Increasing permeability of coal seams using the phase energy of liquid carbon dioxide

Chen, Haidong; Wang, Zhaofeng; Chen, Xien; Chen, Xiangjun; Wang, Liguo

doi:10.1016/j.jcou.2017.03.010

Cited by 100 publications

(64 citation statements)

References 38 publications

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“…The conductivities of the two cases can be described by Equations (7) and (8). f t is the conductivity of the remolded coal at any water saturation.…”

Section: Imbibition Conductivit Y Model In Remolded Coalmentioning

confidence: 99%

“…However, most of the mines in China, India, and a few other countries are in a physical environment of high in situ stress and low permeability, with the mining depth increasing at a rate of 10-25 m/a. [7][8][9][10][11] A series of hydraulic measures, including hydraulic fracturing, [12][13][14] hydraulic slotting, [15][16][17] and hydraulic flushing [18][19][20][21] can promote the development of fractures and pores in the coal reservoir, which effectively improve the gas extraction rate. However, coal seam water injection technology for regional outburst elimination measures was cancelled in the Regulations on Prevention and Control of Coal and Gas Outburst promulgated by the Chinese Government in 2009.…”

Section: Introductionmentioning

confidence: 99%

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Response characteristics of the resistivity and water content during the imbibition process in remolded coal without gas

Yue

Wang

Chen

et al. 2019

Energy Science & Engineering

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The water content distribution in a coal body is closely related to the gas distribution. It is difficult to directly determine the water content distribution in the process water imbibition. To retrieve the water content by the resistivity value and establish a relationship between the resistivity and water content, the response characteristics of the resistivity and water content of remolded coal formed under different loads are studied by a self‐designed resistivity experimental system. The results show that the resistivity of the remolded coal decreases over time during the imbibition process, including a rapidly decreasing stage and a slowly decreasing stage. The resistivity of the remolded coal is related to the water in the macropore in the rapidly decreasing stage. In the slowly decreasing stage, the resistivity is related to the contact between coal particles. The pressing load, imbibition range, and imbibition speed are negatively correlated with porosity. The resistivity of the steady state is also negatively correlated with the water content and pressing load. The relationship between the resistivity of the steady state and the water content fit a power function. This study reveals the law of resistivity and the water content during the imbibition process and provides an effective methodology to bridge the gap for measuring water content distribution during the imbibition process.

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“…The conductivities of the two cases can be described by Equations (7) and (8). f t is the conductivity of the remolded coal at any water saturation.…”

Section: Imbibition Conductivit Y Model In Remolded Coalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Response characteristics of the resistivity and water content during the imbibition process in remolded coal without gas

Yue

Wang

Chen

et al. 2019

Energy Science & Engineering

Self Cite

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“…This technology was firstly developed and used by a British company, Cardox, in 1914, mainly to solve practical engineering problems in coal mining. Because LCPCFT has the advantages of small blasting vibration, no flame, and no toxic and harmful gas in the process of fracturing [1], it has been widely used in the fields of engineering blasting with complex construction conditions and high blasting requirements, such as coal seam permeability enhancement [2], surface soil stripping [3], tunnel excavation [4] and subway construction [5].…”

Section: Introductionmentioning

confidence: 99%

Indoor Test System for Liquid CO2 Phase Change Shock Wave Pressure with PVDF Sensors

