In order to analyze the behavior of a polymer underground in the early stage of flooding, we propose a new method based on power-law steady flow of a fluid, taking into account threshold pressure. We use data from an injection well and geological parameters to calculate the flow behavior index, the average effective viscosity within the polymer-swept portion, the resistance factor, and other important parameters. The reliability of the method is confirmed by comparing the results with data obtained during well development with the results of the ECLIPSE hydrodynamic simulation. The new method lets us track the change in polymer performance over time, and can be recommended for use in drafting recommendations for field development in subsequent stages.