Hydrocarbon Generation Potential of the ETA Zuma Coal Mines, Anambra Basin, Nigeria: Insight from OrganicPetrography

Abstract

The ongoing exploration at the ETA Zuma coal mine uncovers a large coal reserve with unassessed details concerning its hydrocarbon potential.  Thus, organic petrography characterization of sedimentary facies in the mine was carried out to determine the organic matter quantity, quality, and thermal maturity of the potential source rock in the area. The organic petrography method employed involves kerogen preparation for investigation of hydrocarbon potential following the routine palynological slide preparation for biostratigraphic study with slight modification. This involves the non-inclusion of the oxidation stage in the kerogen slide preparation. The results indicate that the kerogens (palynomorphs) show fair abundance and diversity with depth, especially for the claystone and coal. A quantitative-rich occurrence of pollens and spores was retrieved in some samples (depths 12.5-19.7 m, and 23.8 m) with a similar trend in the dinoflagellates recovery. This interval (12.5-23.8 m) which is composed of coal and claystones recorded a reasonable quantity of organic matter (from 20-27) that could generate hydrocarbon. Based on the palynomorph recovery, the study area has mainly Kerogen Type II and III characterized by terrestrial and marine source input. The intervals 12.5-18.8 m, 19.3 m, 19.7 m, 21.3-23.8 m which show yellow-brown and brown-coloured forms represent stages 2 and 3 on the Thermal Alteration Index (TAI) scale. This is an indication that the organic matter within the claystone and coal is thermally matured with source potential capable of generating both oil and gas.