Research on Application of Transient Electromagnetic Method in Hydraulic Fracturing

摘要

Coal is China's dominant energy at present,but gas outburst occurs frequently in gassy coal mines, and it causes significant losses to people's lives and properties. Hydraulic fracturing is a valuable technology for gas permeability improvement in gassy coal mines. In this paper, the field experiment of hydraulic fracturing was conducted in a coal mine located in Yibin City, Sichuan Province. The transient electromagnetic instrument was applied before and after hydraulic fracturing respectively, combined with numerical simulation analysis of FLAC3D, aimed to estimate the influence scope of hydraulic fracturing. The numerical simulation results denote that the plastic zone principally distributes along the interface of the coal seam and roof due to the existence of stratification. Transient electromagnetic method analysis demonstrates that the coal-rock mass firstly cracks at 35 m and 41 m of borehole depth, the dominant fissure distribution range is in the interval of 33-50 m. And the influence area covers the range of 28-64 m, which means the influence scope is up to 36 m. It also reveals that it is feasible to determine the influence scope of hydraulic fracturing through transient electromagnetic method.