Micro-mechanism of geological sequestration of CO₂ in coal seam

Authors

YAO Yanbin, School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China; Coal Reservoir Laboratory of National Engineering Research Center of CBM Development & Utilization, Beijing 100083, ChinaFollow
SUN Xiaoxiao, School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China; Coal Reservoir Laboratory of National Engineering Research Center of CBM Development & Utilization, Beijing 100083, China
WAN Lei, School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China; Coal Reservoir Laboratory of National Engineering Research Center of CBM Development & Utilization, Beijing 100083, China

Abstract

The geological sequestration of CO₂ in coal seam is a most promising carbon storage technology, which can help achieve the dual goals of CO₂ emission reduction and coalbed methane stimulation. Compared with other sealing geological bodies, coal has extremely well-developed micropores. The mechanism of geological sequestration of CO₂ in coal seam is closely related to the interaction of coal-gas-water. However, its internal influence mechanism is still unclear. Herein, the models of macromolecular structure and plat pore of the coals were constructed based on the systematic coal petrological analysis and testing of two bituminous coal samples. Meanwhile, the wetting behaviors of CO₂ and water on different coal-matrix surfaces at different temperatures and pressures were simulated using the molecular dynamics method. Thereby, the change rule of water wettability caused by the injection of CO₂ in coal seam was disclosed, and the influencing factors and microscopic mechanisms of injectability, storage potential and storage effectiveness of CO₂ in coal seam were preliminarily clarified. The results show that: (1) The main factor affecting coal wettability is the polar oxygen-containing functional groups in coal. Specifically, the higher the content of the oxygen-containing functional groups, the stronger the wettability of coal is. (2) The CO₂ injected into coal penetrates the water molecular layer through dissolution, and thus a competitive adsorption occurs with the water molecules, weakening the wettability of water on the coal surface. (3) With the increase of pressure and the decrease of temperature, the more CO₂ is adsorbed on the coal surface, and the more obvious the destruction of hydrogen bond and the decrease of wettability. (4) The hydrophilic coal seam has relatively poor injectability and storage potential of CO₂, but relatively good storage safety. (5) The CO₂ storage potential of coal seams are mainly influenced by the capacities of adsorption trapping and capillary trapping, while the effectiveness and security of storage are affected by the capacities of capillary trapping and structural trapping. (6) The sequestration of CO₂ in coal seam is mainly related to the adsorption trapping, taking capillary trapping under water-bearing conditions into account. The storage potential of high rank coal is higher than the low rank coal, but the “water block” effect needs to be overcome during CO₂ storage and injection. Moreover, the further study was conducted for the interaction of coal-gas-water and the geological sequestration mechanism of CO₂ in the deep coal seam under the in-situ conditions, which is of great significance for the development of CO₂-ECBM technology.

Keywords

geological sequestration of CO2, CBM stimulation technology, carbon-trapping mechanism, coal wettability, adsorption trapping, capillary trapping

DOI

10.12363/issn.1001-1986.22.11.0868

Recommended Citation

YAO Yanbin, SUN Xiaoxiao, WAN Lei, et al. (2023) "Micro-mechanism of geological sequestration of CO₂ in coal seam," Coal Geology & Exploration: Vol. 51: Iss. 2, Article 11.
DOI: 10.12363/issn.1001-1986.22.11.0868
Available at: https://cge.researchcommons.org/journal/vol51/iss2/11

Reference

[1] 李阳,黄文欢,金勇,等. 双碳愿景下中国石化不同油藏类型CO₂驱提高采收率技术发展与应用[J]. 油气藏评价与开发,2021,11(6):793−804.

LI Yang,HUANG Wenhuan,JIN Yong,et al. Different reservoir types of CO₂ flooding in Sinopec EOR technology development and application under “dual carbon” vision[J]. Petroleum Reservoir Evaluation and Development,2021,11(6):793−804.

[2] 申建,秦勇,张春杰,等. 沁水盆地深煤层注入CO₂提高煤层气采收率可行性分析[J]. 煤炭学报,2016,41(1):156−161.

SHEN Jian,QIN Yong,ZHANG Chunjie,et al. Feasibility of enhanced coalbed methane recovery by CO₂ sequestration into deep coalbed of Qinshui Basin[J]. Journal of China Coal Society,2016,41(1):156−161.

[3] 桑树勋. 二氧化碳地质存储与煤层气强化开发有效性研究述评[J]. 煤田地质与勘探,2018,46(5):1−9.

SANG Shuxun. Research review on technical effectiveness of CO₂ geological storage and enhanced coalbed methane recovery[J]. Coal Geology & Exploration,2018,46(5):1−9.

[4] PAN Zhejun，YE Jianping，ZHOU Fubao，et al. CO₂ storage in coal to enhance coalbed methane recovery：A review of field experiments in China[J]. International Geology Review，2018，60(5–6)：754–776.

[5] 叶建平,冯三利,范志强,等. 沁水盆地南部注二氧化碳提高煤层气采收率微型先导性试验研究[J]. 石油学报,2007,28(4):77−80.

YE Jianping,FENG Sanli,FAN Zhiqiang,et al. Micro–pilot test for enhanced coalbed methane recovery by injecting carbon dioxide in south part of Qinshui Basin[J]. Acta Petrolei Sinica,2007,28(4):77−80.

