• Journal of the Korean Institute of Gas
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• v.21 no.2
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• pp.1-9
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• 2017

Enhanced coalbed methane recovery (ECBM), as injecting $CO_2$ or $N_2$ into the coalbed methane (CBM) reservoir for increasing methane recovery, takes center stage in these days. ECBM makes a better recovery than the conventional production method, it called dewatering process. However the characteristics of injection gas affect to methane recovery, thus analysis on the mixed ratio of injection gas should be required. In this study, CBM reservoir model was built to estimate the methane recovery of ECBM method by different mixed ratio of injection gas. Additionally, to consider the characteristics of injection gas such as carbon captured storage, nitrogen re-injection, etc. economic analysis was performed. The results showed that ECBM cases produced methane almost twice as much as dewatering case and $CO_2$ 10% and $N_2$ 90% case resulted in the highest methane recovery among the mixed gas cases. On the other hand, the results of economic analysis showed that $CO_2$ 20% and $N_2$ 80% case made the highest total production profit. Therefore, both the recovery of methane and economical efficiency should be considered to apply ECBM process.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.36-43
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• 2013

In order to asses gas production behavior for $CO_2$ ECBM, the sorption charcteristics on coal are considered to be a key factor. In this study, we have investigated the change of the sorption rate of adsorbed gas as a function of pressure and temperature below the appropriate depth for $CO_2$-ECBM. The experiment were carried out under four different temperatures varying from $15^{\circ}C$ to $45^{\circ}C$, while the coal pressure was varied from atmosphere to 1,400 psi for every temperature. From this results, the sorption rate both $CO_2$ and $CH_4$ increased with increasing the coal pressure. Otherwise, the sorption rate both $CH_4$ and $CO_2$ decreased linearly as the coal temperature increased. From the sensitivity studies on pressure and temperature change, it was experimentally identified that $CO_2$ sequestration rate and $CH_4$ production rate are better at deeper depths below a depth of 800 m in coal seams. However, the results showed continued decline in the increasing ratio of ECBM with formation depth.

• Economic and Environmental Geology
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• v.48 no.1
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• pp.65-75
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• 2015

The CBM(Coalbed Methane) development technology being developed in mid 1980s is the technology to produce the methane gas absorbed in the coal bed. CBM is easy to be developed and its coal deposit is abundant. Therefore, the CBM industry has a large potential as an energy source as well as to deal with the global regulations for reducing greenhouse gas emission. In order to produce coal, the CBM should first be developed as a preliminary action for mine security. So CBM is advantageous in reducing the global greenhouse gas as well as its advantage not being influenced by the changes in gas market. The ECBM (Enhanced Coalbed Methane) is a new technique producing the methane gas which is substituted and disorbed from coal by injecting $CO_2$ or $N_2$ gas into a coal bed. Especially, $CO_2$-ECMB is a low-carbon, green-growth technology, so can expect to the effect of green gas reduction as well as the improved productivity of methane gas. CBM technology is being developed in about 40 nations including Canada, Australia, China, India, Indonesia and Viet Nam, and the coal output using this technology is continually being increased. The CBM is expected to contribute in changing the energy source paradigm from current coal & petroleum energy to unconventional gas.

• Journal of the Korean Institute of Gas
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• v.19 no.2
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• pp.37-44
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• 2015

We proposed the improved Langmuir adsorption relations considering volume change effect of coal matrix during primary production of CBM and Enhanced-CBM with injection of carbon dioxide or CCS in coalseam but also volumetric strain. To verify this model, experimental data of pure gas adsorption such as $CO_2$, $CH_4$, and $N_2$ on coals were used to compare conventional Langmuir model with this model. From the results, we obtained that the larger adsorption capacity of coal and the higher adsorption affinity of gas, the larger error occur with Langmuir model. Using this model, however, we found not only substantially better fit in all condition but also reasonable volumetric strain of the coal matrix. We also applied this volume modified pure gas adsorption model to the IAS model to describe gas adsorption and volumetric strain for mixed gas. This modified-IAS model fitting experimental data by Hall et al(1994) improved accuracy of mixed gas adsorption calculation compared with conventional model.