Palynomorphs and Age Characterization of Rock Succession in Well X-1, OML 108, Offshore Niger Delta Nigeria

Abstract

Palynological studies in Nigeria are mainly confined to the Tertiary Niger Delta, where several studies have been carried out for the discovery of natural oil and gas in this particular basin during late 1950s. The accuracy and profitability of the exploration process can be enhanced by the micropaleontological monitoring through the palynological analysis of ditch cuttings for age determination. Fifty ditch cutting samples from intervals 8040 ft and 11010 ft of Well X-1, OML 108, Ukpokiti field, offshore Niger Delta Nigeria were analyzed for their palynofloral content, in a view to establish the biozonation framework for the purpose of age characterization of the rock succession. Palynological sample processing and analysis followed standard methods of treatments with different concentrations of Hydrochloric acid, Hydrofluoric acid and organic acid for digestion of carbonates, removal of silicates and washing or centrifuging for concentration of the palynomorphs respectively in order to liberate the palynomorphs from the extraneous organic matter in the rock matrix. The palynofloral analysis yielded a total number of forty-three (43) pollen, seven (7) spores and one dinoflagellate cyst, from which four subzones based on palynofloral assemblage of marker species, their stratigraphic tops and base including their abundance and diversity were recognized. The zones are from youngest to oldest: Stereisporites sp, Racemonocolpiteshians, Verrutricolporitesrotundiporus and Retibrevitricolporitesobodoensis/protundens zones corresponding with pollen sub zones:P850-830, P820, P780 and P770respectively, indicatingLate Miocene to Middle Miocene age. In conclusion, the palyno – zones of this study compare well with the pollen zones of [3], therefore shows that the rock succession was deposited during the Middle to Late Miocene epoch.