Experimental study and mechanism analysis on natural water absorption and imbibition test of gas- bearing coal

In order to study the imbibition role of gas-bearing coal under natural water absorption condition,based on self established test platform,the paper had a stu dy on the imbibition effect after natural absorption with different water quantity and under different gas adsorption balanced pressure. The paper theoretically analyzed the i mbibition mechanism. The results showed that after natural water absorption of gas-bearing coal samples,the pressure within coal sample tank would be increased and abs orption gas would be replaced by free gas.The imbibition phenomenon was verified.Under the same absorption balanced pressure,with the moisture content increased,free gas increment and imbibition rate would be steadily increased,it would be increased in linear with moisture content in 2% ~ 6% and then the increased gradient slow down and would be steadily in stable,which indicated the limit moisture content existed could make the imbibition effect at the best.Under gas different absorption balanced press ure,the max imbibition rate of coal sample natural water absorption would be equal. The test verified that imbibition could provide moisture migration power with dual mediu m features of coal mass. The moisture absorption capacity was higher than methane,which could further replace adsorption gas,could promote gas desorption of coal and C ould reduce gas content.