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Abstract: Petroleum Systems of the Brazilian South Atlantic Margin

M. R. Mello, E. A. M. Koutsoukos, W. U. Mohriak, G. Bacoccoli

The characterization of a major petroleum system in the Sergipe Basin, NE Brazil, was undertaken using a multidisciplinary approach. The Lura-Muriboca (!) petroleum system, taken as a representative example for the proto-marine evaporitic stage in the South Atlantic margin, comprises the Carmopolis oil field, which is the largest onshore oil field in Brazil, with about 1.2 MM bbl of oil in place.

The hydrocarbons sourced by the proto-marine Aptian marls and calcareous black shales, started migration during the Paleocene, reaching the maximum at the late Oligocene continuing up to now in some parts of the basin. The hydrocarbons were mainly accumulated in Lower Cretaceous alluvial fans/fan deltas coarse clastics reservoirs, and fractured Precambrian basement. The reservoirs trapping were structured during the Cretaceous. Seals are the evaporites and marine shales deposited during the Aptian and Albian times.

Mapping the geographic extent of the petroleum system emphasizes the association of the Carmopolis oil field with the proposed offshore pod of active Aptian source rocks. The integration of these data with a geochemical modelling allowed the prediction and characterization, in time and space, of the petroleum pathways from source to trap in the basin.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela