Impact research of CH4 replacement with CO2 in hydrous coal under high pressure injection
Liwei Chen1, Mingzhen Zhao1, Xiaohua Li1, Yuan Liu1
1School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo, China
Min. miner. depos. 2022, 16(1):121-126
Full text (PDF)
Purpose. Based on high-pressure gas injection technology that enhances coal seam gas drainage, the effect of CH4 replacement with CO2 in aquiferous coal has been studied.
Methods. Using the laboratory experimental method and the self-built high-pressure gas injection experimental device, high-pressure CO2 is injected into coal with different moisture contents to replace CH4 under different adsorption equilibrium pressures.
Findings. With an increase in coal moisture content, the adsorption capacity of coal for CH4 and CO2 gradually weakens, the adsorption capacity for CO2 is always greater than that of CH4, and the CH4 replacement rate and the CO2 injection ratio gradually decrease. It is concluded that the CH4 replacement rate and the CO2 injection ratio are negatively correlated with the water content of coal. With an increase of the pre-adsorption equilibrium CH4 pressure (0.5, 0.75, 1.0, 1.3 and 2.0 MPa), the CH4 replacement rate and the CO2 injection ratio first sharply and then slowly increase. The transition point is 1.3 MPa (pre-adsorption equilibrium pressure of CH4).
Originality. Based on the adsorption characteristics of coal seam gas injection, the influence of coal water content and gas injection pressure on CH4 replacement rate and CO2 injection ratio is analyzed, and the mechanism is studied.
Practical implications. The experimental results have important guiding significance for selecting reasonable gas injection pressure and the source of gas to drive its injection into underground coal seam.
Keywords: moisture, coal, equilibrium pressure, methane, carbon dioxide, replacement ratio, injection ratio
- Qi-xiang, Y. (2008). Mine gas prevention and control. Retrieved from: https://kns.cnki.net/KCMS/detail/detail.aspx?dbname=SNAD&filename=SNAD000000038821
- Busch, A., Krooss, B.M., Gensterblum, Y., van Bergen, F., & Pagnier, H.J.M. (2003). High-pressure adsorption of methane, carbon dioxide and their mixtures on coals with a special focus on the preferential sorption behaviour. Journal of Geochemical Exploration, 78-79(5), 671-674. https://doi.org/10.1016/S0375-6742(03)00122-5
- Fitzgerald, J.E., Pan, Z., Sudibandriyo, M., Robinson, Jr.R.L., Gasem, K.A.M., & Reeves, S. (2005). Adsorption of methane, nitrogen, carbon dioxide and their mixtures on wet Tiffany coal. Fuel, 84(18), 2351-2363. https://doi.org/10.1016/j.fuel.2005.05.002
- Yi, T., Chuan-li, X., Wu-guang, L., Xing-hua, Z., & Meng, W. (2012). Study on adsorption/desorption of CO2, CH4 and N2 in coal seam. Coal Science and Technology, (02), 70-72 + 93.
- Clarkson, C.R., & Bustin, R.M. (2000). Binary gas adsorption/desorption isotherms: Effect of moisture and coal composition up-on carbon dioxide selectivity over methane. International Journal of Coal Geology, 42(4), 241-271. https://doi.org/10.1016/s0166-5162(99)00032-4
- Sha-sha, G., Yan-bin, W., Li-long, J., Xiang-hao, W., & Hong-jie, W. (2013). Effect of temperature and pressure on substitution of CO2 for CH4. Journal of China University of Mining, (05), 801-805 + 837.
- Zhao-feng, W., Xiao-hua, L., Hong-min, Y., & Chang-chun, Z. (2010). Effect of moisture on methane adsorption characteristics of No. 3 coal seam in Xinjing Mine. Coal Science and Technology, (6), 115-117.
- Shu-gang, L., Peng-xiang, Z., Hong-yu, P., & Peng, X. (2011). Effects of different water content on methane adsorption from coal. Journal of Xi’an University of Science and Technology, (4), 379-382 + 387.
- Hong-min, Y., Dong-liang, X., & Li-wei, C. (2016). Quantitative study of methane in coal displacement/displacement by CO2 injection. China Safety Science and Technology, (05), 38-42.
- Hong-min, Y., Xiao-yang, H., & Ying-ying, J. (2017). Replacement effect CO2 on CH4 in coal under isobaric diffusion and injection conditions. China Production Safety Science and Technology, (08), 24-29.
- Hong-min, Y., Zhao-yang, F., & Li-wei, C. (2016). Displacement effect and its transformation mechanism of nitrogen injection simulation experiment in coal seam. Journal of Coal, (09), 2246-2250.
- Hong-min, Y., Long-hui, L., Zhao-yang, F., & Dong-liang, X. (2017). Effect of injection pressure on the displacement effect of different injection sources. China Safety Science Journal, (09), 122-128.
- Hong-min, Y., & Long-hui, L. (2018). Effect of CO2 on CH4 replacement in coal with different metamorphic degrees under isobaric diffusion. Coal Geology and Exploration, (05), 55-59 + 65.
- Hong-min, Y., Xiao-kai, L., & Li-wei, C. (2018). Difference analysis of methane breakthrough time in coal seam displaced by gas from different injection sources. Journal of Chongqing University, (02), 96-102.
- Hong-min, Y., Tie-gang, Z., Zhao-feng, W., & Chang-chun, Z. (2010). Experimental study on methane displacement by nitrogen injection to promote gas drainage in coal seam. Journal of Coal, (05), 792-796.
- Zhao-feng, W., Gao-wei, Y., Bo, K., & Ce, X. (2014). Experimental study on the inhibition effect of coal gas desorption at low temperature. Journal of Chongqing University, (09), 106-112 + 143.
- Xiang-hao, W., Yan-zhong, W., Lei, Z., & Yan-bin, W. (2018). Effect of CO2 and CH4 competitive adsorption desorption replacement in high and low rank coal. Unconventional Oil and Gas, (03), 46-51.
- Wan-li, X. (2016). The characteristics of CO2 and CH4, N2 and coal adsorption/desorption, diffusion characteristics research. PhD Thesis. Dalian, China: Dalian University of Technology.
- Feng-lan, M., Hong-bo, W., Zhi-min, S., & Gao-feng, L. (2016). Adsorption characteristics of coal on terpolymer mixture. Zhongzhou Coal, (09), 31-34 + 74.
- Wei-bing, T., Ai-fen, L., & Wen-cheng, H. (2017). Effects of water content on adsorption and desorption of coalbed methane. Journal of Coal, (12), 3196-3202.
- Jing-bo, L. (2018). The coal under different temperature, pressure on single/multiple sets of gas partial pressure desorption characteristics experimental study. Master’s Thesis. Xi’an, China: Xi’an University of Science and Technology.
- Li-wei, C., Tian-hong, Y., Hong-min, Y., & Zhao-yang, F. (2017). Experimental study on timing of gas drainage by injecting N2 into coal seam. Journal of Northeastern University (Natural Science), (07), 1026-1030.