Changes in Oil Shale Characteristics During Simulated in-Situ Pyrolysis in Superheated Steam

Wang, L; Dong, Yongxiang; Zhao, Jing; Zhao, Yangsheng; Kang, Zhiqin

doi:10.3176/oil.2018.3.03

Cited by 16 publications

(7 citation statements)

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“…Scientists at Taiyuan University of Technology have been engaged for many years in the development of the technology and theory of oil shale underground retorting, as well as in the related experimental research [27][28][29][30][31][32]. In 2010, the researchers were granted a Chinese patent titled "The method for extracting oil & gas from oil shale by convection heating" [24].…”

Section: Oil Shale In-situ Steam Injection Technologymentioning

confidence: 99%

The feasibility of in-situ steam injection technology for oil shale underground retorting

Kang¹,

Xie²,

Zhao³

et al. 2020

Oil Shale

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The basic principles of in-situ steam injection technology (MTI) for oil shale underground retorting were presented and related technical processes were analyzed. The convection heat transfer of steam enhanced the efficiency of heating the oil shale layer, which shortened the time to achieve a complete pyrolysis of organic matter. Under the influence of steam the migration capacity of oil and gas improved and the oil and gas products were carried out of the production well more quickly. Moreover, by using superheated steam (up to 570 °C) to pyrolyze oil shale, the oil recovery rate exceeded 95%, and the gas production per unit mass was 0.041 m 3 /kg, at the same time, the quality of oil and gas products greatly improved. The proportion of light oils accounted for 75.38%, and the yield of H 2 and CO in pyrolysis gases was increased. The numerical simulation of steam injection indicated that the MTI technology was a rapid and efficient method for oil shale underground retorting to extract oil and gas by using the injection and production wells alternately for injecting steam. It demonstrated that the development period of the MTI technology was only about 300 days for an oil shale reservoir with a well spacing of 50 m, and the roof and floor of the oil shale layer served as thermal and steam insulation. The successful industrial implementation of the MTI technology in the future should alleviate the increasing energy crisis in China and reduce the country's dependence on imported petroleum.

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Section: Oil Shale In-situ Steam Injection Technologymentioning

confidence: 99%

The feasibility of in-situ steam injection technology for oil shale underground retorting

Kang¹,

Xie²,

Zhao³

et al. 2020

Oil Shale

Self Cite

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“…However, the heating cycle is often as long as 3-5 years, because the oil shale formation is not modified. Taiyuan University of Technology [19][20][21] suggested heating the oil shale formation by injecting superheated steam into that formation after hydraulic fracturing of oil shale; once it is injected into the formation, the superheated steam will cool down quickly, and liquefy into water; the water will remain in the oil shale formation, hindering the subsequent heating. As a result, this technology has not been tested in the field.…”

Section: Introductionmentioning

confidence: 99%

Design and Numerical Simulation of In-Situ Pyrolysis of Oil Shale Through Horizontal Well Fracturing with Nitrogen Injection

Jiang¹,

Zhang²,

Li³

et al. 2021

IJHT

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An in-situ pyrolysis technology was proposed for shallow oil shale: drilling horizontal wells to the oil shale formation, connecting the horizontal well sections through hydraulic fracturing, injecting nitrogen from the surface to bottomhole, heating up the nitrogen to a high temperature at the bottom, and directly using the high-temperature nitrogen for oil shale pyrolysis. Then, a mathematical model was established for the heat transfer within the oil shale, and a simplified physical model was created for in-situ pyrolysis of oil shale, and used to simulate the heat transfer process. The simulation results show that, with the extension of heating time, the area of effectively pyrolyzed oil shale formation took up an increasingly large proportion of the total cross-sectional area of the formation; however, the increase of the pyrolysis area ratio was rather slow, and the temperature was unevenly distributed in the formation after a long duration of heating. Therefore, the 300d in-situ heating was split into two stages: 250d of heating in the heating well and 50d of heating in the production well. The two-stage heating maximized the heating area of oil shale, and heated 57% of the cross-sectional area up to 400℃, ensuring the effectiveness of pyrolysis. Moreover, this heating scheme ensured an even distribution of temperature in oil shale formation, a high energy utilization, and a desirable heating effect.

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“…In addition, the boiling erosion effect of the high-temperature steam also enhances the permeability of the oil shale to rapidly heat the oil shale formation. 12 Therefore, the MTI technology might be a more efficient mining technology.…”

Section: Introductionmentioning

confidence: 99%

“…In this technique, the permeability channel of superheated steam is first obtained by hydraulic fracturing, and then, the superheated steam with high specific heat will transport a large amount of energy into the oil shale formation. In addition, the boiling erosion effect of the high-temperature steam also enhances the permeability of the oil shale to rapidly heat the oil shale formation . Therefore, the MTI technology might be a more efficient mining technology.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the in Situ Oil Shale Pyrolysis Process by Superheated Steam Considering the Anisotropy of the Thermal, Hydraulic, and Mechanical Characteristics of Oil Shale

et al. 2019

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The in situ pyrolysis process of oil shale by superheated steam is a complex process that is affected by the thermal−hydraulic−mechanical coupled process. Meanwhile, oil shale's physical properties show strong anisotropy in the thermal, hydraulic, and mechanical characteristics due to the mineral arrangements and sedimentary structures. To accurately simulate the in situ oil shale pyrolysis process, the anisotropic thermal, hydraulic, and mechanical characteristics at different temperatures were first determined through laboratory experiments. Then, a thermal−hydraulic−mechanical coupled model that considers the anisotropic thermal−hydraulic−mechanical characteristics was established to simulate the in situ pyrolysis process of oil shale by superheated steam. The distributions of the pore pressure, temperature, stress, deformation, permeability, and production during the in situ pyrolysis process were analyzed. The main results are as follows: (1) the temperature field distributions in oil shale reservoirs are closely related to the migration of superheated steam in reservoirs, and rapid temperature decrease zones are formed at the edges of the temperature fields; (2) the permeability distribution in an oil shale reservoir presents a strong anisotropy, and the evolution of the permeability is related not only to the temperature but also to the stress;(3) compared with the electric heating method, the steam heating method has the characteristics of faster heating and earlier achievement of the oil production peak; (4) the anisotropy of the permeability has the greatest impact on oil and gas production, followed by the anisotropy of the mechanical parameters, while the anisotropy of the heat transfer coefficient has little effect on the oil and gas production. Our fully coupled thermal−hydraulic−mechanical (THM) model that couples the anisotropic thermal−hydraulic−mechanical characteristics can improve the current understanding of heat and mass transfer in the in situ pyrolysis process of oil shale.

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Changes in Oil Shale Characteristics During Simulated in-Situ Pyrolysis in Superheated Steam

Cited by 16 publications

References 0 publications

The feasibility of in-situ steam injection technology for oil shale underground retorting

The feasibility of in-situ steam injection technology for oil shale underground retorting

Design and Numerical Simulation of In-Situ Pyrolysis of Oil Shale Through Horizontal Well Fracturing with Nitrogen Injection

Numerical Investigation of the in Situ Oil Shale Pyrolysis Process by Superheated Steam Considering the Anisotropy of the Thermal, Hydraulic, and Mechanical Characteristics of Oil Shale

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