Application Of Laser Raman Spectroscopy In Organic Maceral Analysis

Laser Raman spectroscopy is of great significance in the analysis of organic macerals because it can reflect the order and defects of carbon structure in the process of thermal evolution.In this thesis,22 coal samples（Ro%=0.55%～1.88%）from the southern margin of the Junggar Basin and the eastern margin of the Ordos Basin and 8shale samples（eq VRo%=1.99%～2.34%）from well AY1 were collected.The macerals of coal samples are mainly vitrinite,semifusinite and macrinite,and the macerals of shale samples are mainly graptolite and solid bituminite.The spectrum pretreatment parameters of the software WIRE4.1 are optimized to analyze the experimental spectrum.It is found that there are obvious differences in the Raman spectrum parameters of different macerals,which has the following applications in the analysis of macerals:（1）it can effectively characterize the microstructure of different macerals,so as to distinguish the types of macerals.However,with the increase of thermal maturity,its characterization effect will gradually deteriorate.For example,in this study,21 parameter combinations can be used to distinguish mature-high mature coal macerals,while only 3 parameter combinations can distinguish over mature shale macerals.（2）It can effectively characterize the thermal maturity of the sample,and the characterization effect is better than Methylphenanthrene Index.For the analysis of mature-high mature samples,the maturity characterization formula corresponding to the maceral should be used,while the over mature samples do not need it.（3）It can characterize the relative development degree of secondary organic pores in different macerals.For example,in this study,the peak intensity ratio(I_D1/I_G)and peak area ratio(A_D1/A_G)of solid bituminite are greater than graptolite,indicating that the organic pores in solid bituminite are relatively developed,which is consistent with the experimental results of field emission scanning electron microscope.In conclusion,laser Raman spectroscopy has important application value in maceral identification,maturity determination and secondary organic pore research.