Stratigraphic and Unconformity Traps in the Niger Delta
Although hydrocarbons are dominantly trapped by rollover anticlines and fault closures in the Niger delta, some stratigraphic traps have also been recognized. Three types of stratigraphic accumulations are recognized in the Niger delta: (1) crestal accumulations below mature erosion surfaces; (2) canyon-fill accumulations above unconformity surfaces; and (3) facies change traps.
Several important oil discoveries in offshore southeastern Nigeria are associated with crestal accumulations below erosional surfaces. In addition, canyon-fill accumulations have been observed in offshore southeastern Nigeria within the Qua Iboe Shale. Recent discoveries have also shown accumulations within the Opuama channel fill in the western flank of the Niger delta. Facies-change traps have also been observed in the central portion of the Niger delta. All the various stratigraphic traps observed in the Niger delta were identified by interpretation of seismic data.