复杂低渗高瓦斯煤层CO_(2)气相压裂强化增透技术研究

Research on Enhanced Permeability Technology of CO_(2)Gas Fracturing in Complex Low Permeability and High Gas Coal Seams

山西华晋吉宁煤业有限责任公司(吉宁煤矿)开采的山西组2号煤层为典型的复杂低渗难抽煤层,透气性系数为0.023m^(2)/(MPa2·d),瓦斯含量8~10.52m^(3)/t,存在“多分层,多夹矸,采前难抽,采中涌出大”的特点。为此,在吉宁煤矿2201掘进工作面开展185MPa高压力、大容量的CO_(2)气相压裂强化造缝、增透防突瓦斯治理技术,考察其瓦斯抽采和防突效果。结果表明:(1)CO_(2)气相压裂技术能有效提升裂孔瓦斯抽采效率,瓦斯抽采纯流量最大值为0.193m^(3)/min,平均值为0.138m^(3)/min。(2)与前期条带预抽防突技术措施相比,CO_(2)气相压裂技术实施后,煤层瓦斯抽采纯流量提高了4.6~9.7倍,瓦斯有效抽采时间缩短47天,月掘进速度由原来36m提高至80m,提高了2.22倍,瓦斯抽采成本降低为原来的50%。

The No.2 coal seam of Shanxi Formation mined by Shanxi Huajin Coking Coal Jining Coal Industry Co.,Ltd.(Jining Coal Mine)is a typical complex low permeability and difficult to extract coal seam,with a permeability coefficient of 0.023m^(2)/(MPa2·d)and a gas content of 8~10.52m^(3)/t.It has the characteristics of"multiple layers,multiple gangue inclusions,difficult to extract before mining,and large gushing during mining".Therefore,185MPa high pressure and large capacity CO_(2)gas fracturing enhanced fracture formation,enhanced permeability and gas outburst prevention technology was carried out at the 2201 excavation face of Jining Coal Mine to investigate its gas extraction and outburst prevention effects.The results show that:①CO_(2)gas phase fracturing technology can effectively improve the gas extraction efficiency of the fracture hole,and the maximum pure gas extraction flow rate is 0.193m^(3)/min,with an average value of 0.138 m^(3)/min.②Compared with the previous measures of strip pre extraction and outburst prevention technology,the implementation of CO_(2)gas phase fracturing technology has increased the net flow rate of coal seam gas extraction by 4.6~9.7 times,shortened the effective gas extraction time by 47 days,increased the monthly excavation speed from 36m to 80m,increased by 2.22 times,and reduced the gas extraction cost to 50%of the original.