3D seismic data acquired in the Nigerian sector of the offshore Benin Basin reveal two sets of half-graben mini-basins and fault framework trending ENE-WSW and another trending NW-SE and orthogonal to the former, separated by basement horst. It is also seen that the basement, base Albian unconformity and down to basement faults all play key roles on hydrocarbon trapping geometries. Hydrocarbon traps consists of a combined structural and stratigraphic configuration. The structural element is created by the extensional half-graben bounding faults, while the unconformity at the base of the Albian and the basement constitutes the stratigraphic element. Impedance model shows several potention reservoir/seal pairs while the top seal is a regionally extensive shale at the base of the Albian. Isopach map of the syn-rift basins suggest sedimentary fill sufficiently thick for source rock maturation and hydrocarbon generation. Hydrocarbon migration is speculated to be along regional basement faults and sediment-basement interface. The Ogo-2 well discovery has perhaps opened up a completely new syn-rift play in the Nigerian sector of the basin with significant opportunities yet to be tested along the West African Transform Margin trend.
Key words: Offshore Benin Basin, Lower Cretaceous, Syn-rift mini basins, Prospectivity
|
