Abstract
Ditch cutting samples from Well-X drilled in the Eastern part of the Niger delta were subjected to biostratigraphy and paleoenvironmental studies using micropaleontological analysis to identify the foraminifera present in the sections penetrated by the well.A total of 50 (fifty) foraminifera species made up of benthonic and planktic spp were recovered from the sections. The marker species identified are Globorotalia acostaensis, Globorotalia mernadii cultrate, Neogloboquadrina dutertrei, Globorotalia plesiotumida, Globorotalia obesa, Globorotalia nepenthes, Sphaeroidinella subdehiscens, Neogloboquadrina dutertrei, Globigerinoides sudquadratus.The four (4) biozones identified are N16 (Late Miocene 9.5Ma - 10.9Ma), N15-N14, N13-N12 and N12-N11 (Middle Miocene with corresponding ages 10.9Ma -11.8Ma, 11.8Ma-12.2Ma and 12.2Ma respectively).Using the encountered benthonic foraminiferal species, the paleoecology was determined; and it was revealed that the paleoenvironment of the section ranges from Inner Neritic to Outer Neritic Environment. Also, the lithological analysis revealed an intercalation of Shale, Mudstone and Sand which indicates various paleoecological episodes that led to their deposition.The age of the well was inferred from the bioevents of the marker species to be Middle Miocene to Late Miocene with the sparse occurrence of the Calcareous Benthic and the Plankonic species suggesting a shallow marine environment.  Â
Highlights
Biostratigraphy amongst other applications is crucial in hydrocarbon exploration and exploitation in the Niger Delta
Important foraminifera bioevents considered includes; First Downhole Occurrence (FDO) of chronostratigraphically significant plankton/benthic foraminifera species, Last Downhole Occurrence (LDO) of plankton/benthic foraminifera marker species and Foraminifera abundance and diversity peaks dated with foraminifera marker species whose stratigraphic ranges are well established in the Niger delta and worldwide
The results of the analysis indicates that the studied area was deposited during the Late Miocene to Middle Miocene epoch, of estimated numerical age of 9.5 Ma to 10.9Ma and straddling the Globorotalia plesiotumida of Berggren (1995) and Globorotalia acostaensis (N16) zones of Blow (1979)
Summary
Biostratigraphy amongst other applications is crucial in hydrocarbon exploration and exploitation in the Niger Delta. Though different microfossils amongst which are spores, pollen and foraminifera test linings have been employed to reconstruct the environment of deposition of studied sections and in age dating of rocks, the use of foraminifera cannot be overemphasized. This is because their remains are found in variable ecology. This study involves an approach to foraminifera study in interpreting biostratigraphy, age dating of formations and their corresponding environment of deposition as penetrated by a deep-water discovery well (Well-X - 1200ft deep) located within the offshore in Niger Delta Basin
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