• Economic and Environmental Geology
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• v.55 no.5
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• pp.477-495
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• 2022

This study examined the sustainability of CO₂-rich water by analyzing the water level and water quality change pattern with the amount of its use in Angseong area, Chungju. The origin and supply of CO₂ component were discussed in consideration of ⁸⁷Sr/⁸⁶Sr ratio, occurrence of CO₂-rich fluid inclusions in nearby W-Mo deposits and other surrounding geological characteristics. According to the data from 1986 to 2017, the depth of the water level of CO₂-rich water was significantly lowered in the late period (2009-2015) than in the early period (1986-1992) of the development of hot spa wells, and the optimal yields for pumping tests also showed a tendency to gradual decrease. Concentrations of CO₂ component also decreased continuously in the later stages compared to the early stages of development, but it has been stable since 2012. It is inferred that the geological environment related to forming W-Mo quartz vein deposits (0.5×1.5×several km) around the study area are largely involved in the origin and supply of CO₂ component, and the supply of CO₂ component is not infinitely supplied from deep current magma activity. Rather, since it is finitely supplied from a restricted subsurface region formed in the past geological period, it is necessary to efficiently control its use in order to maintain the sustainability of CO₂-rich water in the study area.

• Journal of Soil and Groundwater Environment
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• v.21 no.1
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• pp.49-60
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• 2016

Distribution and behavior of baseline soil CO₂ were investigated in a candidate geologic CO₂ storage site in Pohang, with measuring CO₂ concentrations and carbon isotopes in the vadose zone as well as CO₂ fluxes and concentrations through ground surface. This investigation aimed to assess the baseline CO₂ levels and to build the CO₂ monitoring system before injecting CO₂. The gas in the vadose zone was collected using a peristaltic pump from the depth of 60 cm below ground surface, and stored at gas bags. Then the gas components (CO₂, O₂, N₂, CH₄) and δ¹³C_CO2 were analyzed using GC and CRDS (cavity ringdown spectroscopy) respectively in laboratory. CO₂ fluxes and CO₂ concentrations through ground surface were measured using Li-COR in field. In result, the median of the CO₂ concentrations in the vadose zone was about 3,000 ppm, and the δ¹³C_CO2 were in the wide range between −36.9‰ and −10.6‰. The results imply that the fate of CO₂ in the vadose zone was affected by soil property and vegetations. CO₂ in sandy or loamy soils originated from the respiration of microorganisms and the decomposition of C₃ plants. In gravel areas, the CO₂ concentrations decreased while the δ¹³C_CO2 increased because of the mixing with the atmospheric gas. In addition, the relation between O₂ and CO₂, N₂, and the relation between N₂/O₂ and CO₂ implied that the gases in the vadose zone dissolved in the infiltrating precipitation or the soil moisture. The median CO₂ flux through ground surface was 2.9 g/m²/d which is lower than the reported soil CO₂ fluxes in areas with temperate climates. CO₂ fluxes measured in sandy and loamy soil areas were higher (median 5.2 g/m²/d) than those in gravel areas (2.6 g/m²/d). The relationships between CO₂ fluxes and concentrations suggested that the transport of CO₂ from the vadose zone to ground surface was dominated by diffusion in the study area. In gravel areas, the mixing with atmospheric gases was significant. Based on this study result, a soil monitoring procedure has been established for a candidate geologic CO₂ storage site. Also, this study result provides ideas for innovating soil monitoring technologies.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.42-52
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• 2013

Carbon Capture and Storage (CCS) is a mitigation technology essential in tackling global climate change. In Korea, many research projects are aimed to commercialize CCS business around 2020. Public acceptance can be a key factor to affect the successful proceeds of CCS near future. Therefore this paper provides a concise insight into the application of environmental impact assessment and risk assessment procedures to support the sustainable CCS projects. Futhermore, bottlenecks regarding the environmental impacts assessment and related domestic and foreign legislation are revised. Finally, suggestions to overcome these bottlenecks and recommendations for future research are made in conclusion.

