PALEOENVIRONMENTAL RECONSTRUCTION OF WELL EA USING FORAMS, NIGER DELTA, SOUTHERN NIGERIA

ABSTRACT This study investigates the depositional history, paleoenvironmental conditions, and reservoir characteristics of Well EA within the Niger Delta, using a combination of lithologic descriptions and micropaleontological analyses. The examined interval (8640–9210 ft) consists predominantly of alternating marine shale and continental-to-marginal marine siltstone units, reflecting cyclic fluctuations in sea level and changes in depositional energy. Lithologic observations reveal thick low-energy shale successions at the upper and lower sections of the sequence, separated by a higher-energy siltstone interval that indicates a more proximal environment influenced by fluvial or deltaic processes. Micropaleontological analysis shows a rich and diverse assemblage of benthic and planktonic foraminifera, including species such as Hanzawaia concentrica, Uvigerina subperegrina, Cassidulina neocarinata, and Orbulina universa, all of which support deposition in an Outer Neritic setting. Biostratigraphic zonation identifies six distinct intervals that correlate strongly with the N7–N8 zones of the Blow et al. (1978) classification, confirming an Early Miocene age for the sediments. Reservoir assessment highlights the siltstone interval around 8800–9000 ft as the primary reservoir zone, demonstrating moderate reservoir potential due to its grain characteristics, while the surrounding shale units function as effective seals. The integration of lithostratigraphic, micropaleontological, and biostratigraphic evidence provides a coherent reconstruction of environmental changes and depositional processes affecting the study area. These findings contribute to a clearer understanding of the stratigraphic framework of the Niger Delta and support future hydrocarbon exploration efforts in similar settings.