Analysis and Identification of Biomarkers and Origin of Color in a Bright Blue Crude Oil

Abstract

We describe the detailed analysis and characterization of an unusual blue crude oil and a deposit from the monoethylene glycol (MEG) regeneration unit (MRU) on an offshore crude oil production platform. To characterize the deposit and the components in the crude oil that give it such a distinct blue hue, we investigated the samples with comprehensive two-dimensional gas chromatography (GC × GC), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and two-dimensional (2D) fluorescence spectroscopy. Perylene, a polycyclic aromatic hydrocarbon, known to fluoresce, was identified in the crude oil with all three of these techniques. On the basis of its photochemical properties and abundance (55 ppm), we infer perylene to be the most likely source of the blue color. In addition, we were able to conclusively identify by GC × GC a suite of pentacyclic triterpenoids, of which the most abundant species was 17α(H),21β(H)-25-norhopane. The deposit is greatly enriched in these species. The presence of 25-norhopanes in a crude oil is considered as an indication for severe biodegradation.