Abstract:
In order to well apply the carbon dioxide fracturing technology to a low permeability, high gassy and strong outburst seam, an outburst prevention and gas pre-drainage site test with the carbon dioxide phase transition fracturing was conducted in No.11224 gateway and No. 212 cross-cut of Jinjia Mine. With the comparison on the gas pressure and content variation after the seam fractured, the differences of the carbon dioxide fracturing technology in between the borehole along the seam and borehole passed through strata were determined. The study results showed that a liquid carbon dioxide phase transition fracturing time was 2.0~2.5 hours and with several injections, the liquid carbon dioxide fracturing could improve the gas drainage effect. The application of the liquid carbon dioxide fracturing technology could reduce the seam gas content by 6%~12% on the in-situ basis and could reduce seam pressure by 9%~12%. The liquid carbon dioxide fracturing technology applied to the borehole effect passed through the strata better then the borehole along the seam, but the law of the borehole passed through the strata was not stable than the borehole along the seam. The fracturing radius of the liquid carbon dioxide fracturing technology was 6 m. In order to improve the fracturing effect, the borehole pattern with the overlapped fracturing could be applied and thus the gas drainage effect of the borehole group could be improved. The comparison study could provide the effective basis to the liquid carbon dioxide phase transition fracturing technology applied to the mine gas outburst and prevention.