【作者】 贾望鲁；

【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】 原油沥青质是原油中不溶于低分子烷烃而能溶于苯、甲苯等溶剂的高分子物质。原油沥青质在结构上和母源干酪根的相似性、沥青质能够随原油一起排出并运移到储层以及沥青质的大分子和抗降解等特性子使得原油沥青质被广泛用于石油地球化学研究的很多领域，包括油／源和油／油对比、母源性质、成熟度、原油形成温度等。塔里木盆地是我国典型的叠合盆地，轮南地区是塔里木盆地原油成因类型最复杂的地区。原油的多期次充注使得利用原油低分子部分进行油／油和油／源对比非常困难，至今该区原油的母源还存在争论。 本文首先采用热解-色谱-质谱、甲基化-热解-色谱-质谱、钌离子催化氧化等多种方法研究了塔里木盆地轮南地区原油沥青质的分子结构。在此基础上，主要运用热解-色谱-质谱对比研究了原油沥青质、志留系沥青砂沥青质以及烃源岩干酪根的结构组成，从高分子结构以及原油沉积环境的角度对轮南地区原油的母源进行了探讨。 1．沥青质沉淀实验表明，不同的沉淀条件下沉淀出的沥青质的元素组成、碳同位素组成、分子结构参数没有明显变化，表明原油体系中低分子烃类的加入不会改变原油沥青质的结构特征，因此原油沥青质的分子结构可以用来对遭受后期生成的气体或凝析油注入的油藏进行油／源或油／油对比研究。这一结果为在叠合盆地原油沥青质的应用研究打下了理论基础。 2)Py-GC-MS、甲基化-Py-GC-MS和RICO等多种热降解和选择性化学降解方法对原油沥青质分子结构研究的结果表明，轮南地区原油沥青质分子中的取代官能团以烷基侧链为主，烷基桥次之，另外还有少量的烷基环己烷、支链烷烃和苯系物，这些化合物可能大都以C-C键结合到缩合芳环体系上；部分脂肪酸类化合物通过酯键连接在沥青质分子中。沥青质分子中芳环体系大多数可能是萘或菲类型的芳香结构，高度缩合的芳香结构可能较少。 3)轮南地区不同构造带、不同时代储层和不同类型原油沥青质热解产物的一致性，指示它们可能来自沉积环境相同的母源。塔北和塔中地区志留系沥青砂抽提物中的沥青质的热解产物特征十分一致，与轮南地区原油沥青质的热解产物也比较类似。热解产物中都检测到了较高含量的1，2，3，4-四甲基苯和少量的芳基类异戊二烯类化合物。 通过碳同位素研究证实，轮南地区原油沥青质和志留系沥青砂中的沥青质热解产物中高含量的1，2，3，4-四甲基苯具有很重的碳同位素组成，与热解产物中正构烷烃相比偏重10‰以上。这一结果证明，沥青质中的1，2，3，4-四甲基苯来源于绿硫细菌，从而说明其母源应该形成于强还原条件下的分层水体中，轮南地区原油和志留系沥青砂的母源具有类似的沉积环境。 4)利用Py-GC-MS和甲基化-Py-GC-MS对塔里木盆地寒武-奥陶系烃源岩干酪根进行了分子结构的研究。在此基础上，从沉积环境的角度研究对比研究了寒武系和奥陶系抽提物的分子地球化学特征。1，2，3，4-四甲基苯和长链的1-烷基-2，3，6-三甲基取代的芳基类异戊二烯类化合物在寒武和奥陶系烃源岩中均有检出。但来自方1井和塔东2井的寒武系烃源岩抽提物中这类芳基类异戊二烯化合物的相对含量明显高于塔中6和塔中12井的中上奥陶统烃源岩。此外，寒武系烃源岩抽提物饱和烃部分检出了较高含量的伽马蜡烷。上述结果表明寒武系烃源岩的沉积环境可能是一种强还原条件下的高盐度的分层水体，而奥陶系烃源岩则不具备这些特征。塔里木盆地轮南地区原油沥青质的分子结构及其应用研究 尽管从沉积环境上来看轮南地区原油来源于寒武系烃源岩的可能性很大，但丛前人对烃源岩生烃史的研究来看，该区原油不可能直接来源于该套烃源岩。原油沥青质志留系沥青砂中的沥青质的总碳同位素对比研究不支持塔里木广泛分布的志留系沥青砂作为寒武系生油中间体的设想。因此，轮南地区原油母源的沉积环境尽管和寒武系烃源岩很类似，但来源于寒武系烃源岩的可能性不大。轮南地区原油可能主要来自一套形成于强还原条件下的奥陶系烃源岩，但有待进一步的勘探证实。更多还原

【Abstract】 Petroleum asphaltenes was defined as macromolecules which can be dissolved in benzene or toluene but not soluble in low molecular alkanes. Petroleum asphaltenes have been widely used in many areas of geochemical studies, such as oil/source and oil/oil correlations, tracing the source of studied samples, maturity of petroleum and the temperature of oil formation. Tarim basin is a typical compositional basin in China, and Lunnan oil field is the most complicated area of Tarim basin due to its diversity of oil chemical and physical properties. It was difficult to carry oil/oil or oil/source correlations with low molecular compounds, and the source of oils from Lunnan area is still a question in debate.In this work, the molecular structure of petroleum asphaltenes from Lunnan area was determined by pyrolysis-gas chromatrography-mass spectrometer(Py-GC-MS), methylation-Py-GC-MS and Ruthenium Ion Catalyzed Oxidation(RICO). Moreover, the structure of petroleum asphaltenes, asphaltenes from Silurian oil sandstones and kerogens from source rocks, Tarim basin, were analysed by Py-GC-MS. Based on these results, the source of oils from Lunnan area were discussed with a point