Mechanisms and Numerical Simulations of Liquid CO2 Phase Transition-Induced Permeability Enhancement in Coal Seams
DOI:
https://doi.org/10.54691/9pr8jh14Keywords:
Coal Seam Permeability; Gas Drainage; Coal Seam Permeability Improvement; Carbon Dioxide Fracturing.Abstract
The geological structures of the coal fields in China are complex. With the continuous increase in the mining depth, the coal seams show the characteristics of high gas and low permeability, and the disaster potential of a coal and gas outburst intensifies in the process of coal mining. Gas drainage is one of the primary measures to prevent and control gas disasters. How to effectively improve the permeability of a coal seam is an urgent problem to be solved. Currently, the method of loose blasting is used in engineering to enhance the permeability of coal seams. However, the technology of loose blasting easily leads to the poor development of coal fractures or the severe crushing of coal, which will affect the gas drainage. Thus, this paper studied the technology of liquid CO2 phase transition fracturing in a coal seam. COMSOL was used to determine the influence radius of the liquid carbon dioxide phase transition cracking, which was 13.4 m, and to design the scheme of the borehole. The field test was carried out in the 81506 working face of the Baode Coal Mine. Through the onsite monitoring data, the results showed that the drainage effect increased by 293.9%, the gas drainage concentration increased by 242.4%, the permeability coefficient of the coal seam increased by 3–7.75 times, and the permeability enhancement effect was good.
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