--> Abstract: Kilometre-Scale Uplift of the Early Cretaceous Rift Section, Camamu Basin, Offshore North-East Brazil, by Iain Scotchman and Dario Chiossi; #90082 (2008)

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Kilometre-Scale Uplift of the Early Cretaceous Rift Section, Camamu Basin, Offshore North-East Brazil

Iain Scotchman1 and Dario Chiossi2
1Statoil (UK) Ltd, London, United Kingdom
2Statoil do Brasil Ltda, Rio de Janeiro, Brazil

Analysis of vitrinite reflectance data from released wells drilled in the shallow water shelf area of the offshore Camamu Basin, north-east Brazil, indicates considerable post-depositional uplift has affected the early Cretaceous-aged rift sediments.
The present-day shelf area of the Camamu Basin contains a thick succession of late Jurassic to early Cretaceous-aged pre- and syn-rift sediments. These contain a well developed petroleum system and several oil and gas fields have been discovered, sourced by thick, early syn-rift lacustrine black shales. Seismic data shows major unconformities are present, with evidence of tectonic slides particularly within the younger section. Well data confirms the presence of major unconformities with much of the latest syn-rift and post-break up section missing from the basin. By comparison with similar basins to the south in Alamada and Jequintinhonha, the missing section comprises shallow water Albian carbonates overlain by late Cretaceous turbidites.

Analysis of vitrinite reflectance data from wells in the Camamu shelf show a profile with depth typical of an uplifted basin, with higher than expected maturities at relatively shallow depths. Extrapolation of the maturity trends to a surface value indicates a range of potential uplift of between 1.2 and 2.7km across the shelf area, suggesting that peak oil generation occurred in the past. Apatite fission track and other studies are underway to further constrain the uplift events.

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