Spectrum's geoscientists have completed their extensive review of the hydrocarbon prospectivity offshore Gabon which has emerging from the the study of 5500 km2 of 3D seismic, recently acquired to image the deep syn-rift units and to provide a regional framework for the traditional post-rift hydrocarbon plays.
Two major petroleum systems are present with source rocks and reservoirs distributed in the pre-salt syn-rift sequences and in several post-rift sequences. Each petroleum system is characterized by various source rocks, reservoirs and trapping mechanisms. The Nyonie Deep Gas Discovery has proven reservoir properties in the pre-salt section syn-rift sections of Gamba Sands and Dentale Fms. Oil bearing targets are known in the clastic and calcareous deposits of the Late Cretaceous.
In the syn-rift, mostly lacustrine source rocks, (Melania Fm. s.l.), are expected to be oil generative from the end of the Cretaceous and Paleogene, or even later in case of a burial less than 3-4 km. Post-rift units have a number of marine source rocks, pushed into an early oil window from the Paleogene and during the Neogene, mostly as result of their close proximity to highly conductive salt bodies.
Regional extensional faults show an echelon trend with strike direction between N-S and NW-SE, generating large structural closures at base salt level, potentially over 150-200 km2, clearly visible in the initial stages of the time processing, and expected to be fully imaged by the end of the Depth Migration exercise. Salt withdrawal occurred mainly during the Late Cretaceous-Paleogene, controlling the deposition of the post-rift sequences, which are organized in a variety of structural and stratigraphic traps, most of which remain untested. Finally, the proper imaging of subsalt traps is expected to uncover potential hydrocarbon resources, economically attractive and overlooked from the past exploration.
Spectrum ASA published this content on 05 September 2018 and is solely responsible for the information contained herein. Distributed by Public, unedited and unaltered, on 05 September 2018 08:21:05 UTC