The flow of brine through porous rocks is a common phenomenon in nature and industry. Reactive species of the brine and rock minerals interact with each other during the brine flow. These interactions include precipitation, dissolution, and ion exchange at the rock surface. In the present paper, PHREEQC geochemical package has been used to study the impact of ion exchange in the brine-rock interaction systems. The PHREEQC batch-reaction was employed for modeling the static systems and a geochemical-transport approach was used for modeling the geochemical reactions in the dynamic systems (core-flooding). The impact of ion exchange on effluent concentrations of the reactive species and mass variation of the rock minerals was studied for both sandstone and carbonate rocks. This paper provides an extensive study to achieve more insight into the ion exchange at the rock surface and its impact on the porosity of the porous media. The modeling study shows that the higher ion exchange intensifies the dissolution of the reacting rock minerals. Increasing the exchanger site extends the injection time required to stabilize the system. In addition, it is observed that increasing the salinity of the injected brine weakens the impact of ion exchange on the effluent concentration of the reactive species. The results of this study indicate that during injection of high salinity seawater into a carbonate rock 10% of the porosity enhancement is caused by ion exchange, while 92% of the porosity enhancement is due to the ion exchange when injecting 50 times diluted seawater.