An integrated seismic-scale analysis of reservoir compartmentalisation on continental margins: the Espirito Santo Basin, SE Brazil
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Abstract
Deepwater continental margins constitute one of the ultimate exploration frontiers
where giant oilfields have been discovered. These comprise reservoirs units affected by
multi‐scale compartmentalisation resultant from stratigraphic, structural and/or diagenetic
processes that compromise the lateral and/or vertical connectivity of permeable strata.
A 3D seismic dataset from the deepwater Espírito Santo Basin (SE Brazil) was
analysed to assess and quantify the architectural elements that influence the
compartmentalisation of reservoir units. Mass‐Transport Deposits (MTDs) have growing
importance on reservoir studies as they highly impact the compartmentalisation of
contemporaneous reservoir‐prone turbidite strata. More significant compartmentalisation
occurs in areas with higher MTD proportion, which are associated to wider dimensional
ranges of laterally limited turbidites. However, salt diapirs constitute important barriers for
MTD erosion, thus aiding the preservation of reservoir‐prone turbidites. The internal
compositional heterogeneities and cohese strata on remnant and rafted blocks identified
within the studied MTDs constitute important fluid flow or accumulation compartments,
particularly when linked to underlying permeable faults.
Submarine channels in Palaeocene and Neogene Units comprise important
reservoir‐prone strata, thus it is crucial to understand their spatial distribution. Large
channels are focused along the axis of salt‐withdrawal basins, whereas in sub‐units with
numerous smaller channels these are laterally scattered across the basin. A new
quantitative method used in this study shows that channel confluences and topographic
confinement control significantly the density and spatial distribution patterns of submarine
channels. A novel classification for submarine channel confluences is proposed, based on
channel morphology and distribution of sediment facies within the tributaries.
The key aim of this thesis was to undertake a seismic‐scale qualitative and quantitative
analysis of the compartmentalisation of reservoir units on the Brazilian margin using
methodologies that can be applied to other continental margins worldwide. As such, the
results of this study can provide significant contributions for hydrocarbon exploration