Experimental Investigation of CO2-CH4 Displacement and Dispersion in Sand Pack for Enhanced Gas Recovery

Enhanced 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 10-14 MPa at 40°C with the CO2 injection rate of 0.2, 0.3 and 0.4 ml/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 × 10−7 mm2/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.