Abstract：In order to study the variation law of pore structures of coal mass under different supercritical conditions, the influence of supercritical carbon dioxide on coal pore structures was studied by controlling such variables as the temperature, gas pressure and processing time under supercritical conditions. The results showed that the coal permeability was greatly influenced by the processing time before and after the action of supercritical CO₂, and the coal permeability firstly decreased and then gradually increased with the increase of the processing time, and stabilized after about 10 hours. Under the supercritical condition, the single change pressure or the effect of temperature on coal sample permeability was not significant. Supercritical CO₂damaged the microscopic pore structures of coal mass, and the porosity of coal mass was significantly improved with 96% and the proportion of large porosity and medium porosity increased also. The effect of supercritical CO₂on the pores played a role in pore expansion that was conductive to gas extraction.

Keyword：supercritical CO2;permeability;mercury porosimetry;porosity structure;