Huang

Wei

et al. 2020

Sensors

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Liquid carbon dioxide phase change fracturing technology (LCPCFT) has been widely used in engineering blasting due to the advantage of no flames, and no toxic and harmful gas. However, few studies have been conducted on the acquisition of shock wave pressure and its loading characteristics, which are key parameters in fracturing. Referring to the CO 2 in-situ fracturing technology, an indoor test system for shock wave pressure generated during LCPCFT has been built, with a protected polyvinylidene fluoride (PVDF) piezoelectric sensor. Then three verification experiments with different radial distances between the fracturing tube and test points were carried out on the test system, and in each experiment, four PVDF sensors as four test points were arranged with different axial distance from the detonating point to test the pressure distribution. The experimental results show that when the radial distance between the fracturing tube and test points is not too large (≤345 mm), the pressure generated during LCPCFT is approximately uniformly distributed within the axial length of the fracturing tube, but when it is relatively large (≈895 mm), the results between different test points are in a certain degree of dispersion. And finally, this paper uses the intraclass correlation coefficient (ICC) and coefficient of variation (C V ) of peak pressure and impulse to process the test results to evaluate the reliability and stability of the test system. Evaluation results show that the test results are in good consistency. The test system in this paper has good stability and high reliability. The test system provides a useful tool for accurately obtaining the shock wave pressure, which is helpful for further research on LCPCFT.Hu [6] conducted permeability enhancement experiments of a coal seam by using LCPCFT; the test results show that cracks generated inside the coal seam will greatly increase the gas permeability of the coal seam. In addition, the process of LCPCFT is endothermic, which belongs to cold blasting, so the process of permeability enhancement is safer and more environmentally friendly. Because the small surface tension of supercritical CO 2 , it can penetrate into the interior of rock mass along the cracks, therefore the rock failure is accompanied by the generation of tensile cracks [7], and its rock breaking ability is usually better than that of a water jet [8]. Under the effect of competitive adsorption, the gaseous CO 2 produced during the fracturing process will convert the gas absorbed in the coal seam to a free state, which will increase the amount of gas released and reduce the possibility of a gas outburst during excavation [9]. Through experiments and numerical simulations, Sun [10] believed that the rock breaking under LCPCFT is the result of a stress wave and gasified CO 2 ,and the influence of initial confining pressure and blasting pressure on the effect of LCPCFT are also analyzed [11]. Zhu [12] analyzed the damage evolution process of concrete specimens under the action of high-pressure gas e...

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“…To utilize the energy from phase transition, Hu et al . and Chen et al . developed liquid CO 2 phase‐transition blasting technology to increase coal seam permeability and enhance coal bed methane reservoir.…”

Section: Introductionmentioning

confidence: 99%

“…Lu et al 31 found that instead of Joule-Thomson coefficient, the phase transition and the heat transfer processes may play a more important role in determining the pressure and the temperature profiles in injection wells during geological storage when CO 2 was in a two-phase state. To utilize the energy from phase transition, Hu et al 32 and Chen et al 33 developed liquid CO 2 phase-transition blasting technology to increase coal seam permeability and enhance coal bed methane reservoir. Plenty of scholars have a common view that phase change of CO 2 may have significant effects on leakage rates, heat, and mass transfer processes.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the impact of liquid carbon dioxide injection on temperature in pulverized coal

Yang

Wen

et al. 2020

Greenhouse Gases

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Using liquid carbon dioxide (LCO2) as a medium for underground coal fires prevention and control, while reducing the emissions of CO2, is a promising option for CO2 utilization worldwide. However, the mechanism of LCO2 flow with phase transition on coal temperature is still not clear. In this work, an experimental system was designed and fabricated to investigate the phase transition behavior and temperature variation during injecting LCO2 into pulverized coal and the impact of mass flow rate, nozzle diameter, and injection pressure on cooling effect. The results indicate that when LCO2 was injected into the pulverized coal, the instantaneous phase change into solid and vapor occurred just after leaving the release port. An intensive heat transfer process occurred because of the throttling effect, flashing effect, and sublimation and thereby formed a cooling area (<−56.6°C), which was the main area of cooling effect and phase transition; as injection time increases, the range of this area increases in the form of logarithmic function. In addition, the cooling area exhibited a strong dependence on the injection conditions, and its correlation with mass flow rate, nozzle diameter, and injection pressure are identified as exponential, logarithmic, and linear relationship by dimensionless analysis, respectively. Meanwhile, an empirical formula was developed for calculating the cooling effect under various injection conditions. In summary, the experiments provided fundamental data and regime for predicting the effect of LCO2 injection on the temperature of pulverized coal, which can be used to guide the utilization of LCO2 for coal fires prevention. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Increasing permeability of coal seams using the phase energy of liquid carbon dioxide

Cited by 100 publications

References 38 publications

Response characteristics of the resistivity and water content during the imbibition process in remolded coal without gas

Response characteristics of the resistivity and water content during the imbibition process in remolded coal without gas

Indoor Test System for Liquid CO2 Phase Change Shock Wave Pressure with PVDF Sensors

Experimental investigation of the impact of liquid carbon dioxide injection on temperature in pulverized coal

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