Reconstructing the Age of Formation of some Crude Oil samples from the Niger Delta Basin using Biomarker Fingerprinting

Abstract

The Niger Delta Basin is a prolific petroleum province and is currently the only basin in which commercial petroleum production strives in Nigeria. The Niger Delta Basin has received a lot of research attention but with fewer studies regarding the reconstruction of the age of source rocks from their crude oils using biomarkers. The study aimed at reconstructing the age of the Niger Delta source rocks from crude oils samples from the Basin. The age determination of the sample set was attempted by looking at individual age-specific biomarkers that suggested a source age as well as looking at them together to have a clearer indication of the likely source age. Thirteen (13) crude oil samples from the “Y” Field of the Niger Delta Basin were subjected to Gas Chromatography-Mass Spectrometer analysis. The biomarkers used in this study were; oleanane index (OI), C28/ C29 ratio, C30 /(C27-C30) ratio, and Pr/Ph (pristane/phytane) ratio, with corresponding mean values of 1.08, 0.76, 0.28, and 1.12 respectively. The biomarker data based on some age-specific biomarkers, both individually and especially when used together, suggests a Tertiary age for the source rock that generated the crude oils. These results are based on the occurrences of oleanane, Pr/Ph ratios, and the high C28/C29 ratios, all indicating Tertiary age source rock.