低渗煤层控制水力压裂增透技术研究及应用

Technology and its Application of Controlling Hydraulic Fracturing in Low Permeability Coal Seam

针对低渗煤层水力压裂存在裂缝扩展范围小、增透效果差和在增透影响范围内容易留下空白带等问题,将控制水力压裂引入低渗煤层水力压裂实践。分析了低渗煤层控制水力压裂增透机理,提出了低渗煤层控制水力压裂增透技术及封孔方法,并在夏店煤矿进行了工程应用。结果表明:控制水力压裂使水力裂缝沿着控制孔的方向扩展延伸并有效增加煤层渗透性;组合式封孔技术封孔效果好、成本低,实现了一孔多用;控制水力压裂技术应用后,煤层渗透率有效增大,钻孔瓦斯抽采纯流量为原始煤层的4.969倍,3117工作面瓦斯预抽效果达标,回采期间回风巷瓦斯浓度始终低于0.5%,实现了工作面的安全高效开采。

In view of the problems existing in hydraulic fracturing of low permeability coal seam, such as small crack extension range, poor permeability enhancement effect and easy to leave blank zone in the permeability enhancement influence range, this paper introduces controlled hydraulic fracturing into the practice of hydraulic fracturing of low permeability coal seam, analyses the mechanism of controlling hydraulic fracturing and permeability enhancement of low permeability coal seam, and puts forward the technology of controlling hydraulic fracturing and permeability enhancement of low permeability coal seam. The technology and sealing method were applied in Xiadian Coal Mine. The results show that controlling hydraulic fracturing extends hydraulic fractures along the direction of control holes and effectively increases the permeability of coal seams;the combined sealing technology has good sealing effect, low cost and realizes multi-purpose use of one hole;after controlling hydraulic fracturing engineering application, the permeability of coal seams effectively increases, and the gas purity is 4.969 times of the original coal seam. The effect of gas pre-drainage in 3117 working face is up to the standard, and the gas concentration in the return air roadway is always below 0.5% during the mining period, which realizes the safe and efficient mining of the working face.