The invention relates to a chemical flooding method of a medium-permeability oil reservoir, and belongs to the technical field of
petroleum chemical flooding development. The chemical flooding methodincludes the following steps that 1), a first heterogeneous dispersion
system is injected into a reservoir stratum, and a front
slug is formed; 2), then a
polymer water solution is injected into the reservoir stratum, a main plug is formed, or a
polymer water solution and a profile
control system are alternately injected into the reservoir stratum, and the main
slug and a profile control
slug areformed correspondingly; and 3), a second heterogeneous dispersion
system is injected into the reservoir stratum, and a protective slug is formed. The first heterogeneous dispersion
system is mainly composed of a first
polymer, a viscoelastic particle
oil displacement agent and water. The polymer water solution is mainly composed of a second polymer and water. The second heterogeneous dispersion system is mainly composed of a third polymer, a viscoelastic particle
oil displacement agent and water. By means of the chemical flooding method, the
rock core stemming ratio of the medium-permeabilityoil reservoir can be increased, remaining oil in a strong flooding region and a medium-permeability
rock core is effectively started, and the effect of greatly increasing the raw oil
recovery rate isachieved.