超临界CO_(2)作用下无烟煤结构响应特征及高压吸附机理  

Structural response characteristics and adsorption mechanism of anthracite coal under supercritical CO_(2)

作　　者：王建美 梁卫国[1,2,3] 牛栋[1,2] 陈跃都 王聪伟 贺伟 WANG Jianmei;LIANG Weiguo;NIU Dong;CHEN Yuedu;WANG Congwei;HE Wei(Key Laboratory of In-situ Property-improving Mining of Ministry of Education//Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;College of Mining Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Carbon Neutral Research Institute,Taiyuan Normal University,Jinzhong,Shanxi 030600,China;Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan,Shanxi 030024,China)

机构地区：[1]原位改性采矿教育部重点实验室·太原理工大学 [2]太原理工大学矿业工程学院 [3]太原师范学院碳中和研究院 [4]中国科学院山西煤炭化学研究所

出　　处：《天然气工业》2024年第4期115-125,共11页Natural Gas Industry

基　　金：国家自然科学基金区域创新发展联合基金(重点支持)项目“煤系低渗储层‘一巷采三气’全生命周期智能高效抽采基础研究”(编号:U22A20167);山西省基础研究计划项目“深部煤体细观尺度超临界CO_(2)—CH4—H2O多相吸附解吸—渗流机理研究”(编号:202303021222002)。

摘　　要：中国深部煤层气资源丰富,将CO_(2)注入深部煤层,在提高煤层气采收率同时,还可实现CO_(2)地质封存(CO_(2)-ECBM)。通常,深部煤层CO_(2)处于超临界态并显著影响煤体吸附能力,但对于超临界CO_(2)作用下煤体结构演化及吸附机理尚不清晰。为此,以山西晋城成庄矿二叠系山西组三号煤层为研究对象,开展了无烟煤对超临界CO_(2)的高压吸附实验,结合傅里叶变换红外光谱(FTIR)、X射线衍射光电子能谱(XPS)测试及比表面积(BET)测试,分析了超临界CO_(2)高压吸附引起的无烟煤化学结构与孔隙结构响应特征,最后揭示了无烟煤对超临界CO_(2)的高压吸附特性及吸附机理。研究结果表明:①超临界CO_(2)高压吸附存在突变点,35℃时突变点位于临界压力(8 MPa)附近,在突变点处的吸附能力最小;②超临界CO_(2)可使芳香环枝接官能团、醚氧键、羟基氢键断裂,脂肪结构甲基脱落,可为CO_(2)提供更多的吸附位点,增强了无烟煤表面吸附能力;③超临界CO_(2)改变无烟煤介孔的孔隙结构特征和分形特征,吸附后平均孔径、孔体积、比表面积、分形维数呈增大趋势,孔隙粗糙度增大,对孔隙结构改造作用表现为“增孔、扩孔、粗糙化”,可提供更多吸附空间,增强了无烟煤吸附能力;④在深部煤层中注入CO_(2),应优先选择高孔隙度、高渗透性储层,注入煤层环境应尽可能远离CO_(2)临界点区域,储层对CO_(2)才有最大吸附能力。结论认为,成果认识为深部煤层CO_(2)可注性及封存潜力评估提供了重要的理论依据,对煤层气高效开发具有重要现实意义。China is rich in deep coalbed methane(CBM)resources.Injecting CO_(2) into deep coal seams can not only enhance CBM recovery factor,but also realize CO_(2) geological storage(CO_(2)-ECBM).Normally,CO_(2) existing its supercritical state in deep coal seam and significantly affects the adsorption capacity of coal,but the structure response characteristics and adsorption mechanism of coal under supercritical CO_(2) effect is not clear.Taking the No.3 coal seam of Permian Shanxi Formation in Chengzhuang Mine of Jincheng,Shanxi Province as the research object,this paper experimentally studies the high-pressure adsorbability of anthracite coal to supercritical CO_(2).Then,the response characteristics of chemical structures and pore structures in anthracite coal caused by the high-pressure adsorption of supercritical CO_(2) are analyzed by means of Fourier-transformed infrared spectrum(FTIR),X-ray diffraction photoelectron spectroscopy(XPS)and specific surface area(BET)measurements.Finally,the high-pressure adsorption behaviors and mechanisms of anthracite coal to supercritical CO_(2) are revealed.And the following research results are obtained.First,there is a mutation point mutation point in supercritical CO_(2) adsorption under high pressure.Under 35℃,the mutation point is close to the critical pressure(8 MPa),where the adsorption capacity is the smallest.Second,supercritical CO_(2) exhibits the ability to graft aromatic rings with functional groups,break ether-oxygen bonds and hydroxyl hydrogen bonds and remove methyl groups from the fat structure,which can provide more adsorption sites for CO_(2) and subsequently enhance the adsorption capacity on the surface of anthracite coal.Third,supercritical CO_(2) alters the pore structures and fractal characteristics of anthracite mesopores.After adsorption,the average pore diameter,pore volume,specific surface area and fractal dimension present an increasing trend,and the pore roughness increases.Thus,the reconstruction of pore structure is characterized by pore increase,

关 键 词：CO_(2)-ECBM 超临界CO_(2) 高压吸附特性 化学结构 孔隙结构 无烟煤 封存 可注性 

分 类 号：TE822[石油与天然气工程—油气储运工程]