Differences in CH4 Displacement Efficiency by CO2/N2 Injection in Anthracite under Isobaric and High Pressures: Molecular Dynamics Insights

被引:0
作者
Wang, Long [1 ]
Hu, Longsheng [1 ]
Guo, Huaiguang [2 ,3 ]
Wang, Zhaofeng [3 ]
Xiao, Yao [1 ]
Zhang, Zongxiang [1 ]
机构
[1] Xiangtan Univ, Coll Environm & Resources, Xiangtan 411105, Peoples R China
[2] Shenyang Res Inst, China Coal Technol & Engn Grp, State Key Lab Coal Mine Safety Technol, Shenyang 110016, Peoples R China
[3] Henan Polytech Univ, Collaborat Innovat Ctr Coal Work Safety & Clean Hi, Jiaozuo 454000, Peoples R China
基金
中国国家自然科学基金;
关键词
COMPETITIVE ADSORPTION; COALBED METHANE; ORGANIC-MATTER; CO2; SIMULATION; DESORPTION; DIFFUSION; CO2/CH4;
D O I
10.1021/acs.energyfuels.4c05241
中图分类号
TE [石油、天然气工业]; TK [能源与动力工程];
学科分类号
0807 ; 0820 ;
摘要
Enhanced coalbed methane technology (ECBM) can significantly benefit CBM recovery and geological carbon sequestration. However, blindly raising the injection pressure has not yet achieved an ideal recovery performance. To extract CBM more safely and effectively, it is necessary to investigate the mechanisms of CH4 displacement in coal under different gas injection modes at the molecular scale. In the study, we constructed a unit cell model of anthracite coal and then adopted the grand canonical Monte Carlo method (GCMC), molecular dynamics algorithm (MD), and density functional theory (DFT) to calculate the isothermal adsorption capacity of different gases in coal, as well as the interaction energy between each gas and the coal molecules. Furthermore, we simulated the molecular dynamics processes of the CH4 displacement by injecting isobaric and high-pressure CO2/N-2 and analyzed the variation rules of CO2/N-2 and CH4 diffusivity and the displacement rate in coal. The results show that the adsorption capacities of different gases in the model are ranked as CO2 > CH4 > N-2, and the dispersion interaction between the three gases and coal molecules is dominant. CO2 exhibits the highest dispersion energy (-31.20 kJ/mol), followed by CH4 (-29.36 kJ/mol) and N-2 (-21.54 kJ/mol). In the initial stage of gas injection, the CH4 displacement by high-pressure gas is the main pattern, and free gas is mainly produced at this time. The displacement rate of high-pressure injection before the system equilibrium is higher than that of isobaric diffusion (about 1.5-5 times). Moreover, the CH4 displacement rate of high-pressure injection increases with the pressure rise of the injected gas, but it decays rapidly. After the system reaches equilibrium, the isobaric diffusion effect gradually dominates the CH4 displacement. At this stage, a large amount of adsorbed gas is produced, which greatly determines the overall displacement amount of the system. The total CH4 displacement is influenced by a combined action of the competitive adsorption and the CH4 partial pressure change. In the isobaric diffusion system, CO2 has the strongest competitive adsorption capacity, and the partial pressure change has a greater effect on the CH4 displacement than that of the high-pressure injection, due to the free space enlargement in the system, resulting in the maximum CH4 displacement in the CO2 isobaric injection. The higher the injected CO2/N-2 pressure, the lower the CH4 displacement efficiency after equilibrium, and the CH4 displacement rate decreases by about 34-50%.
引用
收藏
页码:1959 / 1970
页数:12
相关论文
共 52 条
  • [1] Quantitative analysis of carbon dioxide replacement of adsorbed methane in different coal ranks using low-field NMR technique
    Bai, Gang
    Zhou, Zhongjie
    Li, Xueming
    Cheng, Yuantao
    Hu, Kun
    Chen, Ying
    Zhou, Xihua
    [J]. FUEL, 2022, 326
  • [2] Effect of CO2 injection on CH4 desorption rate in poor permeability coal seams: An experimental study
    Bai, Gang
    Su, Jun
    Zhang, Zunguo
    Lan, Anchang
    Zhou, Xihua
    Gao, Fei
    Zhou, Jianbin
    [J]. ENERGY, 2022, 238
  • [3] Critical factors controlling shale gas adsorption mechanisms on Different Minerals Investigated Using GCMC simulations
    Chen, Guohui
    Lu, Shuangfang
    Liu, Keyu
    Xue, Qingzhong
    Han, Tongcheng
    Xu, Chenxi
    Tong, Maosheng
    Pang, Xiaoting
    Ni, Binwu
    Lu, Shudong
    [J]. MARINE AND PETROLEUM GEOLOGY, 2019, 100 : 31 - 42
  • [4] Deformation and swelling of coal induced from competitive adsorption of CH4/CO2/N2
    Chen Li-wei
    Wang Lin
    Yang Tian-hong
    Yang Hong-min
    [J]. FUEL, 2021, 286
  • [5] Molecular Simulation of Bulk Organic Matter in Type II Shales in the Middle of the Oil Formation Window
    Collell, Julien
    Ungerer, Philippe
    Galliero, Guillaume
    Yiannourakou, Marianna
    Montel, Francois
    Pujol, Magali
    [J]. ENERGY & FUELS, 2014, 28 (12) : 7457 - 7466
  • [6] Molecular simulation of CO2/CH4 adsorption in brown coal: Effect of oxygen-, nitrogen-, and sulfur-containing functional groups
    Dang, Yong
    Zhao, Lianming
    Lu, Xiaoqing
    Xu, Jing
    Sang, Pengpeng
    Guo, Sheng
    Zhu, Houyu
    Guo, Wenyue
    [J]. APPLIED SURFACE SCIENCE, 2017, 423 : 33 - 42
  • [7] CO2 and CH4 adsorption on different rank coals: A thermodynamics study of surface potential, Gibbs free energy change and entropy loss
    Du, Xidong
    Cheng, Yugang
    Liu, Zhenjian
    Yin, Hong
    Wu, Tengfei
    Huo, Liang
    Shu, Couxian
    [J]. FUEL, 2021, 283 (283)
  • [8] Solubility Limits in Lennard-Jones Mixtures: Effects of Disparate Molecule Geometries
    Dyer, Kippi M.
    Perkyns, John S.
    Pettitt, B. Montgomery
    [J]. JOURNAL OF PHYSICAL CHEMISTRY B, 2015, 119 (29) : 9450 - 9459
  • [10] Pair Interaction Energy Decomposition Analysis for Density Functional Theory and Density-Functional Tight-Binding with an Evaluation of Energy Fluctuations in Molecular Dynamics
    Fedorov, Dmitri G.
    Kitaura, Kazuo
    [J]. JOURNAL OF PHYSICAL CHEMISTRY A, 2018, 122 (06) : 1781 - 1795