成果归属作者：

姚艳斌

成果归属机构：

能源学院

作者：

Ma, Ruying ; Yao, Yanbin ; Feng, Dong ; Hu, Xiong ; Sun, Xiaoxiao ; Vandeginste, Veerle

单位：

China Univ Geosci, Sch Energy Resources, Beijing 100083, Peoples R China;China Univ Geosci Beijing, Frontiers Sci Ctr Deep time Digital Earth, Beijing 100083, Peoples R China;Shanxi Ctr Technol Innovat Coal Measure Mineral Re, Taiyuan 030006, Peoples R China;KU Leuven Campus Bruges, Dept Mat Engn, B-8200 Brugge, Belgium;China United Coalbed Methane Natl Engn Res Ctr Co, Beijing 100095, Peoples R China

关键词：

WATER; SURFACE

摘要：

Coal wettability plays a significant role in the efficiency of coalbed methane (CBM) extraction since it determines fluid transport and distribution. Deep coal seam aqueous fluids have a high salinity. Consequently, coal wettability experiments utilizing fresh water are not representative for those coal seams. Therefore, the effect of aqueous fluids with inorganic salt ions on coal wettability needs to be investigated. In this study, both experiments and molecular simulations are conducted to unravel the wetting behaviour and mechanisms of saline fluids on coal surfaces, investigating different fluid salt concentrations, temperatures, valence states, and coal pore sizes. The results reveal that a more saline fluid displays a more hydrophobic behaviour on the coal surface. Microscopically, water molecules have a tendency to assemble around cations and anions as hydration shells and gradually detach from the coal surface, leading to a gradual transition from hydrophilicity to hydrophobicity. A change in wettability with fluid salinity can be caused by two mechanisms. On the one hand, an increase in ion concentration constrains the diffusion of water molecules through hydration, weakening the mobility of water molecules. On the other hand, a higher ion concentration weakens the interaction between water molecules and oxygen-containing functional groups, reducing the affinity of the water molecules with the pore wall. Moreover, at higher temperatures, ion valence states, and for coal with smaller pores, the impact of inorganic salt ions in fluids on the wetting behaviour of coal surfaces becomes more significant. The coal wettability influences the capillary pressure of coal pores. This study provides new insights on the effect of saline fluids on coal wettability which may help address challenges of fracturing fluid loss and water-blocking in CBM production activities.

基金：

National Natural Science Foundation of China [42125205, 52204058]; Fundamental Research Funds for the Central Universities [2652023001, 2-9-2023-047]; High-performance Computing Platform of China University of Geosciences Beijing; Science and technology projects of China National Petroleum Corporation [2023ZZ18]

语种：

英文

DOI：

10.1016/j.apsusc.2024.160832

来源：

APPLIED SURFACE SCIENCE,2024():.

出版日期：

2024-11-01

提交日期：

2024-08-21

引用参考：

Ma, Ruying; Yao, Yanbin; Feng, Dong; Hu, Xiong; Sun, Xiaoxiao; Vandeginste, Veerle. Effects of inorganic salt ions on the wettability of deep coal seams: Insights from experiments and molecular simulations[J]. APPLIED SURFACE SCIENCE,2024():.