Upper Amazonian petroleum-gas-bearing basin

UPPER AMAZONIAN PETROLEUM-GAS-BEARING BASIN (RU: Верхнеамазонский нефтегазоносный бассейн) is situated within the limits of the Colombia, Ecuador, and Peru countries. The area is 575 thousand square kilometres. The first field (Orito) has been discovered during the 1963.

The Upper Amazonian petroleum-gas-bearing basin includes 50 fields with the total initial reserves of approximately 450 million tonnes of petroleum, and 190 billion cubic metres of gas. The major fields are: the Orito (with the reserves of petroleum of 134 million tonnes) within the Colombia country, the Sacha (62), Shushufindi (45), and Lago Agrio (35) within the Ecuador country. The basin is confined to the depression with the same name within the pre-Andean foredeep. The foundation is formed with the pre-Cambrian crystalline rocks, while within the limits of the folded boundary, the foundation is formed with the metamorphic complexes of the Paleozoic. The sedimentary cover (with the thickness of more than 9 kilometres) is represented by the marine formations of the Upper Carboniferous, Permian, Triassic, and Lower Jurassic, by the evaporitic strata of the Upper Jurassic, by the marine terrigenous-carbonatic strata of the Cretaceous, and by the thick continental molasse of the Cenozoic.

At the west, the Upper Amazonian petroleum-gas-bearing basin is bounded by the folded structures of the Andes, while at the east, the basin is bounded by the slope of the Brazilian craton. The productive horizons have been identified at the depth of 915-4000 metres, while there serve as the collectors the sandstones, and less often the limestones of the Cretaceous age. The fields are of the multi-layer type. The density of the petroleum is 830-934 kilograms per cubic metre. The annual extraction is 17 million tonnes, including 15 million tonnes within the Ecuador country (1977). The cumulative extraction by the 1978 is 76.5 million tonnes. There exists the Orito - Tumaco trans-Andean pipeline (310 kilometres) on the coast of the Pacific ocean; there exist the Lago Agrio - Esmeraldas (510 kilometres), and Corrientes - Bayóvar (900 kilometres) pipelines.