Li Yaoyu, Zhou Shixin, Li Jing, Sun Zexiang, Pang Wenjun
Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
Key Laboratory of Petroleum Resources, Lanzhou 730000, Gansu Province, China.
ACS Omega. 2023 Aug 24;8(35):31972-31983. doi: 10.1021/acsomega.3c03787. eCollection 2023 Sep 5.
Organic-rich tuffaceous mudstones are important oil and gas resources. The systematic study of the pyrolysis kinetics and characteristics can not only provide the theoretical basis for the rational development and efficient utilization of these rocks but also is an important complement to the theoretical research on the pyrolysis kinetics of organic-rich rocks. In this study, the pyrolysis kinetics, behavior, and mechanism of the organic-rich tuffaceous mudstone in the Junggar Basin were clarified by thermogravimetric analysis. The organic structure and mineral composition were identified by Rock-Eval, Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The results indicated that the mudstone could be described as a type II kerogen with good hydrocarbon generation potential. The mudstone included up to 80.7% quartz, which is associated with Carboniferous volcanic activity. Four isoconversional methods were used to evaluate the activation energies. A novel and simplified method was proposed to separate the pyrolysis processes using the Coats-Redfern method based on the differences in reaction models and activation energies. The pyrolysis processes were divided into four stages, and the reaction models of each stage were preliminarily clarified. The reaction models were further modified by the accommodation function The results showed the kinetic parameters, and the reaction models of each stage were significantly different. Moreover, the obtained kinetic parameters and optimal reaction models can well characterize the pyrolysis processes and mechanism of the tuffaceous mudstone. The results of thermogravimetric-FTIR (TG-FTIR) indicated that the main pyrolysis hydrocarbon volatiles were methane, C aliphatic hydrocarbons, and aromatics. And the types and yields of pyrolysis volatiles differed at each stage.
富含有机质的凝灰质泥岩是重要的油气资源。对其热解动力学和特征进行系统研究，不仅可为这些岩石的合理开发和高效利用提供理论依据，也是对富含有机质岩石热解动力学理论研究的重要补充。本研究通过热重分析阐明了准噶尔盆地富含有机质凝灰质泥岩的热解动力学、行为和机理。利用岩石热解、傅里叶变换红外光谱（FTIR）和X射线衍射（XRD）对有机结构和矿物成分进行了鉴定。结果表明，该泥岩可描述为具有良好生烃潜力的Ⅱ型干酪根。该泥岩中石英含量高达80.7%，这与石炭纪火山活动有关。采用四种等转化率方法评估活化能。基于反应模型和活化能的差异，提出了一种新颖且简化的方法，利用Coats-Redfern方法分离热解过程。热解过程分为四个阶段，并初步阐明了各阶段的反应模型。通过适应函数对反应模型进行了进一步修正。结果表明，各阶段的动力学参数和反应模型存在显著差异。此外, 所获得的动力学参数和最佳反应模型能够很好地表征凝灰质泥岩的热解过程和机理。热重-傅里叶变换红外光谱（TG-FTIR）结果表明，热解烃类挥发物主要为甲烷、C脂肪烃和芳烃。且热解挥发物的类型和产率在各阶段有所不同。
