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The potential for CO2 storage in residual oil zones in onshore Australian basins

Created 16/10/2025

Updated 16/10/2025

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We have investigated whether water-saturated residual oil zones (ROZs), sometimes associated with conventional Australian hydrocarbon plays, could provide a CO2 storage resource and supplement depleted field storage.

Our petrophysical study demonstrates that ROZs occur in Australia’s hydrocarbon-rich regions, particularly in the Cooper-Eromanga Basin. ROZs with more than 10% residual oil saturation are uncommon, likely due to small original oil columns and lower residual saturations retained in sandstone reservoirs than in classic, carbonate-hosted North American ROZs. Extensive, reservoir-quality rock is found below the deepest occurring conventional oil in many of the fields in the Eromanga Basin, potentially offering significant CO2 storage capacity.

Multiphase compositional flow modelling was used to estimate the CO2 storage efficiency of typical Australian ROZs. We developed a novel modelling methodology that first captures oil migration events leading to the formation of ROZs. Modelling CO2 storage over a 20-year injection period demonstrates that CO2-oil interactions increase the density and viscosity of CO2, enhancing CO2 sweep efficiency and lateral flow, improving storage efficiency. The extent of these effects depends on the quantity and spatial distribution of residual oil in place and the miscibility of CO2 at reservoir conditions.

Presented at the Australian Energy Producers (AEP) Conference & Exhibition (https://energyproducersconference.au/conference/)

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Field Value
Title The potential for CO2 storage in residual oil zones in onshore Australian basins
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/d48c3218-f7ec-47c4-8044-e6164f06ba13
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 17/06/2024
Geospatial Coverage
Map data © OpenStreetMap contributors
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Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "The potential for CO2 storage in residual oil zones in onshore Australian basins". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/the-potential-for-co2-storage-in-residual-oil-zones-in-onshore-australian-basins