferson Faria courtesy of Petrobras
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If there is such a thing as a legendary geologist, Petrobras E&P director Guilherme Estrella makes the cut, having participated in the discovery of huge amounts of oil worldwide, specially in Brazil.
“I would put him alongside the great petroleum geologists of the last century,” Gerard Demaison, a former Chevron geologist and president of Capitola, California-based Petroscience, told World Oil. “Few people have been involved in the discovery of more oil than Guilherme Estrella. This guy’s work was prophetic and essential for finding the oil Brazil has today.”
Estrella earned a BS degree in geology from the Federal University of Rio de Janeiro in 1964, and joined Petrobras the next year. In the mid-1970s, as an exploration manager of the Iraqi branch of Braspetro, then international subsidiary of Petrobras (1976–1978), Estrella was on the team that discovered the giant Majnoon field, with 11 billion bbl of reserves. After that he moved up through the company, heading a diverse array of teams: Brazilian east coast interpretation (1978–1981), organic geochemistry (1981), exploration (1981–1985), exploration and production R&D (1985–1989) and the Cenpes R&D center (1989–93). He was called out of retirement by then-Brazilian President Luiz Inácio Lula da Silva in February 2003 to take his current position in Brazil’s largest integrated energy company.
In the mid-1980s, when plate tectonic theory suggested that the geology of the east coast of South America was similar to that of Africa’s west coast, Estrella applied the new geological tools of biomarkers and geochemical profiling to unravel the elusive petroleum geology of the offshore Espírito Santo basin. This work, Demaison said, played an important role in demonstrating that oil of both marine and non-marine origin existed even in very deep reservoirs under the sea—and laid the foundation for Brazil’s most promising petroleum resource.
“That revealed the existence of lacustrine source rocks offshore the Brazilian and the African coast, thus starting to unveil the presalt,” Demaison said. “But it was a very bold move on Estrella’s part to demonstrate a conclusion which was contrary to accepted beliefs by the oil industry at the time.
“Well source-rock geochemical profiling had demonstrated lack of hydrocarbon source rocks in the widespread open marine Cretaceous section above the salt layer. Estrella’s genius was to perceive that, for geologic and paleo-oceanographic reasons, this situation would probably repeat itself all along Brazil’s Atlantic margin.”
Estrella has taken a lead role in presalt E&P from its inception in Cenpes’ successful Procap deepwater R&D program, created in 1986, to the current Prosal program, charged with finding technical solutions to the challenges of E&P beneath thousands of meters each of water, sediment and salt.
“Petrobras first identified the deepwater presalt carbonate reservoirs during the exploration process used for the Campos basin, where the physical expression of traditional electrical logs did not characterize these rocks as potential good reservoir for petroleum,” Estrella said. “However, in conjunction with new geological models, a set of specific electric logs were applied during the exploration of the Aptian presalt section of a very new frontier in the deepwater region of the Santos basin. These technical procedures led to the discoveries of the Lula and Cernambi oil fields by characterizing these carbonate rocks as excellent oil reservoir.”
There are no technological barriers remaining in the way of presalt exploration, says Estrella: “Of the 15 wells we drilled from 2007 to 2009 in the presalt, each one of them struck oil or gas. In fact, we have been drilling in the presalt area since we started drilling in the Campos basin. All of the presalt blocks achieved exploratory success, something that confirms the region’s high prospectivity.”
For Estrella, Brazil’s march to greater depths in E&P is “our space program.” He expects that Brazil’s presalt bonanza will lead to a virtuous cycle in Brazilian industry, which he calls “open development, where knowledge, competence and experiences will be shared, becoming an immense team effort dedicated to technology development goals.” This would set the pace for exploration worldwide, as experts forecast deepwater oil to play a key role in meeting future energy demand. 
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