Advanced Aspects of Crude Oils Correlating Data of Classical Biomarkers and Mass Spectrometry Petroleomics
2017
Santos, Jandyson Machado | Santos, Flávia Micaella Lemos | Eberlin, Marcos Nogueira | Wisniewski, Alberto
The complex geochemical characteristics of crude oils can provide important information on oil generation, such as the input of organic matter and their depositional environments, also supporting exploration, extraction, and production. This work reports the first organic geochemical evaluation of oils from the first commercial Brazilian onshore field (Carmópolis, Sergipe, Brazil) via both classical biomarkers and petroleomics data collected via ultrahigh-resolution and accuracy Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Gas chromatography/mass spectrometry (GC/MS) was used to characterize the oil composition in terms of n-alkane, isoprenoid, terpane, and sterane biomarkers, whereas either positive or negative electrospray ionization (ESI) and FT-ICR were used to profile the polar constituents of the oils. GC/MS revealed geochemical characteristics that classify the oil at different levels of thermal evolution and biodegradation. FT-ICR MS attributed molecular formulas to more than 3000 polar oil constituents, allowing geochemical parameters to be inferred mainly from the carbon number (Cn) and double bond equivalent (DBE) trends, along with the N and O₂ classes. The Dia27(S + R)/αααC₂₇(S + R), % C₂₈, and % C₂₉ parameters and S/(S + R)αααC₂₉, αββ(S + R)/αββ + ααα(S + R)C₂₉, and % C₂₇ biomarkers obtained from GC/MS were responsible to indicate similarity between samples, whereas N and O₂ classes provided the most distinction among the crude oil blends in terms of the level of biodegradation and thermal maturity.
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