• Tunnel and Underground Space
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• v.18 no.3
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• pp.175-184
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• 2008

In this study, state-of-the-art of $CO_2$ geological sequestration as a method of greenhouse gas reduction was reviewed. Thermal-Hydraulic-Mechanically(THM) coupled simulation technology and its application to a stability analysis of geological formation due to $CO_2$ injection as well as a leakage path analysis were investigated and introduced.

• Tunnel and Underground Space
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• v.23 no.1
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• pp.1-12
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• 2013

Enhanced oil recovery (EOR) technology coupled with underground carbon dioxide sequestration is introduced. $CO_2$ can be injected into an oil reservoir in order to enhance oil production rate and $CO_2$ EOR can be turned into CCS in a long term sense. Coupling $CO_2$ EOR with CCS may secure a large scale and consistent $CO_2$ source for EOR, and the $CO_2$ EOR can bring an additional economic benefit for CCS, since the benefit from enhanced oil production by $CO_2$ EOR will compensate costs for CCS implementation. In this paper, we introduced the characteristics of $CO_2$ EOR technology and its market prospect, and reviewed the Weyburn $CO_2$ EOR project which is the first large-scale $CO_2$ EOR case utilizing an anthropogenic $CO_2$ source. We also introduced geotechnical elements for a successful and economical implementation of $CO_2$ EOR with CCS and they were a miscroseismic monitoring during and after injection of $CO_2$, and determination of minimum miscible pressure (MMP) and maximum injection pressure (MIP) of $CO_2$.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.37-43
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• 2006

In 2006, the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) plans to undertake (subject to receiving the necessary approvals) a Pilot program for $CO_2$ storage within a depleted gas reservoir. The Otway Basin Pilot Program (OBPP) aims to demonstrate that subsurface $CO_2$ storage is both economically and environmentally sustainable in Australia. This will be the first $CO_2$ storage program in the world to utilise a depleted gas reservoir and, hence, the experience gained will be a valuable addition to the range of international $CO_2$ storage programs that are underway or being planned. A key component of the OBPP is the design of an appropriate geophysical monitoring strategy that will allow the subsurface migration of the $CO_2$ plume to be tracked and to verify that containment has been successful. This paper presents the results from modelling the predicted gravity response to $CO_2$ injection into the Otway Basin reservoir, where the goal was to determine minimum volumes of $CO_2$ that may be detectable using non-seismic geophysical techniques. Modelling results indicate that gravity measurements at 10 m spacing within the existing observation well and the planned $CO_2$ injection well would provide excellent vertical resolution, even for the smallest $CO_2$ volume modelled (10000 tonnes), but resolving the lateral extent of the plume would not be possible without additional wells at closer spacing.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.59-71
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• 2023

Carbon capture, and storage (CCS) is important for the reduction of greenhouse gases and achieving carbon neutrality. CCS focuses on storing captured CO₂ permanently in underground reservoirs. CO₂-enhanced oil recovery (CO₂-EOR) is one form of CCS, where CO₂ is injected into the underground to enhance oil recovery. CO₂-EOR not only aids in the extraction of residual oil but also contributes to carbon neutrality by storing CO₂ underground continuously. CO₂-EOR can be classified into miscible and immiscible methods, with the CO₂-water alternating gas (CO₂-WAG) technique being a representative approach within the miscible method. In CO₂-WAG, water and CO₂ are alternately injected into the reservoir, enabling oil production and CO₂ storage. The WAG method allows for controlling the breakthrough of injection fluids, providing advantages in oil recovery. It also induces hysteresis in relative permeability during the injection and production process, expanding the amount of trapped CO₂. In this study, the effects of enhancing oil recovery and storing CO₂ underground during CO₂-EOR were presented. Additionally, cases of CO₂-EOR application in relation to CCS were introduced.

• Tunnel and Underground Space
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• v.17 no.6
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• pp.475-483
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• 2007

With increasing demand for LNG as energy resources and need for $CO_2$ sequestration as greenhouse gas, more storage facilities are required in Korea. Due to the recent acute safety concerns and land shortage, storage facilities tend to be located underground. In design and construction of underground storage for low and high temperature materials, besides their mechanical characteristics, the thermal characteristics of rock under temperature variation should be understood. In this study, laboratory experiments for the measurement of the thermal expansion coefficient of rock were performed using strain gauge in consideration of the particle size of mineral and experiment temperature range. Experiment results show that thermal expansion coefficient decreased as the temperature decreases. In addition, linear thermal expansion coefficient was developed for typical Korean rocks such as granite. The results of this study can be utilized for the evaluation of thermal propagation in rock mass and the thermo-mechanical stability of underground facilities.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.309-317
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• 2010

CCS (Carbon dioxide Capture and Storage) is a means of mitigating the contribution of $CO_2$ to the Greenhouse gas, from large point sources such as power plants and steel companies. CCS is a process whereby $CO_2$ is captured from gases produced by fossil fuel combustion, compressed, transported and injected into deep geologic formations for permanent storage. CCS applied to a conventional power plant can reduce $CO_2$ emissions to the atmosphere by approximately 80~90% compared to a plant without CCS. The IPCC estimates that the economic potential of CCS will be between 10% and 55% of the total carbon mitigation effort by year 2100. In this paper, overseas sites where CCS technology is being applied and technical development trends for CCS are briefly reviewed.

