高压脉动水力压裂卸压增透技术及应用

Pressure Relief and Permeability-Increasing Technology Based on High Pressure Pulsating Hydraulic Fracturing and Its Application

为了改进现有卸压增透技术,解决目前煤矿区域瓦斯治理存在的问题,在水力压裂技术的基础上,提出了高压脉动水力压裂卸压增透技术.采用理论分析和现场试验的方法,研究了脉动压力在裂隙中的传播规律以及卸压增透效果.结果表明:脉动水力压裂可以使煤体的某些物理量反复交变,产生疲劳破坏,从而疏通孔隙,提高透气性;脉动压力在24MPa、频率在20Hz时,卸压效果最好;压裂前后抽采体积分数平均增加了264.7%,瓦斯流量增加了245.5%;突出危险性指标q值和S值显著减小,变化幅度降低.该技术可以有效增大单孔影响范围,提高抽采效率,具有广泛的应用前景.

In order to improve the existing pressure relief and permeability increasing technologies,high pressure pulsating hydraulic fracturing technology was put forward on the basis of hydraulic fracturing to solve the current problems of regional gas control in coal mines.The propagation law of pulsating pressure in fractures and the effect of pressure relief and permeability-increasing were investigated by theoretical analysis and field test.The results show that the pulsating hydraulic fracturing can make some physical quantities of coal change repeatedly and produce fatigue failure,which in turn,dredges the pores and enhances the permeability.The effect of pressure relief reaches the best when the pulsating pressure is 24 MPa and the frequency is 20 Hz.The extraction concentration increases by 264.7% after fracturing while the gas flow increases by 245.5%.The values and the change ranges of q and S which are outburst risk indexes reduce obviously.This technology can effectively enhance the affecting range of a single borehole and increase the extraction efficiency.It has a broad industrial application prospects.