Preparation and performance evaluation of a novel temperature-resistant anionic/nonionic surfactant

Aiming at oil extraction from a tight reservoir, the Jilin oil field was selected as the research object of this study. Based on the molecular structures of conventional long-chain alkyl anionic surfactants, a new temperature-resistant anionic/nonionic surfactant (C₈P₁₀E₅C) was prepared by introducing polyoxyethylene and polyoxypropylene units into double-chain alcohols. The resulting structures were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (¹H-NMR), and electrospray ionization mass spectrometry (ESI-MS). Then, based on surface tension, interfacial tension, adsorption resistance, wettability, and emulsification performance tests, the performance of C₈P₁₀E₅C was evaluated. The FT-IR, ESI-MS, and NMR spectra confirmed that C₈P₁₀E₅C was successfully prepared. The critical micelle concentration (CMC) of C₈P₁₀E₅C in water was 2.9510 × 10^-4 mol/L (the corresponding mass concentration is 0.26%), and the surface tension of the aqueous C₈P₁₀E₅C solution at this concentration was 30.5728 mN/m. At 0.3% concentration, the contact angle of the C₈P₁₀E₅C solution was 31.4°, which is 60.75% lower than the initial contact angle. Under high-temperature conditions, C₈P₁₀E₅C can still reduce the oil-water interfacial tension to 10^-2 mN/m, exhibiting good temperature resistance. At 110 °C, upon adsorption to oil sand, the C₈P₁₀E₅C solution could reduce the oil-water interfacial tension to 0.0276 mN/m, and the interfacial tension can still reach the order of 10^-2 mN/m, indicating that C₈P₁₀E₅C has strong anti-adsorption capability. Additionally, it has good emulsifying performance; upon forming an emulsion with crude oil, the highest drainage rate was only 50%. The forced imbibition oil recovery of C₈P₁₀E₅C is 65.8%, which is 38.54, 24.22, and 27.25% higher than those of sodium dodecyl benzene sulfonate, alkyl polyoxyethylene ether carboxylate, and alkyl ether carboxylate, respectively.