Dynamic multifield coupling model of gas drainage and a new remedy method for borehole leakage

Zhang, Junxiang; Li, Bo; Liu, Yanwei; Fu, Jiangwei; Chen, Liang; Ding, Pengchu

doi:10.1007/s11440-021-01444-x

Cited by 31 publications

(16 citation statements)

References 41 publications

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“…2 well is 3 million tons/year. 20 , 21 The No. 2 well is provided with the II04907 coal working face, the II04098 standby working face, and two heading faces including the II04909 ventilation roadway heading face and II04909 transporting roadway heading face, as shown in Figure 12 .…”

Section: Resultsmentioning

confidence: 99%

“…The approved production capacity of Yangchangwan Coal Mine is 12 million tons/year, of which the approved production capacity of the No. 2 well is 3 million tons/year. , The No. 2 well is provided with the II04907 coal working face, the II04098 standby working face, and two heading faces including the II04909 ventilation roadway heading face and II04909 transporting roadway heading face, as shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

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Application of a Simulation Method for the Shock Wave Propagation Law of Gas Explosion

et al. 2022

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Gas explosion is one of the main causes of casualties in coal mines. Studying the propagation law of shock wave of mine gas explosion can reduce the economic loss and personnel injury caused by mine gas explosion. To solve the difficulty in the research of shock wave propagation of gas explosion in the mine scale, the segmented relay simulation method of shock wave propagation of gas explosion in a coal mine was put forward, the related key problems were studied, and the results were successfully applied in Yangchangwan No. 2 Mine. The results show the following: (1) When the length of the forked roadway exceeds 50 m, the length of the forked roadway has little effect on the shock wave overpressure in the main roadway. When the length of the forked roadway is short, the closure of the forked roadway has a great influence on the change curve of the shock wave overpressure in the main roadway. Therefore, the length of the bifurcation roadway should not be less than 50 m in numerical simulation. (2) The angle of the bifurcated roadway has a great influence on the shock wave propagation of explosion in the main roadway. With the increase in the angle of the bifurcated roadway, the overpressure in the main roadway tends to increase at first and then decrease, and the peak overpressure is the highest when the angle of the bifurcated roadway is 90°. (3) The influence range of the roadway pressure-outlet boundary is about 5 m, and the dynamic parameter monitoring point should be set at about 10 m away from the pressure outlet; dynamic boundary monitoring parameters should include static pressure, dynamic pressure, and temperature. (4) When the gas explosion occurs in the heading face, the shock wave will cause great damage to the adjacent heading face. When the shock wave reaches the head-on and upper corner of the heading face, it will be reflected violently, which will cause the local overpressure to rise obviously. The peak overpressure and gas accumulation length conform to the logarithmic function.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Application of a Simulation Method for the Shock Wave Propagation Law of Gas Explosion

et al. 2022

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“…Studies have shown that the permeability of coal seam directly determines the difficulty in gas extraction. − How to improve the permeability of low-permeability coal bed is the key problem to strengthen gas extraction and prevent gas disaster. The pore-fissure system in coal is the main channel for gas flow, so the microscopic pore structure of coal is an important factor determining its permeability. − In essence, the factors affecting coal permeability mainly affect penetrability through affecting the micropore structure of coal. Therefore, adopting effective technical means to improve the pore structure of coal bed and increase its permeability is the key to improve the gas extraction rate.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mixed Acid Fluid on the Pore Structure of High Rank Coal and Acid Fluid Optimization

2022

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Acidizing technology is an important means to increase production in oil-gas reservoirs. In recent years, acidizing technology has been widely used to increase the permeability of coal seams to enhance gas extraction, where acidizing fluid is the key factor to determine the permeability improvement effect by acidizing technology. In order to clarify the influence of mixed acid fluid on the pore structure of high rank coal and seek the optimal mixed acid fluid suitable for acidizing and permeability improvement of high rank coal in the Jiaozuo coal mine area. Taking the Jiulishan Mine in the Jiaozuo mining area as an example, low field nuclear magnetic resonance (LFNMR) test and static dissolution test were conducted to obtain the T 2 spectrum, porosity, movable fluid saturation, pore throat distribution, nuclear magnetic permeability, and dissolution rate of coal samples before and after treatment with distilled water and three mixed acid fluids. On this basis, the influence of mixed acid fluid on the pore structure of high rank coal was analyzed and the optimal mixed acid fluid suitable for high rank coal was selected. The results showed that the pore size, number, and volume of all kinds of pore sizes of coal samples treated with distilled water all decreased, which was manifested by the decrease of effective porosity and nuclear magnetic permeability. After acidification, the proportion of micropore volume in coal decreased significantly, the number and proportion of pore volume of mesopores and macropore-microfractures increased significantly, and the connectivity between mesopores and macropore-microfractures was enhanced, which was characterized by the increase in effective porosity and nuclear magnetic permeability of coal samples. After acidification, the pore-throat ratio of adsorption pores of all coal samples decreased, while the pore-throat ratio of seepage pores increased. By comparatively analyzing the change law of pore structure of coal samples before and after acidizing with three kinds of mixed acid fluids, the optimal mixed acid fluid suitable for acidizing and permeability improvement of high rank coal in the Jiaozuo coal mine area was selected, which was 12%HCL +3%HF.

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“…At the same time, chemical stimulation, freeze-fracturing, destruction blasting, and other technologies had also been applied to improve the permeability of coal seams. 33 − 37 …”

Section: Introductionmentioning

confidence: 99%

New Technology of Mechanical Cavitation in a Coal Seam to Promote Gas Extraction

et al. 2022

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Realizing efficient gas drainage in low permeability coal seams has always been a difficult problem for coal miners. Based on this, this paper proposes a new technology of large-diameter mechanical cave-making to promote gas extraction in a coal seam. This technology mainly uses the pressure of a water injection pump to control the automatic opening and closing of a mechanical reaming device to realize mechanical cavitation, and the hole diameter can reach up to 500 mm. The gas drainage effect of mechanical cavitation drilling is analyzed by a numerical simulation, which shows that under the condition of the same drainage time, the larger the cavitation radius is, the larger the effective influence radius of gas drainage is. According to the field test results, the time of single cave-making is about 5 min, and the speed of cave-making is fast. The coal output of a single cave is 0.42 t/m, and the pressure relief effect is obvious. Compared with ordinary drilling, the gas drainage concentration of mechanical cavitation drilling is increased by 2 times and the net amount of drainage is increased by 1.8 times. Large-diameter mechanical cavitation technology can better improve the gas drainage effect of outburst coal seams with low permeability and has a good application prospect.

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Dynamic multifield coupling model of gas drainage and a new remedy method for borehole leakage

Cited by 31 publications

References 41 publications

Application of a Simulation Method for the Shock Wave Propagation Law of Gas Explosion

Application of a Simulation Method for the Shock Wave Propagation Law of Gas Explosion

Effect of Mixed Acid Fluid on the Pore Structure of High Rank Coal and Acid Fluid Optimization

New Technology of Mechanical Cavitation in a Coal Seam to Promote Gas Extraction

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