Wu Dun, Wang Chenglong, Liang Wenxu, Gao Xia
Key Laboratory of Intelligent Underground Detection Technology, College of Civil Engineering, Anhui Jianzhu University, Hefei 230601, China.
School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China.
Int J Mol Sci. 2025 Mar 17;26(6):2696. doi: 10.3390/ijms26062696.
This study systematically analyzed the composition of organic functional groups and changes in the carbon structure of kerogen at different stages of thermal maturity using Fourier Transform Infrared (FTIR) spectroscopy and Laser Raman spectroscopy techniques. The research selected oil shale samples from the Late Carboniferous deep coal strata in the southern part of the Huainan coalfield. Kerogen was extracted through acid treatment, pyrite removal, and heavy liquid separation processes. Utilizing FTIR and Raman spectroscopy, the study delved into the quantitative and qualitative characteristics of functional groups such as hydroxyl, carboxyl, and methyl in the kerogen, as well as the variations in the ratio between aliphatic and aromatic carbon. The research found that as thermal maturity increased, aromatic structural parameters in the kerogen significantly rose, while aliphatic structural parameters exhibited a downward trend. Specifically, FTIR spectroscopy was used to identify the characteristic absorption wavenumber ranges of different functional groups and calculate key parameters such as the aromaticity of the kerogen and the ratio of aliphatic to aromatic functional groups using relevant formulas. Meanwhile, Raman spectroscopy analysis revealed changes in the orderliness of carbon atoms and the degree of graphitization in the kerogen as a function of thermal maturity, with the intensity ratio of the G band to the D band (A/A) emerging as an important indicator for assessing thermal maturity. Additionally, this study further validated the correlation between thermal maturity and parameters such as reflectance (R) and the H/C ratio by calculating the metamorphic temperature of the kerogen. Combining the results of FTIR and Raman spectroscopy analyses, this study unveiled a close relationship between the thermal maturity of kerogen and its organic functional group composition and carbon structure. As thermal maturity increased, the degree of aromatization in the kerogen rose, aliphatic chain lengths shortened, and the degree of graphitization improved. These findings not only enhance the understanding of the thermal evolution process of kerogen but also provide crucial scientific insights for oil and gas exploration and development.
本研究采用傅里叶变换红外光谱（FTIR）和激光拉曼光谱技术，系统分析了干酪根在不同热成熟阶段有机官能团的组成及碳结构变化。研究选取了淮南煤田南部晚石炭世深部煤层的油页岩样品。通过酸处理、黄铁矿去除和重液分离等过程提取干酪根。利用FTIR和拉曼光谱，研究深入探讨了干酪根中羟基、羧基和甲基等官能团的定量和定性特征，以及脂肪族碳与芳香族碳比例的变化。研究发现，随着热成熟度增加，干酪根中的芳香结构参数显著上升，而脂肪族结构参数呈下降趋势。具体而言，FTIR光谱用于识别不同官能团的特征吸收波数范围，并使用相关公式计算干酪根的芳香度和脂肪族与芳香族官能团比例等关键参数。同时，拉曼光谱分析揭示了干酪根中碳原子的有序度和石墨化程度随热成熟度的变化，G带与D带的强度比（A/A）成为评估热成熟度的重要指标。此外，本研究通过计算干酪根的变质温度，进一步验证了热成熟度与反射率（R）和H/C比等参数之间的相关性。结合FTIR和拉曼光谱分析结果，本研究揭示了干酪根的热成熟度与其有机官能团组成和碳结构之间的密切关系。随着热成熟度增加，干酪根的芳构化程度提高，脂肪族链长度缩短，石墨化程度改善。这些发现不仅增进了对干酪根热演化过程的理解，也为油气勘探开发提供了关键的科学见解。
