Experimental study on the synergic effects of surfactants and nanoparticles on the seepage of water injected into coal seams

Abstract

To study the synergic effects of surfactants and nanoparticles on the seepage of water injected into coal seams, we prepared three chip models with complex cracks using glass etching technology based on the real conformation of cracks in coal mass and set up a visual experimental platform for microscopic seepage. Based on these models, we carried out a series of seepage experiments on gas expelling with different solutions and investigated the effects of surfactants, nanoparticles, and flow velocities on seepage characteristics. The results showed that all tested anionic, non-ionic, and cationic surfactant solutions could reduce flow resistance, showing a downward trend with the rise of the mass fractions of these surfactants. The combination of nanoparticles with these surfactant solutions further reduced flow resistance, showing the best drag reduction effects with hydrophobic nanoparticles at all tested flow velocities. Moreover, all three tested surfactants could displace gas and reduce gas residue in the crack networks. The higher the mass fraction of the surfactant solution is, the more significant the gas displacement effect. Furthermore, the gas displacement effect of the surfactant solution is positively proportional to the flow velocity. The higher the flow velocity is, the more significant the gas displacement effect.