Abstract:

In order to solve the problems of the uneven plane water flooding, great differences between the of vertical water absorption, and low recovery of the waterflooding during the high water cut exploitation period of the oilfield, a series of indoor evaluation experiments were conducted to improve the water absorption profile of CO₂ foam flooding. Then we established the flooding model by multiple core combination with the high and low permeability with the differential of 3, 6 and 9. We used the CO₂ foam to displace the core to study the effect of the differential permeability and oil saturation difference on the improvement of water absorption profile during CO₂ foam flooding, and the CO₂ foam displacement efficiency. The results show that the effects of CO₂ foam improving the injection profile become better when the permeability reduces. And taking into account the displacement efficiency of CO₂ under different permeability ratio, the permeability of the same layer should be controlled within 6. Meanwhile, the effects of CO₂ foam on profile improvement gets better when the oil saturation increased. In the practical application, the range of oil saturation level should be 4 ~ 6. At present, the research results have been applied in the test of CO₂ foam flooding in Block A of Jilin Oilfield.

Key words: CO₂ foam, permeability difference, oil saturation level difference, improve the water absorption profile, flooding efficiency