Stratigraphy and
Sedimentation of the Paleocene-Eocene Deep-Water Section in the
Souza Cruz, C.E.1, L.A.F. Sessegolo1, P.R. Blaskovski2, Eduardo B. Rodrigues3 (1) Petrobras, Rio de Janeiro, RJ, Brazil (2) Petrobras, Vitoria, ES, Brazil (3) PetrobrasResearch Center (CENPES), Rio de Janeiro, Brazil
Tertiary deep-water sandstones are the most important
petroleum reservoirs in the Campos Basin. The Paleocene-Eocene section comprise
reservoirs in at least 16 oilfields, including Barracuda and Marlim Sul
oilfields with 145 and 131 million m3 oil in place respectively. Cycle
boundaries are the key elements in the sequence
stratigraphy
analysis
of the
Tertiary section, being identified in seismic profiles,
well
log
correlation
and biostratigraphic data. The mapping of these sequences, separated by
unconformities, has made it possible to understand the tectonic-sedimentary controls
and the reservoir depositional architecture. The sedimentation of the
Paleocene-Eocene section was controlled by strong halokinesis. The troughs that
acted as conduits for the gravitational flows follow two main structural
directions, NNW-SSE and WNW-ESE, inherited from the rift phase, reactivated
during the Paleocene/Eocene due to the salt movements. Coeval depocentres,
mainly located in the distal portion of the area, are characterized by NE-SW
trending fault-related depressions and troughs, formed by the gravitational
collapse of the sedimentary section above the salt. The depositional elements
identified in our
analysis
comprise: 1) intra-slope, troughconfined
amalgamated sandstones bodies (up to 120m thick), characterized by conglomerate
and massive, coarse- to medium-grained sandstone, interbedded with bioturbated,
medium- to fine-grained sandstone; 2) semi-confined, trough-front terminal
lobes with medium- to fine-grained sandstone; 3) upper slope bottom
current-reworked sandstone, characterized by cross-bedded glauconitic
sandstone, interbedded with bioturbated muddy sandstone; and 4) wide-spread
mud-supported cohesive debris-flows, rich in agglutinated red algae fragments.