碎软煤层底板梳状孔分段压裂抽采瓦斯技术

为提高煤层的瓦斯抽采效果,以阳泉矿区15#碎软煤层为研究对象,对煤层及其底板岩层特征进行分析,融合煤层底板梳状长钻孔和分段水力压裂技术,形成针对各个梳状分支孔的分段压裂方式,并理论分析了该方式水力压裂裂缝扩展延伸规律。试验研究了满足分段压裂技术要求的梳状长钻孔设计与施工工艺,构建了基于裸眼封隔器+滑套投球分段压裂工具组合的压裂参数设计和压裂施工工艺流程,最终形成梳状长钻孔主孔长度534 m,分支孔5个,主孔下入分段压裂工具串490 m,实现了4个分支孔分段压裂,单段最大注水量611 m³,最大泵注压力17.18 MPa;与常规的穿层钻孔瓦斯抽采技术对比,试验后瓦斯抽采浓度提高了10.53倍,百米钻孔瓦斯抽采量提高了2.02倍。

Gas extraction technology of staged fracturing with comb hole in soft seam floor

This paper has investigated 15#broken soft and low permeable coal seam in Yangquan Mining Area. In order to improve the gas drainage effect of the broken soft coal seams, features of the coal seam and its floor rock were analyzed. The staged fracturing method for each comb-shaped branch hole has been formed integrating long comb-shaped boreholes in the coal seam floor and staged hydraulic fracturing. The fracture propagation and extension of hydraulic fracturing is theoretically analyzed using the method. Based on the test using this method, the design and construction technology of long comb-shaped boreholes that meet the requirements of segmented fracturing technology have been studied. Also, the fracturing parameter design and fracturing construction process based on the combination of open-hole packer and sliding sleeve ball segmented fracturing tool have been constructed. The test finally formed a comb-shaped long drilling hole with a main hole length of 534 m, five branch holes, and a main fracturing tool string of 490 m. The four holes branch fracturing was achieved, with a maximum water injection of 611 m³ and the maximum pumping pressure of 17.18 MPa per stage. After the test, the gas drainage concentration increased by 10.53 times and the gas drainage volume of the 100-meter borehole increased by 2.02 times compared with the gas drainage technology of drilling through layers.