Experimental Investigation of the Use of Expansive Materials to Increase Permeability in Coal Seams through Expansive Fracturing

Table 1

Comparison of expansive fracturing with other methods of permeability improvement.

Method	Principle	Advantage	Limitation
Expansive fracturing	Solid expansion and exothermic desorption	Noise-free, dust-free, and vibration-free	Reaction exotherm
Concussion blasting	Gas volume expansion	Quick reaction and obvious effect	Vibration, noise, flying stone, toxic gas, and easy to induce gas outburst
Drilling	Pressurization-discharging	Traditional technology	Large amount of work, long construction period, and rapid drilling-induced coal and gas outburst
Hydraulic method	Liquid punching, fracturing, and displacement	The coal is adequately relieved of pressure	Fracture development has no direction and the process is complex
CO2 phase change fracturing	Gas volume expansion and displacement	Gas can be replaced to improve the recovery rate	The coal body with complex device, high sealing requirement of borehole and excessive crushing is easy to lead to pore blockage