Application of Ultrashort Hydrophobe Surfactants with Cosolvent Characters for Heavy Oil Recovery

A new class of ultrashort hydrophobe surfactants with cosolvent characters was investigated as a sole additive to conventional polymer flooding for heavy oil recovery. No alkali was used for emulsification. The surfactants were composed of a short hydrophobe (phenol in this research) extended by propylene oxide (PO) and ethylene oxide (EO) units to achieve a sufficient level of surface activity and aqueous stability: phenol-xPO-yEO. Results are presented for the selection of ultrashort hydrophobe surfactants, aqueous stability, emulsion phase behavior, and oil displacement through a glass-bead pack at 368 K. Results show that 2 wt % phenol-4PO-20EO was able to reduce the interfacial tension between oil and NaCl brine to 0.39 dyn/cm, in comparison to 11 dyn/cm with no surfactant, at 368 K. Water flooding, 40 cp polymer flooding, and surfactant-improved polymer flooding were conducted for displacement of 276 cp heavy oil through a glass-bead pack that represents the clean-sand facies of a heavy oil reservoir in Alberta, Canada. The oil recovery after 2.0 pore volumes of injection (PVI) was 84% with the surfactant-improved polymer flooding, which was 54 and 22% greater than the water flooding and the polymer flooding, respectively. Results suggest a new opportunity of enhanced heavy oil recovery by adding a slug of one nonionic surfactant with cosolvent characters to conventional polymer flooding.