Experimental study on reducing drag-increasing permeability and enhancing displacement of anthracite with liquid-gas coupling medium

Due to the complex coal mining conditions in China, safe production and environmental preservation are significantly impacted by effective mine gas extraction and orderly mine gas discharge. The surfactant cetyltrimethyl ammonium bromide (CTAB) and micro- and nano-bubbles were dissolved in water to create a liquid-gas coupling medium, which was then utilized as the mass transfer carrier to reduce drag, increase the coefficient of permeability, and improve the displacement of coal gas. Combined with instantaneous seepage flow and gas permeability measurements, the effects of the liquid-gas coupling medium in reducing drag, increasing permeability, and strengthening displacement of anthracite were quantified. The drag-reduction seepage model under the action of the liquid-gas coupling medium was established. The interface characteristics and mechanism of the liquid-gas coupling medium on coal water seepage displacement were revealed. Based on the characteristics of pore seepage and boundary slip, a drag-reduction seepage model was established by comparing the internal pore structure of coal with that of pores in the circular tube. The interface and mechanism of the liquid-gas coupling medium in the coal water seepage displacement were described using Darcian seepage as a basis. The synergistic effect of the liquid-gas coupling medium provides a new technical direction for seepage displacement and anti-outburst extraction from coal seams.