Enhanced Oil Recovery (EOR)

Carbon dioxide can be used to enhance oil recovery from oil fields.  This process is referred to as EOR. Conventional oil production has three phases – primary, secondary and tertiary:

• Primary recovery techniques typically enable a recovery of approximately 25% of a reservoir’s oil reserves. Recoverable oil is limited to the hydrocarbons that naturally rise to the surface or those recovered via an artificial lift device, like a pump jack.
• Secondary recovery begins when natural flow rates decrease. It involves injecting water or gas into the reservoir to displace the oil and drive it to the surface.
• Tertiary recovery is the stage where CO₂ can be used. It is particularly successful in fields with heavy oil or poor permeability. At this stage, steam, chemicals or gas (CO₂) can be injected into the reservoir to generate additional oil recovery.

CO₂ flooding for EOR is growing in popularity, and is acknowledged as being able to add an additional 5 to 12% of recoverable oil to an operation.

The Process:

CO₂ is injected into oil wells under supercritical conditions (high pressure and low temperature).  The CO₂ has three effects on the underground oil that lead to an increase in recoverable oil:

1. The CO₂ acts as a solvent, cleaning oil trapped in the microscopic pores of the reservoir rock.
2. The CO₂ also acts as a pressurizing agent pushing more oil out of the rock.
3. The CO₂ reduces the oil’s viscosity helping it flow easier.

EOR can create a market for CO₂ that can generate revenues that could play a vital part in contributing to the large capital investment that is required for Carbon Capture and Storage deployment.