Surfactants usage in enhanced oil recovery operations coupling harsh reservoir conditions: an experimental review

Surfactant enhanced oil recovery (EOR) technique remains a prominent approach in producing residual oil after primary and secondary recovery schemes. The success of this method is reliant on two main mechanisms; interfacial tension (IFT) reduction and rock wettability modification. Nonetheless, effective implementation of the surfactant EOR technique is challenging given the recovery mechanisms and influencing factors involved. This calls for an in-depth understanding of the aforesaid mechanisms and factors, an area this review seeks to explore and provide valuable insights. By grasping these concepts, an efficient surfactant flooding project can be designed and executed to augment oil recovery. First, the review discusses various surfactant types and their performance in different formations. Also, the surfactant recovery mechanisms and associated processes such as phase behavior and adsorption have been extensively presented in this paper. Additionally, the review touched on the surfactant EOR process in high-temperature high-salinity environments as most reservoirs suitable for surfactant EOR operation are marked by these harsh conditions. Furthermore, the experimental study of surfactant blends through coreflooding, and spontaneous imbibition tests were outlined. This broad review will equip engineers and professionals with a solid mastering of surfactant EOR operation and also lay a strong foundation for the planning and execution of field-scale chemical-assisted operations.