Evolution of the Anthracite Pore Structure under Organic Solvent Dissolution and Its Potential for Coal Powder Blockage Removal

The solubilization of organic matter in coal using organic solvents has the potential to enhance coalbed methane (CBM) production by alleviating coal dust blockage and modifying the coal's pore structure. This paper investigates the effects of dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and diethylene glycol butyl ether (DGBE) on the dissolution rate and pore structure of anthracite coal through proximate analysis and low-temperature nitrogen adsorption. Additionally, the feasibility and influencing factors of using organic solvents to remove coal powder blockage are preliminarily explored. The results indicate that the dissolution rate initially increases with the solvent concentration before decreasing at higher concentrations. The treatment with organic solvents significantly enhances the pore volume and specific surface area of coal; specifically, DMSO and DGBE facilitate the development of 25-35 nm pores, while NMP promotes the formation of 5-10 nm pores. Furthermore, organic solvents increase the roughness of pore surfaces and enhance pore connectivity. The order of effectiveness in enhancing the coal pore structure is DGBE > DMSO > NMP. Sand-filled tube simulation experiments reveal that the solvent concentration, interaction time, injection volume, and coal seam characteristics are critical factors influencing the effectiveness of organic solvents in alleviating coal powder blockage. This study provides valuable insights into the use of organic solvents for unclogging coal powder and enhancing CBM production.