• Tunnel and Underground Space
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• v.9 no.4
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• pp.306-314
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• 1999

In underground spaces including nuclear waste repository, prediction of air quantity, temperature/humidity and pollutant concentration is utmost important for space construction and management during the normal state as well as for determining the measures in emergency cases such as underground fires. This study aims at developing a model for underground space environment which has capabilities to take into account the effects of autocompression for the natural ventilation head calculation, to find the optimal location and size of fans and regulators, to predict the temperature and humidity by calculating the convective heat transfer coefficient and the sensible and latent heat transfer rates, and to estimate the pollutant levels throughout the network. The temperature/humidity prediction model was applied to a military storage underground space and the relative differences of dry and wet temperatures were 1.5 ~ 2.9% and 0.6 ~ 6.1%, respectively. The convection-based pollutant transport model was applied to two different vehicle tunnels. Coefficients of turbulent diffusion due to the atmospheric turbulence were found to be 9.78 and 17.35$m^2$/s, but measurements of smoke and CO concentrations in a tunnel with high traffic density and under operation of ventilation equipment showed relative differences of 5.88 and 6.62% compared with estimates from the convection-based model. These findings indicate convection is the governing mechanism for pollutant diffusion in most of the tunnel-type spaces.

• The Journal of the Korea Contents Association
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• v.14 no.12
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• pp.999-1009
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• 2014

In this paper, $CO_2$ emission and storage amount are evaluated for real RC (Reinforced Concrete) underground structure considering $CO_2$ amount including material manufacturing, moving, and construction, repairing timing stage regarding extended service life. Four mix proportions with mineral admixtures are prepared and $CO_2$ diffusion coefficient are obtained based on a micro modeling. Referred to carbonation durability limit state, $CO_2$ emission and storage amount are evaluated, which shows higher initial $CO_2$ emission is caused due to larger unit content of cement and the storage increases with more rapid carbonation velocity. Furthermore various $CO_2$ concentration is adopted for simulation of $CO_2$ evaluation including measured $CO_2$ concentration (600ppm). With higher concentration of $CO_2$ outside, carbonation velocity increases. In order to reduce $CO_2$ emission through entire service life, reducing initial $CO_2$ emission through mineral admixture like fly ash is more effective than increasing $CO_2$ storage through OPC since $CO_2$ is significantly emitted under manufacturing OPC and $CO_2$ storage in cover concrete of RC structure is not effective considering initial concrete amount in construction.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.293-303
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• 2016

Underground $CO_2$ storage technology is one of the most effective methods to reduce atmospheric $CO_2$. In this study, $CO_2$ storage condition was simulated in the laboratory. Sandstone and shale specimens were saturated in 1M NaCl and were reacted at $45^{\circ}C$, 10 atm for 4 weeks. The physical and microstructural properties of rock specimens were measured. Variations on physical properties of shale specimens were bigger than those of sandstone specimens, such as volume, density, elastic wave velocity, Poisson's ratio and Young's modulus. Microstructure were analyzed using X-ray computed tomography. Total number of pores were decreased, and average volume, average area and average equivalent diameter of each pore were changed after $CO_2$ reaction. Swelling and leakage of clay mineral caused by $CO_2$-mineral reaction were the reason of changes. The results of this study can be applied to predict the physical and microstructural changes in underground $CO_2$ storage condition.

• Tunnel and Underground Space
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• v.23 no.1
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• pp.13-30
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• 2013

Increase of pore fluid pressure resulting from injection of $CO_2$ may reactivate pre-existing faults, and the induced seismic activities can raise the safety issues such as seal integrity, restoration of storage capacity, and, in the worst case, removal of previously injected $CO_2$. Thus, fault stability and potential for $CO_2$ leakage need to be assessed at the stage of site selection and planning of injection pressure, based on the results of large-scale site investigations and numerical modeling for various scenarios. In this report, studies on the assessment of fault stability during injection of $CO_2$ were reviewed. The seismic activities associated with an artificial injection of fluids or a release of naturally trapped high-pressure fluids were first examined, and then site investigation methods for the magnitude and orientation of in situ stresses, the distribution and change of pore fluid pressure, and the location of faults were generally summarized. Recent research cases on possibility estimation of fault reactivation, prediction of seismic magnitude, and modeling of $CO_2$ leakage through a reactivated fault were presented.