Pore-scale experiments on the synergistic EOR mechanisms between the main components of LASP (lipopeptide-alkali-surfactant-polymer) system

Abstract

To improve the oil recovery efficiency of ASP (alkali-surfactant-polymer) flooding, lipopeptide surfactant was added into ASP to form a new system (LASP). Core flooding experiments and field pilots suggested that LASP can achieve better oil recovery with lower costs. To determine the synergistic effects of the LASP system, a series of pore-scale flooding experiments were performed to quantify the displacement and sweep efficiencies of the LASP system and its main components independently. The results suggested that the petroleum sulfonate tends to improve displacement efficiency (by 21.1%) and the polymer tends to widen the effective sweep area (by 14.2%). While lipopeptide improved both oil displacement efficiency (31.2%) and sweep efficiency (10.2%) depending on the oil emulsification. Their mixture, that is; LASP, reached a higher displacement (42.1%) and sweep efficiency (12.9%) that depended on synergistic effects between the components. For instance, the bio- and chemical surfactants and the polymer synergistically improved the stability and deformability of oil emulsion, which reduce flow resistance and then improve displacement efficiency. However, the throat-blocking mechanism, which expanded sweep area during lipopeptide flooding, no longer existed in the LASP system. Nevertheless, the LASP system can depend on high viscosity of polymer to effectively expand sweep area. Oil recovery in the LASP system is more than the sum of the mechanism of each component.

Graphical Abstract

Keywords:

• EOR
• microscopic
• lipopeptide
• ASP
• synergistic mechanism

Acknowledgments

The authors are thankful to Daqing Refining & Chemical Company for providing samples.

Additional information

Funding

This work was supported by National Science and Technology Major Project under Grant [2017ZX05069-003].