Paleozoic Sedimentary Basins and Petroleum Systems of Brazil: Geological Knowledge and Exploratory Status

Felix Goncalves¹, Jason T. Carneiro¹, Ricardo P. Bedregal¹, Flavio L. Fernandes¹, Fabio O. Andrade Jr.¹, Sidnei P. Rostirolla², and Giuseppe Bacoccoli^1
1PGT - Petroleum Geoscience Technology, Rio de Janeiro, Brazil
²Universidade Federal do Paraná, Curitiba, Brazil

Over 60% of the Brazilian sedimentary area belong to Paleozoic basins. Such a huge area, about than four million square kilometers, is nevertheless poorly known, housing only circa 8% of the exploratory wells. Main paleozoic basins in Brazil include Parana, Parecis, Parnaíba, Alto Tapajós, Acre, Solimões and Amazonas. Oil exploration activities on those areas was firstly established on the 1950’s, resulting, since then, in the discovery of a few oil and mainly gas shows in the Parnaíba basin, oil and gas shows and a few small gas accumulations in the Paraná and Amazonas basins and ten oil and gas fields in the Solimões basin. In 2006, this latter basin produced only 2% of the Brazilian oil, but almost 20% of the natural gas. Regarding sedimentary filling, these basins comprise ordovician to tertiary marine to continental deposits, with maximum thicknesses estimated to range from 3.000m to 7.000m. Late Devonian marine black shales are the main hydrocarbon source rocks in the Paraná, Parnaíba, Solimões and Amazonas basins, while Permian oil shales are also found in the Paraná basin. Late Triassic to Early Cretaceous igneous intrusive and extrusive rocks have played a key role in the petroleum system evolution of these basins by controlling source rock and thermal evolution and fluid type (mostly gas). This work integrates all available geologic and geophysical data in order to reestablish the importance of these basins in the Brazilian and international scenarios, providing new insights and guidance for exploration of existing and new plays, including remarks on local logistics, data availability and quality, and environmental and market-related issues.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas