特厚煤层定向长钻孔水力压裂瓦斯抽采技术及应用

Directional long borehole hydraulic fracturing gas extraction technology and application in extra thick coal seam

为解决大佛寺煤矿特厚煤层透气性和瓦斯赋存差异性较大而导致的矿井抽掘采接替问题,提出“分段压裂延展裂隙+整体压裂沟通网络”的定向长钻孔水力压裂技术,通过增加煤层渗透性来提高矿井瓦斯抽采效率,并在40103工作面进行工程应用试验。共完成4个定向长钻孔分段水力压裂施工,累计压裂工程量2190 m,最大泵注压力17.83 MPa,累计压裂注水量4535 m 3,总压裂时间10853 min。相比于未压裂的预抽钻孔,压裂后瓦斯抽采浓度提高了2.20~4.22倍,百米抽采流量提高了4.93~11.03倍。试验结果表明,通过水力压裂后煤层渗透特性增加,瓦斯抽采效果显著提升,初步证实了长钻孔水力压裂强化瓦斯抽采技术的适用性,为彬长矿区的矿井瓦斯高效抽采提供了技术支撑。

In order to solve the problem of significant differences in permeability and gas storage in the ultra-thick coal seam of Dafosi Coal Mine,which seriously affects the replacement of mine extraction and extraction,a directional long borehole hydraulic fracturing technology of“segmented fracturing extension fracture+overall fracturing communication network”is proposed.By increasing the permeability of the coal seam,the efficiency of mine gas extraction is improved,and engineering application tests are conducted on the 40103 working face.A total of 4 directional long borehole segmented hydraulic fracturing constructions were completed,with a cumulative fracturing volume of 2190 meters,a maximum pumping pressure of 17.83 MPa,a cumulative fracturing water injection volume of 4535 m 3,and a total fracturing time of 10853 minutes.Compared to pre-drilled holes without fracturing,the gas extraction concentration after fracturing increased by 2.20~4.22 times,and the extraction flow rate per 100 meters increased by 4.93~11.03 times.The experimental results show that the permeability characteristics of coal seams increase after hydraulic fracturing,and the gas extraction effect is significantly improved.It preliminarily confirms the applicability of long borehole hydraulic fracturing to enhancing gas extraction,providing technical support for efficient gas extraction in the Binchang mining area.