Source, depositional environment and maturity levels of some crude oils in southwest Niger Delta, Nigeria

A suite of crude oil samples, that had not been previously characterized geochemically, was collected from two oil fields in the southwest Niger Delta Nigeria. The saturate biomarkers were used to evaluate geochemical characteristics such as depositional environments, sources of organic matter and extent of biodegradation using gas chromatography–flame ionization detector and gas chromatography–mass spectrometry. Distribution of n-alkanes (Pr/Ph, and isoprenoide/n-alkanes ratios), the abundance of hopanes, oleanane skeleton and C27–C29 steranes in the oils indicate that they were formed from mixed sources (marine and terrestrial kerogen) deposited in an oxic paleoenvironment with no particular maturity trend. These parameters also permit the source grouping of the oils into two families. © 2015, Science Press, Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg.