WEBJul 7, 2023 · Gas disasters have become one of the factors seriously affecting mine safety production. 2,3 Gas pressure is an important indior for preventing gas disasters, which directly reflects the gas content in coal seams and the potential danger level of coal and gas outbursts. 4−6 However, accurate measurement of coal seam gas pressure is very ...
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WEBThe appliion of this concept transforms equilibrium permeability models to nonequilibrium ones. Equilibrium models represent only two end points (before gas extraction/injection and after the completion of gas extraction/injection) while our nonequilibrium one represents the complete evolution of coal permeability between two .
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WEBApr 1, 2013 · The effects of directional compaction, nonDarcy flow and anisotropic swelling on the extraction of natural gas in coal seam reservoirs are important but not well understood so far. This paper investigated these combined effects through a numerical model which fully couples the interactions of coal seam deformation, anisotropic gas .
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WEBJun 1, 2024 · At present, a large area is drilled through the layer in the floorrock roadway to predrain coal seam gas as an outburst prevention measure [45, 46]. However, during the later stages of gas extraction, the gas extraction flow and gas concentration are low, and the extraction efficiency is also low [47].
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WEBMay 1, 2016 · Based on the multiphysics field theory, the hydraulicmechanical coupling model of gas extraction in the unloading coal seam was established, and the gas extraction process by drilling borehole in ...
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WEBNov 6, 2014 · Enhanced coal bed methane recovery (ECBM) is the process in which a displacing gas, such as CO 2 (CO 2ECBM) or N 2 (N 2ECBM) is introduced into the coal seam through an injection well and held there for a sufficient period to enable a substantial amount of methane to be desorbed from the surfaces of the coal seam. Following the .
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WEBJan 7, 2009 · A mathematical model was developed to predict the coal bed methane (CBM) production and carbon dioxide (CO 2) sequestration in a coal seam accounting for the coal seam model predictions showed that, for a CBM production and dewatering process, the pressure could be reduced from MPa to MPa and .
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WEBFeb 26, 2022 · The highest gas pressure and the maximum gas content in the coal seam were MPa and m 3 /t, respectively. There was a high coal and gas outburst hazard in the coal seam and, therefore, it was necessary to improve the elaborate identifiion and realtime monitoring on the outbursthazardous zones in the coal seam.
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WEBApr 1, 2013 · 1. Introduction. Reservoir compaction may accentuate the nonDarcy flow and induce the anisotropy of permeability during both conventional gas production and unconventional gas (such as coal seam gas) extraction (Clarkson et al., 2007, Majewska et al., 2010, Zeng et al., 2003).The gas flow in porous media is usually pressuredriven .
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WEBJan 1, 2023 · A Nonequilibrium model for coal multiphysics. In this section, a nonequilibrium coal multiphysics model is formulated, which includes three governing equations representing mechanical deformation of coal seams, gas flow in the fractures and matrixfracture mass transport, respectively. The new nonequilibrium porosity and permeability .
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WEBDec 21, 2017 · Coal seam gas extraction process (Sajjad et al. 2015). To enlarge fractures and fissures, the compressed liquid, which is a blend of water, sand, and some additives, is driven into the coal seam. The coal seam depressurizes by the process, which permits the trapped gas to become free.
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WEBAlthough numerous studies have tried to explain the mechanism of directional hydraulic fracturing in a coal seam, few of them have been conducted on gas migration stimulated by directional hydraulic fracturing during coal mine methane extraction. In this study, a fully coupled multiscale model to stimulate gas extraction from a coal seam stimulated .
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WEBThe initial phase of CSG production usually involves the extraction of formation water from the coal seams in order to reduce the water pressure and release gas from the coal. At the surface, water in the gas is separated and piped elsewhere for use or further treatment. Gas from underground coal gasifiion (UCG) is sometimes confused with ...
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WEBJan 1, 2023 · Coal permeability is a crucial property for coal seam gas production. In previous studies, it was assumed that both matrix blocks and coal bridges share an average equalized gas pressure.
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WEBCoal seam gas (CSG) is a type of natural gas that is found in coal deposits. It is classified as an unconventional gas resource because it contains a high concentration of methane. CSG is produced by extracting water from the formation, which reduces the pressure and releases the gas from the coal seam. The gas extraction process produces a ...
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WEBMar 4, 2024 · In the process of protected seam mining, the reduction in stress and the enhancement of the gas mobility that affects the protected seam are crucial manifestations of the protection effect. Taking the working face of E832010 and the upper D56 coal seam of the Six Mines of Ping Coal Company Limited as the study object, the research .
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WEBOct 27, 2023 · The gas extraction quantity is affected by gas pressure, permeability, and coal seam buried depth in the actual process of gas extraction, which is variable and complex. There is an interaction influence between each factor, which provides us with valuable guidance for analyzing the coupling change law of gas extraction quantity.
