A novel high temperature tolerant and high salinity resistant gemini surfactant for enhanced oil recovery

A novel high temperature tolerant, high salinity resistant gemini surfactant for enhanced oil recovery was synthesized and is described in this paper. The molecular structure of the synthesized gemini surfactant (named ANG) was first confirmed by infrared (IR) spectroscopy and nuclear magnetic resonance (NMR). Various experiments were then carried out to investigate both the basic properties and the capacity for enhanced oil recovery of ANG. The surfactant ANG showed excellent surface activity (31.7 mN/m). The product ANG also exhibited better interfacial activity (7.81 x 10(-3) mN/m) than sodium dodecyl benzene sulfonate (SDBS) at 120 degrees C. Furthermore, an ultralow interfacial tension (8.75 x 10(-3) mN/m) was still achieved for the surfactant ANG when used in a high-salinity environment (total salinity: 20 x 10(4) mg/L, Ca2+ concentration: 5000 mg/L). The emulsification ability of ANG was stronger than that of TX-100, and the median particle size (d50) of the emulsion droplets for ANG was only 5.05 mu m. The surfactant ANG had a strong wetting reversal ability and could change the originally oil-wet surface (135 degrees) into a water-wet surface (balanced contact angle: 62 degrees). The oil recovery was improved by a reduction in the oil-water interfacial tension, wetting reversal of the core surface and the formation of an emulsion by the synthesized gemini surfactant. Due to the above mechanisms, oil recovery increased by 17.3% of original oil in place (OOIP) for the surfactant ANG. (C) 2019 Elsevier B.V. All rights reserved.