The application discloses a
tackifier, a preparation method of the
tackifier, a composite plug
oil displacement agent and an
enhanced oil recovery method. The
tackifier contains
structural unit A,
structural unit B,
structural unit C and structural unit D, and the
mass ratio of the structural unit A, the structural unit B, the structural unit C and the structural unit D is (2000-20000):(2000-40000):(4000-60000):(6000-100000), n is 1-15, m is 1-20, and the
viscosity average molecular weight of the tackifier is 45-50 million. The tackifier has the following advantages: under the condition of a temperature of 60-70 DEG C and a
salinity of 10000 mg / L, the
viscosity of a
polymer solution is greater than 100 mPa s; when the concentration of the
polymer solution is 1000 mg / L, the
surface tension is less than 40 mN / m, the tackifier has the function of emulsifying and dispersing
crude oil, and the
oil displacement efficiency of a
physical model is increased by more than 12%.