Molecular Simulations on Adsorption and Diffusion of CO2 and CH4 in Moisture Coals
Molecular Simulations on Adsorption and Diffusion of CO2 and CH4 in Moisture Coals
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DOI：
10.1021/acs.energyfuels.7b02898
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发表时间：
2017-12-01
期刊：
影响因子：
5.3
通讯作者：
Li, Xiaogang
中科院分区：
文献类型：
--
作者：
Han, Jinxuan;Bogomolov, Alexander Kh.;Li, Xiaogang
煤层气储层中大多含有水分，水分会影响煤层气的吸附和扩散，因此含水率是影响煤层气产量的重要因素。CO2可用于改善现场煤层气生产。结合这两点，探讨了不同条件下CO2注入含水煤层时CH 4的吸附扩散规律。建立了不同含水率（1%、2%、4%和6%）的裂隙孔隙模型和随机模型。分别在293.15、303.15和313.15 K下从0 MPa到10 MPa进行了分子模拟。相对于CO2，CH 4与-C-C-的相互作用较弱，说明CO2在煤表面的吸附更稳定。水分子优先吸附在含氧官能团上，然后水分子通过氢键相互吸附形成簇，从而干扰CO2和CH 4的吸附和扩散。由于官能团、氢键和填料的影响，H2O的吸附量在很低的压力下就能急剧增加。这种现象不利于煤层气的开发。
Most coalbed methane (CBM) reservoirs contain moisture that can have an impact on adsorption and diffusion of CBM, so moisture content is an important factor that affects CBM production. CO2 can be used to improve CBM production on site. Combined with these two points, regulations of CH4 adsorption and diffusion are sought under different conditions when CO2 is injected into coal seams with moisture. Slit pores with different moisture contents (1%, 2%, 4%, and 6%) and random models are established. Molecular simulations are carried out, respectively, from 0 MPa to 10 MPa at 293.15, 303.15, and 313.15 K. Relative to CO2, the interaction of CH4 and -C-C- is weaker, indicating that CO2 can adsorb more steadily on the surface of coal. Water molecules preferentially adsorb on the oxygen functional groups, and then water molecules adsorb each other with hydrogen bonding to form clusters that can interfere with the adsorption and diffusion of CO2 and CH4. Because of the influence of functional groups, hydrogen bonding, and micropore filling, the adsorption capacity of H2O can increase steeply at very low pressure. The phenomenon is not beneficial to the CBM exploitation.