Polymeric solutions are widely used in Improved Oil Recovery (IOR) applications to increase sweep efficiency in oil reservoirs. Due to its rheological characteristics, polymeric solutions modify the mobility of the injected aqueous phase and make oil displacement more efficient. The viscosity of polymeric solutions typically changes with the deformation rate. The flow of these solutions through porous media can be described using Darcy equation and a characteristic viscosity of flow. In this work, the apparent rheology of these solutions was investigated in three samples of digitally reconstructed rocks by means of images obtained from micro CT-scans. Macroscopic flow simulations were applied through network modeling methods (Pore Network Modeling, PNM), rather than direct numerical simulation (e.g.: Finite Element Method) because of the high computational cost of the last approach. The non-Newtonian behavior of polymer solutions was described with power-law viscosity model and were compared to apparent rheology models from literature such as modified Blake-Kozeny. The effect of viscosity on percolation was evaluated by checking the ratio of pores and throats that participated in the flow. The equivalent viscosity based on Darcy s Law was compared to curves obtained by rheometry and, at the end, the adjustable factor alpha, which predicts the fluid apparent rheology, was calculated.