Although significant efforts have been made in research areas related to Enhanced oil recovery (EOR) and the role of rock wettability alteration (WA) at reservoir conditions using chemicals, a comprehensive study of chemical EOR in terms of chemical classification is still a required. Generally, chemical compounds (CHCs) can contribute to further oil recovery in oil reservoirs through several mechanisms including interfacial tension (IFT) reduction and altering rock wettability mode. This paperwas examined the effect of different types of CHCs on EOR processes and various core flooding processes to increase the oil recovery efficiency.In this regard, a large domain of research reports was extensively reviewed by an in-depth analysis of various chemicals. Besides the application and limitations of chemicals, theareas of conflict and contradictory observations were also discussed. Also, their critical situation is highlighted, and the most promising potential methods were known.Surfactants (SURFs) are known to increase the water wetness of rock surface which leads to the higher relative permeability of the oil phase. Besides, the wetting states of the reservoir, also determine how fluids are dispersed in the pore space. Nanofluids (NFs) improve oil reservoir efficiency through a variety of methods, including a reduction in contact angle (CA), which changes the wettability from oil-wet (OW) to water-wet (WW). Smart and low salinity (LS)waterflooding (WF)are regarded as the very lowcost chemical flooding which is proposed for matured OW reservoirs,since it controls the salinity of injected water to improve oil recovery. Also, the field point of view about the economic feasibility of each type of chemical has been comprehensively discussed. The presented results could help the researchers to select the best CHC for EOR tests and minimizing any damage because of incompatibities. Since the oil recovery mechanisms are more complex in carbonate (CB) reservoirs, this manuscript gocus more on CB formation and the results for CHC injection are well tabulated for different reasons.
