Geological control on carbon isotope equilibrium and kinetic fractionation of CH4-CO2-HCO3 in microbial coalbed and shale gas systems
文献类型：期刊论文
| 作者 | Chen, Xiangrui3,4; Tao, Mingxin4; Zhou, Zheng2; Holland, Greg1; Wang, Yunpeng3 |
| 刊名 | CHEMICAL GEOLOGY
 |
| 出版日期 | 2023 |
| 卷号 | 635页码:121609 |
| 关键词 | DISSOLVED INORGANIC CARBON SAN-JUAN BASIN PRODUCTION WATERS BIOGENIC METHANE IN-SITU HYDROGEN SOLUBILITY EXCHANGE BED CO2 |
| ISSN号 | 0009-2541 |
| DOI | 10.1016/j.chemgeo.2023.121609 |
| 英文摘要 | Microbial coalbed gas (CBG) and shale gas (SG), predominately composed of methane (CH4) and carbon dioxide (CO2), are important economic resources and potent greenhouse gases. Although isotopic equilibrium of CH4 and CO2 has been observed in microbial CBG and SG basins, it is difficult to judge under what geological conditions equilibrium is achieved. Moreover, the effects of CO2 dissolution on the isotopic fractionation process need to be considered. We use data from eight microbial CBG and SG basins to discuss the geological conditions in which equilibrium and kinetic isotopic fractionation in CH4-CO2-HCO3? system is achieved. Based on isotopic equilibrium temperatures calculated using computer codes developed in MatLab software, we show that, in deep and closed reservoirs, the CH4-CO2 and CH4-HCO3? are close to carbon isotope equilibrium. In contrast, in shallow and open reservoirs, they are in disequilibrium. The CO2-HCO3? is in disequilibrium in most reservoirs. We propose that both low free energy gradients and long coexisting time of CH4 and CO2/HCO3? are necessary to attain isotopic equilibrium. However, it is difficult to accurately estimate the timescale for attaining isotope equilibrium among them. In general, a closed and deep CBG/SG reservoir is likely to be geologically and geochemically stable over long timescales, favoring isotopic equilibrium of CH4-CO2 and CH4-HCO3?. However, a shallow and open reservoir is unfavourable for their isotopic equilibrium due to shorter timescales for the coexistence of CH4-CO2-HCO3?. Using data from systems close to equilibrium, we estimated the percentage of CO2 in total CH4 and CO2 in CBG reservoirs in various basins to be from 27% to 50%, where methanogenesis is mainly by CO2 reduction. This is significantly higher than the CO2 content (1% to 15%) in gaseous CH4 and CO2 in these basins but is consistent with those (36% to 48%) from culture experiments for coal conversion by methanogenesis. Further study shows that 53–99% of the CO2 formed during CBG generation has dissolved into groundwaters to form dissolved inorganic carbon (DIC) in CBG reservoirs. We propose that CO2 dissolution likely has significantly affect the abundance and isotopic compositions of gaseous CO2 in subsurface. ? 2023 |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001034379600001 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/80329]  |
| 专题 | 有机地球化学国家重点实验室 |
| 作者单位 | 1.Department of Earth and Environmental Sciences, The University of Manchester, M13 9PL, United Kingdom 2.Lancaster Environment Centre, Lancaster University, LA1 4YQ, United Kingdom 3.State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, China 4.Faculty of Geographical Science, Beijing Normal University, 100875, China |
| 推荐引用方式 GB/T 7714 | Chen, Xiangrui,Tao, Mingxin,Zhou, Zheng,et al. Geological control on carbon isotope equilibrium and kinetic fractionation of CH4-CO2-HCO3 in microbial coalbed and shale gas systems[J]. CHEMICAL GEOLOGY,2023,635:121609. |
| APA | Chen, Xiangrui,Tao, Mingxin,Zhou, Zheng,Holland, Greg,&Wang, Yunpeng.(2023).Geological control on carbon isotope equilibrium and kinetic fractionation of CH4-CO2-HCO3 in microbial coalbed and shale gas systems.CHEMICAL GEOLOGY,635,121609. |
| MLA | Chen, Xiangrui,et al."Geological control on carbon isotope equilibrium and kinetic fractionation of CH4-CO2-HCO3 in microbial coalbed and shale gas systems".CHEMICAL GEOLOGY 635(2023):121609. |
入库方式： OAI收割
来源：广州地球化学研究所
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