Geometry and Environmental Interpretation of the Albian Carbonate Platform — Deep-Water of Campos Basin, Brazil
Marilia V. Sant' Anna1, Délzio L. Machado Jr.1, Victor Viviani1, Cynthia Metelo1, Carlos E. Pontes1, Ana Zelia N. Barros2, Hedio S. Selbach1, Marcelo Bassetto1, Joao Brasil M. Neto1, Dimas F. Coelho2, and Geraldo Santana1
1UN-RIO/EXP/ABIG, Petrobras, Rio de Janeiro, Brazil
2E&P/EXP, Petrobras, Rio de Janeiro, Brazil
The Albian carbonate sequences in Campos Basin - southeastern continental margin of Brazil - have been studied by Petrobras since the discovery of Garoupa Field in 1974. Several geologic models were proposed but most of them are better and almost exclusively applied for shallow water areas. This paper shows a new interpretation of Albian platform evolution in deep-water of central part of Campos Basin, where this play has been intensively tested by Petrobras. The methodology applied on this study was based on principles of seismic stratigraphic interpretation integrated to well data (wireline logs, sidewall and composite samples, core, image logs, biostratigraphy and petrophysical data) and supported by structural restoration.
The Albian platform in deep-water is segmented by salt domes and diapirs that defined turtle back structures. This carbonate platform is composed by four main sedimentary sequences, from Early to Middle Albian in age, which can be correlated even in areas where they are disconnected. Halokinesis related to Aptian salt deposits affected the deposition of all these sequences, but its influence is less intense in the Early Albian. The 3D structural restoration revealed an ancient platform geometry, cut by tidal channels, with high energy facies along the rimmed-platform margin. During the drowning phase occurred a depositional back-stepped migration of sequences until the complete flooding of the platform. Several seismic attributes were tested in order to obtain a good correlation with rock porosity and facies distribution. This study shows that the integration of seismic stratigraphy, well correlation and structural restoration is the best method to define a controlled geologic model to predict depositional facies for the Albian Carbonate platform in deep-water of Campos Basin.
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