• Journal of Soil and Groundwater Environment
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• v.21 no.3
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• pp.35-48
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• 2016

A micromodel was applied to estimate the effects of geological conditions and injection methods on displacement of resident porewater by injecting scCO₂ in the pore scale. Binary images from image analysis were used to distinguish scCO₂-filled-pores from other pore structure. CO₂ flooding followed by porewater displacement, fingering migration, preferential flow and bypassing were observed during scCO₂ injection experiments. Effects of pressure, temperature, salinity, flow rate, and injection methods on storage efficiency in micromodels were represented and examined in terms of areal displacement efficiency. The measurements revealed that the areal displacement efficiency at equilibrium decreases as the salinity increases, whereas it increases as the pressure and temperature increases. It may result from that the overburden pressure and porewater salinity can affect the CO₂ solubility in water and the hydrophilicity of silica surfaces, while the neighboring temperature has a significant effect on viscosity of scCO₂. Increased flow rate could create more preferential flow paths and decrease the areal displacement efficiency. Compared to the continuous injection of scCO₂, the pulse-type injection reduced the probability for occurrence of fingering, subsequently preferential flow paths, and recorded higher areal displacement efficiency. More detailed explanation may need further studies based on closer experimental observations.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.259-272
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• 2004

The purpose of this study is to investigate the effect of hydrochemical variation of groundwater on the gas tigtness in an unlined oil storage cavern. The groundwater chemistry is greatly influenced by the seawater mixing, the water curtain and the dissolution of grounting cements. The chemical composition of groundwater greatly varies ac-cording to both the location of monitoring wells and the sampling period. Most of groundwater shows alkaline pH and high electrical conductivity. The chemical types of groundwater show the dominant order as follows : Na-Cl type > Ca-Cl type > $Ca-HCO_3(CO_3)$ type. Thermodynamic equilibrium state between chemical composition of groundwater and major minerals indicates that carbonate minerals except clay minerals can be precipitated as a secondary mineral. It means that the secondary precipitates can not greatly exerts the clogging effect into fracture aperture in rock mass around oil storage cavern. The content of total organic carbon (TOC) shows a slightly increasing trend from initial stage to late stage. The $EpCO_2$ was computed so as to assess the gas contribution on the $CO_2$ in groundwater. The $EpCO_2$ of 0$\~$41.3 indicates that the contribution of oil gas on $CO_2$ pressure in groundwater system can be neglected.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.69-76
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• 2021

This study is to identify the mineralogical properties of caprock samples from drilling cores of the Pohang basin, which is the research area for the demonstration-scale CO2 storage project in Korea. The interaction of water-rock-gas that can occur due to CO2 injection was identified using geochemical modeling. Results of mineralogical studies, together with petrographic data of caprock and data on the physicochemical parameters of pore water were used for geochemical modeling. Modelling was carried out using the The Geochemist's Workbench 14.0.1 geochemical simulator. Two steps of modeling enabled prediction of immediate changes in the caprocks impacted by the first stage of CO2 injection and the assessment of long-term effects of sequestration. Results of minerlaogical analysis showed that the caprock samples are mainly composed of quartz, K-feldspar, plagioclase and a small amount of pyrite, calcite, kaolinite and montmollonite. After the injection of carbon dioxide, the porosity of the caprock increased due to the dissolution of calcite, and dawsonite and chalcedony were precipitated as a result of the dissolution of albite and k-feldspar. In the second step after the injection was completed, the precipitation of dawsonite and chalcedony occurred as a result of dissolution of calcite and albite, and the pH was increased due to this reaction. Results of these studies are expected to be used as data to quantitatively evaluate the efficiency of mineral trapping capture in long-term storage of carbon dioxide.

