Zhang Xiaoyu, Cheng Jian, Kang Tianhe, Zhou Xianxian, Zhang Liankun
Research Institute of Mine Big Data, China Coal Research Institute, Beijing 100013, P. R. China.
State Key Laboratory of Coal Mining and Clean Utilization, Beijing 100013, P. R. China.
ACS Omega. 2021 Sep 6;6(37):24147-24155. doi: 10.1021/acsomega.1c03661. eCollection 2021 Sep 21.
The wettability of gas and liquid on the coal surface is one of the fundamental factors that affect the depressurization process during the coalbed methane (CBM) extraction. The wettability of coal surface changed after electrochemical modification, leading to the change in methane adsorption/desorption and water movement in coal reservoirs. Thus, the CH adsorption amount, desorption ratio, and coal-water contact angle of raw and modified anthracite samples were measured and simulated. The mechanism of electrochemical modification was analyzed by functional groups, surface free energy, pore characteristics, interaction energies, and coal swelling. The experimental results showed that the saturated adsorption amount of methane decreased from 41.49 to 34.72 mL/g, and the simulation results showed that the saturated adsorption amount of methane decreased from 2.01 to 1.83 mmol/g. The coal-water contact angle also decreased from 81.9 to 68.6°. Electrochemical modification mainly affects the wettability of CH and HO by changing the functional groups and pore structures of anthracite, and the influence on functional groups of coal surface is greater. This work provided a basis for enhancing CBM extraction by electrochemical modification.
气体和液体在煤表面的润湿性是影响煤层气（CBM）开采过程中降压过程的基本因素之一。电化学改性后煤表面的润湿性发生变化，导致煤储层中甲烷吸附/解吸及水的运移发生改变。因此，对原煤和改性无烟煤样品进行了甲烷吸附量、解吸率及煤-水接触角的测定与模拟。通过官能团、表面自由能、孔隙特征、相互作用能及煤的膨胀性对电化学改性机理进行了分析。实验结果表明，甲烷饱和吸附量从41.49 mL/g降至3-4.72 mL/g，模拟结果表明甲烷饱和吸附量从2.01 mmol/g降至1.83 mmol/g。煤-水接触角也从81.9°降至68.6°。电化学改性主要通过改变无烟煤的官能团和孔隙结构来影响CH和HO的润湿性，且对煤表面官能团的影响更大。该研究为通过电化学改性提高煤层气开采效率提供了依据。
