Abstract

TOMAS, Germán Javier; VARGAS, Walter  and  ACUNA, Adrián Javier. Crude oils from Austral and Golfo San Jorge Basins. Similarity and differences based on biomarker ratios. Dyna rev.fac.nac.minas [online]. 2021, vol.88, n.216, pp.62-68.  Epub May 24, 2021. ISSN 0012-7353.  https://doi.org/10.15446/dyna.v88n216.86210.

Biomarker profiles are characteristic of oils. The goal of this study was to evaluate the biomarkers in oil samples using geochemical analysis. Oil samples were obtained from Austral Basin and Golfo San Jorge Basins. Specifically, aliphatic and aromatic fractions were analyzed by Gas Chromatography coupled to Mass Spectrometry. Biomarker ratios were calculated for isoprenoids, terpanes and steranes to correlate the organic matter precursor, deposition environment and source rock to differentiate distinct crude oil sources. Based on the specific parameters, crude from the Austral Basin appears to have been generated from organic matter types II-III (mixed), in deposition environments with moderate oxygen concentration, associated with a siliciclastic lithology and a moderate to high thermal maturity. On the contrary, the crude oils from the Golfo San Jorge Basin displayed biomarkers profiles characteristics of a type II (marine) kerogen, corresponding to an anoxic deposition environment, carbonated lithology and low thermal maturity.

Keywords : deposition environment; thermal maturity; organic material; mother rock lithology.

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