Evolution of Niger delta basin can be divided into two stages.During the early stage

i.e.early Cretaceous

embryonic Niger delta has been formed

and the thermal uplifting associated with volcanic activities has provided heat sources for maturation of Tertiary organic matters.During the late stage

i.e.

Paleocene to Eocene

the framework of Niger delta has been basically finalized

with many growth faults and associated rollover anticlines being developed.The rollover anticlines basically can be divided into 4 types:1) simple rollover anticline;2) rollover anticlines that have been formed by the joint action of two or more growth faults and the master fault;3) rollover anticlines that have been formed by the joint action of one or more antithetic (north-dipping) faults and the master fault; 4)cave-in structures on top of rollover anticlines

due to the uplifting of shale.Most of the reservoirs

mainly of structural type

are related to the rollover anticlines associated with growth faults

and reservoirs of non-structural trap type have also been developed.The major controlling factors of hydrocarbon accumulation in Niger delta include the very thick inherited delta deposits

good hydrocarbon generating conditions

stable and well-developed reservoirs and seals

as well as! faults acting as the major migration pathways.