单质硫和含硫矿物对固体沥青中芳烃化合物热演化过程的影响

Effects of elemental sulfur and sulfur-bearing minerals on the thermal evolution of aromatic compounds in solid bitumen

前人研究表明,部分芳烃化合物比值参数与有机质成熟度具有良好的线性关系。为了明确常用芳烃化合物比值参数在不同含硫地质条件下的适用性,通过对四川盆地低熟固体沥青样品开展在单质硫和含硫矿物(黄铁矿、硫酸亚铁、硫酸铁和硫酸钙)存在条件下的加水热模拟实验,进而探讨上述含硫物质在固体沥青热演化过程中对其中所赋存的芳烃化合物的影响。研究表明:各类含硫物质均不同程度影响了芳烃化合物甲基化、甲基重排及去甲基化的进程和强度,随之改变了常用芳烃化合物比值参数的适用性及适用范围。但也存在一些在含硫环境下仍能稳定表征有机质成熟度的参数,如萘系化合物的1,2,3-TMN/2,3,6-TMN、菲系化合物的P/(P+∑MP)和甲基菲指数MPI、二苯并噻吩系化合物的4,6-DMDBT/3,6-DMDBT等参数,能够应用于含硫地质体中有机质成熟度的表征。

Previous studies have shown that some of the aromatic compound parameters have good correlation with the maturity of organic matter.However,it is still unknown whether the widely used aromatic maturity-related parameters are available with the co-existence of sulfur(elemental and/or sulfur-bearing minerals).Artificial simulation experiments of solid bitumen together with elemental sulfur and/or sulfur-bearing minerals(e.g.,pyrite,ferrous sulfate,iron sulfate,and calcium sulfate)were carried out to investigate the influence of elemental sulfur and sulfur-bearing minerals on the thermal evolution of aromatic compounds.Results illustrated that some reactions including methylation,alkyl rearrangement and demethylation of aromatic compounds were affected with various extents by the existence of elemental sulfur and sulfur-bearing minerals.Thus,the applicability of the aromatic index should be careful.This study also found some parameters that still can effectively evaluate the maturity of organic matter in the sulfur-bearing environment,such as 1,2,3-TMN/2,3,6-TMN,P/(P+∑MP),MPI and 4,6-DMDBT/3,6-DMDBT.