等变质煤系烃源岩的生气特征

Characteristics of hydrocarbon generating source rocks in isometamorphic coal measure

为了更加客观地了解煤系烃源岩的生气性能,采用半开放体系对塔里木盆地库车坳陷侏罗纪煤、碳质泥岩和煤系泥岩3种等变质煤系烃源岩样品进行了生气热模拟实验。实验结果表明:侏罗纪煤、碳质泥岩和煤系泥岩均具有良好的生气性,但其生气性存在一定的差异,煤和碳质泥岩的生气性要好于煤系泥岩;随着热演化程度的增加,这3种煤系烃源岩生气总产率(C1-5)也相应增加,在高演化阶段时主要产甲烷;煤系烃源岩热解气组分的碳同位素值和热解温度有关,随着热解温度升高,甲烷碳同位素值先降低后增大,乙烷碳同位素值一直增大,且在同一温度点有δ13C1<δ13C2的特征。

In order to study the characteristics of hydrocarbon generating source rocks in different coal measure more objectively, the semi-open system is adopted to carry out the pyrolysis experiment on coal, carbonaceous mudstone and mudstone samples collected from isometamorphic Jurassic coal measure source rocks in Kuqa de- pression, Tarim basin. The results showed that the gas generating capacity of the isometamorphic coal measure source rocks was good, but there were differences among them. The gas generating capacity of coal and carbona- ceous mudstone was better than that of coal measure mudstone. With the increasing of thermal evolution degree, the overall yield （C1-5） of the coal-measure source rocks increased correspondingly. In the high thermal evolution stage, methane was the main product.The value of carbon isotope pyrolytic gas component of coal measure source rocks was related to pyrolysis temperature. When the pyrolysis temperature increased, methane carbon isotope value reduced first and then increased, while ethane carbon isotope value kept rising. At the same temperature, the 313Cl.value of pyrolytic gas was higher than the 313C2 value.