To produce gas from coal seams, water must be extracted first, lowering the pressure so the gas can flow out of the coal. The volume of groundwater extracted can vary significantly between individual wells, coal seams and coal basins, depending on geological conditions.
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Liquid CO 2 injection into coal seam for CH 4 displacement is one of the important means to strengthen gas extraction and carbon sequestration in recent years. After liquid CO 2 is injected into coal seam, physical and chemical interactions occur with coal through the process of "liquid phase seepagephase transformation supercharginggasliquid mass transfer", and microscopic ...
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Previous research on protective seam mining and pressure relief gas extraction technology, found that any slight expansion and deformation of the coal seam causes a dramatic increase in the permeability coefficient of the coal seam (Yin et al., 2015). Therefore, increasing a coal seam's permeability can be achieved by enlarging the permeable ...
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5. Conclusion. (1) An improved coupled modeling method for coalbed methane extraction after hydraulic fracturing is proposed. It mainly includes two parts: hydraulic fracturing modeling and coupling modeling for coalbed methane extraction. In the first part, we introduce a state damage variable based on damage mechanics theory to record the ...
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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 models ...
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Liquefied natural gas (LNG) is a natural gas that has been cooled to minus 162°C, a process that is commonly done for gas export purposes as it reduces the volume of the transported gas. ... Conventional gas Coal seam gas; Cumulative production Reserves (2P) Resources (2C) Cumulative production Reserves (2P) Resources (2C) Adavale: 9: 12: 0: 0 ...
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Download scientific diagram | Coal seam gas production process (created by the author using data from Rice and Nuccio 2000) from publication: A study on the carbon dioxide injection into coal seam ...
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Within the USA, both coal seam gas (8% of total natural gas produced) and shale gas industries (30% of total) are in substantial growth phases. Although A. Gore, D and Davies, P (2013) Department of Environment and Geography, Macquarie University, Background paper on produced water and solids in relation to coal seam gas production: Report
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In order to solve the problem that the gas in the upper corner is easy to exceed the limit in the mining process of the deep outburst coal seam. Based on the theory of "Oring" and the distribution of stratigraphy in the field, the development law of mining fissures in the overlying rock layer during the workface retrieval was studied by combining theoretical calculation and ...
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Exploring the evolution characteristics of gas seepage between boreholes during the drainage process is critical for the borehole's layout and highefficiency gas drainage. Based on the dualporous medium assumption and considering the effect of stress redistribution on coal seam gas seepage characteristics, a coal seam gas seepage model with a threedimensional roadway and borehole crossing ...
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During the stable gas production stage, the highest AMCCF value was %, and the PZCF was less than mm. It hardly produced coal fines during the gas production decay stage, and the PZCF was generally less than 1 μm. (4) The control of faults on coal fines production weakened as the distance from a fault increased.
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Coal seam gas overall process The development of unconventional gas resources such as shale gas and coal seam gas has boomed over the past few years [1]. Coal seam gas (CSG) also known as coal bed methane (CBM) is comprised of natural gas that is extracted from low to high rank coal beds [2], [3].
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Integrated coal production and gas extraction must be considered as a system which involves the exploration and measurement of stress field redistribution, deformation and failure of coal and rock, gas pressure and permeability, and gas desorption and migration during the process of coal mining. Fundamental theory
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The gas flow equation of Eq. (33) and the deformation equation of Eq. (7) together describe the interactions among the deformation of coal, free gas flow and gas absorption/desorption in the cleat system and the matrix of coal seam. Fig. 1 graphically presents the fully coupling processes of this developed model in the coal seam gas production. . Mechanical deformation will compact the pore ...
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Coal seam gas extraction: modelling groundwater impacts . uncertainty analysis, presentation and documentation of outputs). The modelling process is influenced by, objectives, conditions, data and scale of impact. Groundwater modelling tools . Groundwater modelling tools can simulate the potential groundwater impacts from coal seam gas production.
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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 determines precise hole placement spacing for a coal ...
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For mines with low permeability and high gas emissions, static blasting technology is used to presplit the coal seam to increase the permeability and strengthen the gas extraction, which will significantly reduce the occurrence of gas accidents in mines. Taking Wangjialing Coal Mine as the research object, the mathematical model of fluidsolid is established. The numerical simulation software ...
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Coalmeasure gas refers to a set of coalbed methane, coalmeasure shale gas (includes shale gas and certain coalderived gas, abbreviated as shale gas), and tight sandstone gas that are linked ...
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In order to reveal the process and mechanism of gas flow in a lowpermeability coal seam, a new multiplerelaxationtime lattice Boltzmann method (MRTLBM) model of gas migration in coal micro/nanopores based on Langmuir monolayer adsorption theory, the slip boundary scheme and Bosanquet effective viscosity was established. The software MATLAB was used to carry out the simulation study of ...
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Fig. 1 Schematic of gas within a coal seam (Williams et al. 2013 ). Coal seam gas is trapped in pores and micropores, in the form of free or adsorbed gas. By reducing the hydraulic pressure, which is exerted via water and overlying aquifers to the seam, the gas is extracted through drilled wells.
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