Abstract
Geopressured sedimentary formations are common within the more prolific deeper hydrocarbon reserves in the Niger Delta basin. While overpressured zones could serve as tools for hydrocarbon prospectivity evaluation, they are significant safety concern to the driller. Pre-drill pore pressure prediction using 3-D seismic data was carried out in the Niger Delta basin to predict subsurface pressure regimes and further applied in the determination of hydrocarbon column, reservoir continuity, fault seal and trap integrity. Results revealed that overpressures in the area are associated with simple rollover structures bounded by growth faults, especially at the hanging walls, while hydrostatic pressures are often observed in areas with k-faults and collapsed crested structures. The depth to top of mild overpressures(<0.71psi/ft) in the basin ranges from about 6000ftss to about 13000ft subsea. Similarly, the depth to top of hard overpressures(>0.71psi/ft) ranges from about 13000ftss to over 30000ftss(throughout the Akata Formation).Post-depositional faulting is believed to have controlled the configuration of the overpressure surface and has played later roles in modifying the present day depth to top of overpressures.
