Distribution of methylhopanes in some Niger Delta oils

Abstract

A suite of oil samples from Niger Delta oil fields were examined for compositional distribution of methylhopane. The samples were obtained from wellhead of oil wells and stored in sample bottles. The oil samples were fractionated and the saturate fraction was subjected to gas chromatography/mass spectrometry (GC–MS) analysis. The methylhopanes in the oils were identified, their abundance delineated, and are of potential use for oil characterization. The mass chromatograms of m/z 205 were extracted and the peaks identified using GC–MS library, literature, and mass spectra form the library. 2α–Methylhopanes and 3β–methylhopanes were identified in Nigerian Niger Delta oils. North Sea and Venezuelan Boscan oil were also examined. Generally, the Nigerian oils showed higher abundance of 2α–methylhopanes and lower abundance 3β–methylhopanes compared to the Boscan and North Sea oils. The plot of C30 hopane/C30 2α–methylhopane and C30 hopane/C30 3β–methylhopane for all the oils showed the discrimination of the oils into Niger Delta, North Sea, and Venezuelan Boscan oil. The ratio of C30 hopanes/methylhopanes can be applied as a correlation tool.