Study on the Quantitative Model of Oil Shale Porosity in the Pyrolysis Process Based on Pyrolysis Kinetics

Liu, J; Liang, W; Kang, Zhiqin; Lian, H; Geng, Yide

doi:10.3176/oil.2018.2.03

Cited by 3 publications

(2 citation statements)

References 9 publications

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“…It can be clearly seen from Figure 1 that the main pyrolysis temperature range of oil shale is 350-600 °C. Based on the thermogravimetric data, the Coats-Redfern (CR) method [17][18][19][20][21] was used for kinetic analysis, and the pyrolysis reaction rate equation of oil shale was obtained as follows:…”

Section: Basic Properties Of Oil Shalementioning

confidence: 99%

Groundwater environmental impact caused by in-situ pyrolysis of oil shale

Yang,

Liu,

et al. 2024

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Based on a sample of oil shale from the Lucaogou Formation in Shichanggou, Xinjiang, China, the mechanism of changes in the physical and mechanical properties of oil shale during in-situ pyrolysis was systematically analyzed, and combined with the kinetics of the pyrolysis reaction, a constitutive model of permeability change during the in-situ pyrolysis of oil shale was established. By leaching experiments, the changes in the physicochemical parameters and pollutant concentration of oil shale immersion solution under different pyrolysis temperatures were studied. Basing on the theoretical permeability value and pollutant concentration under in-situ pyrolysis conditions, a hydrogeological model was established to simulate groundwater pollution caused by the in-situ pyrolysis of oil shale. The results showed that the permeability of oil shale after in-situ pyrolysis increased by three orders of magnitude, changing from a water-proof layer before pyrolysis to a weakly permeable layer after pyrolysis. However, the permeability of oil shale after complete pyrolysis at 600 °C was only 2.062 mD and still very low, and the pollutants had low concentration and were mainly concentrated in the pyrolyzed oil shale layer. The in-situ pyrolysis of oil shale would not pollute the groundwater in the mining area, but the pH of groundwater would gradually increase with rising pyrolysis temperatures. At 600 °C, pH even increased to 27 Groundwater environmental impact caused by in-situ pyrolysis of oil shale 11.68, which is strongly alkaline. It is suggested that the pyrolysis temperature should be 400-500 °C.

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Section: Basic Properties Of Oil Shalementioning

confidence: 99%

Groundwater environmental impact caused by in-situ pyrolysis of oil shale

Yang,

Liu,

et al. 2024

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“…Therefore, numerous pores and fractures can be easily generated during the ICP. In comparison, low-medium-maturity shale is buried at greater depths (>1000 m) with higher reservoir pressure and overburden pressure, which reduces the ease of generating pores and fractures in such reservoirs during the ICP [16][17][18][19][20][21][22][23]. The evolution of pores and fractures during the ICP of shale is complex, and its mechanisms are currently unclear.…”

Section: Introductionmentioning

confidence: 99%

Heat-Induced Pore Structure Evolution in the Triassic Chang 7 Shale, Ordos Basin, China: Experimental Simulation of In Situ Conversion Process

Zhao

Hou

et al. 2023

JMSE

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The reservoir properties of low–medium-maturity shale undergo complex changes during the in situ conversion process (ICP). The experiments were performed at high temperature (up to 450 °C), high pressure (30 MPa), and a low heating rate (0.4 °C/h) on low–medium-maturity shale samples of the Chang 7 Member shale in the southern Ordos Basin. The changes in the shale composition, pore structure, and reservoir properties during the ICP were quantitatively characterized by X-ray diffraction (XRD), microscopic observation, vitrinite reflectance (Ro), scanning electron microscopy (SEM), and reservoir physical property measurements. The results showed that a sharp change occurred in mineral and maceral composition, pore structure, porosity, and permeability at a temperature threshold of 350 °C. In the case of a temperature > 350 °C, pyrite, K-feldspar, ankerite, and siderite were almost completely decomposed, and organic matter (OM) was cracked into large quantities of oil and gas. Furthermore, a three-scale millimeter–micrometer–nanometer pore–fracture network was formed along the shale bedding, between OM and mineral particles and within OM, respectively. During the ICP, porosity and permeability showed a substantial improvement, with porosity increasing by approximately 10-times and permeability by 2- to 4-orders of magnitude. Kerogen pyrolysis, clay–mineral transformation, unstable mineral dissolution, and thermal stress were the main mechanisms for the substantial improvement in the reservoir’s physical properties. This study is expected to provide a basis for formulating a heating procedure and constructing a numerical model of reservoir properties for the ICP field pilot in the Chang 7 shale of the Ordos Basin.

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