--> The Gulf of Guinea Petroleum Systems Pre-Salt and Post-Salt Dichotomy. Is the Exploration History Completed?, Biteau, Jean-Jacques R.; Choppin de Janvry, Ghislain; de Clarens, Philippe; Jarrige, Jean-Jacques, #90100 (2009)

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The Gulf of Guinea Petroleum Systems Pre-Salt and Post-Salt Dichotomy. Is the Exploration History Completed?

Biteau, Jean-Jacques R.1
 Choppin de Janvry, Ghislain1
 de Clarens, Philippe1
 Jarrige, Jean-Jacques1

1Geoscience, TOTAL, Paris, France.

There are several Petroleum Systems identified in the Gulf of Guinea.
Some of them are proven with petroleum occurrences and demonstrated source rock intervals and some are purely conceptual or hypothetical but can be speculated.
Mainly these Petroleum Systems can be separated into two types:
-the one related to pre-salt Cretaceous lacustrine generative systems sourcing hydrocarbons to Cretaceous pre-salt or post-salt Cretaceous and Tertiary reservoir-seal pairs,
-the others linked to post-salt marine (locally with terrestrial influences)generative systems charging hydrocarbons into post-salt reservoir-seal pairs Cretaceous and Tertiary in age.
This simple dichotomy leads also to a couple of first conclusions about their respective efficiencies and detailed comparisons at West African margin scale, as we did show during AAPG Cape Town last year.

On top of these assessments that will be detailed with new cases in the presentation, we intend to emphasize the different exploration histories related to these Petroleum Systems. Largely unknown in the early stages of exploration in the Lower Congo Basin mainly because of their deepwater local contexts, we can consider that the post-salt/post-salt Petroleum Systems are really not far now to have their boundaries recognized in the 3 dimensions of the Gulf of Guinea Basins, at least from Gabon to Lower Congo Basin.
On the contrary the pre-salt series have been intensively explored at the early stage of exploration in the fifties and later on during different phases linked to technological improvements such as seismic imagery for the onshore
Gabon acreage in the eighties for example.

These pre-salt source intervals are well characterized, stratigraphically calibrated and ranked onshore and in the proximal coastal offshore. This is not the case in more distal locations and we aim at presenting what could be the different scenario for their possible evolution in the Deep Offshore contexts in
Gabon and Lower Congo Basins.


 

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