Application of high pressure pulse jet slotting and fracturing anti-reflection technology in low permeability coal seam

Aiming at the complicated geology condition and gas extraction problems of No.20 coal seam, 18 mining area, Daping Coal Mine, Pingguan Town, Panzhou City, a high pressure pulse jet slot-guided fracturing anti-reflection technology was proposed. In order to verify the effect of this technology, the mechanism of anti-reflection technology was analyzed, and four test schemes were designed for comparative analysis. The results show that the high pressure pulse jet slot-guided fracturing scheme is significantly superior to other methods in gas extraction efficiency, and its average daily gas concentration is 3.01 times, 1.41 times and 1.67 times of that of common extraction, high pressure pulse jet slotting and high pressure hydraulic fracturing, respectively. The average daily gas extraction net flow also increased by 2.86 times, 1.42 times and 1.62 times. After 90 days of pumping, the influence radius of the scheme reaches 5.06 m, which is 2.56 times, 1.25 times and 1.29 times of that of common extraction, high pressure pulse jet slotting and high pressure hydraulic fracturing, respectively. Under the condition of the same pumping effect, compared with common extraction, high pressure pulse jet slotting and high pressure hydraulic fracturing, the drilling construction time is shortened by 60%, 32% and 20%, respectively. The time required for gas extraction to meet the standard is shortened by 70%, 50% and 62%, respectively. The high pressure pulse jet slot-guided fracturing technology has an ideal effect on gas control of low permeability coal seam, which can be used for reference in similar mines.