Method for extracting coal bed gas from circulating pulse type low temperature freeze-thawed anti-reflection coal

The invention discloses a method for extracting coal bed gas from circulating pulse type low temperature freeze-thawed anti-reflection coal. Firstly, a borehole and multiple rows of guiding slots are constructed in a coal bed, the guiding slots are communicated with the borehole and extend to two sides of the borehole in the direction perpendicular to the borehole in the coal bed, and coal bed gas extraction boreholes are formed at the outer ends of the guiding slots. A liquid low-temperature medium is injected into the borehole and the guiding slots in a high-pressure pulse mode, the coal bed is freeze-thawed by adopting a pulse circulating low temperature freeze-thawing method to fracture for increasing reflection, and a coal bed gas extraction fracture network is thus formed. Coal bed gas is extracted via the coal bed gas extraction boreholes. By combining freeze-thawing erosion with coal bed gas extraction and combining pulse circulating injection of the liquid low-temperature medium with freeze-thawing p