Application of CO2 Fracturing Technology in Gas Control of Low Permeability Coal Seams in Dayun Mine and Hongfa Mine in Guizhou Province
CO2 fracturing technology is an easy and environmental permeability enhancement technology in coal mines with advantages such as safety,efficiency,and reusability.To explore the application effect of CO2 fracturing technology in high-gas and low-permeability coal mines in Guizhou,we selected two high-gas and low-permeability coal mines to observe the on-site experi-mental results.The comparison of the macroscopic parameters of gas before and after CO2 fractu-ring showed that CO2 fracturing technology demonstrated a significant effect on enhancing the permeability of coal seams.Compared with untreated coal seams,the gas permeability coefficient has increased by three times;combined with the attenuation coefficient of the natural gas flow,the results showed the transformation from the difficult-extracted coal seams to the extractable coal seams.The gas extraction concentration and pure amount significantly increased by four times,and the pure amount of gas extraction after fracturing tended to increase first and then de-crease in the range of 30 d,which could be attributed to the replacement of gas by CO2 after frac-turing.The residual gas content after fracturing was less than 5.5 m3/t,less than the original gas content,and lower than the critical value(8 m3/t)of residual gas content per ton stipulated in the Provisions on Prevention and Control of Coal and Gas Outburst.The study showed that CO2 fracturing technology presented good application effects on permeability enhancement for low-permeability coal seams.
coal and gas outburstCO2 fracturinggas extractioncoal seam permeability en-hancement
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