孔间煤体水力压裂技术现场试验研究

Field Test on the Technology of Hydraulic Fracturing of Coal between Holes

孔间煤体水力压裂就是在实施预抽瓦斯区域防突措施时,向区域防突钻孔中高压注水压裂,在使煤体固有裂隙扩张的同时,使压裂煤体向自由孔方向压挤,从而使孔间煤体卸压增透、塑性增强,以有效防止煤与瓦斯突出。本文在分析了孔间煤体水力压裂技术原理的基础上,以焦作矿区九里山矿为研究对象,研究了孔间煤体水力压裂技术注水参数(如注水压力、水力冲孔等效孔径、顺层钻孔孔间距、注水压裂孔封孔深度、注水时间)的确定,指出根据自由孔水力冲孔后的等效体积,按孔间煤体膨胀变形率不低于4‰来确定注水孔与自由孔之间的距离,并通过在焦作矿区九里山矿进行孔间煤体水力压裂技术现场试验,结果表明注水时有大量瓦斯从自由孔涌出,水力压裂卸压后钻孔流量提高了17倍,煤体透气性增加了420倍,达标预抽期由2年减少为6个月,其防突效果明显。

Hydraulic fracturing of coal between holes refers to inject high pressure water into regional pre- vention outburst drilling holes, which will make fracturing coal squeeze towards free holes, relieve the pressure and increase the permeability of coal between holes. Based on the deformation rate of coal expan- sion between holes,that is no less than 4%0, according to the equivalent volume of free holes shocked by high pressure water,this paper calculates the distance between free holes and injection holes. The field test in Jiulishan Mine shows that large amount of gas pours out from free holes when water is injected into holes, and, after the pressure relieving of fracturing coal, borehole flow increases by 17 times and coal permeability increases by 420 times, and standard pre-draining time is reduced from 2 years to 6 months, so the effect of anti-gas outburst is obvious.