SEDIMENTOLOGICAL AND BIOSTRATIGRAPHICAL STUDIES OF THE SEDIMENTARY SUCCESSIONS PENETRATED BY THE DRILL IN NC-1 WELL, GREATER UGHELLI DEPOBELT, NIGER DELTA BASIN, NIGERIA

ABSTRACT

The NC-1 well is located in the Greater Ughelli Depobelt of the Niger Delta Basin, a major hydrocarbon province in Nigeria. The well penetrated the Agbada Formation, which is composed of alternating sand and shale layers. The objective of this study is to examine the sedimentological and biostratigraphical features of the well, and to establish the sequence stratigraphic framework and depositional environment of the sediments. The study used 117 ditch cutting samples from depths of 4500ft to 11500ft, wireline logs, and geochemical data to analyse the lithology, texture, microfossils, and elemental concentrations of the well. The results showed that the well encountered eight chemozones, which correspond to different systems tracts and depositional sequences. The biostratigraphic analysis revealed that the well was deposited during the Late Oligocene to Early Miocene Epoch, based on the presence of diagnostic foraminifera and palynomorphs. The palaeoenvironmental interpretation suggested that the well recorded phases of delta progradation and retrogradation, and was influenced by marine and fluvial processes. The study also identified potential reservoir intervals and pay zones within the well, and provided insights for exploration and development of the field.