Experimental Study on the Anisotropic Mechanical Properties of Oil Shales Under Real-Time High-Temperature Conditions

Wang, Guoying; Yang, Dinglong; Liu, Shaowei; Fu, Mengxiong; Wang, Lei

doi:10.1007/s00603-021-02624-7

Cited by 31 publications

(10 citation statements)

References 46 publications

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“…Previous investigations into the dynamic evolution of the porosity and permeability of shale and oil shale under increasing temperature have observed similar trends to those identified in the present study [13,29,49,50,[52][53][54][55][56][57][58]. The dynamic evolution of the porosity and permeability of oil shale with increasing temperature was generally consistent with that of shale, and the temperature threshold for the sharp increase in the porosity and permeability in both oil shale and shale was approximately 350 • C (Figure 12).…”

Section: Changes In Shale Porosity and Permeability During Heatingsupporting

confidence: 87%

“…The porosity increased by 10-times, and the permeability increased by 2-4 orders of magnitude (Table 2). Previous studies have shown that, when oil shale is heated above 400 °C, the porosity and permeability increase substantially [49][50][51][52][53][54][55][56][57][58]. Our compilation of published data revealed that the porosity was generally <5% and the horizontal permeability was generally <0.1 md before heating, increasing to around 15-30% and 0.1-100 md after heating to 400-450 °C, respectively.…”

Section: Changes In Shale Porosity and Permeability During Heatingmentioning

confidence: 56%

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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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Section: Changes In Shale Porosity and Permeability During Heatingsupporting

confidence: 87%

Section: Changes In Shale Porosity and Permeability During Heatingmentioning

confidence: 56%

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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“…Horizontal permeability increases faster with porosity than with vertical permeability. The oil and gas transformed from the shale in situ conversion can be transported better horizontally and cannot be well transported vertically, which is favorable for later exploitation. , …”

Section: Resultsmentioning

confidence: 99%

“…The oil and gas transformed from the shale in situ conversion can be transported better horizontally and cannot be well transported vertically, which is favorable for later exploitation. 64,65 3.4. Comparative Analysis of Model-Calculated and Experimental Values.…”

Section: Evaluation Model Of Permeabilitymentioning

confidence: 99%

Dynamic Evolution Mechanism of Reservoir Physical Properties during Oil Shale In Situ Conversion

Hou,

Tian,

et al. 2024

Energy Fuels

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Oil shale in situ conversion is a process where the generated crude oil and the unconverted solid organic matter in immature to lowly mature shales are converted to light oil and gas via artificial heating. The focus of this study was to solve the engineering problems in shale oil production and establish quantitative evaluation models of the dynamic physical properties of reservoirs during shale in situ conversion. Based on thermal pyrolysis experiments, it is concluded that the total organic carbon (TOC) coupled with temperature controls the dynamic reservoir physical properties during shale in situ conversion. After heating, the porosity and permeability can increase 4-fold and 10fold, respectively. The physical properties of the shale reservoir at the same thermal pyrolysis temperature show a good power positive correlation with the TOC. In addition, the permeability anisotropy value showed that the horizontal permeability (K h ) is larger than the vertical permeability (K v ). K h /K v increased as the temperature increased. Furthermore, K h /K v shows a good positive exponential correlation with porosity. The evaluation model of porosity with the TOC and temperature has been established based on the thermal pyrolysis data. There is a good positive correlation between permeability and porosity, and the evaluation model of permeability and K v has been established using porosity. The results provide models for reservoir dynamic physical property prediction during shale in situ conversion. Furthermore, the results provide guidance on shale mechanics anisotropy for furthering fracturing engineering.

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“…Alneasan [12] investigated the effect of temperature on the fracture characteristics of granite under three loading modes and found that the fracture behavior was temperature-dependent and could be changed from brittle to ductile. Wang [13] investigated the anisotropic mechanical behavior of oil shale from room temperature to 600°C using a real-time high-temperature test system.…”

Section: Introductionmentioning

confidence: 99%

Physical and Mechanical Properties and Damage Mechanism of Sandstone at High-Temperature

Zheng,

Zhang,

et al. 2023

Preprint

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The physical and mechanical properties of rocks will change significantly after being subjected to high temperatures, which poses safety hazards to underground projects such as coal underground gasification. In order to investigate the effect of temperature on the macroscopic and microscopic properties of rocks, this paper has taken sandstone as the research object and conducted uniaxial compression tests on sandstone specimens at different temperatures (20-1000 ℃) and different heating rates (5-30 ℃/min) at 1200 ℃. At the same time, the acoustic emission (AE) test system was used to observe the acoustic emission characteristics of the rock damage process, and the microstructural changes after high temperature were analyzed with the help of a scanning electron microscope (SEM). The test results show that the effect of temperature on sandstone is mainly divided into three stages: Ⅰ (20-500 ℃) stage is the strengthening zone, the evaporation of water and the contraction of primary fissures, sandstone densification is enhanced. Specifically, the compressive strength and elastic modulus increase, the macroscopic damage mode is dominated by shear damage, and the fracture micro-morphology is mainly brittle fracture. Stage II (500-600°C) is the transition zone, 500°C is the threshold temperature for compressive strength and modulus of elasticity, and the damage mode changes from shear to cleavage damage, and the sandstone undergoes brittle-ductile transition in this temperature interval. Stage III is the physicochemical deterioration stage. The changes in physical and chemical properties make the sandstone compressive strength and modulus of elasticity continue to decline, the macroscopic damage mode is mainly dominated by cleavage damage, and the fracture microscopic morphology is more toughness fracture. The effect of different heating rates on the mechanical properties of sandstone was further studied, and it was found that the mechanical properties of the rock were more deteriorated under higher heating rates.

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Experimental Study on the Anisotropic Mechanical Properties of Oil Shales Under Real-Time High-Temperature Conditions

Cited by 31 publications

References 46 publications

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

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

Dynamic Evolution Mechanism of Reservoir Physical Properties during Oil Shale In Situ Conversion

Physical and Mechanical Properties and Damage Mechanism of Sandstone at High-Temperature

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