Downhole electric heater with high heating efficiency for oil shale exploitation based on a double-shell structure

Wang, Zhendong; Lü, Xiaoshu; Li, Qiang; Sun, Youhong; Wang, Yuan; Deng, Sunhua; Guo, Wei

doi:10.1016/j.energy.2020.118539

Cited by 19 publications

(9 citation statements)

References 30 publications

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“…The downhole electric heaters with continuous helical baffles have been proposed [9][10][11][12][13][14][15][16]21,22], which are designed to decrease the dead zones upside of the baffle. Table 2 compares these two typical working conditions for the helical-baffled electric heater [21] and the present tubular heater.…”

Section: Compared With Helical-baffled Electric Heatersmentioning

confidence: 99%

“…Sci. 2022, 12, 9508 2 of 12 of enhanced fins [9][10][11][12][13][14][15][16]. Wang et al [9] proposed a double-shell-structured downhole electric heater with continuous helical baffles, which improved the heating efficiency of the downhole electric heaters effectively.…”

Section: Introductionmentioning

confidence: 99%

“…2022, 12, 9508 2 of 12 of enhanced fins [9][10][11][12][13][14][15][16]. Wang et al [9] proposed a double-shell-structured downhole electric heater with continuous helical baffles, which improved the heating efficiency of the downhole electric heaters effectively. Later, Gu et al [10] claimed that the electric heater with the axial separation helical baffle schemes showed better comprehensive index and temperature uniformity than those of the segment baffle ones.…”

Section: Introductionmentioning

confidence: 99%

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Heat Transfer Performance of a Downhole Electric Tubular Resistive Heater

et al. 2022

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A downhole electric tubular resistive heater is proposed for the oil-shale in situ resorting. After flowing through a set of heating tubes, the outlet temperature and the flow rate of the injected gas can be conveniently adjusted to match the requirement of the pyrolysis temperature of the oil shale. The calculation demonstrates the effects of the inner diameter, the length of the heating tube, and the inlet flow rate on the heat transfer performance of the electric heater. It was found that, compared with the armored electric heaters, even with a small inject flow rate of 5 Nm3/min, the convective heat transfer coefficient of the inner flow exceeds 300 W/m2 K, resulting in a much smaller thermal resistance. The outlet temperature of the heating gas can conveniently reach up to 900 °C with the absence of the complex structure of enhanced fins. Though the pressure loss is relatively larger under a high flow rate, the comprehensive index is still 40% higher, indicating that the present tubular electric heater is a promising candidate to deal with complex downhole conditions.

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Section: Compared With Helical-baffled Electric Heatersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heat Transfer Performance of a Downhole Electric Tubular Resistive Heater

et al. 2022

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“…During the in-situ conversion of oil shale, temperature (heat) is an instrumental factor (Sun et al, 2021a). In the actual process, the high-temperature gas enters the oil shale, and part of the gas is lost through the wellbore annulus (Guo et al, 2020;Wang et al, 2020), which not only wastes energy but also causes thermal damage to the casing and wellhead (Liu et al, 2020). The loss of high temperature gas affects the conversion process.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of bedding effect on the bursting liability of coal and coal-rock combination under different bedding dip angles

Guo

Shui

Liu

et al. 2023

Adv. Geo-Energy Res.

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Heat injection is essential for oil shale in-situ conversion technology. The downhole of the heat injection well reaches temperatures above 400 • C during the process of heat injection, and part of the high-temperature gas dissipates through the wellbore annulus. Consequently, in addition to causing energy loss, the dissipation causes thermal damage to the casing and wellhead. To avoid dissipation, components that are suitable for high-temperature environments should be sealed and used during heat injection while mining. Therefore, this study presents the design of a packer composed of elastic graphite rubber and a high-temperature-resistant material. The influence of numerous factors, such as downhole temperature, working load, and height of rubber, on the reliability of the packer was analyzed. Subsequently, the numerical simulation analysis of the packer reliability in insitu conversion mining under high temperature and pressure environments was performed. The results indicate that when the operating temperature is stable, the operating load has the most obvious influence on the sealing reliability of the packer, whereas the change in the height of the rubber has the least significant effect on the maximum contact stress between the casing and rubber. The change in the operating temperature has the least significant effect on the overall sealing performance of the packer. Moreover, the rise of the temperature will increase the sealing reliability of the packer, and on the contrary, the drop in the temperature will decrease it.

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“…The source rock in the early mature stage requires heat treatment before it can be utilized efficiently . Hence, detailed studies on petroleum generation and their pore structure evolution with increasing thermal maturity are significant for the in situ conversion process. − The pyrolysis simulation is an important method for understanding pore evolution mechanisms in the source rock during thermal maturity, and the internal structure and pore space connectivity evolution directly control the hydrocarbon flow behavior through the pore channels .…”

Section: Introductionmentioning

confidence: 99%

Effect of Petroleum Generation and Retention on Nanopore Structure Change in Laminated and Massive Shales─Insights from Hydrous Pyrolysis of Lacustrine Source Rocks from the Permian Lucaogou Formation

Yang

Xiang

et al. 2023

ACS Omega

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The lacustrine shale of the Middle Permian Lucaogou Formation in the Jimusar Sag is the principal prospective unconventional target in the Junggar Basin. The effect of petroleum generation and retention on nanopore structure change during thermal maturity in lacustrine shale is still unclear. In this study, two laminated and two massive shale samples from the Permian Lucaogou Formation were selected to study this change by closed hydrous pyrolysis. The pyrolysis temperatures were 295, 320, 345, 370, and 400 °C, which cover from the mature to the post-mature stage. Total organic carbon (TOC), Rock-Eval, and low-pressure N2 adsorption tests on pyrolyzed shale samples before and after extractable organic matter (EOM) extraction were conducted systematically. The results indicate that (1) the petroleum generation on nanopore structure change is in stages. The peak nanopore volume expanding stage is the late oil window (R o = 0.9–1.35%). At the post-mature stage (R o > 1.35%), the mesopore volume decreased and the majority of the nanopore space is from macropores. (2) The presence of EOM decreased both mesopores and macropores in the peak oil window. (3) The organic-rich laminated shale generated more macropores than massive shale with increasing thermal maturity. The results of this study shed light on the dynamic effect of laminae fabric, petroleum generation, and retention on shale nanopore structure change across the oil window.

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Downhole electric heater with high heating efficiency for oil shale exploitation based on a double-shell structure

Cited by 19 publications

References 30 publications

Heat Transfer Performance of a Downhole Electric Tubular Resistive Heater

Heat Transfer Performance of a Downhole Electric Tubular Resistive Heater

Evaluation of bedding effect on the bursting liability of coal and coal-rock combination under different bedding dip angles

Effect of Petroleum Generation and Retention on Nanopore Structure Change in Laminated and Massive Shales─Insights from Hydrous Pyrolysis of Lacustrine Source Rocks from the Permian Lucaogou Formation

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