Study on the effect of nitrogen-active water wetting modification on methane desorption

To investigate the effects of nitrogen-active water composite fracturing on coal wettability alteration and methane desorption behavior, cationic surfactant 31526 is formulated into activated water and used in fracturing experiments on coal samples from the No. 8 coal seam of the Baode Coal Mine. The changes of methane desorption rate, capillary pressure and wettability under three conditions of raw coal, active water fracturing and nitrogen-active water composite fracturing are compared. The results show that the nitrogen-active water composite fracturing can significantly improve the methane desorption rate, up to 55.74%, which is 11.14% higher than that of raw coal. The mechanism is that the composite fracturing not only reduces the surface tension, increases the capillary radius and contact angle, but also reverses the capillary pressure, transforms the resistance into the driving force, and effectively alleviates the water lock effect. This study provides a theoretical basis and technical support for the efficient development of low permeability and low pressure coalbed methane.