超临界CO_(2)对高阶构造煤微观结构的影响机制  

Influencing mechanisms of SC-CO_(2)extraction on the microstructures of high-rank tectonic coals

作　　者：张小东[1] 张瑜 张硕[1,2] 李贵中[3] 李贤忠[1] ZHANG Xiaodong;ZHANG Yu;ZHANG Shuo;LI Guizhong;LI Xianzhong(College of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China;Postdoctoral Research Station of Safety Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)

机构地区：[1]河南理工大学能源科学与工程学院,河南焦作454000 [2]河南理工大学安全科学与工程博士后流动站,河南焦作454000 [3]中国石油勘探开发研究院,北京100083

出　　处：《煤田地质与勘探》2023年第5期45-53,共9页Coal Geology & Exploration

基　　金：国家自然科学基金项目(42172198,U1904126)。

摘　　要：为揭示深部煤层注入CO_(2)过程中,超临界CO_(2)(SC-CO_(2))对构造煤微观结构的影响规律,以山西大平矿贫煤和贵州振兴矿无烟煤样品为研究对象,对两类不同破坏程度的高阶煤进行萃取实验,比较了萃取前后煤中孔隙结构和芳香碳网结构参数的差异,探讨了SC-CO_(2)对不同破坏程度的高阶煤微观结构的影响机制。研究表明:(1)随着破坏程度增加,两类高阶煤的孔容、孔比表面积增大,孔隙连通性变好。孔径>4 nm时,构造煤分形维数增大,孔隙结构更加复杂。(2)SC-CO_(2)作用下,两类煤的平均孔径明显增大,孔隙分形维数减小,孔隙结构趋于简单化。而不同破坏程度煤的孔容、比表面积、孔隙连通性呈现复杂的变化,表现为SC-CO_(2)作用后,大平矿的构造煤微孔、介孔段比表面积和孔容显著减小,使得总比表面积和总孔容亦明显减小,孔隙连通性变差;振兴矿构造煤的介孔比表面积和孔容显著增大,使得总比表面积和总孔容增加。(3)SC-CO_(2)萃取作用下,不同破坏程度的高阶煤的碳网层间距d002增大,而延展度La、堆砌度Lc和芳香层数Nc呈减小趋势,且随着破坏程度的增加相应的变化趋于显著,促使不同破坏程度煤的碳网层参数趋于一致。研究认为,SC-CO_(2)与煤岩反应产物溶离煤体引起的扩孔效应,促使煤样平均孔径增大,而产物生成量不同和产物滞留造成的堵孔效应,是引起两类不同破坏程度的高阶煤孔隙差异性变化的主要原因;SC-CO_(2)流体对两类高阶煤的芳香碳网层结构参数的影响与构造破坏作用相反,前者表现为疏松作用,而后者主要为压密作用。This study aims to reveal the influencing patterns of supercritical CO_(2)(SC-CO_(2))on the microstructures of tec-tonic coals during the injection of CO_(2)into deep coal seams.The study conducted SC-CO_(2)extraction experiments on two types of high-rank coal samples with different damage degrees,namely the lean coal samples from the Daping coal mine in Shanxi Province and the anthracite samples from the Zhenxing coal mine in Guizhou Province.Accordingly,this study compared the parameters of pore structures and aromatic carbon stacking structures in the coal samples before and after the extraction experiments.Finally,this study explored the influencing mechanisms of SC-CO_(2)on the microstruc-tures of high-rank coals with different damage degrees.The results show that:(1)With an increase in the damage degree,the two types of high-rank coal samples showed increased pore volume and specific surface area and enhanced pore con-nectivity.However,compared with primary structural coal samples,the tectonic coal samples showed higher fractal di-mension and more complex pore structure when the pore size>4 nm.(2)Under the influence of SC-CO_(2)fluid,the two types of coal samples showed significantly increased average pore size,decreased fractal dimension of pores,and sim-pler pore structure.However,the coal samples with different damage degrees underwent complex changes in pore volume,specific surface area,and pore connectivity.Specifically,the tectonic coal samples from the Daping coal mine showed significantly decreased specific surface area and pore volume of micropores and mesopores,which significantly decreased the total specific surface area and the total pore volume and impaired the pore connectivity.By contrast,the tectonic coal samples from the Zhenxing coal mine showed significantly increased specific surface area and pore volume of mesopores,which increased the total specific surface area and the total pore volume.(3)Under the influence of SC-CO_(2)extraction,the high-rank coals with different damage degrees sho

关 键 词：高阶构造煤 SC-CO_(2)萃取 孔隙结构 芳香碳网结构 分形特征 

分 类 号：TD323[矿业工程—矿井建设]