The U.S. Geological Survey reassessed undiscovered, technically recoverable conventional oil and gas in 31 priority geologic provinces of South America and the Caribbean, updating its 2012 assessment.
The 31 geologic provinces assessed. USGS.
The bottom line
| Resource | Mean estimate | Range (F95–F5) |
|---|---|---|
| Oil | 37,584 million barrels (37.6 billion) | 10,160–88,819 million barrels |
| Gas | 281,610 billion cubic feet (281.6 trillion) | 77,604–656,338 billion cubic feet |
| Natural gas liquids | 7,014 million barrels (7.0 billion) | 1,857–16,795 million barrels |
F95 means a 95-percent chance of at least that amount; F5, a 5-percent chance. All results are fully risked.
The largest provinces (means)
| Province | Oil (million barrels) | Gas (billion cubic feet) |
|---|---|---|
| Guyana-Suriname Basin | 7,912 | 19,480 |
| Campos Basin | 5,390 | 14,175 |
| Greater Antilles Deformed Belt | 4,098 | 13,268 |
| Santos Basin | 3,964 | 25,093 |
| Pelotas Basin | 3,052 | 10,380 |
| East Venezuela Basin | 2,691 | 30,130 |
| Foz do Amazonas Basin | 1,914 | 33,496 |
| Lower Magdalena Basin | 956 | 29,772 |
How the basins formed
The provinces are grouped by tectonic setting, which shapes their source rocks and when oil and gas formed.
| Setting | Provinces | Petroleum story |
|---|---|---|
| Interior rift-sag basins | Solimões, Amazonas, Parnaíba, Paraná | Devonian marine source rocks (plus oil shale in the Paraná), matured not by burial but by the heat of Permian–Early Cretaceous volcanic sills and dikes — so maturity and oil and gas are unevenly spread |
| Atlantic passive margins | Guyana-Suriname, Foz do Amazonas, Sergipe-Alagoas, Espírito Santo, Campos, Santos, Pelotas | Formed as South America split from Africa in the latest Jurassic–Early Cretaceous. Source rocks: Lower Cretaceous rift lake shales (presalt in Espírito Santo, Campos and Santos) and Cenomanian–Turonian marine shales, matured by Cretaceous and Oligocene–Pliocene burial |
| Southern rift basins | North Falkland, Malvinas | From the Mesozoic breakup of southern Gondwana; Late Jurassic–Early Cretaceous lake source rocks matured in the Late Cretaceous–Paleogene |
| Andean foreland | Magallanes, San Jorge, Neuquén, Cuyo, Santa Cruz-Tarija, Putumayo-Oriente-Marañón, Llanos, Barinas-Apure | Shaped by long-lived subduction of Pacific plates such as the Nazca Plate, which built the Andean fold-and-thrust belt; Late Paleozoic–Mesozoic source rocks matured by burial, Late Cretaceous to Neogene |
| Caribbean margin | Upper, Middle and Lower Magdalena, Guajira, Maracaibo, East Venezuela, Tobago Trough, Lesser Antilles | Shaped by the Caribbean Plate's eastward movement and oblique collision since the Eocene, still active off Trinidad. Main source: the Upper Cretaceous La Luna Formation and equivalents, maturing from the Eocene in the west and later eastward — as late as the Pliocene–Pleistocene in Trinidad |
| Caribbean islands and platform | Lesser Antilles (Barbados accretionary complex), Greater Antilles (North Cuba Basin), Bahama Platform | Barbados: La Luna-equivalent rocks caught up as the Atlantic Plate subducts, maturing since the Eocene. North Cuba and the Bahamas: Upper Jurassic (Oxfordian, possibly Tithonian) source rocks near the Gulf of America, matured in the Late Cretaceous–Paleogene |
Full results by petroleum system and assessment unit are in the companion data release.
Sources
Based on U.S. Geological Survey Fact Sheet 2026–3066, "Assessment of undiscovered conventional oil and gas resources of South America and the Caribbean, 2025," by the South America and Caribbean Assessment Team (Christopher J. Schenk and others); a work of the United States government in the public domain.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
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