热模拟实验产物中烷烃参数的地球化学意义

THE GEOCHEMICAL SIGNIFICANCE OF ALKANE PARAMETERS IN THE PRODUCTS FROM PYROLYTIC SIMULATION EXPERIMENTS

通过两个系列热模拟实验研究了褐煤干酪根降解与褐煤综合有机母质（包括干酪根和非干酪根物质）热演化生成烷烃的特征。结果表明：干酪根不直接降解生成轻质油，干酪根降解产物中正烷烃无奇偶优势，姥植比较高，而且不随温度变化而大幅度变化，Ｐｒ／ｎＣ１７和Ｐｈ／ｎＣ１８比值随温度升高线性下降；综合有机母质热演化产物中，有轻质油生成，在低温阶段正烷烃有很强的奇偶优势，姥植比随温度升高先是变大然后减小，Ｐｒ／ｎＣ１７和ＰＵ／ｎＣ１８比值随温度升高而反复升降。

With a view to finding out the characteristics of alkane generation during the thermal evolution of kerogen,alkanes generated by kerogen in lignite and by total organic matter(kerogen and EOM) of lignite are studied through two series of pyrolytic simulation experiments.The results show that kerogen can't be directly degraded into light oil,and that alkanes in the products from kerogen degradation do not show any odd or even preference,and that the pristane to phytane ratio is relatively high and does not vary sharply with variation of temperature,and that the pristane to nC_(17)and phytane to nC_(18)ratios decrease linearly with the increase of temperature.In the products from the thermal degradation of total organic matter of lignite,there is light oil generated; alkanes generated during the lower temperature stage show quite strong odd and even preference;the pristane to phytane ratio becomes first larger and then smaller while temperature is rising;and the pristane to nC_(17) and phytane to nC_(18) ratios rise up and drop down repeatedly following the rise of teniperature.