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Pore‐scale imaging of geological carbon dioxide storage under in situ conditions
Author(s) -
Andrew Matthew,
Bijeljic Branko,
Blunt Martin J.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50771
Subject(s) - carbon dioxide , percolation theory , porous medium , saturation (graph theory) , trapping , brine , carbonate , materials science , mineralogy , power law , chemical physics , aquifer , porosity , environmental science , geology , chemistry , groundwater , thermodynamics , composite material , geotechnical engineering , physics , ecology , mathematics , statistics , organic chemistry , combinatorics , metallurgy , conductivity , biology
While geological carbon dioxide (CO 2 ) storage could contribute to reducing global emissions, it must be designed such that the CO 2 cannot escape from the porous rock into which it is injected. An important mechanism to immobilize the CO 2 , preventing escape, is capillary trapping, where CO 2 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 CO 2 clusters in a limestone. We applied high pressures and temperatures typical of a storage formation, while maintaining chemical equilibrium between the CO 2 , brine, and rock. Substantial amounts of CO 2 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.