Dimer acid used as CO2-responsive surfactant for reducing viscosity of heavy crude oil

Abstract

The efficacy of CO₂-switchable surfactants in reducing viscosity of heavy crude oil has received widespread attention due to its switchable surface activity for constructing reversible emulsion. However, the intricate synthesis processes of these surfactants pose a significant challenge in their practical application. The present investigation involved the preparation of surfactants that are responsive to CO₂, specifically dimer acid (DA)/tetramethylpropylenediamine (TMPDA), through a facile mixing approach. These surfactants were subsequently employed to mitigate the high viscosity of heavy crude oil. The study employed a surface tension meter to examine the surface behavior of DA/TMPDA, which demonstrated the potential for reducing viscosity. The study examined the CO₂ responsiveness of DA/TMPDA through the application of alternating CO₂ and N₂. It confirmed the reversible CO₂ responsiveness of the surface activator. The results from the emulsification and viscosity reduction assessments suggest that the amalgamation of DA and TMPDA in a 1:1 molar ratio yielded a surfactant. This surfactant demonstrated favorable stability in water and heavy crude oil emulsions, as well as low viscosity and rapid emulsion breaking upon exposure to CO₂. This investigation demonstrates that it is feasible to produce surfactants that are responsive to CO₂ and possess the ability to reduce viscosity through a straightforward mixing process. This presents a viable approach to utilizing oligomeric surfactants that are CO₂-responsive for the purposes of emulsifying and breaking down heavy crude oil.