Econ. Environ. Geol. 2012; 45(6): 661-672

Published online December 31, 2012

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Study on the Dissolution of Sandstones in Gyeongsang Basin and the Calculation of Their Dissolution Coefficients under CO2 Injection Condition

Hyunmin Kang1, Kyoungbae Baek1, Sookyun Wang2, Jinyoung Park3 and Minhee Lee1*

1Department of Earth Environmental Sciences, Pukyong National University, Busan, 608-737, Republic of Korea
2Department of Energy Resources Engineering, Pukyong National University, Busan, 608-737, Republic of Korea
3Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources

Correspondence to :

Minhee Lee

heelee@pknu.ac.kr

Received: September 5, 2012; Accepted: November 24, 2012

Abstract

Lab scale experiments to investigate the dissolution reaction among supercritical CO2-sandstone-groundwater by using sandstones from Gyeongsang basin were performed. High pressurized cell system (100 bar and 50oC) was designed to create supercritical CO2 in the cell, simulating the sub-surface CO2 storage site. The first-order dissolution coefficient (kd) of the sandstone was calculated by measuring the change of the weight of thin section or the concentration of ions dissolved in groundwater at the reaction time intervals. For 30 days of the supercritical CO2-sandstone-groundwater reaction, physical properties of sandstone cores in Gyeongsang basin were measured to investigate the effect of supercritical CO2 on the sandstone. The weight change of sandstone cores was also measured to calculate the dissolution coefficient and the dissolution time of 1 g per unit area (1 cm2) of each sandstone was quantitatively predicted. For the experiment using thin sections, mass of Ca2+ and Na+ dissolved in groundwater increased, suggesting that plagioclase and calcite of the sandstone would be significantly dissolved when it contacts with supercritical CO2 and groundwater at CO2 sequestration sites. 0.66% of the original thin section mass for the sandstone were dissolved after 30 days reaction. The average porosity for C sandstones was 8.183% and it increased to 8.789% after 30 days of the reaction. The average dry density, seismic velocity, and 1-D compression strength of sandstones decreased and these results were dependent on the porosity increase by the dissolution during the reaction. By using the first-order dissolution coefficient, the average time to dissolve 1 g of Band C sandstones per unit area (1 cm2) was calculated as 1,532 years and 329 years, respectively. From results, it was investigated that the physical property change of sandstones at Gyeongsang basin would rapidly occur when the supercritical CO2 was injected into CO2 sequestration sites.

Keywords CO2 sequestration, supercritical CO2, Gyeongsang basin, geochemical reaction, sandstone dissolution

Article

Econ. Environ. Geol. 2012; 45(6): 661-672

Published online December 31, 2012

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Study on the Dissolution of Sandstones in Gyeongsang Basin and the Calculation of Their Dissolution Coefficients under CO2 Injection Condition

Hyunmin Kang1, Kyoungbae Baek1, Sookyun Wang2, Jinyoung Park3 and Minhee Lee1*

1Department of Earth Environmental Sciences, Pukyong National University, Busan, 608-737, Republic of Korea
2Department of Energy Resources Engineering, Pukyong National University, Busan, 608-737, Republic of Korea
3Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources

Correspondence to:

Minhee Lee

heelee@pknu.ac.kr

Received: September 5, 2012; Accepted: November 24, 2012

Abstract

Lab scale experiments to investigate the dissolution reaction among supercritical CO2-sandstone-groundwater by using sandstones from Gyeongsang basin were performed. High pressurized cell system (100 bar and 50oC) was designed to create supercritical CO2 in the cell, simulating the sub-surface CO2 storage site. The first-order dissolution coefficient (kd) of the sandstone was calculated by measuring the change of the weight of thin section or the concentration of ions dissolved in groundwater at the reaction time intervals. For 30 days of the supercritical CO2-sandstone-groundwater reaction, physical properties of sandstone cores in Gyeongsang basin were measured to investigate the effect of supercritical CO2 on the sandstone. The weight change of sandstone cores was also measured to calculate the dissolution coefficient and the dissolution time of 1 g per unit area (1 cm2) of each sandstone was quantitatively predicted. For the experiment using thin sections, mass of Ca2+ and Na+ dissolved in groundwater increased, suggesting that plagioclase and calcite of the sandstone would be significantly dissolved when it contacts with supercritical CO2 and groundwater at CO2 sequestration sites. 0.66% of the original thin section mass for the sandstone were dissolved after 30 days reaction. The average porosity for C sandstones was 8.183% and it increased to 8.789% after 30 days of the reaction. The average dry density, seismic velocity, and 1-D compression strength of sandstones decreased and these results were dependent on the porosity increase by the dissolution during the reaction. By using the first-order dissolution coefficient, the average time to dissolve 1 g of Band C sandstones per unit area (1 cm2) was calculated as 1,532 years and 329 years, respectively. From results, it was investigated that the physical property change of sandstones at Gyeongsang basin would rapidly occur when the supercritical CO2 was injected into CO2 sequestration sites.

Keywords CO2 sequestration, supercritical CO2, Gyeongsang basin, geochemical reaction, sandstone dissolution

    KSEEG
    Jun 30, 2024 Vol.57 No.3, pp. 281~352

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