DaVID Iacopini, Renata Alvarenga, Juliano Kuchle , Adam J Cawood, Dara E Goldberg, Ben Kneller

The exploration of pre-salt offshore SE Brazil presents a multifaceted deep-water scenario that is bringing new challenges to seismic interpretation in offshore Brazilian exploration and production. Reservoirs in this domain are complex, heterogeneous with layered carbonates which makes accurate reservoir characterization very challenging. Our study here deals with the seismic characterization of the stratigraphy of a lacustrine section from the Lagoa Feia Group (Winter et al., 2007) in the Campos Basin, which extends over an area of 100,000 km2. By using an extensive 2D seismic dataset and two deep well logs and core information, we propose a seismic facies analysis and structural characterization of the Lagoa Feia group focused in the inner proximal domain of the Campos basin. Inferences from well core and seismic stratigraphy clearly suggest that the all Lagoa Feia group has a syn-rift depositional character. Different pre- syn- and post-rift seismic stratigraphic units, with corresponding bounding surfaces, are then defined. Based on their seismic character, four seismic facies representing the main lithological package in the rift section are recognized: border fault deposits; fine grain-dominated re-sedimented deposits; coarse grain-dominated carbonate rich re-sedimented deposits; and an intrusive wipe-out zone affecting all the pre-salt unit. Using some simplified kinematic restoration we show that some of the normal faults affecting the lower units of the Lagoa Feia could be interpreted as pre-rift structures sensu latu but also as pre-existing structures re-activated during the main passive margin rift activities. By proposing this seismic classification and interpretation across the pre salt Campos Basin units, this work represents an introductory step to a facies classification and structural interpretation applicable at regional level in the internal SE Brazil offshore area.