Abstract: In this paper the character of polym ersurfactant foam combination flooding of alternate injection is studied with physical model test under the reservoir condition of central part of Block 2 in central Gudao Oilfield. The long slim tube test shows that at low gas liquid ratio, the blocking pressure difference between inlet and outlet of slim tube increases more slowly and the bigger alternate slug is, the worse the block effect. The oil displacement test on heterogeneous porous model shows that EOR of polymersurfactant foam combination flooding mainly depended on increasing sweep volume, at the same injection volume, its blocking ability is twice bigger than polymer flooding.

Key words: polymersurfactant foam combination flooding, alternate injection, blocking effect, gas liquid ratio, alternate slug, EOR