Molecular Structure of Kerogen in the Longmaxi Shale: Insights from Solid State NMR, FT-IR, XRD and HRTEM

作     者：WANG Xiaoqi ZHU Yanming LIU Yu LI Wu 

作者机构：Key Laboratory of Coalbed Methane Resources and Reservoir Formation on ProcessMinistry of EducationChina University of Mining and TechnologyXuzhou 221008JiangsuChina School of Resources and GeosciencesChina University of Mining and TechnologyXuzhou 221116JiangsuChina 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2019年第93卷第4期

页      面：1015-1024页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：supported by the National Science and Technology Major Project(2017ZX05035004–002) the National Natural Science Foundation of China(no.41702167) the Fundamental Research Funds for the Central Universities(No.2017CXNL03) the Scientific Research Foundation of the Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education(China University of Mining and Technology)(No.2017–007) 

主　　题：organic-rich shale molecular structure kerogen HRTEM Sichuan Basin 

摘      要：Kerogen plays an important role in shale gas adsorption,desorption and ***,it is necessary to characterize the molecular structure of *** this study,four kerogen samples were isolated from the organic-rich shale of the Longmaxi *** spectroscopy was used to determine the maturity of these kerogen *** transmission electron microscopy(HRTEM),13 C nuclear magnetic resonance(13 C NMR),X-ray diffraction(XRD)and Fourier transform infrared(FT-IR)spectroscopy were conducted to characterize the molecular structure of the shale *** results demonstrate that VReqv of these kerogen samples vary from 2.3%to 2.8%,suggesting that all the kerogen samples are in the dry gas *** macromolecular carbon skeleton of the Longmaxi Formation kerogen is mainly aromatic(fa’=0.56).In addition,the aromatic structural units are mainly composed of naphthalene(23%),anthracene(23%)and phenanthrene(29%).However,the aliphatic structure of the kerogen macromolecules is relatively low(fal*+falH=0.08),which is presumed to be distributed in the form of methyl and short aliphatic chains at the edge of the aromatic *** oxygen-containing functional groups in the macromolecules are mainly present in the form of carbonyl groups(fac=0.23)and hydroxyl groups or ether groups(falO=0.13).The crystallite structural parameters of kerogen,including the stacking height(Lc=22.84?),average lateral size(La=29.29?)and interlayer spacing(d002=3.43?),are close to the aromatic structural parameters of anthracite or overmature ***-resolution transmission electron microscopy reveals that the aromatic structure is well oriented,and more than 65%of the diffractive aromatic layers are concentrated in the main *** to the continuous deep burial,the longer aliphatic chains and oxygen-containing functional groups in the kerogen are substantially ***,the ductility and stacking degree of the aromatic structure increases during therm