A method of in-situ pyrolysis gas fluidized mining in high gassy coal seams

Abstract

An in-situ pyrolysis gas fluidized mining method for high gas coal seams is suitable for use in low permeability, low temperature strong oxidation, high gas content coal seams or leftover coal seams in closed goafs. Drill horizontal drilling and gas drainage drilling from the ground to the target coal seam or the remaining coal seam in the closed goaf, use the blasting method to create a large number of cracks around the horizontal drilling, seal the vertical shaft, and inject air with an appropriate flow rate into the horizontal drilling, when the target After the coal seam or the remaining coal seam is in contact with a small amount of air for a certain period of time, the coal seam is smoldering with a flame arrester. The elevated temperature can induce the penetration of a large number of multi-scale pores and fissures, and promote the desorption of the adsorbed gas in the coal seam. At the same time, the smoldering generated CO 2 The gas can effectively displace the adsorbed gas in the coal matrix, causing it to seep and diffuse along the fracture network, and finally carry out negative pressure drainage through gas drainage drilling. The method has high feasibility, simple operation, and can maximize the efficient utilization of coal resources.

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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