Only about 25% of the ultimate oil resources world wide have been produced so far. Since the chances of discovering new giant fields are getting lower and lower, current research focuses on improving recovery from already explored reservoirs in the most efficient way possible. To achieve this goal, enhanced oil recovery methods (EOR) are essential. One EOR method is flooding the reservoir with viscous polymer solutions to achieve a favourable mobility ratio thus getting a better sweep. Heterogeneous reservoirs are good candidates for polymer flooding because their high variability in permeability promotes early water breakthrough and bypassed oil. In this work, the effects of the chemical and physical properties on sweep are investigated. The practical part is a simulation study conducted with a commercial reservoir simulation package. Two-dimensional heterogeneous models have been created with HYDRO_GEN, a program for the generation of spatially distributed fields of permeability. On those two models, sensitivity analyses have been performed and compared: a waterflood, polymer floods with different polymer concentrations and polymer floods with different slug sizes. The results have been compared regarding their effectiveness and sweep. Results establish how polymer concentration and slug size influence the onset of viscous fingering and sweep efficiency in heterogeneous reservoirs.