The Discovery of a Paleogene Carbonate Platform Using 3-D Seismic Geometry, Espirito Santo Basin, Offshore Brazil

Campbell, A. Ewan¹, Klaus Fischer¹, Matthias Stollenwerk², Wolfgang H.H.J. Ludwig¹, Christian Derer³, Michael Zechner¹ (1) Wintershall AG, Kassel, Germany (2) Wintershall Nordkaspische Explorations- und Produktions GmbH, Moscow, Russia (3) Wintershall Noordzee B.V, Den Haag, Netherlands

Acquisition and interpretation of a PrSTM 3D seismic cube in the Espirito Santo basin, Brazil allowed for the interpretation of a Tertiary carbonate platform and the definition of a new offshore play. Initial exploration efforts in the exploration area focused on exploring for Late Cretaceous and Paleogene turbidites. Improved seismic resolution allowed for the iden­tification of stratal geometries unique to carbonate platforms. There was no well coverage in the block so a regional correlation study was made, based on 2D seismic data to tie the platform to wells containing the same carbonate interval. The study showed a Tertiary plat­form development with large-scale, prograding, clinoforms with 40^o slope angles, raised rim and margin geometry and a flat-lying, back-reef lagoon. Seismic geometry clearly shows the outbuilding of the platform followed by an incipient drowning with an associated back­stepping build up. Carbonate growth continued with a subsequent drop in sea level and the rapid progradation of smaller platforms off, and away from, the buildups with small-scale clinoforms clearly visible on seismic sections and attribute maps. Carbonate growth termi­nated and the platforms were capped in marine shale. Regional cuttings studies from off­platform intervals indicated the “carbonate factory” was dominated by large benthic fora­manifera, bryozoans and red algae. Seismic geometries imply high-energy depositional environments while analogues indicate the potential for favourable reservoir.