沁水盆地山西组煤岩的生气热模拟实验研究

Study on Thermal Simulation Experiment of Gaseous Hydrocarbon Generation of Shanxi Formation Coal in Qinshui Basin

热模拟实验是研究烃源岩有机质成烃演化的重要手段。为了客观了解沁水盆地高演化煤系烃源岩的生烃特征和生气性能，采用封闭高压釜体系对沁水盆地山西组煤岩样品进行了生气热模拟实验。结果表明：沁水盆地山西组煤岩样品可以生成大量的气态烃（其产率高达226 m^3／t），是良好的气源岩；随着热模拟温度的增加，气态烃产率增大，气态烃产率表现出“两急两缓”的增加模式，高演化阶段以产甲烷为主，主生气期为热模拟温度450～600℃（ Ro＝1．2％～2．7％）；温度影响煤岩热解气组分碳同位素值的变化，总体上甲烷、乙烷、丙烷的碳同位素值随热模拟温度升高有逐渐变重的趋势，并且相同热模拟温度时具有δ13 C1＜δ13 C2＜δ13 C3的特征，符合气态烃碳同位素正序系列。

Thermal simulation is an important means to study the hydrocarbon generation evolution of organic mat-ter in hydrocarbon source rock.In order to objectively understand the characteristics of hydrocarbon generation and gas generating ability of high maturity coal-bearing source rocks, a closed autoclave system is used to carry out the thermal simulation experiment on the coal sample of Shanxi Formation in the Qinshui Basin.The results showed that the coal sample of Shanxi Formation in the Qinshui Basin can produce large amounts of gaseous hy-drocarbons （ Its yield up to 226 m3/t） , which belongs to a good gas source rock.It is shown that gaseous hydro-carbon yield of the coal sample in the Qinshui Basin increases with the increasing of thermal simulation tempera-ture, which has the two fast two slow＆quot;increasing mode.At the high evolution stage,it is mainly produced by methane.Its main phase of gas generation is among 450~600℃of pyrolysis temperature （Ro=1.2%~2.7%）. Temperature influences the carbon isotope values of pyrolysis gas component.In general, the carbon isotope val-ues of methane, ethane and propane have a variation trend to get heavier with increasing thermal simulation tem-perature, and have the features of δ13 C1 〈δ13 C2 〈δ13 C3 at the same temperature, which are consisted with the positive carbon isotope series of gaseous hydrocarbons.