Pyrolysis Characteristics and Effect on Pore Structure of Jimsar Oil Shale Based on TG-FTIR-MS Analysis

• Published in: Geofluids 2022-07, Vol.2022, p.1-9
• Main Authors: Liu, Zhijun, Ma, Haotian, Guo, Jianping, Liu, Gang, Wang, Zhen, Guo, Yuzhen
• Format: Article
• Language: English
• Subjects: Analysis; Analytical methods; Carbon dioxide; Carbonates; Chemical precipitation; Chemical reactions; Clay; Clay minerals; Crude oil; Decomposition; Dehydration; Energy industry; Evolution; Experiments; Exploitation; Fourier analysis; Fourier transforms; Gases; Gypsum; Hydrocarbons; Infrared analysis; Infrared spectroscopy; Mass spectrometry; Mass spectroscopy; Minerals; Oil recovery; Oil shale; Oil-shales; Organic matter; Petroleum mining; Pores; Precipitation; Pyrolysis; Quartz; Recrystallization; Sedimentary rocks; Shale oil; Shale oils; Temperature sections; Underground mining; Weight; Weight loss
• ISSN: 1468-8115; 1468-8123
• DOI: 10.1155/2022/7857239

The study of the pyrolysis characteristics of oil shale, an important strategic resource, is of great significance for oil shale refining and in situ underground mining. In this study, using the oil shale from Jimsar region of Xinjiang, in combination with thermogravimetric analyzer (TG), Fourier transform infrared spectroscopy (FTIR), and mass spectrometry (MS) techniques, the pyrolysis characteristics and mechanism of the oil shale are analyzed according to the experimental results and explored the effect of its pyrolysis on the development of the pore. The results, the pyrolysis with three stages, show the following: (1) The first stage is 23-390°C. The precipitation of adsorbed water within the oil shale and the dehydration of gypsum are mainly at 100°C or so, appearing some microcapillary pores and other temperature sections change little. (2) The second stage is 390-527°C. The organic matter pyrolysis of Jimsar oil shale accounts for 71.1% of the total weight loss of oil shale. This stage has the greatest impact on the evolution of pore structure, and there are two weight loss peaks at 458°C and 506°C, respectively, in the thermogravimetric curve. Combined with FTIR-MS, the main products of its pyrolysis gas are H2, H2O, CO2, CH4, and CnHm and will change the original pore surface of oil shale, create new pore volume, and produce complex and irregular pore structure. (3) In third stage (527-800°C), the formation of H2, CO2, and hydrocarbon gases suggests that this stage includes not only the decomposition of major inorganic components like carbonate and clay but also the degradation process of some organic matter. At this stage, the CO2 generated in the precipitation process will lead to a large number of pores in oil shale. Crack grids will appear, due to the melting and recrystallization of some clay minerals. Once the interaction between the two is particularly intense, the mineral skeleton may rupture and collapse. The pyrolysis characteristics above provide a basis for the analysis of the pore structure evolution of oil shale and are of implications and practical application value to the exploitation of shale oil.