Niger Delta oil geochemistry: Insight from light hydrocarbons

A suite of oil samples from an onshore–swamp field in the northwestern Niger Delta was analyzed using whole oil gas chromatography. The oil samples were analyzed to correlate the oils and to evaluate post generative alterations using light hydrocarbons. Light hydrocarbon based parameters were compared with higher molecular weight hydrocarbon correlation based parameters. Two distinct oil groups were identified based on light hydrocarbon parameters, which agreed with the correlation based on higher molecular weight hydrocarbon parameters. The discrimination of the two groups is a reflection of post generative alteration–biodegradation. The study showed that light hydrocarbon distribution has strong influence on evaporative fractionation of the oils. It also revealed that the process that initiates biodegradation has significant influence on carbocyclic ring closure.