Geochemical comparison of three oil families from the Gippsland Basin, SE Australia

Lian Jiang*, Simon C. George

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The biomarker and aromatic compounds, including polycyclic aromatic hydrocarbons (PAHs), in three oil families composed of 29 crude oils from the Gippsland Basin, SE Australia were studied using gas chromatography-mass spectrometry. Environment-related parameters, such as the Pr/Ph ratio and the gammacerane index, indicate that all the oils originated from a lacustrine/fluvial-deltaic environment with fresh water. Thermal maturity-related parameters, including aliphatic and aromatic maturity indicators (e.g. C29 sterane isomerisation parameters, alkylnaphthalene indices, and methylphenanthrene index), show that all the oils from the GA1 oil family have a similar thermal maturity in the peak-late oil window. However, oils from the GA2 and GB families vary in thermal maturity and are interpreted to be mixtures of less mature and more mature crude oils. Source-related biomarkers (e.g. isopimarane, labdane and phyllocladane) and PAHs (e.g. retene and oleanane-/ursane-/lupane-derived aromatic triterpenoids) suggest that the GA1 oils were mainly derived from source rocks rich in conifer-derived organic matter. The organic matter source of the GA2 and GB oil families included both angiosperms and gymnosperms, with a relatively stronger angiosperm contribution to the organic matter in the source rock(s) of the GB oils, based on the PAH analysis. Moreover, higher plant-derived triterpenoids can be effectively used to correlate oil families across the study area, supplementing the n-alkane carbon isotope and biomarker data of the three oil families reported previously.

Original languageEnglish
Article number104575
Pages (from-to)1-23
Number of pages23
JournalMarine and Petroleum Geology
Volume121
DOIs
Publication statusPublished - Nov 2020

Keywords

  • Angiosperm
  • Gymnosperm
  • Polycyclic aromatic hydrocarbon
  • Aromatic triterpenoids
  • Oil-oil correlation

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