Experimental Study on Multiscale Pore Structure Evolution and Methane Desorption Characteristics of Coal with Controlled Electrical Pulse Treatment

Controlled electrical pulse (CEP) treatment is an emerging technology for coal seam permeability enhancement. To investigate the multiscale pore structure evolution of coal bodies under CEP action, scanning electron microscopy (SEM), low-temperature CO2 adsorption (LTCA), and low-temperature N2 adsorption (LTNA) tests were applied, and the evolution pattern of the multiscale pore structure of coal was elucidated under different breakdown voltages (BVs). Furthermore, methane desorption testing was conducted to analyze the methane desorption characteristics of the coal under CEP action. Results show that CEP treatment facilitates the development of multiscale pores in coal. With increasing BV, pores and cracks in coal develop further, and the connectivity between them is enhanced, resulting in a significantly improved structure of mesopores and macropores; this process is significant, as it provides a channel for methane desorption and transport. And the amount of coal methane desorption and the initial desorption rate were positively correlated with BV. Overall, CEP treatment significantly affects the desorption and migration of coalbed methane (CBM) mainly by improving mesopores and macropores of the coal body.