基于纳米红外光谱技术表征页岩中有机质的分子结构  

Characterization of organic matter molecular structure in shale based on nano-infrared spectroscopy

作　　者：赵生辉 赵建华[1] 刘可禹[1] 胡钦红 王齐鸣 陈扬 于孟想 ZHAO Shenghui;ZHAO Jianhua;LIU Keyu;HU Qinhong;WANG Qiming;CHEN Yang;YU Mengxiang(State Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao 266580,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

出　　处：《天然气地球科学》2024年第7期1249-1260,共12页Natural Gas Geoscience

基　　金：国家自然科学基金项目(编号:42172148)资助。

摘　　要：纳米红外光谱技术(Nano-IR)是一种结合原子力显微镜与红外光谱的新技术,可以对页岩内的有机质进行纳米尺度分子结构的研究,这项技术在微观地质领域有着广泛的发展前景。以Fort Worth盆地不同成熟度Barnett页岩为研究对象,基于总有机碳(TOC)含量测试、镜质体反射率测试、Rock-Eval分析、光学显微镜和扫描电镜(SEM)观察,明确Barnett页岩内显微组分类型、含量和赋存特征,在此基础上通过Nano-IR技术对不同显微组分分子结构之间的差异与演化程度开展研究。结果表明:Barnett页岩有机质主要由无定形有机质、藻类体、固体沥青与惰质体4种显微组分构成。无定形有机质与藻类具有较强的C=O吸收峰与脂肪链吸收峰,固体沥青的脂肪链吸收峰较为明显,惰质体内C=C吸收峰最强。同一显微组分微米—纳米尺度也存在分子结构的非均质性,其中藻类、无定形有机质和固体沥青较为明显,惰质体的非均质性并不显著。不同成熟度Barnett页岩样品中藻类、无定形有机质和固体沥青基本遵循着Ⅱ型干酪根的演化趋势,表明固体沥青的生烃母质主要来源于藻类和无定形有机质。Nano-infrared spectroscopy(Nano-IR)is an emerging technology that combines atomic force micros⁃copy and infrared spectroscopy,which allows for the study of micro-component organic matter in shale at the na⁃noscale for fine-scale delineation and molecular structure.This technology has far-reaching and wide-ranging prospects in the field of micro-geology.The subject of this study is the Barnett Shale of the Fort Worth Basin at different maturities.Definition of maceral types,contents and hosting characteristics within the Barnett Shale based on total organic carbon(TOC)content testing,vitrinite reflectance test,Rock-Eval analysis,optical mi⁃croscopy and scanning electron microscopy(SEM)observations.On this basis,each of the four different microcomponent types of the Barnett Shale in the Fort Worth Basin was described and molecularly structured by Na⁃no-IR.The results show that the organic matter in Barnett shales with two maturities is mainly composed of amorphous organic matter,alginite,solid bitumen and inertinite.Among them,the C=C absorption peak in in⁃ertinite is the strongest,the amorphous organic matter and alginite have strong C=O absorption peak and fat chain absorption peak,and the fat chain absorption peak of solid bitumen is more obvious.Furthermore,the het⁃erogeneity of molecular structure of the same maceral also exists at micro and nano scale,among which al⁃ginite,amorphous organic matter and solid bitumen are more obvious,but inertinite is not significant.The al⁃ginite,amorphous organic matter and solid bitumen in Barnett shale samples of different maturity basically fol⁃low the evolutionary trend of type II kerogen,indicating that the hydrocarbon generating material of solid bitu⁃men is mainly derived from the alginite and amorphous organic matter.

关 键 词：页岩 有机质 纳米红外光谱 

分 类 号：TE122.113[石油与天然气工程—油气勘探]