Experimental Study And Application Of Inhibitory Effect On Gas Desorption Of Coal Seam Injected With Water

With the main line of coal and gas outburst prevention mechanism in coal seam water injection, this paper points at problems of less study and lack of quantitative study on inhibitory effect on gas desorption at home and abroad. With methods of laboratory tests, numerical simulation and field test, inhibitory effect on gas desorption in coal seam water injection is studied. In the laboratory test, laboratory simulation test device of inhibitory effect on gas desorption after water injection is developed, and research methods and indicators are brought forward. By tests of adsorption-desorption characteristics of pre-injected water coal sample; desorption isotherm, desorption rate and residual gas content at atmospheric pressure of pre-adsorbed gas then water-injected coal sample, the inhibitory effect is researched in quantitative style, then it is obtained of the response relationship between inhibitory effect and water injection parameters. At the same time, the inhibitory effect is further demonstrated by numerical simulation, field test method and comparative analysis of coal pore structure characteristics before and after injection, and the mechanism of outburst prevention is further explored.Test results show that: To a coal sample after water injection, residual moisture has an blocking effect on methane desorption, so its adsorption volume in desorption isotherms and its residual gas content is greater than that of dried coal, with the increase of water content, initial desorption rate decreases and its decay rate slows down; Under overburden pressure, initial desorption rate increases and decay rate accelerates, but, after water injected, initial desorption rate decreases and decay rate becomes slower.The research indicates that inhibitory effect on gas desorption is related to water injection quantity, injection pressure, overburden pressure, particle size of coal sample and original gas content, and it is an important role in the mechanism of coal and gas outburst prevention, and it is conducive to prevent and control coal and gas outburst.