Structural Styles and Fluid Distribution in the Coastal Swamp Depobelt, Eastern Niger Delta
ONICHABOR, F., and M. OGUNLEYE
For each macrostructure in the Niger Delta, it has been shown that GOR increases basinward. This distribution pattern has been correlated with the most active fault for a given pollen subzone and is independent of the position of the fault in the trend.
Recent 3D seismic/geological evaluation of the Elepa-Nembe Creek-Belema-Olua macrostructure in the Coastal Swamp depobelt, reveals two distinct fault styles: an oblique trend and a near East-West trend. The structures of the oblique trend lie on the major paleo-drainage trends of the eastern Niger Delta, and were the major depocentres of the macrostructure. The structures of the East-West fault trend lie outside of the direct influence of the main paleo-drainage, and thus experienced a lower intensity of deformation.
Analysis of the fluid type distribution in the macrostructure shows that the fields of the east-west fault trend have low GOR, while those of the oblique trend have high GOR. This distribution pattern may be attributed to the change in structural style, subsidence rate, retention factors, burial history, maturation and gas flushing.