依据热模拟实验动态建立煤成烃模式

依据构成煤岩端元组分（壳质组、镜质组和惰质组）热模拟实验的生烃潜力和甲烷同位素组成数据，结合已建立的煤成油有效排出门限(30 mg/gTOC)，建立了煤成烃模式，该模式表明：只有富氢的显微组分才有利于煤岩生油，且壳质组含量最低为5.0%，而镜质组最高含量为95.0%；当壳质组含量高于22.9%时，煤成油不受镜质组和惰质组二端元组成的影响。同时，按照煤成烃模式计算了不同端元组分在不同热演化阶段甲烷碳同位素组成的变化，结果表明：构成煤岩的显微组分含量能够引起烷烃气碳同位素组成的变化；在同一热演化阶段，甲烷碳同位素组成最大差异可达2.3‰。认为煤成气甲烷碳同位素组成不仅受热成熟度控制，而且也受煤岩显微组分相对含量的影响。

Mathematical Simulation of Coal-generating Hydrocarbons Based on Pyrolysis Products from Coal Macerals under Closed System

Based on the hydrocarbon yields and carbon isotopes of methane from the three end-member macerals (vitrinite, exinite, inertinite) under closed system pyrolysis, isothermal temperature conditions, a mathematic model of oil generation and efficient expulsion from coal as a hydrocarbon-sourcing rock was done when the efficient expulsion of hydrocarbons from coal is experientially assumed to be 30 mg/g_TOC.According to the simulated results, the hydrogen\|enriched maceral is prone to the oil generation, where the relative proportion of exinite component in coal as an active oil source is at least 5.0% whereas vitrinite is at most 95.0%. If the exinite content is more than 22.9% of coal components, the oil is generated and efficiently expelled from coal whatever the contents of two other macerals (vitrinite and inertinite). Meanwhile, the carbon isotope fractionation of methane from the maceral components at thermal stages was matched according to the simulated model. These mathematically calculated observations imply that coals with the different end\|member macerals would generate natural gas with changed δ¹³C_CH4values, where the maximum δ¹³C_CH4 value  is  2.3‰. Thus, the δ¹³C_CH4 value is constrained by not only thermal maturity of source rock, but also maceral components.