【作者】 刘大永；

【导师】 彭平安；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 地球化学， 2004， 博士

【摘要】 近年来在中国西北地区一些中生界含煤盆地,如准噶尔东部盆地、吐哈盆地陆续发现了与煤及煤系泥岩有关的具有工业价值的油气田。但石炭二叠系煤系地层却没有迹象表明其有生油的可能。镜质组是煤岩的主要显微组分,同时氢指数与基质镜质体的含量或壳质体与基质镜质体的总量具有非常好的相关性。因而研究镜质组的结构特征及差异对于从分子水平认识煤成油的机制十分关键。本项研究、实验及结论如下: 1.本次研究选取了中国主要含煤盆地不同年代煤岩样品,通过手选的方式富集了镜质组样品,进行瞬时热解.色谱/质谱实验。热解产物主要为酚类、脂肪烃及芳烃。结果表明热解产率及组分随成熟度、亚显微组分及沉积环境的不同而有很大差别。相对于均质镜质体,基质镜质体热解产物中含有更为丰富的长链脂肪烃类而酚类产物则相对较少。而长链脂肪烃类在中国新疆地区侏罗系含煤盆地基质镜质体中最为富集。而相同成熟度的不同类型镜质组热解产物中酚类分布特征却较为相似,表明其可能具有相同母质来源。 此外,还对镜质组样品进行了不同条件下的瞬时热解实验。不同温度点瞬时热解实验结果表明随热解温度的不同,热解产物组分特征也有很大差异。随温度的升高,热解产物中脂肪烃所占比例不断降低。而分段热解实验中正构烷烃与正构烯烃的比例随温度的升高而不断降低,表明自350℃到650℃均有吸附烃的产生。甲基化热解实验表明镜质组结构中具有大量脂肪酸结构,而这些极性物质在常规热解色谱质谱实验中检测不到。 2.选取部分镜质组样品进行碳谱核磁共振实验以了解镜质组总体结构特征。研究表明基质镜质体中结构中油潜力碳,如亚甲基碳,在脂碳峰中所占比例相对较高,而均质镜质体脂碳结构则以气潜力碳,如甲基碳,甲氧基碳为主。而芳碳率（f_a）与R_O成正比,而与H/C原子比成反比。此外,不同结构碳对应不同的化学位移,文中通过这些不同范围内峰面积的比值组成的参数,如f_a、S_ox、f_CO2H以及f_COH来进一步研究镜质组总体的特征。结果表明S_OX对成熟度最为敏感。 3.以镜质组结构研究为基础,探讨了影响镜质组结构的控制因素。侏罗系富氢基质镜质体沉积于流水沼泽相,而均质镜质体则沉积于潮湿森林沼泽。通过与几种壳质体热解色谱质谱色特对比,可得出基质镜质体中类脂物最有可能来源于高等植物的类脂组分。 4.金管封闭体系热模拟条件下镜质组生烃动力学研究表明:活化能随镜质组类型、结构的不同而有很大差异。均质镜质体裂解活化能最高而基质镜质体活化能分布相对较低。而由不同类型镜质组裂解生成的甲烷均具有非常相似的碳同位素分布,热模拟早期δ¹³C₁随温度的升高而下降,晚期逐渐上升,更高温度热更多还原

【Abstract】 The certain oil and gas pertained to coals and coaly mudstones have been found in the Jurassic coal-bearing basins in NW China. But little oil has been found in any Carboniferous-Permian coal-bearing basins. Vitrinite is the most dominant maceral in coals. And HI of coals shows good correlation with proportion of desmocollinite or summation of liptinite and desmocollinite. Therefore, it’s meaningful to study structure of different vitrinites for understanding formation of coal-generated oils. The main conclusions of this study are followings:1. Jurassic and Carboniferous-Permian coal used for this study is obtained from Jungger, Turpan-Hami, Ordos and other basins of China. Flash pyrolysis-gas chromatography/ mass spectra (Py-GC/MS) have been applied to the quantitative determination of different groups of hydrocarbons and non-hydrocarbons presented in pyrolysates of hand purified vitrinites isolated from coals.Aliphatics, phenols, alkylbenzenes and other aromatic hydrocarbons are the mayor components in pyrolysates of vitrinites. Long chain aliphatics are more abundant in pyrolysates of hydrogen-rich desmocollinites while phenols are more abundant in pyrolysates of telocollinites. And aliphatics are the most abundant components in pyrolysates of Jurassic hydrogen-rich desmocollinite of Xinjiang Area. However, similar phenol distributions are presented in pyrolysates of vitrinites at the same maturation level. And this indicates pheols may be originated from diagenetically altered lignins.Flash pyrolysis at different temperatures point and step pyrolysis have been applied to study variation of production ratio and relative proportion of major components in pyrolysates. Relative abundance of n-alkanes reaches the highest in pyrosates generated at 350℃, and then shows decreasing trend with increasing temperature while relative abundance of alke-1-nes, phenols and alkylbenzenes show contrary variation.Flash pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) has been employed for the characterization of polar components that cannot be detected using normal pyrolysis GC-MS. And large quantity of carboxylic acid methyl esters is determined.2. 13C NMR spectra, which provide direct measurements of the chemical structure of organic matter, have been obtained for vitrinites. The oil-prone carbons, such as methylene carbon, are relatively rich in spectra of desmocollinites, and the gas-prone carbons, such as methyl carbon and methoxyl carbons, are relatively rich in spectra oftelocoUinites. Converted into numerical parameters, the spectra show differences relate to vitrinite type and rank. NMR parameters, fa, Sox, fCO2H and fCOH, are examined for characterization of macromolecular structure of vitrinites. Result shows Sox is sensitive to rank of coals.3. The depositional environment of vitrinites has been discussed based on the characterization of vitrinite structure. It shows Jurassic hydrogen-rich desmocollinites has been deposited in running water swamp and telocoUinites has been deposited in moist forest swamp. Several isolated lipid macerals have been subject to perform flash pyrolysis-GC/MS for comparison between desmocollinites and lipids, and the result shows that aliphatics in desmocollinite may be originated from lipid parts of high plants.4. Hydrocarbon generation kinetics study of vitrinites based on pyrolysis of gold tube closed system shows: Activation energies of methane generated from telocollinite are higher than that from desmocollinite due to macromolecular structure differences. But carbon isotope distributions of generated methane in pyrolysates of vitrinites are similar. Carbon isotope ratio of methane decreases in the early stage of gas generation and increases in later stages. At higher temperature, δ13C1 decrease slightly or almost keep stable with increasing temperature. Decreasing trend of δ 13C, in the early stage may be caused by heterogeneous structure or differences of activation energies between 12C-12C and 12C-13C are not strictly constant at different range of activation energy area.5. Aliphatics, especially long chain n-alkanes are more abundant in liquid fraction originated from Zhunji-1 desmocollinite than that from Tujun-1 telocollinite in gold tube pyrolysis. And distribution of n-alkanes in liquid fraction shows even to odd predominance that indicates anhydrous gold tube pyrolysis is not suitable for the simulation of oil generation.更多还原