煤成气轻烃组分和碳同位素分布特征与天然气勘探

采用烃源岩热模拟实验和轻烃单体烃碳同位素分析方法,对煤热解轻烃生成模式及煤系烃源岩热解轻烃碳同位素组成特征的研究表明，在成熟度 R_o 值为1.1%～1.7%时,煤热解轻烃大量生成;当 R_o 值大于1.7%时，以芳烃生成为主。煤热解轻烃中苯和甲苯碳同位素均较重，苯的碳同位素值平均为－22.2‰，甲苯的碳同位素值平均为－22.1‰，与母源有机质干酪根碳同位素值非常接近，具有良好的碳同位素继承效应。对塔里木、准噶尔、鄂尔多斯、四川和松辽等盆地煤成气轻烃组分和碳同位素分析表明，煤成气具有甲基环己烷分布优势，在甲基环己烷、二甲基环戊烷和正庚烷相对组成中，173个煤成气样品中有92%的样品甲基环己烷相对含量大于50%；煤成气轻烃中苯、甲苯、环己烷和甲基环己烷碳同位素重，碳同位素值平均分别为－20.9‰、－20.4‰、－21.9‰和－22.0‰。应用轻烃组成变化对苏里格煤成气大气田天然气运移方向进行的研究表明，在气藏形成时期，天然气运移方向为由南向北。

Composition and carbon isotopic distribution characteristics of light hydrocarbon in coal-derived gas and natural gas exploration

The thermal simulation test of light hydrocarbon and the individual light hydrocarbon carbon isotope analysis method were used to investigate the generation model and carbon isotopic composition of light hydrocarbon obtained from coal.The results showed that a large amount of light hydrocarbon was generated from coal when the maturity Ro ranged from 1.1% to 1.7%,and the aromatic amount was the most while the maturity Ro was over 1.7%.The carbon isotope values of benzene and toluene in coal pyrolysed gas are...