Sequence Stratigraphy of "X" Field in the Coastal Swamp Depobelt of the Niger Delta, Nigeria

Ademolu Balogun
University of Ibadan, Ibadan, Oyo, Port Harcourt, Nigeria

A sequence stratigraphic approach was applied to sedimentary study of the Western Coastal Swamp Depobelt of the Niger Delta using wireline logs (gamma ray and resistivity) of eight wells and high resolution biostratigraphic data of well-"A" and well-"B". These Middle Miocene strata were deposited by interaction of subsidence, eustatic changes in sea level and varying sediment supply. Two sequence boundaries and one maximum flooding surface were identified from minimum and maximum faunal abundance and diversity peaks respectively.

The strata in the study area are divided into basin floor fan and prograding wedge of the lowstand, transgressive and highstand systems tracts. Biostratigraphic data reveal that these sediments were deposited in inner neritic to bathyal marine environments. Reservoir characterization shows the sand distribution for each systems tract. The massive sand formation of the basin floor fan, the sand-rich prograding wedge and the highstand sands constitute good (potential) reservoirs. The distal shale toes of the prograding wedge and transgressive shales form seals for the (potential) stratigraphic traps formed in the study area.