Jeferson M. Kinzel¹, Jaime F. Eiras¹, Cesar Augusto G. Pereira¹
(1) PETROBRAS, Belém, Brazil

Abstract: Oil habitat in the Paleozoic Solimões and Amazonas basins, Northern Brazil

The Paleozoic Solimões (450,000 sq. km) and Amazonas (489,000 sq. km) basins are two vast, east-west trending, intracratonic sedimentary basins, located in the heart of the Brazilian Amazon rain forest. These basins are filled with 3,800 m and 5,000 m of Phanerozoic rocks, respectively, and are separated from each other by the Purus arch. A Proterozoic rift system is deeply buried below the Phanerozoic sequences. The stratigraphic framework consists of Paleozoic, Mesozoic, and Cenozoic sedimentary rocks. The Paleozoic sequence contains the source, reservoir, and seal rocks. The thermal evolution is controlled by the Triassic diabase dikes and sills, intruded into the Paleozoic sequence.

Source rocks are Upper Devonian, marine, radioactive black shales. The main reservoirs are Lower Pennsylvanian eolian and tidal bars sandstones. Efficient seals (halite and anhydrite) overlie reservoir rocks. The main traps are hangingwall anticlines formed during the Mesozoic Juruá compressional tectonics.

There are 19 light oil, gas, and condensate fields in the Solimões basin, and 1 gas field in the Amazonas basin. Total reserves are over 900 million barrels of oil equivalent. The Solimões basin is the only commercial Brazilian basin producing from Paleozoic rocks, and contains the second greatest reserves in Brazil.

Many exploratory opportunities will arise in these basins, not only due to the potential for oil, condensate and gas in the Solimões basin and for light oil in the Amazonas basin, but also because demand for oil and gas is expected to increase in the Amazonian region and in Brazil as a whole.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana