Pore changes of slickwater-containing shale under supercritical CO2 treatment

•The effect of hybrid ScCO2-slickwater treatment on shale mineral and pores structure was studied.•He-slickwater and ScCO2-water treatment methods were set to study the cause of pore changes.•Pore change was synergistically caused by CO2 dissolution, secondary mineral precipitation and PAM adsorption.•The fractal dimensions of pore structure obtained from MIP and N2GA were increased.•Hybrid ScCO2-slickwater treatment can realize integration of shale gas stimulation and CO2 geological storage.