Abstract：For high gas pressure,high gas content,and preliminary hydraulic punching effect is not ideal and borehole drainage efficiency is low in Pingdingshan thirteen mine,the fracturing technology by phase transformation of liquid CO₂is used to secondary antireflection of coal seam.Both theoretical analysis and field test were used.It is describes the fracturing technology process and fracturing mechanism by phase transformation of liquid CO₂,the advantages of fracturing technology by phase transformation are analyzed,and the fracturing technology by phase transformation is investigated.The field test shows that,after the fracturing,the borehole fissure is greatly increased,after 54 days pumping,the borehole average extraction pure quantity is increased to1.08 ~ 1.73 times before the fracturing.

Keyword：low gas permeability coal seam;fracturing by phase transformation;secondary antireflection;gas drainage;liquid CO_2;