不同成烃生物的拉曼光谱特征

Raman Spectroscopic Characteristics of Different Hydrocarbon-Forming Organisms

为了区分不同的成烃生物,本文利用拉曼光谱对烃源岩中两种常见的成烃生物,即浮游藻类和底栖藻类进行了研究。发现不同生源有机质成烃后的拉曼光谱各具特征。G峰与D峰间的位移差能够指示不同成烃生物分子结构中芳环的稠合程度,D峰和G峰的强度比可以反映有机质芳香结构有序度。通过对比不同成烃生物的拉曼光谱参数,发现成烃后浮游藻类的芳环稠合程度明显小于底栖藻类,芳香结构有序度也低于底栖藻类。相同层位烃源岩中不同成烃生物的G峰与D峰位移差有明显区别,即可以通过拉曼光谱检测芳环的稠合程度来区分不同的成烃生物。D峰与G峰强度比不仅受成熟度控制,而且成烃生物的性质对其有重要的影响,也能作为区分不同成烃生物的参考标准。

This study proposed a method to distinguish the bio-precursors of organic matter in hydrocarbon source rocks.Through analysis of the Raman spectra of two common types of organisms,phytoplankton and benthic algae,in hydrocarbon source rocks,we found that the organic matter originated from different organisms have different Raman spectra characteristics.The difference in Raman shift between G-mode peak and D-mode peak normally indicates the polymerization degree of aromatic structures,and the intensity ratio of D-mode peak to G-mode peak reflects the order degree of aromatic structures.By comparing the spectra parameters of different hydrocarbon-forming organisms,we found that the polymerization degrees of the macerals originated from benthic algae are greater than those of phytoplankton as well as the order degree of phytoplankton is also greater than benthic algae.Our research shows that the difference in Raman shift between G-mode peak and D-mode peak of different hydrocarbon organisms sampled from the same layer displays significant difference.The polymerization degree of aromatic structure of organic matter can be detected by Raman spectroscopy to distinguish different organisms.Although the intensity ratio of D-mode peak to G-mode peak is not only subject to the thermal maturity of materials but also sensitive to their structure properties of bio-precursor organism,it may also serve as a reference for distinguishing different hydrocarbon-forming organisms in practice.