• Economic and Environmental Geology
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• v.53 no.4
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• pp.491-504
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• 2020

Given the continued climate change and global warming, various technologies for greenhouse gas reduction were discussed worldwide as all 195 countries participated in the Paris Agreement on the reduction of greenhouse gases. The agreement was adopted at the 21st Conference of Parties to the UNFCCC (COP21), which was held in Paris, France, in December 2015, and it revealed that reducing CO₂ is the most efficient method of greenhouse gas reduction. Accordingly, carbon capture/utilization/storage (CCUS) technology has been noted as a means of making practical contributions to CO₂ reduction, and research and development (R&D) activities in many countries are active in the field of CCUS technology. Therefore, this study aims to provide a basis for CCUS R&D and strategic support measures by analyzing patent trends in technologies related to CCUS. The patent analysis collected a total of 10,137 patents in the United States, Korea, Japan, Europe, and China; the number of patents in the United States was the highest according to patent analysis by country. According to an analysis by technology, capture-related technology was high at 60%, but given the recent increase in technology related to utilization, technology demonstration, R&D, and policy support should be continued.

• Geophysics and Geophysical Exploration
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• v.26 no.4
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• pp.157-170
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• 2023

In South Korea, carbon capture and storage (CCS) techniques have attracted considerable attention as part of efforts to achieve the 2030 Korean Nationally Determined Contribution. However, owing to delays in large-scale CCS projects in South Korea, interest in cross-border CCS projects, wherein CO₂ captured in South Korea is stored in overseas CCS facilities, has increased. In this study, we investigated the development status of the CarbonNet project in the Gippsland Basin, Australia. First, we provide a brief overview of sedimentary basins and CCS projects in Australia. Subsequently, we review the geological history of the Gippsland Basin, the site of the large-scale CCS project. Finally, we summarize the site selection process for the CarbonNet project and discuss the suitability of the Pelican site for large-scale CCS projects.

• Journal of the Korean Institute of Gas
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• v.27 no.1
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• pp.23-32
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• 2023

In this study, the Al₂O₃ nanofluid was synthesized as an additive for improving the injection efficiency and storage capacity of carbon dioxide (CO₂) in a depleted sandstone reservoir or deep saline aquifer. As the base fluid, deionized water (DIW) and saline prepared by referring to the composition of API Brine were used, and the fluid was synthesized by using Al₂O₃ nanofluid with CTAB (cetyltrimethyl-ammonium bromide), a cationic surfactant. After that, the dispersion stability was evaluated by using visual observation, dynamic light scattering (DLS), transmission electron microscope (TEM), and miscibility test. As a result, it was presented that stable nanofluid without agglomeration and precipitation after reaction with 70,000 ppm of brine could be synthesized when the nanoparticle concentration was 0.05 wt% or less.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.221-232
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• 2023

Carbon neutrality requires carbon dioxide reduction technology and alternative green energy sources. Palygorskite is a clay mineral with a ribbon structure and possess a large surface area due to the nanoscale pore size. The clay mineral has been proposed as a potential material to capture carbon dioxide (CO₂) and possibly to store eco-friendly hydrogen gas (H2). We report our preliminary results of grand canonical Monte Carlo (GCMC) simulations that investigated the adsorption isotherms and mechanisms of CO₂ and H₂ into palygorskite nanopores at room temperature. As the chemical potential of gas increased, the adsorbed amount of CO₂ or H₂ within the palygorskite nanopores increased. Compared to CO₂, injection of H₂ into palygorskite required higher energy. The mean squared displacement within palygorskite nanopores was much higher for H₂ than for CO₂, which is consistent with experiments. Our simulations found that CO₂ molecules were arranged in a row in the nanopores, while H₂ molecules showed highly disordered arrangement. This simulation method is promising for finding Earth materials suitable for CO₂ capture and H₂ storage and also expected to contribute to fundamental understanding of fluid-mineral interactions in the geological underground.