New Frontiers for Deep Water Exploration: Senegal-Guinea Bissau Joint Exploration Zone

By

 E. Valmori¹, V. Barletta², G. Bricchi², J. Dainelli², G. Di Liegro²

(1) Agip Guibsen Dakar, S. Donato Milanese (Milan), Italy (2) ENI SpA-Agip Division, S. Donato Milanese (Milan), Italy

 For many years ENI has focused much of its exploration interest and investments in the offshore of West Africa, with an activity which is gradually moving from conventional to deep water areas. One of the latest acquired exploration Permits is “Cheval Marin”; it lies in territorial waters that are jointly managed by the Senegal and Guinea Bissau Governments. The “Cheval Marin” permit is located in the Casamance sub-basin, geologically belonging to the regional Mauritania-Senegal-Gambia-Bissau (MSGB) Basin. A thick sedimentary section aged from Paleozoic to recent is present, including pre, syn- and post-rift sequences. The exploration activity in Senegal and Guinea Bissau has been so far focused only on the platform domain, with many exploratory wells drilled onshore. The analysis of the well data samples shows the presence of an efficient petroleum system, whose oil generation has to be mainly referenced to the Cenomanian-Turonian source rocks; this sequence can be correlated to the “black shales” found on DSDP-367 well, located just over 200 km to the west of the Permit. Halokinesis phenomena related to the presence of a Triassic evaporitic sequence, led to the formation of structural closures that increase the possibility for the generated hydrocarbons of being locally trapped. The main target is represented by the Cretaceous sedimentary series, deposited on a slope environment during the post rift phase. The deep water domain of the Casamance sub-basin constitutes a fully unexplored area that can be considered as an emerging frontier area with high potential and moderate risk.