Abstract: In view of the problem that 43.7% reserves remain underground after polymer flooding in the main oil layer of Daqing Oilfield, the adjustment technology of "Adjustment + Displacement + Water Plugging + Fracturing" using polymer-surfactant agent after polymer flooding is studied. By the means of laboratory physical simulation, reservoir numerical simulation and dynamic analysis of field test, the technology of "Adjustment + Displacement + Water Plugging + Fracturing" and its feasibility are put forward and demonstrated. "Adjustment" is first of all the well pattern adjustment for the purpose of adjusting the seepage direction, exploiting the residual oil in the diverging line and increasing the displacement pressure gradient. The second step of "Adjustment" is "Profile Control" in which seperated layer injection is implemented as soon as possible, and conflicts between layers is alleviated by stepwise injection. The 0.3 PV polymer-surfactant agent type I (concentration:2 000 mg/L) is injected, and its association is used to play a dynamic viscosity increasing role to alleviate in-layer contradictions. "Displacement" is using 0.7 PV polymer-surfactant agent type II (concentration:1 000 mg/L), which is injected with step-down viscosity and increased rate, and is adjusted accordingly to development dynamics. "Water Plugging" is forming emulsified oil type plugging, by using the polymer-surfactant agent type II. "Fracturing" is moderate fracturing, that releases the emulsified remaining oil, side interlining barrier remaining oil on top reservoir and thin layer emulsified residual oil. The field test shows that the EOR is more than 9% with good economic benefits. It is expected to be a new way of EOR technology after polymer flooding.

Key words: Daqing Oilfield, after polymer flooding, polymer-surfactant agent, adjustment+displacement+water plugging+ fracturing, enhanced oil recovery