Petroleum Geology of the Amazonas Basin, Brazil: Modeling of Hydrocarbon Generation and Migration
F.G. Gonzaga, F.T.T. Gonç;alves, L.F.C. Coutinho, 2000. "Petroleum Geology of the Amazonas Basin, Brazil: Modeling of Hydrocarbon Generation and Migration", Petroleum Systems of South Atlantic Margins, Marcio Rocha Mello, Barry J. Katz
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The Amazonas Basin is a 500,000-km2 intracratonic basin in northern Brazil. The ~6000-m lithologic section encloses mainly Paleozoic sedimentary rocks intruded by Triassic–Jurassic diabase dikes and sills, and subsequently buried by Cretaceous–Tertiary rocks. Geochemical and geologic data point to the Upper Devonian marine black shales from Barreirinha Formation as the main hydrocarbon source rocks.
Data from 11 selected wells were used to perform thermo-mechanical modeling. Backstripping and stratigraphic analyses indicate four extensional events: Ordovician–Early Devonian, Devonian–Early Carboniferous, Middle Carboniferous–Permian, and Cretaceous–Tertiary The tectonic subsidence curve of each well was compared to theoretical subsidence curves to define the extensional factors and determine the heat flow history. The integration of 1-D basin modeling with geologic and geochemical data suggests that the Barreirinha Formation source rock started to generate petroleum during the Late Carboniferous. Modeling of primary migration indicates that the main phase of oil expulsion began when the source rock attained a transformation ratio of ~50% and a maturation level of 0.80% Ro. The main phase of petroleum generation and expulsion occurred from Late Carboniferous to Permian time and was completed by the Early Triassic. Any later tectonic event remobilized those hydrocarbons previously trapped.
Preliminary volumetric calculations indicate that up to 1 trillion bbl of oil equivalent were expelled from the source rock. Because of the long distances of both vertical and horizontal migration, it is believed that an important amount of the expelled hydrocarbon was dispersed along migration pathways. A significant part could also have been remobilized and lost during Cretaceous uplift of the basin margins.
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Petroleum Systems of South Atlantic Margins
“Giant oil and gas fields have been discovered through recent exploration in the deep and ultra-deep water regions of Angola, Brazil, and Nigeria. This volume includes 1. Descriptions of the petroleum geology of more than 12 basins along the two margins 2. Discussion of various components of the petroleum systems within these basins 3. Discussion on the use of the petroleum systems concept in the South Atlantic marginal basins to classify and characterize the diversity of the systems 4. Methodologies used in the assessment of petroleum system components 5. Overviews of the different components of the region's petroleum systems. Petroleum explorationists and researchers working in the South Atlantic will welcome this addition to their libraries.
The printed version of Memoir 73 was the Winner of the 2000 Dott Award for best AAPG Special Publication.”