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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WEBFeb 1, 2024 · Characteristics of plugging methods for horizontal inseam gas extraction boreholes in coal seams can be seen in Table 1. Table 1. ... Determination of sealing depth of inseam boreholes for seam gas drainage based on drilling process of a drifter. Eng. Geol., 210 (2016), pp. 115123. View PDF View article View in Scopus Google Scholar.
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WEBJun 14, 2023 · The FLAC 3D numerical simulation software simulated the gas extraction process from the coal seam using directional boreholes. Optimal drilling parameters were determined by analyzing plasticity, stress, and enhanced permeability zone distribution patterns during gas extraction with different borehole radii. A .
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WEBIn industrial chemistry, coal gasifiion is the process of producing syngas—a mixture consisting primarily of carbon monoxide (CO), hydrogen (H 2), carbon dioxide (CO 2), methane (CH 4), and water vapour (H 2 O)—from coal and water, air and/or oxygen.. Historically, coal was gasified to produce coal gas, also known as "town gas".Coal gas .
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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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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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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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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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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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WEBMay 9, 2018 · Coal seam gas (CSG) is an increasingly important source of natural gas all over the world. Although the influence of conventional oil and gas extraction on surface subsidence has been widely ...
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WEBApr 17, 2019 · 1 INTRODUCTION. China is one of the countries with the largest coalbed methane resources. The exploration and development of CBM resources are of great significance for ensuring the safe production of the coal mine, improving the energy structure and purifying the environment in China. 13 CBM is a kind of unconventional .
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WEBMay 9, 2018 · Coal seam gas (CSG) is an increasingly important source of natural gas all over the world. Although the influence of conventional oil and gas extraction on surface subsidence has been widely recognized and studied, few studies are carried out on the surface subsidence in coal seam gas fields and its impact on surface infrastructure and .
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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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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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WEBJan 15, 2019 · One potential source of energy is extraction of unconventional gases, such as basincentered gas, tight gas, coal seam gas (CSG) and shale gas [1]. The extraction of natural gas from low permeability unconventional reservoirs requires methods to improve access to the reservoir. 'Hydraulic fracturing' is one such technique which has made gas ...
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WEBApr 19, 2022 · As a result, it is difficult for the coal seam sealing process to meet engineering quality sealing requirements, which results in problems such as low gas concentration during the extraction process. In this paper, based on the analysis of coal pore and fissure characteristics, and in view of the current situation of gas drainage and .
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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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WEBMay 2, 2018 · The temperature of the coal seam will be lower than ambient temperature after gas extraction because of the endothermic process, as a result, heat energy flows from the environment into the coal seam. ... Liu,, Cheng,, Jiang,, Li, W., Jin, K.: Interactions between coal seam gas drainage boreholes and the impact of such on ...
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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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WEBFeb 16, 2023 · Mining coal. Coal miners use large machines to remove coal from the earth. Many coal deposits, called coal beds or seams, are near the earth's surface, but others are deep mining methods allow coal miners to easily reach most of the nation's coal reserves and to produce about three times more coal in .
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WEBSep 20, 2019 · Coal Seam Gas: Evaluation, Extraction, and Environmental Issues. September 2019. DOI: /. In book: Sustainable Energy and Environment () Authors: Debadutta Mohanty ...
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WEBOct 1, 2019 · The selection of proppants is critical in the coal seam gas extraction process, where the softer coal rock surface restricts the use of high strength proppants due to its vulnerability of embedding into the surface. 2) coal properties – elastic modulus of coal is the most important factor deciding the proppant behaviour in the extraction ...
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WEBSep 19, 2023 · The gas migration process in the coal seam can be divided into gas desorption and diffusion in the matrix to the fractures and then into the borehole through seepage. ... Zhang J, Liu Y, Ren P, Han H, Zhang S (2021) A fully multifield coupling model of gas extraction and air leakage for inseam borehole. Energy Rep 7:1293–1305
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WEBMay 1, 2016 · Coal seam gas (CSG) is a growing industry in Queensland and represents a potential major employer and deliverer of financial prosperity for years to come. CSG is a natural gas composed primarily of methane and is found trapped underground in coal beds. During the gas extraction process, significant volumes of associated water are also .
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WEBMay 10, 2024 · During the gas extraction drilling process, especially the soft coal seam drilling process, due to the constraints of geological conditions, technical conditions, and other factors, it is easy to encounter stuck holes, blowout, lost circulation, and hole collapse, which affect the realization of efficient gas management. In the petroleum industry, .
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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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WEBJan 19, 2016 · Biochemical reactions associated with this process transform the organic matter into humic substances, which are the precursors of coal macerals. ... an isotherm should be obtained from each major coal seam. These isotherms can be used to determine the saturation state and estimate a recovery factor by comparing the expected gas .
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WEBMay 15, 2024 · As the initial coal seam temperature during the gas extraction process increases, the disparity between the coal seam temperature and the initial temperature becomes more pronounced, as illustrated in Figure 21. This is because as the initial coal seam temperature rises, the desorption amount of gas at the same extraction time also .
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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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WEBRealizing 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 largediameter mechanical cavemaking to promote gas extraction in a coal seam. This technology mainly uses the pressure of a water injection pump to control the automatic .
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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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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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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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WEBSep 27, 2021 · DSI is a function of the gas pressure, and its magnitudes are regulated by the Langmuir constants of both the solid grains and the coal bulk. Furthermore, a DSIbased coal permeability model is incorporated into the coupled multiphysics model for coal seam gas production. The model results of both laboratoryscale and fieldscale show .
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