Gas recharging process, as a supplemental technique for heavy oil reservoirs with thin layers, has attracted researchers’ attention. This thesis focused on three post-cold production process studies-CH4 recharging and depletion, CO2 and C3H8 huff-puff, and C3H8 flooding. Two 18m in length glass beads and sand packed cores and one 1.5m in length sand packed core were used for testing. The mechanisms of each process were investigated. Foamy oil flow under the solution gas drive mechanism was clearly observed during two long core methane depletion processes. The effects of core length and permeability on oil recovery were discussed. CT scanning technique was applied to capture core saturation variations after each process at the 1.5m core, which helped better understanding of the mechanisms of the three gas recharging processes and also was successfully applied to explain what happened in two long cores.