New exploratory frontiers in Brazil

Abstract

Brazilian petroleum exploration commenced onshore in the Reconcavo Basin. By the mid fifties several small fields were discovered in the Neocomian/Barremian rift section. In the beginning of the sixties, exploring the same rift section, the first brazilian giant oil field was discovered onshore in the Sergipe Basin. In the seventies, several medium size fields were also discovered in the marine section of the continental shelf area of that same basin. As the demand for energy increased in Brazil, exploration of other basins also was initiated and by the end of the seventies several offshore fields were discovered in the continental shelf of Campos Basin. Based on Petrobras developed sedimentological and stratigraphic models, exploration activities rapidly moved toward deep water regions. By the mid eighties giant deep water fields were discovered in Campos Basin in the continental slope region (e.g., the Marlim, Albacora, Caratinga and Roncador Fields). Very innovative technology was used to produce from marine siliciclastic reservoirs. These oil-bearing reservoirs are basically turbidite systems deposited in deep water areas at a very great distance from the shoreline and also sand-rich systems generated by contourite systems. Recently similar medium to large-size fields were discovered in the Espirito Santo Basin. Continuing on this quest, exploration activities started focusing on the Sao Paulo Plateau, a prominent regional topographic feature in water depths ranging from 2.000 to 3.000 meters. A thick and continuous Aptian evaporitic sequence, thicker than two thousand meters, exists in this region, contrasting with the very thin marine section above the salt. The explored reservoirs are located below the salt layer in sediments deposited before the marine drift phase of the margin began. The first exploratory results indicate that this region may very possibly represent one of the most significant hydrocarbon provinces to be explored in this millennium.