Systems and methods for performing a polymer flood having a graded polymer concentration

A method for performing a polymer flood of a hydrocarbon-bearing, subterranean reservoir, the method comprising:

• (a) determining a nonlinear dependence of the viscosity of a polymer solution to a polymer concentration of the polymer solution;
• (b) simulating the injection of a graded polymer slug into the subterranean reservoir based on the nonlinear dependence of the viscosity of the polymer solution to the polymer concentration of the polymer solution;
• (c) determining an optimum configuration of a polymer slug based on the simulation;
• (d) injecting a polymer solution to form a polymer slug in the subterranean reservoir having the optimum configuration;
• and
• (e) injecting an aqueous solution from the injection well into the subterranean reservoir following the injection of the polymer solution to displace the polymer slug through the subterranean reservoir.