eScript used in geosequestration project
Injecting compressed carbon dioxide gas (C02) deep underground in a process called geosequestration could potentially be one approach to reducing it in the atmosphere. It is already being implemented in several countries including Germany, USA and Canada; and investigated at CO2CRC’s Otway research facility, Australia’s first demonstration of the deep geological storage of CO2.
An extremely important aspect of geosequestration is monitoring the injected CO2 to ensure that it stays within the porous rock zone as anticipated. Dr Andrea Codd and her team from The University of Queensland have turned their expertise and eScript code to simulate how supercritical CO2 fluid infills porous rock space at the CO2CRC project and model the geophysical signatures it creates.
NCRIS-enabled eScript code, developed by AuScope’s Simulation, Analysis and Modelling team based at The University of Queensland, has been an integral part of a new workflow to monitor injection of CO2 at CO2CRC’s Otway research facility, which has been operational since 2003. Essentially, it has helped the CO2CRC research team understand how to monitor injection projects using gravity and electrical sensors.
Andrea was funded by the Carbon Capture and Storage Research Development and Demonstration Fund (CCSRDDF) to help determine where gravity and electrical sensors could be placed to detect differences to gravity, electrical potential and electrical field in order to devise plausible monitoring strategies.
eScript’s role in this project was to determine if‚ using measurement changes only — the plume could be detected using a process called inversion. These methods use limited localised data, in this case, gravity differences and changes to electrical potential at a small number of locations, to predict properties encompassing the entire burial site.
Dr Andrea Codd explains that outcomes from inversion are not exact, as the number of measurements is much less than the number of unknowns:
“Inversion solutions are just the best possible solution given specific restrictions and assumptions.”
Prof Stephan Matthai and his team from the University of Melbourne produced a detailed ground map incorporating rock properties, layers and faults. Next, they ran simulations of supercritical CO2 fluid injected into an aquifer layer predicting plume evolution. With these results combined, Andrea was then able to use eScript to determine the impact of the plume on rock density and electrical conductivity.
The team found that changes in electrical conductivity could be used to find the plume when the plume was small, and for larger plumes, density changes associated with the plume could be identified in the gravity field.
Dr Andrea Codd comments on this project and next steps:
“Inversion methods are an excellent way of looking beneath the ground and are clearly more reliable if they incorporate extensive and detailed ground models demonstrated in this project. Next, our team will focus on developing new inversion methods that are faster and can solve bigger problems using gravity, magnetotelluric and seismic data.”
Andrea would like to thank Prof Stephan Matthai from the University of Melbourne who ran the simulations in this project using his code, Australian Subsurface Carbon Sequestration Simulator (ASCSS), and As Prof Lutz Gross from The University of Queensland and the CO2CRC team for project support.
AUTHORS
By Dr Andrea Codd (The University of Queensland) and Jo Condon (AuScope)
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please email Dr Andrea Codd