大分子结构和氢同位素分析的热解方法及其在塔里木盆地油气成因中的应用研究

发布时间：2017-12-30 22:37

本文关键词：大分子结构和氢同位素分析的热解方法及其在塔里木盆地油气成因中的应用研究　出处：《中国科学院广州地球化学研究所》2017年博士论文　论文类型：学位论文

【摘要】：受多套烃源岩发育、多期次生烃和构造活动的影响,塔里木盆地海相原油的成因一直是国内地质-地球化学领域的研究热点和难点。已有研究主要依据可溶低分子部分的同位素和生物标志化合物组成,但低分子的地球化学特征受原油物性以及二次过程的影响大,需要针对高分子有机质建立新的方法并开展相关的应用研究,以深化对塔里木盆地海相原油的成因认识。针对这些问题,本论文建立了用于沥青质键合态正构烷烃氢同位素组成测定的热解方法,优化了地质大分子组成研究的两阶段热化学降解条件,以此为基础开展了原油饱和烃与沥青质中正构烷烃氢同位素组成的对比分析并重点研究了塔里木盆地志留系沥青砂岩中固体沥青的地球化学特征。通过这些工作主要取得了以下结论和认识:(1)建立了用于沥青质中正构烷烃氢同位素测定的热解方法:首先,采用混合溶剂热萃取和氢氟酸溶解-溶剂萃取两种方式洗脱5?分子筛吸附的不同类型样品的正构烷烃,证明混合溶剂热萃取方式简便、快速,可以用于分离、纯化正构烷烃进行氢同位素测定。其次,利用低温封闭体系研究了热解温度对沥青质热解产物中正构烷烃氢同位素组成的影响,确定了合适的热解温度。最后对不同来源的原油沥青质进行了分析,结果表明键合态正构烷烃的氢同位素组成差异显著,可以用来进行油源特征和油-油对比研究。(2)优化了地质大分子的两阶段离线热化学降解方法:首先,以沥青质为实验对象,建立了用于研究地质大分子组成的封闭体系高温快速热解方法。在此基础上,对不同类型的干酪根和沥青质开展了高温瞬间热解、离线热化学降解和两阶段热化学降解分析,证明本次工作建立的两阶段离线热化学降解方法能够区分吸附-包裹态和键合态分子的组成差异,并且可以指示不同类型地质大分子组成的差异。(3)塔里木盆地多数海相原油与储层沥青质中正构烷烃的氢同位素组成变化较小,几乎不受生物降解作用的影响,指示了早期充注原油的同位素特征。塔东2井原油沥青质中正构烷烃具有显著偏轻的氢同位素组成和较重的碳同位素组成,与原油低分子可溶部分的同位素组成差异明显,指示其与盆地多数海相原油具有不同的母源。(4)综合利用元素分析、谱学分析(核磁共振、红外光谱、X射线光电子能谱)、高温瞬间热解和两阶段离线热化学降解方法对塔里木盆地志留系沥青砂岩中的不溶固态有机质进行了分析,结果显示生物降解型和热蚀变型两类固态有机质具有不同的芳碳率且结合到缩合芳环体系上的结构单元明显不同,沥青质是不溶固态有机质的主要物质来源,非烃和部分芳烃也有一定的贡献,可溶低分子和不溶固态有机质同位素组成的相关性反映了多期次充注和生物降解改造的共同贡献。
[Abstract]:It is affected by the development of multiple source rocks, multi-stage secondary hydrocarbon generation and tectonic activity. The origin of marine crude oil in Tarim Basin has been a hot and difficult point in the field of geology and geochemistry in China. However, the geochemical characteristics of low molecular weight are greatly affected by the physical properties and secondary processes of crude oil, so it is necessary to establish a new method for polymer organic matter and to carry out related application research. In order to deepen the understanding of the origin of marine crude oil in Tarim Basin, a pyrolysis method for the determination of hydrogen isotopic composition of asphaltene bonded normal alkanes has been established in this paper. The two-stage thermochemical degradation conditions for the study of the composition of geological macromolecules were optimized. Based on this, a comparative analysis of the hydrogen isotopic compositions of normal alkanes between saturated oil and asphaltene has been carried out and the geochemical characteristics of solid asphalt in Silurian bituminous sandstone in Tarim Basin have been studied. The main conclusions and understandings are as follows:. (. 1) the pyrolysis method for the determination of hydrogen isotopes of n-alkanes in asphaltenes was established. Mixed solvothermal extraction and hydrofluoric acid dissolution-solvent extraction were used to elucidate 5? It is proved that the mixed solvothermal extraction method is simple and rapid, and can be used for the separation and purification of n-alkanes for the determination of hydrogen isotopes. The effect of pyrolysis temperature on the hydrogen isotopic composition of n-alkane in pyrolysis products of asphaltene was studied by using low temperature sealing system, and the suitable pyrolysis temperature was determined. Finally, the asphaltene from different sources was analyzed. The results show that the hydrogen isotopic compositions of bonded n-alkanes differ significantly and can be used to study the oil source characteristics and oil-oil correlation. 2) the two-stage off-line thermochemical degradation method of geological macromolecules is optimized: firstly. Taking asphaltene as the experimental object, a fast pyrolysis method for studying the composition of geological macromolecules at high temperature was established. On this basis, the pyrolysis of different types of kerogen and asphaltene was carried out. The analysis of off-line thermochemical degradation and two-stage thermochemical degradation shows that the two-stage off-line thermochemical degradation method established in this paper can distinguish the differences of adsorption-wrapped and bonded molecules. The hydrogen isotopic composition of normal alkanes in most marine crude oil and asphaltene in Tarim Basin is relatively small. Almost no effect of biodegradation indicates the isotopic characteristics of early filling crude oil. Normal alkanes in asphaltene of well Tadong 2 have significantly lighter hydrogen isotopic composition and heavier carbon isotopic composition. The isotopic composition of the low molecular soluble part of the crude oil is obviously different from that of the most marine crude oil in the basin, indicating that it has a different parent source from most of the marine crude oil in the basin. It is characterized by comprehensive utilization of elemental analysis, spectroscopic analysis (nuclear magnetic resonance, infrared spectroscopy). The insoluble solid organic matter in Silurian bituminous sandstone in Tarim Basin was analyzed by X-ray photoelectron spectroscopy (XPS), transient pyrolysis at high temperature and two-stage off-line thermochemical degradation. The results show that the biodegradable and thermally altered solid organic matter have different aromatics and different structural units bound to the condensed aromatic ring system. Asphaltene is the main material source of insoluble solid organic matter. Non-hydrocarbon and some aromatics also contribute to some extent. The correlation between the isotope composition of soluble low molecule and insoluble solid organic matter reflects the contribution of multi-stage secondary filling and biodegradation transformation.
【学位授予单位】：中国科学院广州地球化学研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P618.13

【相似文献】