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145 / 2023-06-30 10:12:22
Microscopic distribution characteristics of gas hydration bearing coal and its permeability characteristics
coal and gas outburst,coal and gas outburst prevention technology based on hydrate method,X-CT,microscopic distribution characteristics,permeability
6. Coal mine gas control and utilization
摘要录用
Baoyong Zhang / Heilongjiang University of Science and Technology
haohui li / Heilongjiang University of Science and Technology
Xia Gao / Heilongjiang university of science and tech
With the increase of mining depth and intensity, the ground stress, gas content and gas pressure of coal seam gradually increase, the geological structure of coal seam becomes more and more complex, the risk of coal and gas protrusion disaster is increasing, and the importance of safe and efficient mining of coal resources becomes more and more prominent. Coal and gas outburst prevention technology based on hydrate method aims to achieve the goal of preventing and controlling coal and gas protrusion. However, the microscopic distribution and evolution rules of gas hydrate formation process in coal and its permeability characteristics are not clear yet, which restricts the efficiency of gas hydration curing. To this end, the in-situ scanning test device of X-CT for gas hydration curing in coal was used to carry out hydrate generation/decomposition experiments in gas-bearing coal bodies, obtain CT image data of gas hydrate bearing coal at different moments in the process of gas hydrate generation/decomposition, obtain the spatial location relationship between coal pores and hydrate based on image recognition means such as threshold segmentation method, and construct a three-dimensional pore network model of gas hydrate bearing coal using the maximum sphere algorithm. The three-dimensional pore network model is used to analyze the pore number, throat number, pore radius, throat radius, pore-throat ratio, shape factor, coordination number, porosity, permeability and hydrate distribution pattern of gas hydrate bearing coal during the process of gas hydrate generation/decomposition, and to compare the permeability models (parallel capillary model[1], Kozeny particle model[1] and Masuda decline model[2], etc.) of hydrate bearing porous media based on To analyze the dynamic relationship between permeability and hydrate distribution pattern of coal during gas hydrate generation/decomposition, and to analyze the evolution of microscopic distribution of gas hydrate in coal and its permeability characteristics from microscopic perspective. The results show that with the formation of gas hydrate, the distribution mode of gas hydrate shows a mixed distribution mode (pore-filling mode and granular cementation mode are mixed). During the process of gas hydrate generation, the hydrate distribution mode changes from a mixed distribution mode dominated by the particle cementation mode to a mixed distribution mode dominated by the pore filling mode. With the increase of hydrate saturation, the normalized permeability of coal containing gas hydrate decreases, with a decrease of 66.7%, and the number of pores and throats are significantly reduced, with a decrease of 36.28% and 35.05%, respectively. After hydrate generation, the porosity and permeability of the coal are significantly reduced. The pore radius, throat radius and pore-to-throat ratio of the pore network model of coal containing gas hydrate show an overall decreasing trend, and the shape factor and coordination number show an overall increasing trend. In the process of gas hydrate decomposition, the hydrate mode of distribution changes from a mixed distribution mode mainly of pore filling to a mixed distribution mode mainly of particle cementation. With the decrease of hydrate saturation, the normalized permeability of coal containing gas hydrate increases by 128.6%, and the number of pores and throats gradually increases by 83.7% and 60.4%, respectively. After the decomposition of hydrate, the porosity and permeability increase significantly. The pore radius, throat radius and pore-throat ratio of the pore network model of coal containing gas hydrate show an overall increasing trend, and the shape factor and coordination number show an overall decreasing trend.

 
重要日期

  • 会议日期

    08月18日

    2023

    至

    08月20日

    2023

  • 07月07日 2023

    初稿截稿日期

  • 08月20日 2023

    注册截止日期

主办单位
International Committee of Mine Safety Science and Engineering
承办单位
Heilongjiang University of Science and Technology
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