Preparation and performance evaluation of sulfate-quaternary ammonium Gemini surfactant

Abstract

Sulfate-quaternary ammonium amphoteric Gemini surfactants with hydrophobic chains (C12ZGS, C14ZGS and C16ZGS) were prepared using formic acid, formaldehyde, long-chain tertiary amine, epichlorohydrin, chlorosulfone and NaOH. Their structures were characterized by IR and 1H NMR, and the synthesized target products was confirmed. The critical micelle concentrations (CMCs) of C12ZGS, C14ZGS and C16ZGS were 5.4 × 10−4 mol/L, 3.1 × 10−4 mol/L and 2.8 × 10−4 mol/L, respectively. Their corresponding surface tensions were 28.62 mN/m, 30.98 mN/m and 32.45 mN/m. It was found that the surface tension increases with increasing hydrophobic chain length. The three Gemini surfactants have good emulsifying and foaming properties for kerosene, and they have good solubility at low temperature. The results of thermogravimetric analysis (TGA) showed that the decomposition temperatures of C12ZGS, C14ZGS and C16ZGS were 153 °C, 157 °C and 150 °C, respectively. The salinity resistance of C12ZGS reached 4 × 104 mg/L, C14ZGS reached 5 × 104 mg/L, and the salinity resistance of C16ZGS was worst. C12ZGS and C14ZGS can reduce the oil–water interfacial tension to 10−2 orders of magnitude, but C16ZGS can only reduce it by 10−1 orders of magnitude. The stability of the surfactant flooding system was evaluated by aging time. Under the simulated reservoir formation environment, three amphoteric Gemini surfactants with different chain length (C12ZGS, C14ZGS, C16ZGS) can enhance oil recovery by 11.63%, 10.91% and 9.87% respectively.