Unraveling the Sequence Stratigraphic Architecture of Ogbo Field, Niger-Delta Basin, Nigeria Using Well Logs and Biostratigraphic Proxies

Ogbo Field, one of the prolific hydrocarbon field in the Niger Delta basin was studied for the purpose of delineation of the environment of deposition of sediments and reconstruction of sequence stratigraphic framework within the field. Methodology employed in this study include well logs and biostratigraphic analyses. Two major lithologies were identified in the field and consist of sandstone and shale. Sediment depositional environments varied from marginal marine (deltaic) to shallow marine. Five depositional sequences (SEQ.1, SEQ.2, SEQ.3, SEQ.4 and SEQ.5) bounded by five sequence boundaries (SB) and six maximum flooding surfaces (MFS) were identified in the sequences. The SBs dated 13.1Ma, 12.1Ma, 10.6Ma, 10.35Ma and 8.5Ma while the MFSs dated 15Ma, 12.8Ma, 11.5Ma, 10.4Ma, 9.5Ma and 7.4 Ma. The sequences were grouped into highstand system tracts (HST), transgressive system tracts (HST) and lowstand system tracts (LST), indicating aggrading, retrograding and prograding stratal stacking patterns respectively. The sandy unit was characterized by TST while HST dominated the shale zone.