[6] JOSEPH G J,FREUND P. Coal–bed methane enhancement with CO₂ sequestration worldwide potential[J]. AAPG Bulletin,2000,84:210−217.

[7] GODEC M,KOPERNA G,GALE J. CO₂–ECBM:A review of its status and global potential[J]. Energy Procedia,2014,63:5858−5869.

[8] YAO Yanbin,LIU Dameng,XIE Songbin. Quantitative characterization of methane adsorption on coal using a low–field NMR relaxation method[J]. International Journal of Coal Geology,2014,131:32−40.

[9] 姚艳斌,刘大锰. 基于核磁共振弛豫谱的煤储层岩石物理与流体表征[J]. 煤炭科学技术,2016,44(6):14−22.

YAO Yanbin,LIU Dameng. Petrophysics and fluid properties characterizations of coalbed methane reservoir by using NMR relaxation time analysis[J]. Coal Science and Technology,2016,44(6):14−22.

[10] DAY S，SAKUROVS R，WEIR S. Supercritical gas sorption on moist coals[J]. International Journal of Coal Geology，2008，74(3/4)：203–214.

[11] WANG Feng,YAO Yanbin,WEN Zhi’ang,et al. Effect of water occurrences on methane adsorption capacity of coal:A comparison between bituminous coal and anthracite coal[J]. Fuel,2020,266:117102.

[12] SUN Xiaoxiao,YAO Yanbin,LIU Dameng,et al. Investigations of CO₂–water wettability of coal:NMR relaxation method[J]. International Journal of Coal Geology,2018,188:38−50.

[13] ZHENG Sijian,YAO Yanbin,DEREK E,et al. Dynamic fluid interactions during CO₂–ECBM and CO₂ sequestration in coal seams. Part 2:CO₂–H₂O wettability[J]. Fuel,2020,279:118560.

[14] 孙晓晓,姚艳斌,陈基瑜,等. 基于低场核磁共振的煤润湿性分析[J]. 现代地质,2015,29(1):190−197.

SUN Xiaoxiao,YAO Yanbin,CHEN Jiyu,et al. Determination of coal wettability by using low–field nuclear magnetic resonance[J]. Geoscience,2015,29(1):190−197.

[15] PAN Zhejun,CONNELL L D,CAMILLERI M,et al. Effects of matrix moisture on gas diffusion and flow in coal[J]. Fuel,2010,89(11):3207−3217.

[16] CYGAN R T,ROMANOV V N,MYSHAKIN E M. Molecular simulation of carbon dioxide capture by montmorillonite using an accurate and flexible force field[J]. The Journal of Physical Chemistry B,2012,116(24):13079−13091.

[17] 徐志强,刘向阳,涂亚楠,等. 褐煤与水分子相互作用的量子化学计算[J]. 中国矿业大学学报,2022,51(3):554−561.

XU Zhiqiang,LIU Xiangyang,TU Yanan,et al. Quantum chemical calculation of the interaction between lignite and water molecules[J]. Journal of China University of Mining & Technology,2022,51(3):554−561.

[18] CHANG Yanhai,YAO Yanbin,LIU Dameng,et al. Behavior and mechanism of water imbibition and its influence on gas permeability during hydro–fracturing of a coalbed methane reservoir[J]. Journal of Petroleum Science and Engineering,2022,208:109745.

[19] SUN Xiaoxiao,YAO Yanbin,LIU Dameng,et al. How does CO₂ adsorption alter coal wettability? Implications for CO₂ geo–sequestration[J]. Journal of Geophysical Research:Solid Earth,2022,127(5):e2021JB023723.

[20] WU Hao,YAO Yanbin,LIU Dameng. A modified Guggenheim–Anderson–Boer model for analyzing water sorption in coal[J]. Chemical Engineering Journal,2023,451:138760.

[21] ROSHAN H,AL–YASERI A Z,SARMADIVALEH M,et al. On wettability of shale rocks[J]. Journal of Colloid and Interface Science,2016,475:104−111.

[22] AL–YASERI A Z,ROSHAN H,LEBEDEV M,et al. Dependence of quartz wettability on fluid density[J]. Geophysical Research Letters,2016,43(8):3771−3776.

[23] STUMM W，MORGAN J. Aquatic chemistry：Chemical equilibria and rates in natural waters[M]. New York：John Wiley & Sons，1996.

[24] 王宝俊,李敏,赵清艳,等. 煤的表面电位与表面官能团间的关系[J]. 化工学报,2004,55(8):1329−1334.

WANG Baojun,LI Min,ZHAO Qingyan,et al. Relationship between surface potential and functional groups of coals[J]. Journal of Chemical Industry and Engineering(China),2004,55(8):1329−1334.

[25] IGLAUER S. CO₂–water–rock wettability:Variability,influencing factors,and implications for CO₂ geostorage[J]. Accounts of Chemical Research,2017,50(5):1134−1142.

[26] 卢义玉,周军平,鲜学福,等. 超临界 CO₂ 强化页岩气开采及地质封存一体化研究进展与展望[J]. 天然气工业,2021,41(6):60−73.

LU Yiyu,ZHOU Junping,XIAN Xuefu,et al. Research progress and prospect of the integrated supercritical CO₂ enhanced shale gas recovery and geological sequestration[J]. Natural Gas Industry,2021,41(6):60−73.