茂名油页岩中干酪根的热模拟地球化学演变及表征

Simulation and characterization of thermal evolution of kerogen in Maoming oil shale

将页岩样品在高压密封、加水、除氧的条件下放入马弗炉中,以程序升温方式进行烃源岩干酪根的人工熟化热模拟实验,并对原始样品与经过不同温度人工熟化热模拟实验处理的各个样品进行了元素分析、有机岩石学测定、傅里叶变换红外光谱分析、固体13C CPMAS核磁共振分析、拉曼光谱分析、BET比表面积测定等一系列定性、定量的表征。结果表明,随着热模拟实验处理温度的升高,干酪根的H/C、O/C摩尔比下降,镜质组反射率增加,反映芳香结构的红外谱图特征增加,13C核磁共振谱图中芳香碳的比重增加,拉曼光谱所展现的分离度和结晶度增加,BET比表面积先减小后增大;这些现象均表明随着热模拟温度的升高,干酪根的成熟度和芳香度逐渐增加,完成了由低成熟度干酪根向高成熟度干酪根的演化。

In this study, artificial maturation experiments on a kerogen of Maoming oil shale were carried out in a muffle furnace using temperature-programmed heating, high pressure, closed, hydrous and oxygen-free laboratory conditions. Physicochemical properties of the original and pyrolyzed kerogen samples were determined by a series of quantitative and qualitative methods, such as elemental analysis, organic petrology analysis, solid state ^13C cross-polarization and magic angle spinning nuclear magnetic resonance spectroscopy （CPMAS ^13C NMR）, Fourier transformed infrared spectroscopy （FT-IR）, Raman spectroscopy and BET specific surface area （BET-SSA） analysis. The results show that with the increase of heating temperature, the H/C and O/C atomic ratios of kerogens decrease, vitrinite reflectance values increase, aromatic characters in FT-IR increase, proportion of aromatic carbon in ^13C NMR increases, separation and crystallinity of Raman spectra increase, and specific surface area decrease at first and increase subsequently. All of those indicate that the aromaticity and maturity of kerogen increase with heating temperature during the evolution of kerogen from low maturity to high maturity.