Niger Delta Petroleum Systems: Inferences from Light Hydrocarbons Geochemistry

Akinsehinwa Akinlua¹, T. R. Ajayi¹, and B. B. Adeleke^2
1 Obafemi Awolowo University, Ile-Ife, Nigeria
² University of Ibadan, Ibadan, Nigeria

Some Niger Delta oils were analyzed for the light hydrocarbons contents using whole oil gas chromatography, to evaluate the influence of light hydrocarbons on the petroleum systems of the Niger Delta. Cross plot of K1 versus K2 calculated from ratios of light hydrocarbons revealed two main groups of oils, which is a reflection of post generative alterations. The plot of Toluene/n-heptane and n-heptane/methylcyclohexane showed that two of the oil samples were fractionated whilst other are pristine. This plot also indicates that two of the oil samples have migrated short distance to their present accumulation whilst others have migrated long distance to accumulate at their present sites. Polar plot based on the ratios of labile light hydrocarbons to a stable light hydrocarbon showed different patterns, which is due to post generative transformation. The results of this study suggest that light hydrocarbon distribution patterns can be understood in terms of genetic origin and post accumulation alterations, which have strong influence on the petroleum systems of the basin.