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Evidence for a Permian petroleum system in the Timor Sea region, northwestern Australia

Created 16/10/2025

Updated 10/01/2026

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Petroleum exploration in the Timor Sea region, Bonaparte Basin, has focussed on plays that are charged and sealed by Mesozoic sediments. However, there is increasing evidence that Palaeozoic oil and gas have contributed to the hydrocarbons found in this area. Geochemical appraisal of the palaeo-oil column at Torrens-1 on the Londonderry High, the gas/condensate reserves in the Petrel and Tern fields in the Petrel Sub-basin, and the gas accumulation at Kelp Deep-1 on the Sahul Platform in the Zone of Co-operation, have revealed that these hydrocarbons are most likely generated from organic-rich Permian sediments.

Oil stains and fluid inclusion oil from the Permian Highland Bay and Fossil Head formations at Torrens-1 have similar biomarker compositions indicating a terrestrial source affinity. Carbon isotope values from bulk and compound-specific analyses show that the Fossil Head-reservoired oil is enriched in 13C (13Csat=-26.1 ‰). Despite having lost its lower molecular weight hydrocarbons, the n-alkane isotope profile exhibits a strong negative slope and is similar to the Petrel and Tern condensates reservoired in the Hyland Bay Formation. Onshore in the Petrel Sub-basin, Weaber-4 oil has an isotopic signature enriched in 13C, as observed at Petrel and Tern. These data are distinct from those of the Carboniferous-sourced Barnett/Turtle oils (offshore Petrel Sub-basin) which have  13Csat values in the order of -28 ‰.

Dry gas from Kelp Deep-1 in the Hyland Bay Formation has an isotopic composition in keeping with generation from land-plant-rich source rocks, and its stratigraphic and structural position is suggestive of a Permian origin.

Presented at the 2000 AAPG International Conference and Exhibition, Bali

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Field Value
Title Evidence for a Permian petroleum system in the Timor Sea region, northwestern Australia
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/6980e5f2-4e6c-4871-8170-d22ced2bbea2
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/11/2025
Geospatial Coverage
Map data © OpenStreetMap contributors
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Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Evidence for a Permian petroleum system in the Timor Sea region, northwestern Australia". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/evidence-for-a-permian-petroleum-system-in-the-timor-sea-region-northwestern-australia