Surfactant and surfactant-polymer effects on wettability and crude oil liberation in carbonates

Surfactants and polymers are used in enhanced oil recovery (EOR) to reduce interfacial tension and increase the viscosity of displacing fluid, respectively. For oil-wet to mixed-wet systems, especially carbonates, which tend to be heavily fractured, wettability becomes a key parameter that strongly affects oil recovery. Therefore, studying the impact of surfactant and surfactant-polymer chemicals on carbonate wettability is important to understand the underlying mechanisms responsible for incremental oil recovery in surfactant-polymer flooding.