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WEBMay 21, 2015 · By integrating coal production with gas extraction, coal seam gas becomes a useful resource. Advantage is taken of the effect of strata movement on gas pressurerelief and flow during the coal mining process to establish a single production system for simultaneous coal and gas extraction.
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WEBDec 29, 2023 · In order to increase the permeability of low permeability and high gas coal seam and improve the efficiency and utilization of gas extraction, the permeability enhancement technology of deep hole presplitting blasting is proposed, and the mechanism of blasting induced cracking of deep hole presplitting blasting is analyzed. .
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WEBAug 1, 2018 · The initial temperature of coal seam has a significant influence on gas extraction, the higher the initial temperature of the coal seam, the smaller the gas production rate is. This is because the gas drainage process is the joint action of coal seam damage, gas pressure, adsorption and desorption of gas, and temperature.
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WEBFeb 25, 2021 · Coal bed methane (CBM) is a primary clean energy source found in coal seams. The recovery ratio of CBM is very low, especially with ground extraction, due to the strong adsorption of CH4 on the pores and fissures of coal and low permeability of the coal bed. On the basis of the theory of energy balance, a theory of enhanced CBM (ECBM) .
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WEBApr 1, 2022 · Gas extraction and transport process in coal seam (a) gas flow field (b) mesh generation. Fig. 3 (b) shows the mesh division and the node numbering of the solution area. The mesh nodes in the x axis direction past the point (0, N ) belong to the fracture flow field, and the intersection of x axis and r axis horizontal along vertical mesh ...
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WEBFeb 13, 2020 · Coal seams, particularly deep unmineable coal reservoirs, are the most important geological desirable formations to store CO2 for mitigating the emissions of greenhouse gas. An advantage of this process is that a huge quantity of CO2 can be sequestrated and stored at relatively low pressure, which will reduce the amount of .
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WEBJun 6, 2022 · The coal output of a single cave is approximately t/m, and the pressure relief effect is obvious. When the measurement range is 50 m, the average gas concentration for the mechanical cavitation drilling is 50%. The net amount of gas drainage is m 3 /min. The net volume of single cycle drainage is 60,480 m 3.
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WEBJul 16, 2022 · The slitting pressure is set to 100 MPa. The 3# coal seam is the main mining seam, the original gas pressure of the second panel area of the 3# coal seam is MPa, the original gas content is ~ m 3 /t, the firmness coefficient is about, and the permeability coefficient of 3# coal seam is ~ MPa 2 ·d.
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WEBApr 1, 2023 · Zhangcun coal mine is loed at the northeast of Changzhi City in Shanxi Province, China. The 3# coal seam is characterized by thickness of ∼6 m, high gas content of m 3 /t, and low permeability of × 10 −17 m shown in Fig. 3 (a), gas extraction is adopted to deplete gas from coal seam, and the inseam boreholes with .
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WEBMay 1, 2022 · The process of deformation and failure of coal sample ZZ3 was simulated using the ... The underground coal seam gas extraction project is ... Based on the Darcy's law in the flow of gas in the ...
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WEBDownload scientific diagram | Coal seam gas production process (created by the author using data from Rice and Nuccio 2000) from publiion: A study on the carbon dioxide injection into coal seam ...
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WEBNov 3, 2023 · The indirect method is to predict the gas content of coal seam by gas emission and adsorption isotherm curve 14,15,16. Permeability is a key factor to determine the development process and ...
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WEBJan 1, 2021 · Airleakage is one of the main reasons leading to poor coal seam gas (CSG) extraction performance, and needs to be mitigated urgently. ... and (Wang et al., 2021a,b) conducted an experimental study on the air leakage process of coal seam gas drainage by using an integrated apparatus in the laboratory. Although this has a certain reference .
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WEBJan 13, 2023 · The method of predicting whether it is an outburst danger zone stipulated in the "Coal and Gas Outburst Prevention Rules" is based on the coal seam gas pressure of MPa and the content of 8 m 3 / t as the critical value. Reducing the gas pressure of coal seam to MPa during the extraction process is an important discriminant index.
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WEBOct 26, 2023 · In order to develop precise hole placement technology for gas extraction, this paper combines industrial testing, the evolution law of coal rock damage permeability, and the coal doublepore doublepermeability model; establishes a coupling model of the coal damage deformation field and matrixfracture double diffusion seepage field; and .
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WEBSep 1, 2015 · Despite long extraction times, the amount of extracted gas is very low due to low gas permeability in Chinese coal seams. Therefore, the coal seam requires significant structural changes to improve the efficiency of the gasextraction process and reduce the gasextraction time (Zhou et al., 2012).
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WEBDec 9, 2023 · Efficient gas extraction is important for reducing coal mine gas accidents and protecting the environment. A prerequisite for achieving efficient gas drainage is to clarify the evolution rules of mining fractures and the development characteristics of gas migration channels. In this study, aiming at the rock structure of coal seam composite .
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