High-resolution sequence stratigraphy applied to reservoir characterization of the Brazilian Cretaceous pre-salt section, Campos Basin: Guidelines for geological modeling and reservoir management

Abstract

The giant accumulations in the pre-salt section of the Brazilian sedimentary basins stand out among the recent world discoveries of oil and gas provinces. The purpose of this case study was to provide inputs to refined 3D geological modeling and reservoir management by characterizing a pre-salt reservoir in the Marlim and Voador fields in the Campos Basin using high-resolution sequence-stratigraphic methodology. This methodology was strong enough to combine different data types, such as seismic and well data, into a high-resolution chronostratigraphic framework. The investigation classified the geological record of the reservoir within a sequence-stratigraphic framework with at least five hierarchies. The 1st- and 2nd-order sequences relate to distinct phases of the Basin's tectonic evolution. Sequences of carbonate lake sedimentation within the post-rift tectonic configuration, where the reservoir is found, were attributed to multiscale transgressive-regressive (T-R) cyclicity. Lake T-R cycles observed in any hierarchical setting are generally governed by faciological tendencies that determine petrophysical features. Regressive tracts produce a more significant proportion of facies with high porosity, whereas transgressive tracts produce facies with reduced porosity. The proposed detailed stratigraphic zoning satisfactorily explains the depletion behavior of the reservoir, revealing that high-resolution sequences condition the fluid flow. Several recommendations for 3D geological modeling, development planning, and reservoir management are made based on these results. The detail highlighted in this study is fundamental in searching for additional oil reserves, production factors, and final recovery.