Biomarker Characteristics of Crude Oil Blends from Some Flow-Stations in Bayelsa State, Nigeria

Three different crude oil samples from three crude oil flow stations in Bayelsa state, Nigeria, were chosen for this study and were used to analyze the geochemical characteristics such as thermal maturity, depositional environments, sources of organic matter and extent of biodegradation. The crude oil samples were separated into saturated hydrocarbons, aromatic hydrocarbons and polar compounds. The saturated hydrocarbons were determined by Agilent (HP) 5890 Series II gas chromatography equipped with a Flame Ionization Detector (California, USA). Ratios of the biomarkers pristane/phytane, Isoprenoids/n-alkanes and CPI were determined. The pristane/phytane ratio in the oils reflects that the oils originated mainly from a source rock with a significant terrestrial contribution deposited under oxic environment with high maturation level due to the high pr/ph ratio of the oils. The ph/n-C18 ratios of the oils were less than one (< 1.0) suggesting that the oils were non-biodegraded. The CPI values of the three crude oil samples were below 1.0 indicating that the crude oil samples can be described as matured.