Seismic facies and geobody characterization in the pre-salt rift section

Over the past decade, fundamental advances in seismic imaging of carbonate strata in nonmarine carbonate reservoirs of the South Atlantic pre-salt have improved our understanding of the complex stratigraphic architecture of late- and postrift lacustrine carbonate systems in areas like the Campos and Santos basin. However, a lack of 3D seismic data imaging of the pre-salt reservoir, combined with sparse well data, still represent a common challenge for the early Cretaceous pre-salt reservoirs in the South Atlantic. To improve our ability to model complex reservoirs in such a challenging exploration context, this study proposes an interpretive workflow based on the recognition and characterization of carbonate seismic facies. The methodology is grounded in the use of seismic attributes from 2D seismic profiles, supervised by well data. The study focuses on the syn-rift deposits (Lagoa Feia Group) across a half graben of the Campos Basin. The methodology proposed allows the mapping of several carbonate reservoirs, and their interpolation as volumetric units called geobodies. A total of 10 large carbonate geobodies, distributed across the Lagoa Feia Group, are mapped and reconstructed in 3D, four of which are verified by well lithological information. Using the seismic facies, size and position of these geobodies in the rift structure, a discussion of the genetic processes and depositional environments underpinning those reservoir geobodies is also proposed, distinguishing between in situ and resedimented origins of the mapped geobodies. The proposed methodology opens up new possibilities for the characterization of carbonate reservoirs in both deeper and distal syn-rift troughs of the Campos Basin, but also in adjacent basins with similar context, such as the Santos, Espírito Santo basins in Brazil and their African counterparts, currently still either poorly explored or unexplored