Late Miocene Foraminiferal and Palynologic Events of Oborduka-1 Well, Deep Offshore, Niger Delta, Nigerian

A biostratigraphic study has been carried out on thirty (30) cutting samples retrieved from Oborduka- 1 well. The studied intervals were taken at 60ft, ranging from 10510ft-12310ft depth, to determine the chronology, biozonation and paleoenvironment that characterized the well. The lithostratigraphic description of the cuttings revealed that the bulk of the lithofacies constitutes shaly sandstone and sandy mudstone with intercalations of medium to fine-grained sandstone beds. The well yielded well preserved and fairly rich palynomorphs. The microfossil biozones of Cyclammina minima and Haplophragmoides narivaensis have been established (N17). A peak abundance surface of foraminifera was identified at 12070ft. A major palynological zone established was P800 with two subzones of P820 and P830. The top of P830 (youngest) is placed at 10510ft and its base at 11710ft which is marked by base occurrence of Stereisporites sp. and the P820 (oldest) which has its top marked at 11710ft with its base placed at 12310ft respectively. This zone is correlated with the broad Pan-tropical zone of Echitricolporites spinosus based on the index taxa recorded. The fauna and flora recovered suggest late Miocene age, nearshore and/or marginal marine environment. A cycle of transgression/regression was also identified based on the facies assemblage.