The core scale heterogeneity is an important factor to account for enhanced oil recovery. The pore geometry and surface structure on the microscale were listed among the important factors, responsible for the different results from different rocks upon injection of low salinity brine. However, the core-scale heterogeneity has not drawn sufficient attention in the field of smart waterflooding, and its importance for the results of the flooding experiments has been overlooked. In this work we intend to find the evidence of the impact of heterogeneity on smart waterflooding under similar core flooding procedures. We have investigated smart waterflooding with homogeneous and heterogeneous carbonaceous cores from the North Sea reservoirs. Two processes have been tested: low salinity flooding with subsequent compression of a core, and injection of the brine containing bicarbonates. In both cases flooding of the heterogeneous cores resulted in a higher recovery than for the homogeneous cores.