The Bacalhau Field: New Insights into Lacustrine Carbonate Platform Development, Santos Basin, Brazil

Summary The giant pre-salt Bacalhau field in the Santos basin comprises two distinct Aptian Barra Velha Formation reservoir intervals (BVE200 and BVE100) developed on an isolated lacustrine platform. The reservoirs were deposited onto a complex paleotopography comprising both rifted BVE300 Paraty volcanics and younger volcanic pedestal highs. Bacalhau is a high-pressure field, with a 500 m hydrocarbon column. Hydrocarbons occur in rocks interpreted as being from both shallow water platform top and slope environments. Here we discuss how comprehensive new data from the 2018/2019 appraisal campaign, integrated with existing well data, narrow-azimuth 3D seismic, together with stratigraphic- and seismic-forward modeling provides new insights as to the controls on: 1) rifted and volcanic paleotopography, 2) relative lake-level changes, 3) dominant wind directions, and 4) slope re-deposition on lacustrine carbonate platform, margin, slope development and so reservoir heterogeneity.