The Application of Surfactin Biosurfactant as Surfactant Coupler in ASP Flooding in Daqing Oil Field

After conventional water flooding processes the residual oil in the reservoir remains is likely to be around 70% of OOIP. The EOR method socalled alkaline-surfactant-polymer (ASP) flooding has proved to be effective in laboratory experiments and field projects .At present restricts to application of this technique is surfactant development. biosurfactants has characteristic of low poisonous, no pollution, inexpensive. Therefore biosurfactants could be used as an economical alternative to chemical surfactants in ASP flooding is feasible. This paper studied the feasibility of using biosurfactant-Surfactin-fermentation liquor (SF) as a complementary agent of alkaline-surfactant-polymer (ASP)-flooding was conducted in the laboratory. The results show that The activity of Surfactin is tolerance to high salinity(0~12 wt%), high temperature(50-100 °C), wide pH range(6.0~11.0) and high Ca²⁺/Mg²⁺ concentration. And this surfactin could reduce IFT of water/oil from 23.53 mN/m to 4.57 mN/m , Its critical micelle concentration was tested to be 33.3 mg/L, and it had excellent emulsifying(2.89U) and foaming property. The interfacial tensions (IFTs) between solutions containing SF or mixture of SF and alkylbenzene sulfonate (ORS) at different ratios and crude oil were studied at a constant NaOH concentration. The results show interfacial characteristics (IFT) of SF and significant synergic effect between SF and ORS. The core-flooding tests show that the enhanced oil recovery with the formulation of ASP of 0.1 wt.% SF and 0.1 wt.% ORS is 7% more than that with the formulation of ASP of only 0.1 wt.% ORS, and is equal to that with the formulation of ASP of 0.3 wt.% ORS. This indicates that using SF can reduce the cost of ASP flooding.