Abstract: In order to study the effect of supercritical CO₂ on the enhanced permeability of shale reservoirs, a study was performed on the permeability enhancement pattern of supercritical CO₂ injection into shale reservoirs with the self-developed rock triaxial seepage experimental device. The results of the study showed that the CH₄ permeability of shale reservoirs varied negatively exponentially with increasing pore pressure, and the permeability was significantly enhanced after supercritical CO₂ injection into shale samples; taking sample 3 as an example, the CH₄ permeability could be increased by 103.98% at a maximum; the enhanced permeability of supercritical CO₂ at injection pressure of 9.0 MPa was better than that at 8.0 MPa under the condition of constant temperature; as the injection pressure of supercritical CO₂ gradually increased to 10.0 MPa, the shale started to fracture; when the test temperature was 35 to 55 ℃, the enhanced permeability of supercritical CO₂ in shale was decreased with temperature raise, and the wave velocity attenuation rate and the porosity were decreased by 0.15 percentage points and 0.90 percentage points with temperature raise, respectively, showing a linear decreasing relationship between wave velocity attenuation rate and temperature. The study results provide a theoretical basis for enhancing the permeability of shale gas reservoirs during the development of supercritical CO₂-enhanced shale gas.

Key words: shale gas, supercritical CO₂, enhanced permeability, temperature, wave velocity attenuation rate