Depleted hydrocarbon reservoirs are one of the main types of geological structure suitable for permanent storage of CO2. The Stage 1 project verified the fundamental science of CO2 storage in Australia and further validated the technology globally.

What was involved in Otway Stage 1

CO2CRC injected approximately 65,000 tonnes of CO2 -rich gas (Buttress gas) into the 25m thick Waarre Unit C sandstone within the depleted Naylor natural gas field at a depth of 2,000m in the Otway Basin, Victoria Australia. 

Buttress gas, containing tracers to track dispersion and diffusion, was injected through injection well CRC-1 located at the flank of the reservoir at a rate of approximately 120 tonnes per day for 18 months. As modelled, the injected gas migrated up-dip to accumulate at the crest of the reservoir below the Flaxman formation (regional top seal). The Naylor-1 well, a legacy well on the structure (suspended gas producer) and located at the crest of the reservoir was used as the monitoring well. U-tubes were used to obtain downhole fluid samples during and after the injection and provided a direct measurement of storage efficiency.

Assurance monitoring included surveillance of the atmosphere, soil gas and shallow groundwater. To date, no tracer compounds have been detected above background levels in samples taken as part of the assurance monitoring program.

What did the project deliver

This research demonstrated that the CO2 can be safely stored and monitored in reservoirs that previously contained hydrocarbons. The research:

  • Confirmed that modelling predictions for the storage project were reliable.
  • Verified the fundamental science of CO2 storage in underground reservoirs.
  • Validated a workflow for CO2 storage at field scale.
  • Validated technologies utilised to monitor CO2 storage sites (both deep and assurance monitoring), including tracer injections, pressure monitoring, U-tube fluid sampling, atmospheric measurement, etc.
  • Demonstrated that added gas tracers, including deuterated methane, krypton and sulphur hexafluoride can be successfully used to label stored CO2 for both monitoring and reservoir characterisation.
  • Established groundwater surveillance as useful in supporting the validation of safe storage of CO2.
  • Demonstrated the ability of re-purposing existing wells.
  • Showed that analyses of well fluids obtained using a U-tube sampling system at over two km depth can provide information on the composition of the stored CO2.
  • Provided over eight years of geochemical analyses of the stored CO2 plume.
  • Contributed to the development of regulatory frameworks for CO2 storage in Australia.

Resulting Publications

Cook P. J Geologically Storing Carbon, Learning from the Otway Project Experience, CSIRO Publishing 2014.
link to publication reference

Ashworth P, Rodriguez S and Miller A, Jenkins C, Case study of the CO2CRC Otway National Project, Energy Transformed Flagship, CSIRO, 2011.
link to publication reference

Underschultz, J., Boreham, C., Dance, T., Stalker, L., Freifeld, B., Kirste, D., Ennis-King, J., 2011. CO2 storage in a depleted gas field: An overview of the CO2CRC Otway Project and initial results. International Journal of Greenhouse Gas Control 5, 922-932.
link to publication reference

Jenkins C, 2013, Statistical aspects of monitoring and verification, International Journal of Greenhouse Gas Control 13, 215- 229.
link to publication reference

Boreham, C., Underschultz, J., Stalker, L., Kirste, D., Freifeld, B., Jenkins, C., Ennis-King, J., 2011. Monitoring of CO2 storage in a depleted natural gas reservoir: Gas geochemistry from the CO2CRC Otway Project, Australia. International Journal of Greenhouse Gas Control 5, 1039-1054.
link to publication reference

Dance T, Spencer L, and Xu J 2018 Geological characterisation of the CO2CRC Otway Project Site – What a difference a well makes. Link to poster.
link to publication reference

Dance T, A Workflow for Storage Site Characterisation: A Case Study from the CO2CRC Otway Project Site. Conference Presentation AAPG 2009 Hedberg Conference.
link to publication reference

Noble, R, Stalker, L, Wakelin S, Pejcic B, Leybourne M, Hortle A, Michal K; 2012, Biological monitoring of carbon capture and storage – A review and potential future developments. International Journal of Greenhouse Gas Control 10, 520 – 535.
link to publication reference

Sandrine Vidal-Gilbert, S, Tenthorey E,  Dewhurst, D, Ennis-King J, Hilli R, Geomechanical analysis of the Naylor Field, Otway Basin, Australia: Implications for CO2 injection and storage 2010, International Journal of Greenhouse Gas Control, Volume 4, Issue 5, 827-839.
link to publication reference

Sharma, S, Cook, P, Robinson S, Anderson, C. 2007, Regulatory challenges and managing public perception in planning a geological storage pilot project in Australia, International Journal of Greenhouse Gas Control, Volume 1, Issue 2, 247-252.
link to publication reference

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