Print this pageRelating Petroleum System and Play Development to Basin Evolution: Brazilian South Atlantic Margin
Sedimentary basins can be classified according to their structural genesis and evolutionary history and the latter can be linked to petroleum system and play development. The Brazilian marginal basins, comprising the Sergipe-Alagoas, Jacuipe, Almada-Camamu, Jequitinhonha, Cumuruxatiba, Espirito Santo, Campos and Santos basins, have experienced a similar tectonic and sedimentary basin evolution. Four basin cycles have been distinguished (pre-rift, syn-rift, transitional and post-rift), of which three are associated with at least one type of source rock giving rise to a specific type of petroleum system (PST). The lacustrine syn-rift PST is regionally extensive and the most productive. Despite the widespread distribution of transitional and post-rift source rocks, the restricted hypersaline marine transitional PST and shallow and deep marine post-rift PSTs have only been proven active locally, due to the relatively low maturity of these source rocks. Play development is closely related to basin tectonic and sedimentary evolution: syn-rift plays are associated with lacustrine/fluvial facies in combination with trap geometries related to graben development. Post-rift plays include deltaic and shallow to deep marine clastic and carbonate facies in combination with traps which formed due to halokinesis. The number and variety of plays increase with basin evolution, as tectonic- and sedimentary patterns become more complex. Three basin families have been identified, each characterized by approximately the same tectono-stratigraphic basin evolution, from a lacustrine/fluvial syn-rift and restricted hypersaline marine transitional period to a shallow to deep marine post-rift, but with varying subsidence patterns and hence varying maturity distributions of the different source rock intervals. Basin family I is characterized by the existence of lacustrine syn-rift and marine post-rift PSTs, and potentially a restricted hypersaline marine PST. Basins belonging to basin family II contain lacustrine syn-rift and restricted hypersaline marine transitional PSTs, and potentially a marine post-rift PST. Basin family III is characterized by the sole development of a lacustrine syn-rift PST. The recognition of basin families allows for analogue comparison between basins with a similar geological background with respect to prospectivity, since similar tectono-stratigraphic basin evolution leads to the development of similar PSTs and plays.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil