Methane Seepage Characteristics in Coal Seams under Microwave Radiation

Microwave radiationis an effective method for simulatingthe exploitationof coalbed methane (CBM). Herein, structural coal seepage is evaluatedusing a self-developed experiment system to explore the temperatureand permeability response changes exhibited by coal samples undermicrowave radiation and stress loading. Microwave radiation experimentsare used to conduct the numerical simulation of the microwave radiation,and the temperatures and permeability values of the coal samples undersimulated and experimental conditions are compared and analyzed. Theresults show that the higher the microwave radiation power, the higherthe temperature of coal samples within the specified time. Under thesame effective stress conditions, the higher the microwave radiationpower and the longer the action time, the greater the coal samplepermeability. Moreover, effective stress is shown to be importantfor permeability. The curve change trends and numerical values ofthe experiment and simulation are consistent, and the accuracy ofthe experiment and simulation is verified in both directions. Furthermore,a numerical model of coal seams under microwave radiation is establishedto simulate the change law of pressure, gas seepage velocity, andfree methane content of actual coal seams under microwave radiation.It is concluded that the fast heating and stable temperature resultingfrom microwave radiation are beneficial for the crack propagationof coal near reservoirs. The results of this study provide a new technologicalmethod for actual CBM exploitation and a new research direction forunconventional natural gas energy output.