Abstract: To study the effects of microwave heating on the properties of coal, the temperature rise and cracking laws of coal under microwave action were studied through physical and numerical simulation methods.The research shows that the water cut of coal has a direct impact on the microwave heating effect, and the temperature rise rate inside the coal mass is anisotropy, which leads to the uneven heating of different parts, thereby generating thermal stress.Higher microwave power leads to more severe coal fragmentation.Microwaves applied to the fractured coal can further expand the artificial cracks.The additives in the fracturing fluid can improve the dielectric properties of coal.The production-increasing effect of slickwater fracturing fluid is significant, and it is expected to replace active water (KCl) for efficient production-increasing technology transformation. In the early stage of implementation, hydraulic fracturing technology is used for the fracturing fluid fill into the depth of the fracture as much as possible,which can enhance the dielectric properties of the coal seam. In the later stage,using microwave heating technology can enhance the effectiveness of coalbed methane recovery.This study can provide guidance for the refracturing process of coalbed methane development.

Key words: coalbed methane, microwave heating, coal, fracturing, thermal stress, dielectric properties