Impact of clean fracturing fluids on sustainable coalbed methane mining

Modification of coal seams using fracturing fluids is a critical means to enhance methane extraction efficiency from low-permeability coal reservoirs in China. Nevertheless, some of the existing fracturing fluids pose risks of groundwater contamination due to their toxicity and corrosiveness, which severely limits the engineering application of this technology. Three types of green and clean fracturing fluids were developed in this paper using Huainan bituminous coal in China as the research object. Through the combination of macroscopic experiment and molecular dynamics simulation, the systematic study of the changing law of molecular structure, which has an important implication on the gas desorption and permeability characteristics of the treated coal samples, was carried out, and the fracturing fluids suitable for the test coal seam with high efficiency, environmental protection and safety were preferred. The clean fracturing fluid effectively regulates the microcrystalline structure of coal, reduces methane adsorption energy, and improves gas migration pathways. Simultaneously, it enhances electrostatic interactions and interfacial electron transfer to decrease methane-coal interaction energy, thereby synergistically improving methane migration efficiency. The findings are vital for promoting clean production, efficient extraction and safe production of coalbed methane.