海相煤系烃源岩热解碳同位素生烃动力学研究

Study on Carbon Isotope Hydrocarbon Generation Kinetics of Marine Coal Measures Source Rocks

在限定封闭体系(密封金管-高压釜体系)下,对杨家岩剖面雷口坡组海相煤样品进行了生烃模拟实验,利用热模拟实验模拟有限地层温度及静压力,短时间内恢复地质条件下漫长的生烃过程。结果表明:随热解实验的进行,甲烷产量一直呈持续增长的趋势,其他烃类气体均存在一个生气值峰,随后产量开始下降,这与高温时期重烃气体热解成甲烷及非烃类气体有关;气态烷烃的碳同位素值都有随着热解过程的进行“先轻后重”的趋势。根据所得数据计算生烃动力学参数,对生烃演化及碳同位素分馏差异进行了初步对比分析。

In the limited closed system(sealed gold tube autoclave system),the hydrocarbon generation simulation experiment of marine coal samples from Leikoupo Formation in yangjiayan section was carried out.The thermal simulation experiment was used to simulate the limited formation temperature and static pressure,and the long hydrocarbon generation process under geological conditions was restored in a short time.The results show that:with the pyrolysis experiment,methane production has been increasing continuously,and other hydrocarbon gases have a gas value peak,and then the production begins to decline,which is related to the pyrolysis of heavy hydrocarbon gas into methane and non hydrocarbon gas;the carbon isotope values of gaseous alkanes tend to be“light first and then heavy”with the pyrolysis process.According to the obtained data,the kinetic parameters of hydrocarbon generation are calculated,and the differences of hydrocarbon generation evolution and carbon isotope fractionation are preliminarily compared and analyzed.