Stratigraphic framework and petrophysical analysis of Oligocene-miocene turbidite systems in the eastern Marlim oilfield (SE Brazil)

Abstract

The Eastern Marlim oilfield, located in the northeastern offshore of the Campos Basin, is a portion of the Marlim Complex, one of the most important oil accumulations ever found in Brazil. This paper presents findings from lithofacies, sequence stratigraphy and petrophysical analyses for the Oligocene-Miocene section of the Eastern Marlim oilfield. Here, we evaluate at least four main lithofacies associations and three major zones recognized in the latter section, presenting sedimentological and stratigraphical interpretations based on stratigraphic correlations, distribution and sand proportion maps, and accompanying petrophysical analysis. Our findings suggest at least two bipartite turbiditic flows representing different stages of deposition associated with a deep-water turbidite sequence, composing the elements of a submarine lobe complex. Massive unconsolidated amalgamated sandstone bodies, displaying very good porosity, lateral and vertical continuity, reflecting excellent reservoirs. The final depositional model of the studied Oligocene-Miocene interval in this work is part of the first-order Highstand System Tract (HST) of the Campos Basin, which in turn represents a second-order, exploration-scale depositional sequence. Finally, the sequence stratigraphic model of the Oligocene-Miocene section of the Eastern Marlim oilfield has an architecture similar to those that have been developed from Oligocene-Miocene global sea level changes.