Low gas-liquid ratio foam flooding for conventional heavy oil

The recovery of heavy oil by water flooding is 10% lower than that of conventional crude oil, so enhanced oil recovery (EOR) is of great significance for heavy oil. In this paper, foam flooding with a gas-liquid ratio (GLR) of 0.2:1 for the Zhuangxi heavy oil (325 mPa.s at 55 degrees C) was performed on cores, sand packs and plate model. In sand pack tests, polymer enhanced foam flooding increased oil recovery by 39.8%, which was 11.4% higher than that for alkali/surfactant/polymer (ASP) flooding under the same conditions. Polymer enhanced foam flooding in plate models shows that the low GLR foam flooding increased oil recovery by about 30%, even when the extended water flooding was finished at 90% water cut. Moreover, it was discovered by microscopy that foam was more stable in heavy oil than in light oil. These results confirm that low GLR foam flooding is a promising technology for displacing conventional heavy oil.