Palynofacies and Thermal Maturity Studies of Kudu-3 Well, Northern/Central Bida Basin, Nigeria

Abstract

Petroleum prospection in the Bida Basin is still in its initial stage of exploration. Palynofacies and thermal maturation studies are key parameter for early basin evaluation by improving exploration success and understanding of the potential hydrocarbon source rock. The purpose of this study is to carry out palynofacies characterization of the sediments retrieved from Kudu-3well, Northern/Central Bida Basin, to determine the sediment maturity. These were accomplished by processing 19 ditch cutting samples within the depth interval of 31 – 58 m using acid maceration technique. Microscopic analysis of both palynological and palynofacies slides yielded diverse pollen, spores, dinoflagellate and palynomacerals. The palynomaceral types recovered include 51% of dark brown to orange, brown structureless resinous cortex material of palynomaceral 1, 32% of brown to orange platy like structured plant materials of palynomaceral 2, 14% of pale-coloured small to medium-sized stomata bearing plant materials of palynomaceral 3 and 3 % of black equant needle shaped plant materials of palynomaceral 4. Thermal maturation was determined from microscopic observation of exine wall colour of the palynomorph and the palynomacerals, which range from orange-brown, light-brown, and light-medium brown to dark brown. The estimated values for thermal alteration index (TAI), vitrinite reflectance (%Ro) and burial temperature extrapolated from correlation of the observed palynomorphs/palynomacerals colour changes with other calibrated scale yielded 3/4–5 TAI, 0.55–0.95% and 60–120℃ respectively. These values indicate early mature to mature stage of petroleum generation. The abundance records of palynomacerals 1, 2 and 3, and terrestrial palynomorphs in the studied section are an indication of more gas prone than oil. This work suggests possible potential of hydrocarbon accumulation in the Bida Basin and that the Enagi Siltstone is a potential hydrocarbon source rock.