Fluidized mining method for on-situ pyrolyzed gas of high gas coal seam

Abstract

The invention relates to a fluidized mining method for on-situ pyrolyzed gas of a high gas coal seam. The method is suitable for being used in a low-permeability, low-temperature strong oxidability and high gas content coal seam or a remnant coal seam in a closed goaf. The method comprises the following steps of drilling a horizontal drilling well and a gas extraction drilling well from the groundto a target coal seam or the remnant coal same in the closed goaf; generating a lot of cracks around the horizontal drilling well by way of detonation; sealing a hole of a shaft; injecting air at a proper flow rate into the horizontal drilling well; after the target coal seam or the remnant coal seam is in contact with a small amount of air for a certain time, carrying out smoldering on the coalseam by using a fire striker, wherein raised temperature can induce penetration among a lot of multi-scale hole cracks to accelerate desorption of adsorbed gas in the coal seam, and meanwhile, CO2 gasgenerated by smoldering can displace the adsorbed gas in a coal matrix effectively, so that the gas seeps and is diffused along a crack network; and finally, carrying out negative pressure extractionby the gas extraction drilling well. The method is high in feasibility and simple to operate, and can achieve efficient utilization of a coal resource to the maximum extent.

Description

technical field [0001] The invention relates to an in-situ pyrolysis gas fluidization mining method for high-gas coal seams, especially suitable for high-gas coal seam in-situ pyrolysis coal seams with low permeability, low-temperature strong oxidation, high gas content coal seams or leftover coal seams in closed goafs. Solution gas fluidization mining method. Background technique [0002] With the continuous increase of mining depth, high ground stress makes high-strength coal seams generally have the characteristics of high degree of metamorphism, compact structure, low porosity, and poor permeability. Due to the limitation of mining technology, there are usually a large number of residual coal seams in many closed goafs. . Correspondingly, the coal seam to be mined needs to meet the construction sequence of gas drainage first and then coal mining. On the other hand, the remaining coal seam contains a large amount of gas. Anti-reflection methods such as fracturing techno...

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Problems solved by technology

[0003] However, conventional coal seam permeability enhancement methods have certain defects. For example, hydraulic fracturing technology needs to provide a large volume of water resources, which increases the water pressure in water-scarce areas. For coal seams with strong water sensitivity, a large amount of After the pressure water is injected into the coal seam, it will cause water lock reaction in the coal seam inner pore and fracture structure, and block the CH 4 gas flow channels, greatly reducing the CH 4 Drainage efficiency; heat injection technology requires the use of a large amount of water vapor, microwave radiation and other heating methods to increase the temperature in the coal seam, thereby producing many pore and fissure structures of different scales, promoting the desorption of adsorbed gas into free states, along the pore and fissure structures Seepage diffusion occurs, but there are also certain application limitations. For example, the water vapor or electric energy consumption required to increase the temperature of the coal body to reach the crushing temperature is extremely large, which lacks certain feasibility for field application; secondly, the high The temperature is easy to cause spontaneous combustion of coal or gas explosion, which has poor controllability of catastrophe

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