LEI Yun, LIU Jianjun, ZHANG Shaonan. 2017: PERMEABILITY IMPROVMENT TECHNOLOGY BY CRACKING COAL SEAM WITH CO2 PHASE TRANSITION. JOURNAL OF ENGINEERING GEOLOGY, 25(1): 215-221. DOI: 10.13544/j.cnki.jeg.2017.01.028
    Citation: LEI Yun, LIU Jianjun, ZHANG Shaonan. 2017: PERMEABILITY IMPROVMENT TECHNOLOGY BY CRACKING COAL SEAM WITH CO2 PHASE TRANSITION. JOURNAL OF ENGINEERING GEOLOGY, 25(1): 215-221. DOI: 10.13544/j.cnki.jeg.2017.01.028

    PERMEABILITY IMPROVMENT TECHNOLOGY BY CRACKING COAL SEAM WITH CO2 PHASE TRANSITION

    • Liquid CO2 phase transition characteristics and coal to gas phase CO2 and CH4adsorption regularity are researched. Experiment finds out that under different coal quality, temperature and equilibrium pressure, the adsorption ability of CO2 in coking coal and anthracite coal is as 1.8~2.4 times to that of CH4. The volume of CO2 phase transition expands to 794 times instantaneously within 0.2 s. Theoretical studies are carried out to establish a mathematical model for the non-coupling fracturing under the condition of blasting hole initial shock pressure peak, fissured circle effective radius and blasting induced cracking borehole three main blasting parameters. Blasting machine is used and has 200MPa outlet pressure when the liquid CO2 phase transition instantaneously. According to on-site experiment research of the coal seam, its permeability improvement leads to bursting. The control hole has 2m and 3m distance to the blasting hole. After blasting the one drilling gas extraction from scalar increases up to 6 times and 4 times, the one drilling gas extraction concentration up to 5 times and 4 times. The one drilling gas extraction concentration is in 35%~55%.The control hole has 4m distance from the blasting hole after five days, the gas extraction effect attenuates to the level before blasting. The field test shows that under the initial impact pressure peak value of 200MPa and the borehole diameter of 0.094m, the effective radius of the fracture zone of the coal seam is 3m.
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