Implications of Sequence Stratigraphic Technique to Petroleum Exploration and Production: A Case Study of XP Field, Onshore Niger Delta, Nigeria

This work builds on the detailed sequence stratigraphic analysis that has been carried out on the XP Field. It highlights the implications of the technique to exploration and production potentials in the XP field. Well logs and biostratigraphic data integrated revealed key Maximum Flooding Surfaces (MFS1, MFS2, and MFS3) and sequence boundaries designated SB1, SB2 and SB3, between the intervals of 3140 and 4232m. Maximum Flooding Surfaces are intervals showing high abundance and diversity of foraminifera which represent three regional marker shales identified, and act as seals to the hydrocarbon-bearing sands. The erosional surfaces coincide with intervals that are barren in faunal activity and are interpreted as sequence boundaries. The delineated sequences show three depositional patterns (progradation, retrogradation and aggradation) resulting from fluctuation in sea level (regression and transgression).Three systems tracts recognized include lowstand systems tracts (LST), transgressive systems tracts(TST) and highstand systems tracts (HST). The LST has excellent reservoir quality compared to TST (heterolithic reservoirs), and forms an exploration target during subsurface mapping. The stratigraphic positions of sequences with highest prospect falls within 4232m to 3140m (productive interval) and can be penetrated at approximately the same depth range across the field, except for fault interception. The youngest sequence has more water-bearing reservoirs, which provides a potential for water injection at the depleting stage of the reservoirs when natural drive mechanism can no longer be effective.