Imbibition behavior of water on coal surface and the impact of surfactant

Abstract

Coal seam water injection is vital in mitigating dust pollution in coal mining operations. To investigate water imbibition and adsorption behavior on the coal surface following injection into coal seams, as well as the impact of surfactants, coal particles with sizes of 6–8 mm, 3–5 mm, and 0.4–0.85 mm were selected from the Dongtan Coal Mine in Shandong Province, China. Coal particle imbibition experiments were designed for coal particles at varying surfactant concentrations and temperatures, and molecular simulation was employed to examine the micro adsorption behavior of water within coal rock pores. The findings indicate that smaller coal particles exhibit significantly higher water absorption capacity compared to larger particles when ample water supply is present. This suggests that coal pore water absorption is inherently limited. Moreover, elevated formation temperatures hinder the wetting process of water injection. Importantly, introducing surfactants leads to the blockage of coal fractures, constriction of fracture channels, and restriction of the effective wetting range of coal seam water. Furthermore, the influence of sodium dodecyl sulfate is greater than that of cetyltrimethylammonium bromide. In low-temperature environments, surfactants exert a more prominent inhibitory effect on water injection wetting. These research findings provide valuable theoretical guidance for coal seam dust prevention efforts and water injection technology.