【作者】 秦艳；

【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， 2006， 博士

【摘要】 我国的盐湖沉积盆地含有丰富的油气资源,比如江汉盆地是我国最为典型的一个盐湖盆地,在其第三系沉积中广泛发现了未成熟油。在盐湖沉积环境的不同沉积阶段,烃源岩具有不同的有机地球化学特征,本论文选取了江汉盆地小板凹陷一个剖面样品,研究了盐湖沉积环境不同沉积阶段烃源岩的生物标志物特征、单体碳、氢同位素组成和干酪根热解产物特征,进行了母源和沉积环境的探讨,并用干酪根加硫模拟实验研究了高硫干酪根的裂解机制。 1) 盐湖沉积环境烃源岩的生物标志物特征表明,在碳酸盐沉积阶段有丰富的藻类输入,异常明显的植烷优势,较高含量的伽马蜡烷,C₃₅升藿烷、硫芴、丰富的含硫化合物、芳基类异戊二烯化合物、C₄₀ isorenieratane和含硫键的C₄₀ isorenieratane的检出都说明了碳酸盐沉积阶段具有强还原的、水体分层的沉积环境。在卤化物沉积阶段,检出了丰富的C₂₁⁺类异戊二烯烷烃和鲛鲨烷、三芳甾烷、苯并藿烷,说明在卤化物沉积阶段有较多的喜盐细菌输入。低含量的含硫化合物以及氧芴（硫芴含量较低）的检出,说明其形成于相对较为氧化的沉积环境。 2) 盐湖沉积环境烃源岩的碳、氢同位素组成研究结果表明,卤化物沉积阶段烃源岩比碳酸盐沉积阶段的烃源岩相对富集¹³C,说明了在不同的沉积阶段具有不同的生物输入,也可能是盐度的增加使卤化物沉积阶段烃源岩相对富集¹³C。氢同位素组成反映了小板凹陷潜江组烃源岩形成于盐湖沉积环境,在不同的沉积阶段氢同位素组成变化不明显。可以从两个方面来解释:①有机质的氢同位素组成主要受大的沉积水环境的影响,在盐湖沉积环境不同沉积阶段δD值的变化并不明显;②小板凹陷在潜三段-潜四段沉积时期可能并不是浅水沉积环境,而属于深水盐湖相沉积。 3) 用Py-GC-MS对盐湖沉积环境碳酸盐沉积阶段和卤化物沉积阶段烃源岩干酪根的热解产物进行了研究。研究结果表明,江汉盆地小板凹陷板70井潜江组烃源岩以浮游生物的输入为主,但是也有细菌、陆源生物的输入。该烃源岩形成于水体分层的缺氧的沉积环境,从碳酸盐沉积阶段到卤化物沉积阶段,湖水还原程度减小。 4) 对茂名油页岩干酪根及其加硫醚、硫磺进行了干体系的热裂解模拟。实验结果表明:硫的存在提高了干酪根的产烃率,并使重烃和芳烃的生烃高峰温度降低,脱氢芳构化作用加快;从裂解产物的组成看,干酪根加硫的裂解产物与文献报道的高硫干酪根裂解产物相似,说明高硫干酪根除较弱的C-S键、S-S键断裂可以使高硫干酪根在低温生烃之外,硫的催化或脱氢作用也可能是一个主要因素。另外,硫的存在对干酪根裂解产生的气态烃和正构烷烃的单体碳同位素组成没有明显的分馏作用。更多还原

【Abstract】 Many oil and gas are closely related to salt lake sedimentary basin in China, such as Jianghan Tertiary sedimentary basin. The geochemical characteristics of organic matter may be diverse at different sedimentary stage in salt lake deposition. A geological section in Xiaoban depression, Jianghan basin was selected in this paper to study the variation in biomarkers, carbon and hydrogen isotope composition, the pyrolysates of kerogen by Py-GC -MS. And also study on the pyrolysis mechanism of sulfur-rich kerogen by a closed system pyrolysis using kerogen with the addition of sulfur was carried out in this paper.1) The characteristics of biomarkers show different organic sources at different deposition stage. Alga was the mainly input of the source rocks during the carbonate depositional stage. High abundances of phytane, gammacerane, C35homohopane, dibenzothiophene, sulfur containing compounds, aryl isoprenoids, C40 isorenieratane and sulfur containing C40 isorenieratane in the samples in carbonate depositional stage indicate that source rocks were formed under anoxic depositional environment with stratified water column. Higher relative abundances of C21+ isoprenoids and squelane, triaromatic-sterane, benzohopane indicate more input of halophilic bacteria in chloride stage. Low content of sulfur containing compounds and the detection of dibenzofuran in the samples in chloride depositional stage show that source rocks were formed under relative oxic condition.2) 13C is richer in the source rocks deposited in the carbonate depositional stage than that in the chloride depositional stage, showing that different organic source input in different depositional stage or it is the increase of salinity that lead to the rich of 13C in the chloride stage. The hydrogen isotopes of the individual compounds show source rocks in Qianjiang formation, Xiaoban depression was deposited in salt lake sedimentary environment. Hydrogen isotopes show little difference among the samples from different depths which was interpreted as ① the hydrogen composition is mainly controlled by the big sedimentary environment. No obvious difference of the hydrogen composition was found in the source rocks deposited in different stage. ② source rocks in Xiaoban depression were perhaps deposited in deep-water saline lake environment during Eq3-Eq4 formation, not shallow-water environment because in the shallow-water deposition environment the evaporation of water will make D enriched in the organic matter.3) The pyrolysates of kerogen show source rocks were mainly derived from plankton, also including some bacteria and terrestrial soure input in Qianjiang formation, Xiaoban depression, Jianghan basin and were source from the stratified water column, anoxicdepositional environment. The depositional environment became more reducing from, from the carbonate to chloride depositional stage.4) A closed system pyrolysis was performed on Maoming oil shales kerogen(Type I ), compared to this kerogen with addition of sulfur ether and this kerogen with addition of sulphur. The results suggest that the existence of sulfur:(l) makes the kerogen generate more hydrocarbon yields;(2) makes the temperature of the maximum generation of heavy hydrocarbon (the Cis+ fraction) and the aromatics fraction lower;(3) accelerates the aromatization process. The pyrolysates of the kerogen with the addition of sulfur are similar to the heating products of the sulfur-rich kerogen in the literatures. It seems that the sulfur catalysis is also an important factor that makes the sulfur-rich kerogen generate low mature oil at earlier diagensis, except for the weakness of the C-S and S-S bonds. It does not show obvious carbon isotope fraction of gas and n-alkane in the presence of sulfur.更多还原