封存过程中二氧化碳对煤体理化性质的作用规律

Effect of CO_2 on physico-chemical characteristics of coal during sequestration process:A perspective

强化煤层气(CH4)开采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进行有效存储,但基于煤体特征和适宜储层条件下的CO2流体特性,CO2流体和煤体之间存在除吸附作用以外的其他流-固作用。CO2流体和煤体之间的流-固作用关系既会影响煤层的CO2封存潜力又会引发潜在的环境问题。为此,本文结合国内外的相关研究工作,介绍了煤层封存CO2过程中煤体理化性质变化的研究成果,归纳了煤体理化性质变化对煤层封存CO2潜力的影响,指出了煤体理化性质变化由此造成的环境安全与健康风险问题。分析表明:深部煤层封存CO2过程中流-固作用及其影响主要包括两个方面:1CO2流体能够诱导煤基质发生溶胀效应,因而会影响注入的CO2流体在煤层内部的扩散和吸附能力;2CO2流体具有萃取煤基质内部有机物的能力,会对环境安全与健康造成威胁。此外,本文还指出了煤基质溶胀机理及其可逆性、煤基质中被萃取出有机物的定性与定量分析是后续煤和CO2流体作用关系的重要研究方向。

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. It is acknowledged that complex fluid-solid interactions exist other than adsorption between CO2 fluid and coal due to their special characteristics under optimum reservoir conditions. The above fluid-solid interactions not only influence the CO2 sequestration capacity of coal seams,but also incur some potential environmental issues. The recent research progress of coal physico-chemical characteristics transformation during sequestration process is summarized. The effect of coal physico-chemical characteristics transformation on CO2 sequestration capacity of the targeted coal seams is elaborated and environmental safety and health（ESH）problems due to coal physico-chemical characteristics transformation are also indicated. The fluid-solid interactions during CO2 sequestration in deep coal seams mainly incorporate two aspects as follows. On one hand,coal matrix swelling occurs due to CO2 injection which will influence diffusion and adsorption behavior of CO2 in coal seams. On the other hand,supercritical CO2 fluid has the potential to extract organic matter in coal matrix,causing ESH problems. Furthermore,investigation on the mechanism and reversibility of coal matrix swelling,and qualitative and quantitative analysis of the organic matter extracted from coal matrix should be paid attention in the future.