Synthesis, characterization and application of MNDEAS, an amphiphilic hydrophilic head-based single-tailed surfactant for chemical oil recovery

Surfactant oil recovery is an effective method to enhance oil recovery. A series of anionic-nonionic surfactants, known as MNDEAS, were synthesized using dimethyl maleate, long-chain amines (C12, C14, C16, C18), diethanolamine, and sodium bisulfite to address the issues of unsuitable surfactants under harsh reservoir conditions and reduced efficiency due to excessive adsorption in the reservoir. The structure was analyzed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance hydrogen spectroscopy ( 1 HNMR). The surface tension, interfacial tension, wettability, emulsification, Zeta potential, adsorption, temperature and salt resistance, as well as oil recovery efficiency of surfactants were studied. The results showed that MNDEAS surfactants were successfully synthesized. Among them, MNDEAS-12 has the best surface-active performance, which can still reduce the oil-water interfacial tension to 10 −3 mN/m under 100,000 mg/g salinity and 120°C high temperature, its adsorption on minerals is only 1/4 of that of ionic surfactants, and it can improve the oil recovery degree by more than 15 %. This study provides a new idea for the synthetic design of surfactants for oil recovery and can promote the industrial application of anionic-nonionic surfactants.