Abstract:

The Campos basin at the east margin of South America is a typical passive margin basin of the  Atlantic type. Campos Basin went through four evolution phases: Pre-rift、Syn-rift、Transitional and Post-rift. The Lower Cretaceous lacustrine black shales of the Lagoa Feia formation formed in the syn-rift phase is the primary source rocks, which started to generate oil at Eocene(52 Ma) and reached its oil generation peak during the Miocene(22-8 Ma). The Upper Cretaceous and Tertiary turbidities, Lower Cretaceous carbonate of the Macae formation, oolitic grainstones of the Lagoa Feia formation and the fractured basement of Cabiunas formation are the four main reservoirs developed in the basin. The evaporate rock of the Alagoas formation of the transitional phase provides a regional seal for the underlying reservoirs and the Tertiary intra-formational marine shale provides a local seal. There are four main reservoir assemblages developed in the basin and the upper turbidities assemblage of the Carapebus formation is the most important one, which takes about 80% of the total recoverable reserves of the basin. Two potential exploration targets in the basin are: the turbidities of the Carapebus assemblage and oolitic grainstones of the Lagoa Feia assemblage.

Key words: Campos basin, passive margin basin, petroleum geology, exploration potential