Published Article

Geochemical Study of oil extracts from Oben (OB), Okpoho (OK) and Qua Iboe (QIT) crudes from Niger Delta was carried out. Elution liquid chromatography, gas chromatography – mass spectrometry, gas chromatography–flame ionization detector, atomic absorption spectroscopy, X-ray florescence spectroscopy,ultraviolet-visible spectroscopy and statistical methods were used to analyse the oils based on some hydrocarbon diagnostic ratios and cross-plots as parameters. Analysis of the oil samples revealed that the concentrations of the saturates, aromatics and biomarkers present varied tremendously from one oil to the other. Some diagnostic ratios and cross-plots used classified the oils produced into oxicand transitional environments of deposition with terrestrial organic input. Pristane to plytane ratio (Pr/Ph) for OB, OK and QIT were 3.74, 2.84 and 1.66 indicating that OB was derived from more oxidizing depositional environment and a typical of oil mainly from coastal swamp, while OK and QIT were deposited in a less oxidizing environment and typical of oils derived from fluviomarine source. Pristine to nC17 (pr/nC17) values for OB, OK and QIT were 0.62, 0.83 and 0.95 while phytane to nC18 (phy/nC18) values were 0.16, 0.31 and 0.68 respectively, showing that the oil were non-biodegradable. A cross-plot of pr/nC17 versus ph/nC18 classified the oil into transitional (marine and terrestrial) environment. The monoaromaticsterane and triaromaticsterane values were 0.56, 0.49, 0.55 and 0.53, 0.47, 0.77 for OB, OK and QIT respectively indicating that the oils were resistance to biodegradation. Anthracene to anthracene plus phenanthrene ratio for OB, OK and QIT were 0.47, 0.46 and 0.46 revealing the origin of polycyclic aromatic hydrocarbon as autochthonous sources of hydrocarbons. Statistical analysis of geochemical data and oil locations revealed that they were reliable tools for characterization and correlations of the oils.