Brazil's Subsalt Polygon, the offshore area that has already yielded some of the world's largest recent oil finds, may hold enough undiscovered petroleum and gas to supply the world's current oil needs for more than five years, researchers said.
The Polygon, which covers most of Brazil's Santos and Campos offshore sedimentary basins, contains at least 176 billion barrels of undiscovered, recoverable resources of oil and natural gas (barrels of oil equivalent), according to study released last week by Cleveland Jones and Hernane Chaves of the National Institute of Oil and Gas (INOG) at Rio de Janeiro-State University.
That is more than four times the 30 billion to 40 billion boe already discovered in the area.
This is a conservative estimate with a high probability of coming true, 90% in fact, Jones said. In theory, total undiscovered, recoverable resources in the Subsalt Polygon could be as high as 273 billion barrels, but the higher number only has a statistical certainty level of 10%.
Subsalt refers to oil trapped far beneath the Earth's surface or seabed by a layer of mineral salts. The Polygon is a Brazilian legal district that covers an offshore area near Rio de Janeiro and Sao Paulo where Brazil already extracts about 85% of its oil and gas.
The INOG's estimate is the only major public assessment of the Subsalt Polygon's potential. The 2015 estimate is 54% bigger than the INOG's 2010 estimate of 114 to 288 billion boe. That survey put the probability of the lower estimate at 90% and the higher outlook at 10%.
Unlike other democratic, oil-producing countries such as the United States, Canada, Britain and Norway, Brazil's government and petroleum regulator ANP does not publish estimates of potential Brazilian offshore resources.
Brazil has been remiss in not making such numbers public, said John Forman, a former director of Brazil's oil regulator ANP. He added that the INOC estimate is the only reliable public estimate available and that it uses industry-accepted methods.
Taken individually, the average size of undiscovered fields within the Subsalt Polygon is 246 million boe, according to the 2015 study's most conservative estimate.
Recoverable resources are exploitable using current technology, but may not be viable depending on the price of oil, the cost of equipment and the financial health of the companies that own the rights to produce them. Resources can only become reserves if they economically exploitable.