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Wednesday, March 22, 2023
RIO DE JANEIRO, Nov 16 2007 (IPS) - The discovery of a huge oilfield 250 kilometres off the southeastern coast of Brazil will not have an immediate effect on world crude markets, but it opens up future prospects of a new oil frontier in the South Atlantic which may deter the pursuit of clean energy sources, experts say.
The Brazilian government and the state oil company Petrobras announced on Nov. 8 that between five and eight billion barrels of oil and gas had been found in a block in the off-shore Tupí field, in the Santos geological basin. These are in addition to proven national reserves of 13.8 billion barrels.
It is the largest reserve that has been located in the country, and the biggest deep sea oilfield in the world.
The most promising feature of the discovery is that it is part of a complex formed by the Santos, Campos and Espíritu Santo sea-floor basins on the continental margin of Brazil. Their combined area is 800 kilometres by 200 kilometres, and Brazil is already extracting most of its oil there.
It was known that there were much greater quantities of oil, beneath a salt layer.
“That whole area contains reserves of at least 50 billion barrels, as a conservative estimate,” said Marcio Mello, for 26 years a researcher at Petrobras’ technology centre, who is now a partner in the consulting firm HRT Petroleum and head of the Brazilian Association of Petroleum Geologists (ABGP).
Across the ocean, along the southwest African coasts of Angola, Congo and Namibia, there are similar amounts of oil. The Latin American and African coasts share a common geological formation which was split apart by the South Atlantic ocean, which separated the continents in prehistoric times, Mello, who has been studying the subject for 10 years, told IPS.
There is a correspondence between the oil reserves in the Brazilian Campos basin and those in Angola. Both contain about nine billion barrels of oil, and a similar pairing appears likely between Namibia and the Santos basin, the expert said.
But in Africa the salt layer, beneath which these additional deposits lie, has not yet been perforated. Petrobras drilled its first well in Tupí last year, and found signs of an oilfield. A still imprecise estimation of its size was arrived at after the second test well was drilled in July.
Petrobras struck oil 6,000 metres below the surface, after descending through 2,000 metres of water and perforating a salt layer as well as rocks and sand. This difficult exploratory drilling indicates that extraction will be expensive, even before considering the cost of transport from the high seas.
It was the high costs that delayed exploration, in spite of the longheld opinion among geologists that large reserves lay under the salt layer.
The Campos basin, near Rio de Janeiro, is currently the most productive oilfield because a great deal of crude has seeped through the salt layer, which is more permeable there than in the other basins, geologist Giuseppe Bacóccoli, who worked for Petrobras as an exploration scientist for 32 years, until 1997, told IPS.
Therefore there must be less oil left beneath the salt layer in the Campos basin, as opposed to the Santos and Espíritu Santo basins, said Bacóccoli who is now a researcher in the postgraduate engineering programme at the Federal University of Rio de Janeiro.
“The three basins are sisters, but have different characteristics,” he said.
Oil and gas are trapped by the rock formation under the salt layer, the Lagoa Feia formation, which is shared with Africa, Mello said.
Many people did not believe oil reserves could be extracted from under so many kilometres of sedimentary rock, because the temperature would be above 200 degrees Celsius “and the heat would destroy everything, oil and drilling gear alike. But salt is an excellent conductor and dissipates the heat, reducing temperatures to less than 100 degrees,” he said.
Confirmation of the Tupí reserves may also stimulate investment in the African basins, “which have hardly been explored because of political conditions there,” said Mello. He regretted that Petrobras did not accept Angola’s offer of the concession to all its deep water fields in 1990. Now oil companies from rich countries hold the concessions.
There are other promising marine areas in the south of the Gulf of Mexico and the waters off of Venezuela, but all these new frontiers will not have much effect on the world crude market, in Mello’s view. The present high prices of crude are due to the time-lag between finding oil and beginning to extract it, he said.
In Tupí, for example, it will take around eight years to reach full production, and the whole of its reserves would only meet world consumption needs for three months. Finding other oilfields in the basin will demand huge investment, time, and many exploratory wells dispersed throughout an area four times the size of Switzerland.
For all these reasons, as well as increasing domestic demand for oil-based fuels, Brazil will not become a leading exporter of oil, Mello said.
Bacóccoli fears a reduction of investments from abroad, because of a move towards nationalisation spurred by the discovery of the Tupí reserves. The government cancelled a public tender for concessions for new blocks in the Santos basin, saying that it had to review contract conditions in light of the changed situation.
Meanwhile, environmentalists point to a new challenge, because the sudden increase in oil reserves tends to detract from support for clean, renewable energy sources, said Délcio Rodrigues, an energy expert with the non-governmental organisation Vitae Civilis which is active on climate change issues.
Most scientists attribute climate change largely to the burning of fossil fuels, such as oil, coal and gas.
It is too soon to assess the effects of the new Atlantic oil frontier on international negotiations to mitigate and counteract climate change, but in Brazil “there is concern, because perspectives have changed,” Rodrigues told IPS.
This country developed fuel alcohol derived from plants and other non-fossil energy sources in response to the oil crisis in the 1970s, because it lacked oil reserves and due to the high international price of crude, he pointed out.
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