of view of structure of macromolecules and sedimentary environments.1.It was found that the elemental compositions, isotopic compositions and the molecular structure of asphaltenes precipitated from oil didn’t change under different conditions in the precipitation experimnet. The pyrolysate of asphaltenes can be used as the substituent of low molecular compounds for oil-source rock correlation and also for identification of oil source whatever the oil reservior in superposed basin was charged by secondary gas or condensate oil.2. The molecular structure of oil asphaltenes from Lunan area of Tarim basin was elucidated by flash pyrolysis, methylation-pyrolysis and RICO. The substituted functions in oil asphaltenes from Lunan area were dominated by n-alkyl side chains. H-Alkyl bridges and minor alkyl cyclohexanes, branched alkanes and alkyl benzenes were also identified. These functions maybe were linked to the structure of asphaltenes by C-C bonds. The aromatic ring systems of oil asphaltenes were mainly composed of naphthalene and phenanthrene and seldom of highly condensed aromatic rings.3.The pyrolysates of oil asphaltenes from different tectonic belt, reservoirs, and different kinds of oils from Lunnan area were similar, which suggested these oils were generated from sources under the same sedimentary environment. Moreover, The pyrolysates of asphaltenes extracted from Silurian oil sandstones of Tabei and Tazhong area, Tarim basin, also exhibited similar characteristics to that of petroleum aspaltenes from Lunnan area. A most striking feature of the pyrolysates was identification of high abundance of 1,2,3,4-tetramethyl benzene and minor amounts of aromatic isoprenoids. The 1,2,3,4-tetramethyl benzene of pyrolysates from closed system pyrolysis of asphaltenes from oils and Silurian oil sandstones show very heavy carbon isotopic compositions, and the 1,2,3,4-tetramethyl benzene was enriched in 13C by more than 10%o compared with the normal alkanes in pyrolysates. This results unambiguously proved that high1,2,3,4-tetramethyl benzene in asphaltenes from oils and Silurian oil sandstones was from green sulfur bacterial, and the source of Lunnan oils and Silurian oil sandstones was derived from an stratified water column under strong reducing conditions. 4. The molecular structure of kerogens from source rocks, Tarim basin, were also studied by Py-GC-MS and methylation-Py-GC-MS, and the depositional enviroment of Cambrian and Ordovician source rocks was compared based on the geochemical characteristics of extracts from these two sets of source rocks. 1,2,3,4-tetramethyl benzene and l-alkyl-2,3,6-trimethyl benzenes were both detected from extracts of Cambrian and Ordovician source rocks. However, the abundance of l-alkyl-2,3,6-trimethyl benzenes from extracts of Cambrian source rocks from Fang 1 and Tadong 2 wells was much hi更多还原