Applications of cationic surfactant

The invention discloses applications of a cationic surfactant represented by a formula I as an adsorption sacrificial agent in reducing adsorbing capacity of a polymer used for oilfield oil displacing. The polymer is a hydrophobic associated polymer; the cationic surfactant represented by the formula I possesses strong adsorptive action with negatively charged reservoir minerals; at the same time, electrostatic repellent effect between the cationic surfactant with cationic hydrophobic groups of the hydrophobic associated polymer is achieved, and interaction of the cationic surfactant with the polymer is weakened, the polymer is isolated from the reservoir stratum, and polymer absorbing capacity is reduced. The cationic surfactant is capable of reducing absorbing capacity of the polymer at low concentration, and application cost of the polymer is reduced. The adsorption sacrificial agent possesses excellent compatibility with formation water and the polymer, and can be widely applied to oilfield polymer-related oil displacing process, and used for reducing absorbing capacity of the polymer at near wellbore areas.