Experimental Study of Drag Reduction with Surfactants in Porous Media for Coal Seam Water Injection
This study systematically investigates the synergistic drag reduction mechanism of surfactants and porous media in coal seam water injection. Four surfactant types—cationic CTAB, anionic SDBS, amphoteric BS-12, and nonionic OP-10—were tested with five porous media pore sizes (3–12 mm) using a custom-built all-in-one drag reduction test system. The effects of surfactant type, mass concentration, driving frequency, and pore diameter on drag reduction efficiency were evaluated. Results show that in an empty tube, drag reduction efficiency increases with mass concentration. As driving frequency increases, drag reduction first rises then falls, peaking at 35 Hz. With porous media, drag reduction exhibits pore size dependence, reaching a maximum at 8 mm and decreasing thereafter. The composite surfactant-porous media system achieves synergistic enhancement over single systems. At 0.05% mass concentration, all surfactants attain maximum drag reduction, with CTAB showing the highest efficiency. Optimal conditions (0.05% CTAB, 35 Hz, 8 mm pore size) yield a drag reduction rate of 66.14%, a 1.4-fold improvement over 20 Hz. These findings demonstrate that tailoring surfactant and porous media parameters can significantly optimize coal seam water injection efficiency, offering a practical approach for dust control in mining.