深部低透气性煤层上向穿层水力压裂强化增透技术

煤层气的长时间、高效抽采的是当前煤层气灾害治理与煤层气资源利用过程中亟需解决的问题。利用数值模拟实验与工程试验相结合的方法,系统地研究了井下底抽巷对目标煤层进行水力压裂强化增透技术。研究发现,水力压裂的裂隙扩展过程经历了能量与应力累积、微裂隙产生、局部压裂损伤、煤体抵抗失效与裂隙迅速拓展以及压裂水能量再蓄集再扩张循环5个阶段,水力压裂产生了大量的裂隙,再加上顶底板碎胀作用而使煤层卸压,使得煤体透气性大幅提高。水力压裂工程试验验证了压裂水的运移轨迹,与数值模拟与分析结果相吻合,实现了大范围增透和长时效的煤层气抽采,从而为深部低透气性煤层强化增透和煤层气高效抽采提供了技术保障。

Simulation and experimental research on upward cross-seams hydraulic fracturing in deep and low-permeability coal seam

Long-time and high-efficiency CBM drainage is a problem for current CBM disasters control and CBM resource utilization.Numerical simulation and engineering experiments were conducted to systematically study the underground hydraulic fracturing technique for greatly increasing the permeability of coal seam.The research results show that there are five stages in the process of hydraulic fracturing,including energy and stress accumulating,micro cracks growing,local damage,local cracks growing and connecting,and fail to resistance of coal and rapid expansion of cracks.A large number of cracks created by hydraulic fracturing,and swelling effect of roof and floor make coal seam pressure relieved,thus,the permeability of coal seam is greatly increased.The engineering experiments validate the migration path of water,and it is in agreement with numerical simulation results.A large-range permeability increase and long-time CBM drainage are achieved.This study provides a technical way for intensified permeability increase and high-efficiency CBM drainage in deep and low-permeability coal seams.