Synthesis of alkylbenzenesulfonate and its behavior as flow improver in crude oil

Small molecule flow improver for heavy oil recovery has attracted great attention in oilfield chemistry. In this study, 24 alkylbenzenesulfonates were synthesized and evaluated as crude oil flow improvers. The results show that all of the alkylbenzenesulfonates were effective, the chromium alkylbenzenesulfonate (CrDBS) and zinc alkylbenzenesulfonate (ZnDBS) were found to have the best performance with the viscosity reduction rate of higher than 90%. Besides, the CrDBS and ZnDBS can depress the pour point of the crude oil sample by 21.0 °C and 16.0 °C, respectively. The co-crystallization of alkylbenzenesulfonate with the saturated hydrocarbons in the crude oil could disorder the wax crystals and depress the pour point. In addition, DSC was used to reveal the mechanism of viscosity reduction and pour point depressing by alkylbenzenesulfonates. The flow improver can disturb the formation of hydrogen bonds and the π-π interaction bonds among the polycyclic aromatic hydrocarbons and the resin macromolecules. Besides, the field test using ZnDBS confirmed its good performance and promising application potential in enhancing the heavy oil recovery.