Surfactant oil displacing system forming micro emulsion in low critical micelle concentration

The invention discloses a surfactant oil displacing system suitable for forming micro emulsion flooding in the low critical micelle concentration for a low permeability reservoir. The problems that the concentration and the cost of an existing surface active agent required when the micro emulsion of the low permeability reservoir is formed are high are solved. The oil displacing system is prepared from, by mass, 0.3% to 1.5% of bis(p-cresol) sulphobetaine, 0% to 2.0% of normal butanol and the balance water. According to the surfactant oil displacing system, a formed micro emulsion system can have the effects of fluidity controlling and residual oil emulsified carrying, the phenomenon that when fluidity controlling is achieved through polymers, an oil reservoir is blocked is avoided accordingly, and the surfactant oil displacing system can be better applied to the low permeability reservoir and the ultra-low permeable reservoir.