Stabilization and performance of a novel viscoelastic N2 foam for enhanced oil recovery

A novel viscoelastic N-2 foam (0.12% sodium dodecyl sulfate + 0.18% erucyl dimethyl amidopropyl betaine) with ultra-low interfacial tension and alkali-free was developed. With the conditions of Xinjiang Oilfield (45 degrees C, c (salinity) = 7880 mg/L), the foam performances were investigated by the modified Rose-Miles method. The modified Rose-Miles method is in non-shear action, in which N-2 enters a porous media and pumps into the solution to produce foam. The stability mechanism was explained based on the dilatational surface viscoelasticity and liquid viscoelasticity. The EOR effect was evaluated by the displacement experiment. The results showed that the foam volume of viscoelastic N-2 foam was five times compared with the initial solution. The foam half-life and the drainage half-life were 6.5 and 6.2 times higher compared with that of stabilized by the polyacrylamide, respectively. The surface of N-2 foam possessed high elasticity modulus, and the solution had high viscoelasticity, so the particle size and drainage of liquid film changed slowly. Finally, the viscoelastic N-2 foam flooding (0.4PV surfactant + 0.4PV N-2) enhanced oil recovery by 22.95%, compared with the surfactant flooding (0.8PV surfactant) by 4.06%. The viscoelastic N-2 foam could greatly reduce the amount of surfactant and had an excellent EOR application in the Xinjiang Oilfield. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A novel viscoelastic N-2 foam with ultra-low interfacial tension and alkali-free was developed and showed excellent foam performance and enhanced oil recovery (EOR) effect in Xinjiang Oilfield. The foam's volume, stability, and oil displacement efficiency were significantly better than conventional methods in the study.