A thermal-stable and salt-tolerant biobased zwitterionic surfactant with ultralow interfacial tension between crude oil and formation brine

A thermal-stable and salt-tolerant biobased zwitterionic surfactant N, N-Dimethyl-N-[2-hydroxy-3-sulfo-propyl]-N'-phenyloctadecanoyl-1, 3-diaminopropane (SPODP) was successfully obtained from modification of oleic acids which can be regenerated from waste cooking oils, and its structure was characterized using GC-MS, ESI-MS and H-1 NMR approaches. The biobased zwitterionic surfactant demonstrated a strong interfacial activity at high salinity and high temperature conditions at a very low surfactant dosage in formation brine. The ultralow interfacial tension (<= 10(-3) mN/m) between crude oil and brine was reached at 0.5 g/L in brine with a wide range compatibility of NaCl up to saturation, Ca2+ up to 500 mg/L, and temperature up to 95 degrees C. Meanwhile, it also exhibited strong wetting ability and resistance against adsorption on sands. All the results from this study suggest that the biobased zwitterionic surfactant is promising over varieties of traditional surfactants in applications in alkali free systems in enhanced oil recovery (EOR).