Experimental Study Of Water Lock Effect In Coal With Gas

Coal seam infusion is an important measure to prevention coal and gas outburst,but this measure will result in water lock effect,and the effect of outburst elimination and gas extraction will be affected.To research the influence of water lock on gas desorption in coal,the experimental device of imbibition/desorption in coal with gas and external water was established,the experiments of desorption under the conditions of different water content and adsorption equilibrium pressure were carried on,and water lock effect in coal with gas was evaluated through measurement and comparison of gas desorption amount,desorption velocity,desorption rate and residual gas content in dry and moist coal.The results indicated that spontaneous imbibition water could promote replacement desorption of absorbed gas,under the same adsorption equilibrium pressure,the amount of replacement desorption gas increase with water content;under the same water content,the higher the adsorption equilibrium pressur,the more replacement desorption gas.After pressure relieved,the accumulated amount and the maximum amount of desorption gas are all decrease with water content rising. Desorption velocity and desorption rate of moist coal sample show the aging characteristics because of water lock,in the first 30 minutes,desorption velocity decrease with water content rising,as time advance,the gas which blocked by water began to discharge,desorption velocity of moist coal sample would gradually exceed the dry coal sample's;in the first 1 hour,the pressure-relief desorption rate of dry coal was greater than moist goal's,but after long desorption process,the moist coal's begun gradually exceed the dry coal sample's.The indexes of after desorption termination were used to analyze the comprehensive effect of water lock on gas desorption,under the same adsorption equilibrium pressure and the certain water content range from 2% to 10%,the more water,the bigger the total amount of desorption and the total desorption rate,the fewer the residual gas content.The research indicates that the influence of water on gas desorption is the comprehensive effect of replacement and water-lock, For the experimental coal sample from Yonghong coal mine in Jinchen,under water content range from 2% to 10%,the pressure-relief desorption would be delayed by water lock,however there is no monotonous relations,As prolonging desorption time,the gas which blocked by water began to discharge,spontaneous imbibition water manifest acceleration effect on gas desorption as a whole from the view of ultimate effect.