金刚烷类化合物的热稳定性研究及其地质意义  

Thermal stability of diamondoids and their geological significance

作　　者：王伟 李芸[1,2] 熊永强[1,2] 蒋文敏[1,2] WANG Wei;LI Yun;XIONG Yongqiang;JIANG Wenmin(State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院广州地球化学研究所,有机地球化学国家重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640 [3]中国科学院大学,北京100049

出　　处：《地球化学》2023年第1期29-40,共12页Geochimica

基　　金：广东省杰出青年科学基金项目(2018B030306006)资助。

摘　　要：金刚烷类化合物由于其强抗热降解的能力对揭示深层油气藏的地化信息具有重要价值。对金刚烷类化合物热稳定性和裂解演化规律的研究较少,制约了金刚烷类化合物指标的实际应用。选择3种典型的金刚烷化合物(单金刚烷、1,3-二甲基单金刚烷和双金刚烷)作为模型化合物,分别开展金刚烷类化合物单体的黄金管封闭体系裂解动力学实验,以此揭示金刚烷类化合物的热稳定性和裂解演化规律。结果显示:单金刚烷和1,3-二甲基单金刚烷具有相似的热稳定性,均在Easy Ro值为1.5%时发生裂解,而双金刚烷具有更高的热稳定性,在Easy Ro值达到1.8%时才发生裂解,它们的裂解产物包括以甲烷为主的气态烃、以萘系列化合物为主的芳烃和其他同笼状单元数的金刚烷类化合物;当Easy Ro值分别小于2.1%、2.5%和2.5%时,单金刚烷、1,3-二甲基单金刚烷和双金刚烷的单体C同位素组成几乎不变。以上结果表明,金刚烷类化合物的热稳定性与分子结构中笼状单元的数目有关,分子结构中所带的甲基不会明显影响其稳定性;金刚烷类化合物的单体C同位素组成在较宽的成熟度范围内不变,可以用来示踪烃源。研究结果可为新的金刚烷类化合物指标的建立和应用提供实验依据和理论基础。Diamondoids are essential for revealing the geochemical information of deep oil and gas reservoirs owing to their strong anti-degradation ability.However,few studies had focused on the thermal stability and cracking evolution characteristics of diamondoids;hence,their practical application has been restricted.Three typical diamondoid compounds (e.g.,adamantane,1,3-dimethyladamantane,and diamantane) were used as model compounds in this study to conduct a series of cracking simulation experiments to reveal the thermal stability of diamondoids.Results of the experiments showed that adamantane and 1,3-dimethyladamantane have similar thermal stability because both of them cracked when thermal maturity was 1.5%Easy Ro;however,diamantane had a higher thermal stability than the former two because it cracked when the thermal evolution level was 1.8%Easy Ro,and the cracking products included gaseous hydrocarbons dominated by methane,aromatic hydrocarbons dominated by naphthalene series,and other diamondoids with the same cage unit number.When Easy Rowas less than2.1%,2.5%,and 2.5%,the compound specific carbon isotopic compositions of adamantane,1,3-dimethyladamantane,and diamantane were almost unchanged.The results indicated that the thermal stability of diamondoids has a strong association with the number of diamond-like cage unit in the molecular structure,and the methyl group in their molecular structure cannot significantly affect their stability.The stable carbon isotopic composition of diamondoids is stable under a wide maturity range,which can be used to trace hydrocarbon sources in this case.The conclusions obtained in this study can provide experimental and theoretical bases for the establishment and field application of new diamondoid indices.

关 键 词：金刚烷类化合物 热稳定性 裂解 C同位素 

分 类 号：P593[天文地球—地球化学]