Palynological characterization and source rock evaluation of the anambra basin, southeastern nigeria

Abstract

An integrated palynofacies, organic petrological, and biostratigraphic investigation was carried out on seventeen (17) ditch-cutting samples from the Akukwa-2 (8) and Nzam-1 (9) wells in the Anambra Basin, southeastern Nigeria, with the aim of assessing source rock characteristics and hydrocarbon generation potential. Seventeen samples were analyzed to evaluate organic matter abundance, kerogen type, thermal maturity, depositional environment, and stratigraphic age. Palynofacies data indicate organic matter richness ranging from lean to fairly rich, with assemblages dominated by mixed terrestrial and marine components. The kerogen population is principally composed of Type II and Type III kerogens, suggesting both oil and gas-prone source intervals. Thermal maturity assessment based on kerogen colour indices and maceral composition indicates that several stratigraphic units have attained conditions favorable for hydrocarbon generation. Palynological assemblages characterized by key marker taxa, including Echitricolporites spinosus, Longapertites spp., Wetzeliella sp., and Afropollis jardinus, constrain the age of the penetrated sequences to Albian–Tertiary. The co-occurrence of terrestrial pollen and spores with marine dinoflagellate cysts suggests deposition in a marginal marine to deltaic environment. Overall, the results demonstrate that selected intervals within the Akukwa-2 and Nzam-1 wells possess favorable conditions for hydrocarbon generation, highlighting the petroleum potential of the Anambra Basin.