Petroleum Systems Analysis of Turbidite Reservoirs in Rift and Passive Margin Atlantic Basins (Brazil and Portugal)

Abstract

Due to the success of oil and gas production, turbidites have become exploratory targets over the past 40 years in the rift and passive margin basins in the North and South Atlantic. The turbiditic reservoirs in rift and passive margin settings of Atlantic sedimentary basins located in Brazil (Campos Basin) and Portugal (Lusitanian Basin) represent potential economic units for the hydrocarbon exploration. However, despite being considered analogous reservoirs, these units present distinct potentials for the accumulation of hydrocarbons. In this context, the work presented discusses the results obtained from the analysis of static (source rock, reservoir rock, seal and trap) and dynamic elements (migration, tectonic, diagenetic and thermal processes) of both studied petroleum systems, using geological, seismic, well, geochemical and petrographic data. The developed methodology of multiscalar characterization of the two petroleum systems was successful, leading to a specific classification of the efficiency of the static and dynamic elements. These served as the basis for a petroleum systems analysis of the potential of turbiditic reservoirs in both analyzed basins. In the Campos Basin, the salt diapirs and the associated faults provided the origin of excellent migration routes for the hydrocarbons generated in lower intervals, allowing them to reach Cretaceous turbidite reservoirs. At Lusitanian Basin, the diagenetic processes reduced significantly the porosities of the potential turbiditic reservoirs, besides the intense influence of the salt tectonics that may have been responsible for the migration of hydrocarbons along faults or by their walls, towards upper formations and to the surface.