Status of surfactant EOR technology

Surfactant enhanced oil recovery (EOR) includes surfactant flooding and surfactant stimulation. The main functions of surfactants are to reduce interfacial tension and wettability alteration. This paper is to review the EOR technology related to surfactant injection. The reviewed topics include the following:
• Surfactant EOR mechanisms
• Factors affecting interfacial tension
• Trapping number
• Screening criteria
• Laboratory work
• Numerical simulation work
• Summary of pilot and large-scale applications
• Surfactants used
• Salinity gradient
• Surfactant EOR in carbonate reservoirs
• Surfactant EOR in shale reservoirs