--> Abstract: Biostratigraphic Units of BDX-1 and BDX-2 Wells of Deep Offshore Niger Delta Using Calcareous Nannofossils, by Esther A. Ojo, Olugbenga A. Ehinola, and L. S. Fadiya; #90082 (2008)

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Biostratigraphic Units of BDX-1 and BDX-2 Wells of Deep Offshore Niger Delta Using Calcareous Nannofossils

Esther A. Ojo1, Olugbenga A. Ehinola2, and L. S. Fadiya3
1Geology, University of Ibadan, Ibadan, Nigeria
2Geology, University of Ibadan, Ibadan, Nigeria
3Geology, Obafemi Awolowo University, Ile-Ife, Nigeria

The need for absolute age determination and refined zonation of the deep offshore Niger Delta area has made calcareous nannofossil very useful over other fossils, though they still compliment each other. This study is aimed at subdividing the sequence within the depth intervals of the two wells into zones. 124 and 220 ditch cutting samples for BDX-1 and BDX-2 wells respectively were analyzed for nannopalaeontology. The calcareous nannofossils species identified were used to make biostratigraphic deductions, using the standard zonation schemes.

The zones encounter in this study are Cyclicargolithus floridanus zone (NN6), Discoaster bollii zone (NN7-NN8), Discoaster hamatus zone (NN9), Minylitha convalis zone (NN10), Discoaster berggrenii zone (NN11a), Discoaster quinqueramus zone (NN11b), Ceratolithus spp. zone (NN12), Gephyrocasa spp. zone (NN13) and it ranges from Middle Miocene to Early Pliocene. This zones were derived based on the First and Last occurrences of marker species as well as their relative abundance.

Stratigraphy positioning was used to mark the top and the base of NN7and NN8 interval, since the boundary between the two can not be determined. The presence of Ceratolithus spp. at the upper part of BDX-2 marks the boundary of Miocene-Pliocene.
The two wells correlate with each other based on the related zones derived. The resulting biozonation has further helped to subdivide the Deep Offshore Niger Delta Neogene sequence into easily recognizable biostratigraphic units which will enhance oil exploration in the area.

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