79 / 2023-06-10 15:38:19

Modelling the influence of different surfactants on water transport behavior in coal with lattice Boltzmann method

Lattice Boltzmann method; surfactant; pore structure; seepage velocity

Surfactants are widely used in the coal industry to expand the range of coal seam water injection, which is vital for preventing dust, coal and gas outburst, and reduce gas concentration. Unfortunately, the investigations of water seepage capacity in coal seams before and after surfactants from a microscopic perspective were scarce. In this study, a novel lattice Boltzmann (LBM) - based methodology was developed to estimate the water seepage capacity by incorporating the effects of cocoamidopropyl Betaine (CAB), coconut oil fatty acid (CDEA), and sodium dodecyl sulfate (SDS). The main conclusions are as follows: the addition of surfactants can enhance the wetting effect but impede the seepage stage of coal seam water injection, which deteriorates the seepage velocity. Comparing the water seepage velocity field in the four coal samples, the velocity distribution law is as follows: raw coal > coal sample modified by CAB > coal sample modified by SDS > coal sample modified by CDEA. The water flow rate in the coal sample modified by CDEA is the lowest, which can be attributed that its contact angle is the smallest, its hydrophilicity is the highest, and the adsorption layer of water molecules on its surface of pore-fracture structures is thicker, resulting in a narrow flow channel and low flow velocity. This study can provide a theoretical guidance for the development of wetting and infiltration enhancement technologies in coal seams.