PHYSICO-CHEMICAL CHARACTERISATION OF BITUMEN DEPOSITS IN AGBABU ENVIRONS, SOUTHWESTERN NIGERIA

Abstract

Nigeria ranks globally among the nations with largest natural bitumen reserves with a proven reserve of roughly 42.47 billon tonnes. The solid hydrocarbon resource is reservoired in Cretaceous siliciclastic deposits of Dahomey Basin with significant surface expressions as bituminous sands and seepages in many localities in southwestern Nigeria, including Agbabu and its environs. Organic geochemical and physiochemical analyses of bitumen samples from Agbabu was undertaken with the aim of determining the physical properties and hydrocarbon potentials. Analytical results shows that the density of the bitumen ranging from 0.61 to 1.011g/cm3, specific gravity of 1.04 g/cm3, flash and fire point of 170 to 1750C and pour point of 44 and 47 0C respectively. The Total Organic Carbon (T.O.C) Content values for the samples range from 0.34 to 0.83 wt.% with an average T.O.C value of 0.55wt% which is slightly higher than the 0.5 wt. % minimum threshold for a potential petroleum source rock. The Soluble Organic Matter (S.O.M) of the samples generally exceeds 5000 p.p.m for all samples with Soluble Organic Matter (S.O.M) values ranging from 1530 to 17306 ppm which classify the bitumen in the area as moderately rich for hydrocarbon generation. Deductions on data obtained from the study on bitumen indicates that both surface and subsurface natural bitumen deposits in Agbabu and its environs can be mined at profit for the benefit of mankind if appropriate technologies are deployed.