Experimental study on dynamic response of anisotropic adsorption swelling of anthracite

Abstract

In order to study the anisotropic adsorption swelling characteristics of coal-rock after CO2 injection, taking anthracite in Qinshui Basin as the research object, the experiments regarding CO2 adsorption capacity and anisotropic swelling of coal-rock were carried out, and the relationship between CO2 adsorption capacity and swelling strain was discussed. Results show that the volume of coal-rock is deformed after CO2 injection, the volume strain changes periodically with time; the Langmuir model can be used to describe the relationship between the CO2 absolute adsorption capacity and the adsorption swelling strain of coal-rock with the CO2 injection pressure; the adsorption swelling deformation of coal-rock presents obvious anisotropic characteristics. The strain in vertical bedding direction is the largest, followed by the shear direction of parallel plane, and the strain in the shear direction of parallel end is the smallest; the relationship between absolute adsorption capacity and swelling strain of coal-rock is in accordance with S-curve, which can be fitted by the Slogistic function; the matrix swelling of CO2 adsorbed by coal-rock is mainly internal swelling at first, and it begins to expand to the outside after cleats or fractures are compressed. Finally, when the internal stress state of coal rock reaches equilibrium, the expansion deformation of coal rock tends to be stable.

Keywords

• co2-ecbm
• adsorption capacity
• swelling deformation
• anisotropy
• anthracite
• coal bed methane development