龙马溪组页岩干酪根平均分子结构模型的构建

doi:10.16085/j.issn.1000-6613.2017.02.019

摘要/Abstract

摘要： 以四川盆地下志留统龙马溪组下段页岩中提取的干酪根为研究对象，利用等温吸附、XRD、FTIR和¹³C NMR实验分析其基本的结构特性，获得了重要结构信息。研究结果表明：该地区干酪根是非晶态高聚物；通过对比干燥干酪根和平衡水干酪根的等温吸附曲线，发现平衡水干酪根的吸附能力较低，这与干酪根表面吸附的水分子有关，说明干酪根分子中含有亲水的官能团；通过FTIR对龙马溪组干酪根分析发现其含有苯环、羟基、亚甲基和甲基等官能团；¹³C NMR谱图表明该地干酪根由芳碳、脂碳和羰基碳构成，其中芳烃是其主要的结构成分，脂碳和羰基碳起连接芳香结构单元的作用。利用这些信息，进而建立起了龙马溪组干酪根的平均分子结构模型，最后通过对比实验结构参数和模拟模型的结构参数，可以发现两者结果接近，说明模拟的干酪根分子模型是可以用于下一步干酪根吸附性能的分子动力学模拟。

关键词: 龙马溪组, 页岩, 干酪根, 平均分子结构

Abstract: Taking the kerogen from the lower segment of the Longmaxi formation in Sichuan Basin as the study objects,some essential structural characteristics are obtained based on analysis of isothermal adsorption,XRD,FTIR and ¹³C NMR. XRD analysis confirms that the kerogen exists with the long-range disordered state of aggregation. Through the adsorption isothermal experiments of the dry kerogen and equilibrium water kerogen,it is easily found that the kerogen can adsorb the water molecules and the chemical structure of the kerogen must contain hydrophilic oxygen-containing functional groups because the methane adsorption capacity of kerogen decreases after the dry kerogen adsorbed the water molecules. Adopted the FTIR to qualitatively analyze the functional groups in kerogen from Longmaxi formation,it is noted that this type of the kerogen contains the benzene ring,the hydroxyl,the methylene,the methyl and so on. Taken advantage of ¹³C NMR to express the chemical structure of carbon atoms in kerogen,the aromatic carbon,the aliphatic carbon and the carbonyl carbon can be found there. The main structure component is the aromatic carbon,while the aliphatic carbon and the carbonyl carbon just serve as the connections among the aromatic constitutional units. In addition,the initial molecular model of kerogen is achieved based on these information. And then,the gNMR software is helpful to predict the NMR spectrum of the initial molecular model. The predicted NMR spectrum is in contrast with the experimental one. Thus,the molecular model of kerogen structure is amended until both of them are very close to gain the correct molecular model of kerogen. Meanwhile,some experimental structure parameters are acquired by the previous experiments which can compare with the structure parameters from the simulative molecular model. The contrast analysis results show that the simulative structure parameters conform with the experiment ones,indicating that the simulative molecular model can serve as the model simulated adsorption performance of kerogen from the Longmaxi formation in Sichuan Basin.

Key words: Longmaxi formation, shale, kerogen, average molecular structure

中图分类号:

P618.13

刘向君, 罗丹序, 熊健, 梁利喜. 龙马溪组页岩干酪根平均分子结构模型的构建[J]. 化工进展, 2017, 36(02): 530-537.

LIU Xiangjun, LUO Danxu, XIONG Jian, LIANG Lixi. Construction of the average molecular modeling of the kerogen from the Longmaxi formation[J]. Chemical Industry and Engineering Progree, 2017, 36(02): 530-537.

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