Experimental study on the influence mechanism of injection pressure on water seepage and imbibition in coal pores

Pre-mining water injection into coal seams via boreholes mitigates dust formation during subsequent coal extraction, reducing coal dust explosion hazards in underground mines. This study employed anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant cetyltrimethylammonium bromide (CTAB) to prepare solutions for investigating the enhancement mechanism of water injection pressure on coal pore imbibition, alongside surfactant and temperature. Furthermore, molecular simulations were adopted to examine pressure-enhanced imbibition mechanisms in coal under combined effects of temperature and surfactants. The results show that coal water imbibition capacity increases with injection pressure, although the rate of increase gradually diminishes at higher pressures. Surfactant addition under pressurized injection enhances the coal imbibition capacity by 1.5–3.5 times at 25°C and 40°C, respectively. An increment in temperature leads to a reduction in the amount of water absorbed by coal, which reduces the enhancing effect of surfactants on coal wetting capacity. Water infusion pressure can be increased to reduce the hindering effect of deep geothermal water in coal seams on water injection. A rational selection of water injection pressure can ensure water injection efficiency while reducing energy consumption required to achieve high pressure. The findings reported in this paper provide theoretical guidance for developing more efficient water injection operations and improving dust reduction and explosion prevention technologies.