1. Surfactants

Surfactants are critical for reducing surface and interfacial tension between oil and water. These compounds improve oil mobility and enhance displacement from reservoir rock.

• Anionic surfactants: Improve water wettability in oil-wet formations.
• Nonionic surfactants: Enhance emulsification and stability in various conditions.
• Cationic surfactants: Modify surface charges to aid oil release.

Surfactants play a significant role in chemical flooding, helping oil flow more freely to production wells.

2. Polymers

Polymers are used in water-based EOR methods to increase fluid viscosity, improving sweep efficiency and reducing water breakthrough.

• Partially hydrolyzed polyacrylamide (PHPA): Increases water viscosity to push oil through porous rock.
• Biopolymers (xanthan gum, guar gum): Offer high thermal stability and improve mobility control.

These agents help push oil toward production wells, preventing premature water breakthrough.

3. Alkaline Agents

Alkaline chemicals, such as sodium hydroxide (NaOH) and sodium carbonate (Na₂CO₃), react with acidic components in crude oil to form natural surfactants. These reduce oil-water interfacial tension and enhance recovery.

Alkaline flooding is often combined with surfactants and polymers (ASP flooding) for improved efficiency.

4. Emulsifiers

Emulsifiers stabilize the interaction between oil and water phases, ensuring uniform distribution of injected fluids. They are particularly useful in heavy oil recovery, where they prevent phase separation and enhance transport properties.

5. Demulsifiers

While emulsifiers help create stable mixtures, demulsifiers break water-in-oil emulsions to separate crude oil from water efficiently. Effective demulsification is crucial for processing and refining recovered oil.