液态CO_2相变致裂技术在金佳煤矿的应用

Liquid carbon dioxide phase transition fracturing technology applied to Jinjia Mine

为更好地在低渗透、高瓦斯、强突出煤层中应用CO_2致裂技术,在金佳煤矿11224运输巷与212石门进行CO_2相变致裂的防突预抽现场试验,通过比较煤层致裂后的瓦斯压力与含量变化,确定CO_2致裂技术在顺层孔与穿层孔中的差异,研究结果表明:一次液态CO_2相变致裂时间为2.0～2.5 h,且需要多次注入液态CO_2致裂才能提高瓦斯抽采效果;采用液态CO_2致裂技术可在原来基础上减少煤层瓦斯含量6%～12%,减少煤层瓦斯压力9%～12%,并且运用在穿层孔的效果要优于顺层孔,但是穿层孔的规律不如顺层孔稳定;液态CO_2致裂技术的致裂半径为6 m,为提高致裂效果可采用叠加致裂的布孔方式,增大钻孔群的抽采效果。该对比研究结果为液态CO_2相变致裂技术运用在煤矿瓦斯突出与防治领域提供了有效依据。

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.