Abstract This paper describes experimental work to study the impact of longitudinal heterogeneity of porous medium (in terms of permeability) on the efficiency of ASP flooding that has been practiced in Enhance Oil Recovery (EOR). EOR becomes increasingly important as the globally proved crude oil reserves are being depleted. Chemical flooding is one of the tools to increase recovery; however, is still an active area for integrated research as it involves geochemistry, pore structure, microemulsion, fluid flow and chemical transport in porous media. This present study is based on the use of carefully designed heterogeneous sand packs and monitors the effect of heterogeneity on the enhanced oil recovery by ASP slug. Oil recovery measurements were made based on mass measurements. Results include the chemical profiles and its relation to EOR. The results indicate that longitudinal heterogeneities can impact EOR and the flooding of ASP slug from lower-to-higher permeability transition can mitigate the heterogeneity influence on EOR. In this experimental investigation, an enhancement of 5% (Original Oil in Place) was found when the ASP flood goes from lower-to-higher permeability transition as compared to that from higher-to-lower permeability transition. This finding can be of great importance to operators interested in implementing ASP floods.