RECOVERY OF CRUDE OIL from U.S. domestic oil reservoirs typically involves three well-defined stages: primary, secondary and tertiary (or “enhanced”). In primary recovery, the natural pressure of the oil reservoir drives oil into the wellbore where, assisted by pumping equipment, the oil is brought to the surface. On average, approximately 10 percent of a reservoir’s oil is delivered in primary recovery while secondary recovery, which involves gas injection, water injection, gas lift, or in situ combustion, results in the recovery of another 20 to 40 percent.

Today, with much of the oil already recovered in older U.S. fields by primary and secondary methods, oil producers are concentrating their efforts on tertiary or enhanced oil recovery (EOR) techniques. And why not? The U.S. Energy Information Administration estimates that nearly 400 billion barrels of domestic oil is still recoverable.

One of the more notable, and most rapidly growing EOR techniques involves what are known as carbon dioxide “floods” – injecting carbon dioxide (CO₂) that expands in the oil reservoir, mixes with and thins the trapped oil and pushes it to a production wellbore.

According to the Western Research Institute, the overall U.S. crude oil production that could be recovered using CO₂ is estimated at 234,000 barrels a day, or five percent of domestic production. 
download complete story PDF→