Enhanced CMM Drainage with High-pressure Gas Fracturing: A Novel Way to Control Greenhouse Gas Emissions in the Coal Mine

Cardox system as one kind of high-pressure fracturing device has a prominent advantage in security, thus in recent years, this system has been widely applied in increasing permeability of a coal seam. Firstly the system component and its explosive mechanism are introduced, and the phase change of carbon dioxide is also provided. Secondly, based on research of mechanical characteristics of coal, the crack development of coal and its stress condition in the process of high-pressure gas fracturing are analyzed respectively. Through comparison between explosive fracturing and hydraulic fracturing, it is found that fracturing method can develop many cracks along drilling radial direction with high permeability, which can benefit methane drainage. Then from the analysis of drainage results, we found that methane drainage quantity had been increased by 3–5.2 times after fracturing in crossing borehole, and methane drainage quantity had been increased by 1.8–3.5 times after fracturing in borehole along the seam, and the former is better than the later. Finally, this paper proposes a method to improve Cardox system to meet the requirements of fracturing in the long borehole along coal seam. Besides, the potential danger caused by carbon dioxide of coal seam should also be taken into account in the future.