A Fluid–Structure Interaction Model of Coal Considering the Dynamic Slippage Effect and Its Application

Gas extraction has always been an important means of promoting the safe and high-efficiency development of coal, and the key to enhancing gas extraction performance is to clarify the dynamic variation in permeability during extraction. The slippage effect that occurs in permeability regulation is largely governed by the pore structure within coal seams, and it always varies dynamically during gas extraction. Therefore, characterizing the dynamics of this effect and constructing corresponding permeability models are crucial to high-efficiency gas extraction. Thus, using the double-medium model as the basis, this study solved the dynamic Klinkenberg coefficient through Poiseuille’s law and developed a fluid–structure interaction model of coal incorporating the dynamic slippage effect. On this basis, COMSOL software was applied to model multi-borehole gas drainage inside coal seams under vertical stress, and the porous extraction effect and gas migration characteristics of coal seams under vertical stress were obtained.