Enhanced Oil Recovery (EOR)

Enhanced Oil Recovery (EOR)

Enhanced Oil Recovery (EOR)

Enhanced oil recovery (EOR), also known as Tertiary Recovery, is a crucial process used to extract additional oil from reservoirs after primary and secondary recovery techniques. It involves advanced methods to increase reservoir pressure or improve oil mobility for better extraction.

Target of EOR for Different Crude Oil Systems.

Enhanced Oil Recovery Techniques

1. Thermal Injection

   • Steam Flooding: The most commonly used method, especially in shallow reservoirs with high-viscosity crude oil. Steam is injected to heat the oil, lowering its viscosity and enhancing flow.
   • Cyclic Steam Stimulation: Uses a single well for both steam injection and oil production.
   • Fire Flooding: A high-oxygen gas mixture is injected and burned to create a combustion front, heating the reservoir.

   

2. Chemical Injection

   • Polymer Flooding: Long-chain polymers are mixed with water to increase viscosity, improving the mobility ratio between water and oil, and enhancing sweep efficiency.
   • Caustic Flooding: Sodium hydroxide (NaOH) is added to the injection water, reducing surface tension and mobilizing oil.
   • Surfactant Injection: Surfactants reduce interfacial tension, allowing oil droplets to flow more easily through the reservoir.

   

3. Gas Injection

   • CO₂, Nitrogen, or Natural Gas Injection: Injected gases expand in the reservoir to push oil toward production wells or dissolve in the oil to reduce viscosity and improve flow.
   • Water-Alternating-Gas (WAG): Combines gas and water injection for improved oil recovery by maintaining pressure and increasing oil mobility.

   

Summary of EOR Advantages and Disadvantages

• Thermal Injection
  • Advantages: Cost-effective, environmentally friendly, and easy water availability.
  • Disadvantages: Requires handling of large water volumes, potential damage to well structures.
• Chemical Injection
  • Advantages: Enhances oil recovery through improved mobility ratios and wettability changes.
  • Disadvantages: High costs, potential scaling, corrosion, and polymer degradation.
• Gas Injection
  • Advantages: High recovery potential, widely available CO₂, and improves oil mobility.
  • Disadvantages: CO₂ storage, equipment corrosion, and risk of leaks affecting safety and operations.

Summary of Screening Criteria for EOR Methods