--> Forecasting Reservoir Potential in Cretaceous Rift Basins of the South Atlantic Using Forward Stratigraphic Modeling, Gerber, Thomas P.; Francis, Jason M.; Perlmutter, Martin A.; Buursink, Marc L.; Granjeon, Didier, #90100 (2009)

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Forecasting Reservoir Potential in Cretaceous Rift Basins of the South Atlantic Using Forward Stratigraphic Modeling

Gerber, Thomas P.1
 Francis, Jason M.1
 Perlmutter, Martin A.1
 Buursink, Marc L.1
 Granjeon, Didier2

1Chevron Energy Technology Company, Houston, TX.
2
IFP - Institut Francais du Petrole,
Rueil Malmaison, France.

Recent major discoveries of carbonate reservoirs in the pre-salt Santos and Campos Basins has reinvigorated exploration efforts in these areas and motivated further studies of syn-rift carbonate development. In this study we use the stratigraphic model Dionisos to investigate how lake level, paleoclimate, and siliciclastic sediment supply control the growth of lacustrine carbonates in an evolving rift basin. We predict the large-scale (≈10-20 myr) architecture of syn- and post-rift strata accommodated by a pattern of normal faulting consistent with continental extension. Paleoclimate and paleogeographic reconstructions suggest most water and sediment was delivered to the South Atlantic rift basins by a large axial river system draining Gondwanan highlands to the north. Hence in our simulations siliciclastic sediment is supplied primarily from an axial river on the northern basin boundary with local secondary sources active during wet periods. Water flow in the model domain is routed around local topographic highs and into topographic lows, which during wet periods become lakes where carbonates grow at rates that depend on water depth, water chemistry, and clastic supply. We explored the stratigraphic response to three types of allogenic variation that likely influenced the pre-salt stratigraphy of the proto-South Atlantic: (1) hinterland climatic cycles that varied the water and sediment delivery to the northern basin boundary, (2) local climatic cycles that varied precipitation within the rift basin and across its flanks, and (3) associated changes in water chemistry that affected the viability of different carbonate-producing species. The model results shed light on model sensitivity and provide end-member cases that help further constrain pre-salt reservoir prediction in the South Atlantic.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil