碎软低透突出煤层定向长钻孔整体水力压裂高效增透技术

High effective technology through overall hydraulic fracturing of long directional borehole in crushed and soft coal seam with low permeability and outburst potential

针对碎软低透突出煤层增透范围小、衰减速度快、抽采有效周期短等问题,以阳泉矿区15#煤层为研究对象,分析了长钻孔压裂增透机理,提出与煤层定向长钻孔相结合的煤矿井下长钻孔整体压裂增透技术。结合自主研发的整体压裂装备和工艺技术,实现了压裂钻孔的快速、稳定封孔,一次性压裂段孔长202 m的整体水力压裂施工,累计注水量2865m^3,最大泵注瞬时流量57.75 m^3/h,最大注水压力14.8 MPa。检测结果表明:压裂增透施工后,煤层透气性系数提高了4.88倍,最大影响半径达到了60m,流量衰减系数降低至压裂前的0.13倍,瓦斯含量降低至原始含量的0.55倍,实现了增透范围大、抽采时效长的瓦斯抽采效果,为碎软低透突出煤层强化增透和井下瓦斯高效抽采提供了技术保障。

Aim to the problem of small range of permeability increased and fast attenuation of gas extraction and shortage of cycle availability in crushed and soft coal seam with low permeability and high outburst potential.Taking No.15 coal seam in Yangquan mining area as the object of the research,this paper analyzed the permeability enhancement mechanism of hydraulic fracturing,proposed the strengthened permeability enhancement technology by the hydraulic fracturing for long directional borehole in coal seam.The research realized high-speed and stable sealing based on self-developed integrated fracturing equipment and technology,the length of coal segment of the borehole underground for whole fracturing was up to 202 m,the total water injection rate was 2865 m～3,the maximum instantaneous flow of fracturing pump was 57.75 m～3/h,the maximum injection pressure was up to 14.8 MPa.The test results showed that the influencing range of borehole fracturing was up to 60 m,the permeability coefficient of coal seam increased by 4.88 times,the attenuation factor of borehole gas flow decreased to 0.13 times before fracturing,gas content was 0.55 times the gas content of primitive.It realized the gas extraction which had larger permeability increasing range and much longer aging,providing technical support for strengthening efficient gas drainage in crushed and soft coal seam with low permeability and outburst potential.