After the several giant oil fields discovered in the Campos Basin deep water province, off the Rio de Janeiro State, Southeastern Brazil, it was generally believed that analogues should be soon discovered in other sedimentary areas along the Brazilian Continental Atlantic Margin. However, the last important oil discovery in the Campos deep water was the Roncador Oil Field in 1996. Despite the notice of an important discovery in Santos Basin and probably less important in Espirito Santo Basin, no other relevant or giant discoveries occurred since then, even though Petrobras has put a great effort in drilling several wildcats in Campos and also in the deep water areas of other Brazilian basins. Several studies, mostly derived from the interpretation of exploratory data, within the overall Brazilian deep water areas have led to some important conclusions about the high exploratory risks of this region. Even in the Campos Basin deep water, the risk in finding new oil giants in deeper seaward areas, could be related to the existence of reliable source rocks, useful migration pathways and adequate.timing of hydrocarbon generation / migration. Similarities to the Campos Basin are encountered to the north, in the Espirito Santo Basin, and to the south, in the Santos Basin, but do not extend far away from these areas. In the sedimentary basins, along the offshore brazilian northeastern margin, the most important source rock sequence in shallow water region tend to disappear into the deep water region, where they are eroded at the base of younger strata of the open marine sequences. Generaly, over mature source rocks and complex tectonic features characterize the so called Equatorial Basins. Assuming the presence of the deltaic Tertiary deep water source rocks, better expectation comes from the two large submarine fans situated in the extreme north and south Brazilian Margin, accordingly:
the Amazonas Fan and;
the Rio Grande Fan, in the Pelotas deep water.
Similar possibility is also expected in the Pará-Maranhão deep water area where another submarine deltaic area is expected to occur.
The Brazilian sedimentary area is analyzed with emphasis to the offshore and to the deep water region, in particular. The previous exploratory efforts were used to characterize the stage of knowledge of each area. After almost 1500 exploratory wells drilled in the brazilian offshore area by Petrobras, during the last three decades, some important conclusions can be now outlined.
Considering the existing subdivision of the offshore area in large geographic sectors or in a large number of "basins" that, in fact, correspond more to geographic and operational compartments, the offshore Brazilian region was here divided into six distinctive provinces with proper exploratory history and geologic fram