原油似甲基二苯并噻吩含量与沉积环境及次生变化的关系

如果把芳烃TIC(总离子色谱图)上所有芳烃峰的峰面积之和作分母,以m/z198质量色谱图上三个甲基二苯并噻吩异构体峰面积之和作分子,计算出来的比值本文称为似甲基二苯并噻吩含量。它既是甲基二苯并噻吩化合物在原油中的丰度参数,也是苯并噻吩类化合物总和的含量参数。根据对中国含油气盆地112个原油样品中似甲基二苯并噻吩含量统计发现,当原油无TSR作用时,海相原油的似甲基二苯并噻吩含量要大于陆相原油;陆相原油中,盐湖相原油的似甲基二苯并噻吩含量又大于淡水湖相。当有TSR经历时,无论是海相或陆相原油,其似甲基二苯并噻吩含量都急剧增加,而且与伴生天然气中H2S的含量呈正相关。分析数据也表明,虽然原油的生物降解也可以使似甲基二苯并噻吩含量增加,但与TSR和烃源岩的沉积环境相比,生物降解的贡献可能并不大。似甲基二苯并噻吩含量可以作为沉积环境、TSR和原油的生物降解研究的地球化学参数。

The content of methyldibenzothiophenes in oil and its relationship with depositional environment and catagenesis

If we define the sum of all aromatic peaks area in a TIC(total ion chromatogram) as the denominator,and the sum of the three peaks of methyldibenzothiophene in m/z 198 mass chromatogram as the numerator,the ratio in percent may be thought as the content of methyldibenzothiophenes in oil.It reflects both the abundance of methyldibenzothiophenes and the abundance of total benzothiophene compounds in oil.According to the statistics of the content of methyldibenzothiophenes in 112 oil samples from China,the content of methyldibenzothiophenes in marine oil is more than that in terrestrial oil if there is no TSR in oil.The content of methyldibenzothiophenes in oil from terrestrial salt lake facies formation is greater than that from fresh water lake.The content of methyldibenzothiophenes may be sharply increased for both marine and terrestrial oil,when TSR occurs,and the H2S concentration of natural gas from oil is correlated directly with the content of methyldibenzothiophenes.The analytical data show that although the biological degradation of oil may result in an increase in the content of methyldibenzothiophene,but its contribution is smaller than that of TSR and of the depositional environment of source rocks.The content of methyldibenzothiophene may serve as a geochemical parameter in the research on TSR,depositional environment of source rocks,and biological degradation of oil.