Modeling and evolution characteristics of coal reservoir energy during gas and water production

Jia, Tianrang; Wei, Jianping; Wei, Guoying; Yan, Jun; Wu, Caifang

doi:10.1016/j.jngse.2021.104329

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…Coal is one of the important basic energy sources, which provides a solid guarantee for the sustainable and healthy development of society and economy [1][2][3][4]. In particular, China is characterized by a coal−based energy resource endowment, which concludes that coal will continue to be China's primary energy source for the foreseeable future [5,6].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Effect of Gas Adsorption and Desorption on Ultrasonic Velocity and Elastic Mechanical Parameters of Coal

Liu

Wang

et al. 2022

Sustainability

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The rapid and accurate identification of the physical characteristics of coal by means of ultrasonic detection is of great significance to ensure safe mining of coal and efficient development of coal seam methane. In this paper, the ultrasonic velocity testing experiments of coal during gas adsorption and desorption were carried out, utilizing a low frequency petrophysical measurement device with primary and fractured coal as the research objects. The variations in the elastic mechanical parameters and ultrasonic velocity of coal samples were analyzed to elucidate the influence mechanism that gas adsorption and desorption have on them. During gas adsorption and desorption, the longitudinal wave velocity of the primary structure coal varies from 1990 m/s to 2200 m/s, and the transverse wave velocity varies from 1075 m/s to 1160 m/s, while the longitudinal wave velocity of the fractured structure coal varies from 1540 m/s to 1950 m/s, and the transverse wave velocity varies from 800 m/s to 1000 m/s. The elastic modulus and wave velocities, in both directions of the primary structural coal, were higher than those of the fractured structural coal. In comparison to the fractured structural coal, the main structural coal had a lower Poisson’s ratio. In addition, the spread of the elastic mechanical parameters and wave velocities, in both the longitudinal and transverse directions, was more pronounced in the fracture−structured coal than in the primary−structured coal. During gas adsorption and desorption, the speed of the coal’s longitudinal waves increased, and then decreased, due to the combined effect of gas adsorption expansion and pore gas pressure compression matrix effect. For this experiment, the maximum longitudinal wave velocity of the coal occurred at a gas pressure of 1.5 MPa. Primary structural coal has a longitudinal wave speed of 2103 m/s, whereas fragmented structural coal has a speed of 1925 m/s. The variation in the shear wave velocity of the coal is controlled only by the gas adsorption expansion effects. The shear wave velocity increases during gas adsorption and decreases during gas desorption. With the change of gas pressure, the longitudinal wave velocity can increase by 23.34%, and the shear wave velocity can increase by 17.97%. Coal undergoes changes to both its Poisson’s ratio and elastic modulus as a result of gas adsorption and desorption; these modifications are analogous to the velocity of longitudinal and shear waves, respectively.

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Section: Introductionmentioning

confidence: 99%

Experimental Study on the Effect of Gas Adsorption and Desorption on Ultrasonic Velocity and Elastic Mechanical Parameters of Coal

Liu

Wang

et al. 2022

Sustainability

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Research on outburst gas pressure dynamics and water-injected coal damage

Wei,

Li,

et al. 2024

Physics of Fluids

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Coal and gas outbursts are complex dynamic disasters closely associated with gas pressure dynamics and coal damage. An experimental system was established to investigate the effects of water injection on coal particles. The experiments utilized helium (He) and carbon dioxide (CO2) gases, at initial pressures ranging from 0.25 to 1.0 MPa and water injection periods ranging from 0 to 12 days, to measure gas pressure variation, particle size distribution, equivalent diameter, and newly generated surface area. The results indicated that outburst gas pressure follows a power-law decay, with He decaying more rapidly than CO2. Elevated gas pressure and adsorptivity intensified coal particle damage: each 0.25 MPa rise in pressure increased the new surface area by 1.02 times for He and 1.28 times for CO2, with the CO2's surface area being 5.03–5.20 times larger than that of He. Water injection mitigated the damage caused by adsorptive gases; as the injection time increased, the new surface area initially decreased and then increased, with the least damage at 6 days. For every 3 day increase in the water injection time, the average surface area of He-fractured coal increases by 0.69 times. A gas pressure decay model and a coal damage model considering pressure differential tension, gas adsorption expansion, and adsorption-induced strain were developed and validated against experimental results. These findings provide theoretical insights into coal and gas outbursts.

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Modeling and evolution characteristics of coal reservoir energy during gas and water production

Cited by 2 publications

References 23 publications

Experimental Study on the Effect of Gas Adsorption and Desorption on Ultrasonic Velocity and Elastic Mechanical Parameters of Coal

Experimental Study on the Effect of Gas Adsorption and Desorption on Ultrasonic Velocity and Elastic Mechanical Parameters of Coal

Research on outburst gas pressure dynamics and water-injected coal damage

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