The hydrocarbon reserves of the Niger Delta are an extremely valuable natural resource. Biostratigraphy and Correlation play important roles in the discovery, development and maturing of hydrocarbon fields. Calcareous nannofossils have been important tools for the stratigraphers in the Niger Delta and in recent years exploration has moved into deeper offshore areas where nannofossils are more abundant and diverse. Little has been published about the calcareous nannofossil chronostratigraphy of the Niger delta. fills the gap for earth scientists and those working in the oil and gas industry.