Geochemical Assessment of the Biodegradation Levels of Some Crude Oils from Bayelsa State, Nigeria

Coastal swamp crude oil samples obtained from Clough creek, Azuzuama and Tebidaba oil fields were analyzed to obtain their biodegradation rankings. The studied samples were fractionated by column chromatography into saturated and aromatic hydrocarbons. The saturated hydrocarbons were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Some diagnostic ratios such as C30αβhopane/(Pr+Ph), (Pr+Ph)/(nC17+nC18) and C29αβ25norhopane/C30αβhopane were used in assessing the biodegradation rankings. Though biodegradation was evident in the studied samples, their individual levels were compared based on these ratios. Assessment of the crude oil samples using C29αβ25norhopane/C30αβhopane ratio show that the oils from AZU ST and TEB12 are more degraded when compared to oils from WELL 2. Consequently, (Pr+Ph)/ (nC17+nC18) ratios show that TEB 12 is the most degraded while WELL 2 is the least degraded. AZU ST was also shown as the most degraded oil using C30αβhopane/(Pr+Ph) diagnostic ratio.