• Open Access

Pore-scale imaging of geological carbon dioxide storage under in situ conditions

Authors

  • Matthew Andrew,

    Corresponding author
    1. Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, Imperial College London, London, UK
    • Corresponding author: M. Andrew, Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, South Kensington Campus, Imperial College London, London SW7 2AZ, UK. (m.andrew11@imperial.ac.uk)

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  • Branko Bijeljic,

    1. Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, Imperial College London, London, UK
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  • Martin J. Blunt

    1. Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, Imperial College London, London, UK
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Abstract

[1] While geological carbon dioxide (CO2) storage could contribute to reducing global emissions, it must be designed such that the CO2 cannot escape from the porous rock into which it is injected. An important mechanism to immobilize the CO2, preventing escape, is capillary trapping, where CO2 is stranded as disconnected pore-scale droplets (ganglia) in the rock, surrounded by water. We used X-Ray microtomography to image, at a resolution of 6.4 µm, the pore-scale arrangement and distribution of trapped CO2 clusters in a limestone. We applied high pressures and temperatures typical of a storage formation, while maintaining chemical equilibrium between the CO2, brine, and rock. Substantial amounts of CO2 were trapped, with an average saturation of 0.18. The cluster sizes obeyed a power law distribution, with an exponent of approximately −2.1, consistent with predictions from percolation theory. This work confirms that residual trapping could aid storage security in carbonate aquifers.

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