Abstract
Changes in the physical properties of the supercritical CO2 (scCO2) reservoir rock is one of the most important factors in controlling the storage safety at a scCO2 sequestration site. According to recent studies, it is probable that geochemical reactions influence changes in the rock properties after a CO2 injection in the subsurface, but quantitative data that reveal the interrelationship of the factors involved and the parameters needed to evaluate the extent of scCO2-rock-groundwater reactions have not yet been presented. In this study, the potential for employing the surface roughness value (SRRMS) to quantify the extent of the scCO2 involved reaction was evaluated by lab-scale experiments. For a total of 150 days of a simulation of the scCO2-sandstone-groundwater reaction at 100 bar and 50 °C, the trends in changes in the physical rock properties, pH change, and cation concentration change followed similar logarithmic patterns that were significantly correlated with the logarithmic increase in the SRRMS value. These findings suggest that changes in surface roughness can quantify the extent of the geochemical weathering process and can be used to evaluate leakage safety due to the progressive changes in rock properties at scCO2 storage sites.
Highlights
Various CO2 capture and sequestration technologies have been developed to reduce CO2 emissions and the International Energy Agency (IEA) has announced that CO2 capture and sequestration (CCS) technology will cover 19% of the total CO2 reductions by 2050 [1,2,3,4,5,6]
The results showed that the physical properties of the sandstone changed rapidly within a few months due to the geochemical reaction with the injected CO2, but the rate decreased in a relatively short time, verifying that the physical property change of the CO2 reservoir rocks occurred faster than expected from previous research [56,57,58]
Such findings suggested the possibility that the geochemical reaction may generate further changes in the reservoir rock properties
Summary
Various CO2 capture and sequestration technologies have been developed to reduce CO2 emissions and the International Energy Agency (IEA) has announced that CO2 capture and sequestration (CCS) technology will cover 19% of the total CO2 reductions by 2050 [1,2,3,4,5,6]. Geological sequestration will be deeply considered to reduce CO2 emissions at low cost [7,8,9,10,11]. CO2 sequestration projects in the world have been successfully conducted [12,13,14,15], but some CO2 injection sites were found to be impractical, even though their site characterization, such as geophysical exploration, geo-structural investigation, and drilling core analysis, was thoroughly conducted [16,17].
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