A mechanism study of sodium dodecylbenzene sulfonate on oil recovery: effect of branched chain structure

The effects of the branched structures of SDBS molecules on oil recovery are investigated by molecular dynamics method. The relative density of oil molecules shows that SDBS molecule with benzene ring located near the center of alkyl chain has the best effect on oil displacement. Dynamic trajectories show that the water and SDBS molecules gradually occupy the calcite surface and replace the oil droplets. In this process, more water molecules gather nearby the polar groups of SDBS, indicating that the polar group has a significant effect on the water infiltration and the formation of water channels. Contact angle between SDBS molecule and calcite surface indicates that compared to straight chains, the branched structure tends to spread on the calcite interface. Moreover, adsorption energies of the simulation systems further prove that as the aromatic ring is closer to the middle of the alkyl chain, the oil displacement effect is better.

Experimental Study on the Physical Performance and Flow Behavior of Decorated Polyacrylamide for Enhanced Oil Recovery

With the rapid growth of energy consumption, enhanced oil recovery (EOR) methods are continually emerging, the most effective and widely used was polymer flooding. However, the shortcomings were gradually exposed. A novel decorated polyacrylamide might be a better alternative than polymer. In this work, the molecular structure and the properties reflecting the viscosity of decorated polyacrylamide, interfacial tension, and emulsification were examined. In order to better understand the interactions between decorated polyacrylamide and oil as well as the displacement mechanism, the displacement experiment were conducted in the etched-glass microscale model. Moreover, the coreflooding comparison experiments between decorated polyacrylamide and polymer were performed to investigate the displacement effect. The statistical analysis showed that the decorated polyacrylamide has excellent characteristics of salt tolerance, viscosity stability, and viscosification like polymer. Besides, the ability to reduce the interfacial tension in order 10−1 and emulsification, which were more similar to surfactant. Therefore, the decorated polyacrylamide was a multifunctional polymer. The displacement process captured by camera illustrated that the decorated polyacrylamide flooded oil mainly by means of ‘pull and drag’, ‘entrainment’, and ‘bridging’, based on the mechanism of viscosifying, emulsifying, and viscoelasticity. The results of the coreflooding experiment indicated that the recovery of decorated polyacrylamide can be improved by approximately 11–16% after water flooding when the concentration was more than 800 mg/L, which was higher than that of conventional polymer flooding. It should be mentioned that a new injection mode of ‘concentration reduction multi-slug’ was first proposed, and it obtained an exciting result of increasing oil production and decreasing water-cut, the effect of conformance control was more significant.