Abstract
Laboratory experiments were performed to measure the supercritical CO2 (scCO2) storage ratio (%) of conglomerate and sandstone in the Janggi Basin, which are classified as rock in Korea that are available for CO2 storage. The scCO2 storage capacity was evaluated by direct measurement of the amount of scCO2 replacing the pore water in each reservoir rock core. The scCO2 sealing capacity of the cap rock (i.e., tuff and mudstone) was also compared by measuring the scCO2 capillary entry pressure (Δp) into the rock core. The measured average scCO2 storage ratio of the conglomerate and the sandstone were 30.7% and 13.1%, respectively, suggesting that the scCO2 storage capacity was greater than 360,000 metric tons. The scCO2 capillary entry pressure for the tuff ranged from 15 to 20 bar and for the mudstone it was higher than 150 bar, suggesting that the mudstone layers had enough sealing capacity from the aspect of hydromechanics. From XRF analyses, before and after 90 d of the scCO2-water-cap rock reaction, the mudstone and the tuff were investigated to assure their geochemical stability as the cap rock. From the study, the Janggi Basin was considered an optimal CO2 storage site based on both its high scCO2 storage ratio and high capillary entry pressure.
Highlights
Eco-friendly plans and policies to reduce CO2 emission are being driven forward around the world.In developed countries, CO2 capture and sequestration (CCS) technology is partially commercialized and the total amount of subsurface CO2 storage has been on the rise [1,2,3,4]
The Noeseongsan block contains rudaceous sandstone and conglomerate layers that are considered promising for CO2 storage sites more than 800 m deep; these have mudstone and dacitic tuff layers above them that are able to serve as stable shield layers [8,9]
The Korean government has a plan to inject a hundred thousand metric tons of CO2 in a pilot-scale onshore CO2 storage test site in 2030 and the Janggi Basin is considered a suitable place for the supercritical CO2 (scCO2) storage test site
Summary
Eco-friendly plans and policies to reduce CO2 emission are being driven forward around the world. The best way to determine the amount of scCO2 storage possible in a specific rock formation is direct measurement of scCO2 displacement of water under scCO2 injection conditions This occurs using rock cores at a laboratory scale, from which the results are extended to macro scale, including the entire reservoir formation [21,22]. Laboratory experiments were performed to measure the amount of scCO2 displacing water from the pore spaces of the sandstones and conglomerate cores sampled from 800–1000 m depth in the Janggi Basin, which is classified as an available CO2 storage reservoir in Korea. From the experimental results on the scCO2 storage ratio for the reservoir rock, on the initial scCO2 capillary entry pressure for the cap rock, and from mineralogical analyses for rock cores, the feasibility of the Janggi Basin as an available pilot-scale CO2 storage test site where a hundred thousand metric tons of CO2 could be injected was evaluated. The results of this study will provide ideas for further quantitative research about the CO2 storage capacity and CO2 leakage safety based on practical measurements of the scCO2 storage ratio and initial scCO2 capillary entry pressure
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