This study, based on selected high resolution geochemical analyses, comprises a detailed investigation of the Petroleum Systems of the Northern area of the Brazilian Equatorial Margin, including Foz do Amazonas, Pará-Maranhão and Barreirinhas basins. High-resolution geochemical methods were applied to 35 selected oil samples spanning all the oil types identified in the Foz do Amazonas, Pará-Maranhão and Barreirinhas basins. Also, 35 wells were selected for source rock evaluation using Total Organic Carbon (TOC) and Pyrolysis Rock Eval analyses. The objective of this study was to identify and characterize the active petroleum systems present in the basins and their putative elements and processes.