Fluid Performance in Coal Reservoirs: A Comprehensive Review

Gao, Changjing; Liu, Dameng; Li, Zhentao; Cai, Yidong; Fang, Yufeng

doi:10.1155/2021/6611075

Cited by 7 publications

(7 citation statements)

References 137 publications

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“…8 + 9 coal seams both contain CO 2 generated by coal pyrolysis, which belongs to organic genetic gas [28], while shallow CO 2 is greatly affected by the action of microorganisms and belongs to biogenic gas. In the stagnant CBM system, the water-soluble consumption of CO 2 produced by coalification (including associated gas during microbial methane production and thermal degradation gas of coal-forming material) is not complete [32], resulting in high CO 2 concentration in gas components, and increases with the increase of burial depth.…”

Section: Compositional Characteristics Of Cbmmentioning

confidence: 99%

Genesis of Coalbed Methane and Its Storage and Seepage Space in Baode Block, Eastern Ordos Basin

et al. 2021

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The Baode block on the eastern margin of the Ordos Basin is a key area for the development of low-rank coalbed methane (CBM) in China. In order to find out the genesis of CBM and its storage and seepage space in Baode block, the isotopic testing of gas samples was carried out to reveal the origin of CH4 and CO2, as well, mercury intrusion porosimetry, low temperature nitrogen adsorption, and X-ray CT tests were performed to characterize the pores and fractures in No. 4 + 5 and No. 8 + 9 coal seams. The results showed that the average volume fraction of CH4, N2, and CO2 is 88.31%, 4.73%, and 6.36%, respectively. No. 4 + 5 and No. 8 + 9 coal seams both have biogenic gas and thermogenic methane. Meanwhile, No. 4 + 5 and No. 8 + 9 coal seams both contain CO2 generated by coal pyrolysis, which belongs to organic genetic gas, while shallow CO2 is greatly affected by the action of microorganisms and belongs to biogenic gas. The average proportion of micropores, transition pores, mesopores, and macropores is 56.61%, 28.22%, 5.10%, and 10.07%, respectively. Samples collected from No. 4 + 5 coal seams have developed more sorption pores. Meanwhile, samples collected from No. 8 + 9 coal seams exhibited a relatively low degree of hysteresis (Hg retention), suggesting good pore connectivity and relatively high seepage ability, which is conducive to gas migration. The connected porosity of coal samples varies greatly, mainly depending on the relative mineral content and the proportion of connected pores.

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Section: Compositional Characteristics Of Cbmmentioning

confidence: 99%

Genesis of Coalbed Methane and Its Storage and Seepage Space in Baode Block, Eastern Ordos Basin

et al. 2021

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“…In an original coal reservoir, water and free gas occupy the coal cleat network space, and are mainly composed of formation water [1,2]. The cleats of a coal seam are mainly caused by the change in the coal material structure in the process of coalification.…”

Section: Introductionmentioning

confidence: 99%

Study on Numerical Simulation of Gas–Water Two-Phase Micro-Seepage Considering Fluid–Solid Coupling in the Cleats of Coal Rocks

Qian,

Xie,

Zhang

et al. 2024

Energies

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The increasing demand for natural gas energy will promote unconventional natural gas, such as coal seam gas and shale gas, to play a key role in future energy development. The mechanical properties of coal seams are weaker compared with conventional natural gas reservoirs. The fluid–solid coupling phenomenon exists widely at the pore scale and macro scale of coal seams, and runs through the whole process of coalbed gas exploitation. The objective of this study is to establish a microscale gas–water flow model for coalbed methane considering fluid structure coupling. Frist, this study used scanning electron microscopy (SEM) to obtain microscopic pore images of coal rocks. Then, we constructed a numerical model to simulate the movement of coalbed methane and water within the scale of coal cleats based on the Navier–Stokes equation, phase field method, and solid mechanics theory. Finally, we analyzed the effects of injection pressure and wettability on the microscopic two-phase seepage characteristics and displacement efficiency of coal. Our research shows that when the injection pressure is increased from 60 kPa to 120 kPa, the displacement completion time is shortened from 1.3 × 10−4 s to 7 × 10−5 s, and the time is doubled, resulting in a final gas saturation of 98%. The contact angle increases from 45° to 120°, and the final gas saturation increases from 0.871 to 0.992, an increase of 12.2%.

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“…China is currently the world's largest coal producer and consumer, with coal consumption accounting for 56.0 per cent of total energy in 2018 [1], and China's coalbed methane resources ranked third globally [2]. Most of the mines that experienced disasters associated with rockburst and gas were high gas mines, in which rockburst created conditions for a large number of rapid gas emissions, and high gas pressure also constituted the dynamic conditions for rockburst [3][4][5]. With the gradual increase of coal mining depth, the gas pressure, gas content, and ground stress of coal seam were increasing; the gas permeability was gradually decreasing, in which the deep coal seam with high gas content gradually transformed into the outburst coal seam; and the coal-gas dynamic disaster was becoming more and more serious [6,7].…”

Section: Introductionmentioning

confidence: 99%

Study on the Precursor Characteristics of Instability Failure of Gas-Bearing Coal Based on Stress and Gas Seepage Volume

Xie

Liu

et al. 2022

Geofluids

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In coal mining activities, the original stress of the coal body changes, resulting in structural deformation and destruction, which will cause changes in gas seepage volume. The conventional triaxial loading test was carried out by using the triaxial loading-gas adsorption seepage experimental device. The effects of different loading rates, confining pressures, and gas pressures on the peak strength of coal were analyzed; the evolution laws of coal stress, gas seepage volume, stress rate, and gas seepage volume rate at different deformation stages were studied; and it was found that the time, at which the specimen began to enter the crack propagation deformation stage, determined by the change of gas seepage rate or stress rate was not the same. Therefore, combined with gas seepage and stress, a theoretical model of stress rate-seepage volume rate under triaxial pressure was proposed, and the ratio F of the two was used as an early warning index. It was found that the F value was basically stable in the elastic stage and decreased rapidly in the crack propagation stage. Thus, the F value was used as an early warning index for the instability and failure of gas-bearing coal. The F value of the experimental results was consistent with the theoretical model, and the F value entered the crack propagation stage earlier than the stress rate or the gas seepage volume rate. The research results provided a theoretical basis for coal mine safety mining and disaster prevention.

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Fluid Performance in Coal Reservoirs: A Comprehensive Review

Cited by 7 publications

References 137 publications

Genesis of Coalbed Methane and Its Storage and Seepage Space in Baode Block, Eastern Ordos Basin

Genesis of Coalbed Methane and Its Storage and Seepage Space in Baode Block, Eastern Ordos Basin

Study on Numerical Simulation of Gas–Water Two-Phase Micro-Seepage Considering Fluid–Solid Coupling in the Cleats of Coal Rocks

Study on the Precursor Characteristics of Instability Failure of Gas-Bearing Coal Based on Stress and Gas Seepage Volume

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