Petroleum Geology of the Pre Salt of the South Atlantic Margins Phase I – West Africa

Core Laboratories has now built up extensive expertise in the regional petroleum geology of both the Brazilian and West African Atlantic Margin Basins. Our recent geological studies of nine (9) Brazilian basins (Core Laboratories non-proprietary studies, 2001 – 2003) have established an integrated geological model for the shelfal and deepwater areas of the eastern Brazilian Margin. In the mid-1990’s Core Lab completed two land mark geochemical and reservoir evaluations of the Pre Salt of West Africa. The Gabon/Congo areas were substantially updated and expanded during 2003.

Recent hydrocarbon discoveries in pre-salt reservoirs have rekindled international interest within the clastic and carbonate rift and pre-rift plays along both the Brazilian and West African Margins.

The study was undertaken on ditch cuttings, cores, sidewall cores and fluids from a suite of wells and oils.

The primary technical objective of the study is to extend the geological model of pre-salt plays established for the shelfal parts of the Atlantic Margin Basins to establish a high-resolution, fully integrated, geological model for the rift and pre-rift reservoirs and source horizons. The study will primarily focus on sediments of Berriasian to Aptian age which include a range of fluvial-continental, shallow lake and re-sedimented deep lake facies. Interpretation of data will include high-resolution biostratigraphy, geochemistry and detailed analysis of depositional environments, reservoir and seal geometries.

Besides the well-documented fluvial and shallow lacustrine facies of the Atlantic Margin Basins, data from our Atlantic Margin studies (Core Laboratories, 2002/3) suggests the presence of some deeper water lake turbidite or debris flow deposits and local pre-rift Aeolian sandstones with considerable reservoir potential.

In addition to detailed sedimentology, the project will include full evaluation of reservoir quality and reservoir fracturing as appropriate through detailed petrographic analysis of thin sections and macroscopic analysis of any core fracture systems. Detailed regional evaluation of the Berriasian to Aptian succession will provide the integrated geological dataset required for geological modeling and optimum reservoir description of all rift plays.

Five (5) bound interpretive volumes of each margin will be provided. These volumes are fully illustrated with figures, analytical data and regional data in the form of maps and cross sections. Conclusions from the analytical and interpretative program will be synthesized into regional interpretations.