This work has been established based on core flooding data and simulation modelling to investigate the low salinity waterflooding performance and its related mechanisms in carbonate and sandstone reservoirs. At first, the optimum water composition, ion exchange equivalent fractions, change in mineral moles, and effluent ion concentration have been studied and analysed on a core scale model. Optimum results of the core scale model were then upscaled for homogenous/ heterogeneous fractured and non-fractured five-spot pilot-scale models. An explicit study of the effect of multi-ion exchange and mineral dissolution/ precipitation was conducted. In addition, the double layer expansion phenomena were investigated implicitly. The LSWF mechanisms impact was found to be different for the different lithologies. The effluent ion analysis resulted in an increase in the produced Ca2+ ion concentration, evidence of mineral dissolution for the sandstone core. For the carbonate core, the reduction of the Ca2+ concentration resulted in mineral precipitation. Simulation results showed that the fractional adsorption of the Ca2+ ion in the carbonate core was higher than the sandstone, which led to lower recovery for the carbonate core. In the pilot-scale model, an increase in the potential determining ions (PDIs) were observed in the fractured/ non-fractured homogeneous reservoir, confirming the calcite and dolomite dissolution, which causes an increase in the pore volume. Results show that as the Cation Exchange Capacity (CEC) increases, the recovery reduces in the presence of clay since equilibrium requires time with the larger surface area. However, in the absence of clay, CEC has less influence on the recovery. Finally, based on the studied cores, multi-ion exchange was not the sole mechanism behind LSWF. It requires the support of other mechanisms such as mineral dissolution/ precipitation and double-layer expansion.