Accumulation and distribution of giant oil and gas fields in Campos Basin, Brazil

The Campos Basin in Brazil is a typical passive continental margin basin of Atlantic type.It has experienced 3 stages of tectonic evolution including rifting,transitional and drifting,and the corres-ponding sequences of continental facies,evaporate rock and marine facies have been deposited respectively.During the rifting stage,the black lacustrine calcareous shale in the continental sequence worked as the main source rock.The evaporate rocks in the transitional sequence divided the reservoirs in the basin into 2 sections: pre-salt and post-salt.About 90% of the total reserves of the basin have been found in the turbidity sandstones in the marine facies sequence deposited during the drifting stage.The most important petroleum system in the basin is Lagoa Feia-Carapebus.Petroleum generated from the source rocks in Lagoa Feia Group migrated along faults into the turbidity sandstones in Carapebus Formation of Campos Group.Petroleum distribution was mainly controlled by source rock burial depth,evaporate rock generation,turbidity sandstone distribution and fault generation.