海相过成熟页岩有机质孔隙与分子官能团的响应关系:来自基于原子力显微镜红外光谱的证据  

Response of organic matter pore development to functional groups in overmature marine shale:Insights from AFM-IR spectroscopy

作　　者：赵建华[1] 刘可禹[1] 赵生辉 胡钦红 吴伟 陈扬 刘国恒 李俊乾[1] 俞凌杰[4,5] 游祖辉 王晔 ZHAO Jianhua;LIU Keyu;ZHAO Shenghui;HU Qinhong;WU Wei;CHEN Yang;LIU Guoheng;LI Junqian;YU Lingjie;YOU Zuhui;WANG Ye(State Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao 266580,China;Sinopec Southwest Oil&Gas Company,Chengdu 610041,China;Shale Gas Research Institute,PetroChina Southwest Oil&Gas Field Company,Chengdu 610051,China;Sinopec Key Laboratory of Petroleum Accumulation Mechanisms,Wuxi 214126,China;Wuxi Institute of Petroleum Geology,Sinopec Petroleum Exploration and Production Research Institute,Wuxi 214126,China;Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education,Chang’an University,Xi’an 710054,China)

机构地区：[1]深层油气全国重点实验室(中国石油大学(华东)),山东青岛266580 [2]中国石油化工股份有限公司西南油气分公司,成都610041 [3]中国石油西南油气田公司页岩气研究院,成都610051 [4]中国石化油气成藏重点实验室,江苏无锡214126 [5]中国石化石油勘探开发研究院无锡石油地质研究所,江苏无锡214126 [6]长安大学西部矿产资源与地质工程教育部重点实验室,西安710054

出　　处：《石油勘探与开发》2025年第2期395-407,共13页Petroleum Exploration and Development

基　　金：国家自然科学基金面上项目(42172148,42172142)。

摘　　要：以四川盆地下志留统龙马溪组页岩为例,采用基于原子力显微镜的红外光谱(AFM-IR)对不同类型和赋存状态有机质开展亚微米尺度分子官能团分析,结合扫描电镜下孔隙发育程度定量统计,探讨海相过成熟页岩中有机质孔隙形成演化机理与有机质化学组成及结构变化之间的关系。研究结果表明,页岩中笔石表皮体和焦沥青AFM-IR光谱在波数约1600 cm^(-1)处代表芳香族化合物共轭双键C═C的伸缩振动占主导地位,1375,1450,1720 cm^(-1)波数附近代表脂肪族和羰基/羧基官能团吸收位出现微弱峰值。整体上,相同成熟度页岩样品中有机质的AFM-IR光谱结构参数与面孔率有很好的对应关系,即A和C因子值越低,有机质孔越发育,与其热演化过程中较多的脂肪链和含氧官能团脱离形成油气有关。焦沥青-黏土矿物复合体孔隙发育普遍较好,这可能与黏土矿物脱水参与生烃反应,导致较多的官能团脱离有关。此外,在高—过成熟阶段有机质-黏土复合体内部有机质热演化生烃可导致体积增大而发生爆裂并释放油气,较高的排烃速率有利于形成孔径较大的孔隙和沿片状黏土矿物呈裂缝形态的孔隙。研究成果显示,亚微米尺度分子官能团的研究可以更为深入诠释过成熟页岩有机质演化路径和有机质孔发育机制,并为页岩油气地质勘探提供储层评价方面的参数依据。Taking the Lower Silurian Longmaxi Formation shale in the Sichuan Basin as an example,this study employs atomic force microscopy-based infrared spectroscopy(AFM-IR)to analyze the submicron-scale molecular functional groups of different types and occurrences of organic matter.Combined with the quantitative evaluation of pore development via scanning electron microscopy(SEM),the response of organic pore formation and evolution mechanisms to chemical composition and structural evolution of organic matter in overmature marine shale is investigated.The results indicate that the AFM-IR spectra of graptolite periderms and pyrobitumen in shale are dominated by the stretching vibrations of conjugated C═C bonds in aromatic compounds at approximately 1600 cm^(-1),with weak absorption peaks near 1375,1450 and 1720 cm^(-1),corresponding to aliphatic chains and carbonyl/carboxyl functional groups.Overall,the AFM-IR structural indices(A and C factors)of organic matter show a strong correlation with visible porosity in shales of equivalent maturity.Lower A and C factor values correlate with enhanced development of organic pores,which is associated with the detachment of more aliphatic chains and oxygen-containing functional groups during thermal evolution.Pyrobitumen-clay mineral composites generally exhibit superior pore development,likely attributable to clay mineral dehydration participating in hydrocarbon generation reactions that promote the removal of more functional groups.Additionally,hydrocarbon generation within organic-clay composites during high-over mature stages may induce volumetric expansion,resulting in microfracturing and hydrocarbon expulsion.The associated higher hydrocarbon expulsion rates promote the formation of larger pores and fracture-shaped pores adjacent to flake-shaped clay minerals.This study highlights that the research of submicron-scale molecular functional groups provides a deeper understanding of organic matter evolution and pores development mechanisms in overmature shales,thereby offering c

关 键 词：AFM-IR光谱 有机质分子官能团 有机孔发育程度 龙马溪组页岩 

分 类 号：TE122[石油与天然气工程—油气勘探]