AbstractEnhanced Gas Recovery by injecting CO2 is one of the efficient scenarios to accelerate gas production if the excessive mixing can be avoided in the process of CO2-CH4 displacement. A laboratory investigation was presented to describe the detailed CO2-CH4 displacement and analyze CO2 dispersion into CH4 in the sand pack for pressure of 10-14MPa at 40°C with the CO2 injection rate of 0.2, 0.3 and 0.4ml/min. And the displacement process was scanned by an X-ray micro-CT scanner. The results of CT scan images were consistent with the breakthrough profile obtained from outlet gas composition analysis. The dispersion coefficient is in the range from 4.478×10-7 to 9.898×10−7mm2/s and it increase with interstitial velocity of CO2 and decrease with pressure. The dispersivity of BZ04 sand pack is calculated as 0.0054 m.