Numerical simulation of damage and permeability evolution mechanism of coal seam under microwave radiation

Abstract

Microwave heating is an effective method to improve the recovery rate of coalbed CH4. In this study, a fully coupled electromagnetic thermodynamic model was developed to study the effects of coal compaction, thermal expansion and thermal gas desorption on coal deformation. The simulation results show that although in the initial stage, the decrease of gas pressure by microwave is not obvious, the distribution of gas pressure in coal seam is obviously affected by microwave after a period of time. The microwave can also affect the mineral composition of rocks, cause rock damage, promote the development of cracks, and promote the increase of permeability