Abstract: Carbon dioxide (CO₂) sequestration in deep coal seams with enhanced coal-bed methane (CH₄) recovery (CO₂-ECBM) can store the main anthropogenic greenhouse gas (CO₂) in geological time. In consideration of the properties of both CO₂ and coal, swelling effect induced by CO₂ will occur during the sequestration process. The swelling effect can show negative effect on CO₂ sequestration in coal seams. Therefore, the recent research progress in coal swelling during sequestration process has been summarized. The effects of fluid on coal swelling were concluded, and the influences of coal swelling on sequestration process were analyzed. The analytical methods for coal swelling were provided and the future trends of coal matrix swelling during CO₂ sequestration in deep coal seams were also pointed out. The results indicate that coal swelling is related to fluid type, pressure, temperature and degree of coalification. Coal matrix swelling can decrease the permeability in coal seams and further affect fluid transport within the reservoir. Swelling can also change the CO₂ sequestration capability, thus establishment of coal adsorption model incorporation the swelling effect is of importance. Furthermore, there are still disagreements on the mechanism and reversibility of coal matrix swelling and the investigations on the coal physico-chemical structure will be helpful to address the above-mentioned problems.

Key words: coal seams, sequestration, carbon dioxide, coal matrix, swelling

摘要： 强化煤层气甲烷(CH₄)采收率的深部煤层封存二氧化碳(CO₂)技术能够将主要人为温室气体(CO₂)进行有效的地质存储。考虑到CO₂流体和煤体的自身特性, 封存过程中的CO₂流体将会诱导煤基质发生溶胀效应。溶胀效应将会对煤层封存CO₂技术构成潜在的影响。为此, 本文结合国内外相关研究工作, 归纳了流体诱导煤基质溶胀的规律, 指出了煤基质溶胀对煤层封存CO₂过程的影响, 介绍了流体诱导煤基质溶胀的分析手段, 提出了封存过程中煤基质溶胀的研究趋势。分析表明:①煤基质溶胀程度与流体种类、压力、温度和煤的变质程度有关;②CO₂诱导煤基质溶胀效应将会降低煤层的渗透性能, 进而影响CO₂等流体在煤层内部的有效运移;③溶胀效应会影响煤层的CO₂封存性能, 建立涉及溶胀效应的煤吸附理论模型是溶胀效应研究的重要课题;④煤基质溶胀机理及其可逆性能研究目前存在争议, 研究人员需要从煤体理化结构的研究出发以明确上述问题。

关键词: 煤层, 存埋, 二氧化碳, 煤基质, 溶胀