Predictive Petroleum System Model of Prospective
Anambra basin; a Cretaceous/Tertiary basin is the structural link
between the Cretaceous Benue trough and the Tertiary Niger Delta basin.
Spatially, it is the Sedimentary wedge bordered by the Abakaliki anticlinorium
to the East, the basement rock and the
Petroleum-Hydrocarbon system encompass source rocks, the process of generation and migration of the hydrocarbons and the geologic elements of traps, seals, and reservoirs that are essential for a hydrocarbon accumulation to exist,
The Anambra basin contains about 6000m thickness of Shales and Sandstones. Potential source rocks are the shales of Asata/Nkporo formation and Mamu formation that have total organic contents ranging from 0.4% to 4.8%. Kerogen is mostly of type Ц and Ш. Sandstone stringers in the Nkporo formation and Sandstone interbed of the coal measures have proven to be adequate hydrocarbon reservoir with porosity value from 15% to 35% and adequate permeability.
The early Cenomanian and later Santonian deformation lead to the formation of simple folds and faults that play a part in the hydrocarbon trapping mechanism of the basin. The stacking of sediments in a Southerly direction, have also promoted the formation of growth faults. The rejuvenation of movements on the basement faults also lead to formation of possible traps. The alternation of marine and continental deposits is also highly conducive to the formation of stratigraphic traps.
The Imo shale deposited during the Tertiary marine transgression has good sealing characteristics as it has not suffered any regional deformational event.