二甲基二苯并噻吩生成实验及地球化学意义

Experiments on the generation of dimethyldibenzothiophene and its geochemical implications

吴嘉 齐雯 罗情勇 陈泉 师生宝 李美俊 钟宁宁

WU Jia QI Wen LUO Qingyong CHEN Quan SHI Shengbao LI Meijun ZHONG Ningning

1. 中国石油大学(北京) 油气资源与探测国家重点实验室, 北京 102249; 2. 中国石油大学(北京) 地球科学学院, 北京 102249; 3. 中国科学院大学, 北京 100049; 4. 中国石油勘探开发研究院 西北分院, 兰州 730020

1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; 2. College of Geoscience, China University of Petroleum, Beijing 102249, China; 3. University of Chinese Academy of Science, Beijing 100049, China; 4. PetroChina Research Institute of Petroleum Exploration & Development-Northwest, Lanzhou, Gansu 730020, China

二苯并噻吩类化合物（DBTs）是当前油气地球化学研究中常用的一类分子标志化合物，但因其地质成因机理尚存争论，导致与之相关的地化参数大多源自经验，缺乏理论基础。在10 MPa和200~500℃下，对3，3'-二甲基联苯和单质硫混合物进行封闭体系热模拟实验。结果表明，在无催化条件下由联苯类化合物生成DBTs具有特定的空间选择性。在地质条件下该反应所需的温度可低于200℃，因为体系压力的增加可降低反应门限温度。与实际地质样品相似，随着温度的升高，产物中不同甲基取代位的DBTs相对含量会发生变化，进而导致热成熟度参数MDR（4-/1-MDBT）先升高后降低。因此，MDR作为成熟度参数时需要结合实际地质条件，在合适的成熟度范围内使用。

Dibenzothiophene (DBT) and its homologues are important molecular markers in petroleum geochemistry. However, DBT-related geochemical indicators were derived mainly based on empirical observations due to insufficient understanding of the mechanisms through which these organosulfur compounds were generated in sedimentary environments. Thermal simulation experiments with 3,3’-dimethylbiphenyl and sulfur in closed gold tubes at 200-500 ℃ and 10 MPa afforded three main dimethyldibenzothiophene isomers (DMDBTs). Importantly, DBTs could be generated at a temperature as moderate as 200 ℃ under geological conditions, because the temperature threshold of the reaction could be reduced by increasing the system pressure. Further investigations revealed that the regioselectivity of the thiophene formation reaction was strongly influenced by temperature. This is similar to the process that occurs in natural geological systems. It should also be noted that the maturity index 4-/1-MDBT (MDR) reaches a maximum around 1.5% (Easy%Ro). It indicates that MDR index should be used in a suitable maturity regions combined with the given geological setting.

国家重点研发计划"超深层环境油气生成与烃源灶有效性评价"（2017YFC0603102）、国家自然科学基金青年项目"含水体系中二苯并噻吩热稳定性的实验研究"（41403049）和油气资源与探测国家重点实验室自主课题"沥青质次级结构与中小分子的相互作用"（PRP/indep-3-1715）联合资助。

https://doi.org/10.11781/sysydz201902260