In the coal and gas outburst process, considerable amounts of coal and gas may be violently ejected, which potentially results in significant harm. In addition, the main component of coal seam gas is methane, and the greenhouse effect of methane is 28 times that of carbon dioxide (Wu et al. 2020; Booth et al. 2017; Karacan et al. 2011).
4. Coal seam gas also is called coal seam methane (CSM) and coal bed methane (CBM). 5. During the earliest stage of coalification (the process that turns plants into coal), biogenic methane is generated as a byproduct of microbial action, which is similar to the mechanism that generates methane in landfills. 6.
Gas flow in a coal seam is a complex process due to the complicated coal structure and the sorption characteristics of coal to adsorbable gas (such as carbon dioxide and methane). It is essential to understand the gas migration patterns for different fields of engineering, such as CBM exploitation, underground coal mine gas drainage, and CO2 geosequestration. Many factors influence gas ...
Coalbed methane (CBM), is also known as coalbed gas and coal seam gas/methane (CSG/CSM), which are terms referring to the unconventional natural gas resource stored in coal beds and are expected to be an important energy resource of global significance in the future (Rightmire 1984; Rice 1993; Flores 1998, 2013; Palmer 2010; Yang and Liu 2021). ...
The amount of gas retained in coal depends on a number of factors such as the rank of coal, the depth of burial, the immediate roof and floor to the coal seam, geologic anomalies, tectonic pressures, and temperature prevailing at the end of the coalification process. In general, the higher the rank of coal and the greater the depth of coal seam ...
The output process of underground coal seam gas displacement by injecting nitrogen can be divided into two stages approximately. In stage I, driven by the pressure gradient, CH 4 in the original free state is the main product. While in stage II, the desorbed CH 4 from adsorbed state is the main product driven by the concentration gradient. In ...
Coal and gas outburst is a kind of dynamic phenomenon and mainly driven by gas pressure. 12, 13 The coal seams are prone to be fractured, and outburst process will be largely accelerated with the presence of high gas pressure. 14 By and large, the phenomenon of outbursts is the process of coal energy dissipation, 15, 16 which is accompanied by ...
Gas extraction is the main method to reduce gas content and eliminate gas accidents, and due to the influence of mining stress in the coal seam mining process, there are elastic damage zones and plastic damage zones of coal seams [3, 7]. Therefore, in order to improve the efficiency of gas extraction, it is necessary to study the elastic ...
Coal seam gas (abbreviated "CSG") is formed by the geological process of heating and compressing plant matter to create coal. Over millions of years, methane forms within the coal. The methane is trapped by water in the gaps and cracks between the coal molecules. These gaps are known as cleats.
Coal seam gas is a natural gas held in coal seams under pressure by groundwater. Coal seam gas wells release the gas by reducing the pressure through groundwater extraction. Extracted water and gas is diverted to surface infrastructure treatment and processing plants (Figure 1). The extracted water is termed 'coproduced water' (also ...
During the mining process, gas disasters such as gas explosion, gas combustion, and coal and gas outburst may occur, resulting in serious casualties and property,2 Especially when it enters deep mining, stress and gas pressure rise markedly, while permeability of the coal seam becomes extremely low, which leads to a poor gas extraction ...
Coal seam gas collects in the coal seams by bonding to the surface of coal particles. The coal seams are generally filled with water, and it is the pressure of the water that keeps the gas as a thin film on the surface of the coal. CSG is extracted through wells drilled into coal seams.
Coal seam predrainage technology is widely used to prevent and control gas in China's highgas coal seams, and upward drilling is a safe and reliable technology. Using the Luling Coal Mine as the study location, according to the actual situation of the site, a layerthrough drilling process was proposed.
Coalbed methane ( CBM or coalbed methane ), [1] coalbed gas, or coal seam gas ( CSG [1]) is a form of natural gas extracted from coal beds. [2] In recent decades it has become an important source of energy in United States, Canada, Australia, and other countries. The term refers to methane absorbed into the solid matrix of the coal.
CBM refers to methane that is found in and extracted from coal seams. It is formed during the coalification process, which is the transformation of organic plant material into coal. CBM is also known as virgin coal seam methane or coal seam gas, and is widely considered an "unconventional" source of natural gas.
The gas migration provides a "material basis" for the gas extraction from the fractured zone of the goaf. The pressurerelief gas from the layer adjacent to the coal seam, as well as the residual gas from the mining process, flow through fracture channels and accumulate in the goaf, creating an area of gas enrichment.
Underground coal gasification (UCG) is an industrial process which converts coal into product gas. UCG is an insitu gasification process, carried out in nonmined coal seams using injection of oxidants and steam. The product gas is brought to the surface through production wells drilled from the surface. The predominant product gases are methane, hydrogen, carbon monoxide and carbon dioxide.
Coal seam gas is primarily made up of methane gas, generally 9598%. This gas is also called coal bed methane (CBM) if extracted from a coal deposit as unconventional natural gas for economic purposes. ... During the coalification process, methane gas is captured in the coal seams and later released during coal mining operations. Coal bed ...
Coal seam gas pressure is a key parameter of gas accident control and gas drainage. At present, there are some problems in field pressure measurement, such as long period, and there is often a need to drill more holes to ensure the reliability of pressure measurement.
FD mechanism in coal seam underestimated the gas diffusion in coal seam and consequently, overestimated the reaction rate of coal seam. The diffusion problem was corresponded with the theory about the diffusioncontrolled reaction of a coal particle combustion [18, 42]. Therefore, TD diffusion was applied in the following investigations.
Tailings are the oftentoxic residue left over from the process of separating coal from gangue, or economically unimportant minerals. Toxic coal tailings can pollute local water supplies. ... is baked in an oven for about 1236 hours at about 1,0001,100°C (1,8002,000°F). This drives off impurities such as coal gas, carbon monoxide, methane ...
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To study the differences between various gas injection sources in the process of coal seam methane replacement, experimental research was conducted to study the influences of different gas injection sources and gas injection ratios on coal seam methane replacement by considering the strong adsorption gas CO 2 and the weak adsorption gas N experimental results show that the temperature ...
The coal and rock mass will produce rapid deformation, crack or fracture change with the action of high stress, and the gas stored in the coal seam will gush out to the working face along the coal seam under the action of the pressure gradient during the tunneling process. These phenomena may produce signals such as AE, EMR, or infrasound.
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