One-pot Synthesis and Static Bulk Foam Studies of C₁₈-conjugated Zwitterionic Surfactant

This study reports a one-pot-synthesis of C₁₈-conjugated zwitterionic surfactant, linolyel dimethyl amidopropyl betaine (Lino-DAB) for application in oil and gas industry. The synthesis proceeded with the direct thermo-condensation of N,N-dimethyl-1,3-propandiamine with C₁₈-polyunsaturated omega-6 fatty acid (linoleic acid) and subsequent treatment with sodium chloroacetate. The structure of the (Lino-DAB) products (19 g) was identified by ¹H-NMR and FTIR experiments and by comparing with the other long chain zwitterion surfactants from the literature. The static bulk foam tests in the absence and presence of crude oil under range of reservoir conditions (0 - 3.5 % salinity and 25 - 90 °C temperature) were conducted, the results indicated that the high salinity and presence of crude oil were detrimental to the foamability of the Lino-DAB (0.2 %) at ambient condition (25 °C), but the foamability were significantly improved at the higher temperature (60 - 90 °C). Similarly, the Lino-DAB exhibits viscoelastic properties in brine solutions and has the ability to retain its viscosity by 10% at 90°C. Thus, this study demonstrates that Lino-DAB surfactant could have a potential application to enhance oil recovery particularly in foam assisted flooding.