Arizona State Geologist Lee Allison points out on his blog that a new study commissioned by the U.S. Chamber of Commerce says more oil can be recovered from existing wells by using carbon dioxide enhanced production. The Chamber report says that carbon dioxide based enhanced oil recovery (CO2 EOR) accounts for nearly 6% of U.S. onshore oil production, or 350,000 barrels a day, but it could be expanded to produce a potential of 4 million barrels a day of oil for 50 years from existing U.S. oil fields.
Much of the carbon dioxide could come from Arizona. In my post: Helium potential of Arizona may help fill shortage I point out that “Some of the richest helium-bearing gas in the world was produced from fields completed specifically for helium in northeastern Arizona in the 1960s and 1970s.” Carbon dioxide is a major byproduct of helium production.
According the Chamber report, CO2 EOR could produce almost as much oil as primary or secondary production.
“In the first phase of the oil field’s productive life, called primary production, the well is produced without the addition of anything to the oil containing formation. The natural pressure from the earth is the mechanism for the oil to flow to the wellbore. Depending on the characteristics of the rock formation, primary production can result in the recovery of up to 20% of the oil originally in the rock. This means that at least 80% of the oil may remain in the rock unless additional technology is used to increase the recovery.
“Usually, the next step in the oil field life cycle is the injection of water into the oil-bearing formation to maintain reservoir pressure, which produces more oil… This is called secondary recovery or water flooding. The water used for this step is largely recycling the water that is produced as part of the oil production operations. Water, typically saltwater, exists in the formation with the oil and natural gas. This water is separated and collected during production and reinjected into the oil-bearing formation to slow pressure decline. As oil fields age, they produce more water as a percentage of the total fluids recovered. The addition of secondary recovery has the potential to recover a further 15% to 20% of the original oil in place.
“Even after primary and secondary recovery, a significant amount of oil still exists in the rock formation. CO2 EOR is a type of tertiary oil recovery that can recover even more oil from these existing wells and reservoirs. In CO2 EOR, carbon dioxide is pumped into the oil-bearing rock formation to recover even more oil. CO2 EOR has the potential to recover an additional 15% to 20% of the original oil.”
The Chamber report goes on to explain how the CO2 EOR process works:
“The CO2 EOR process is primarily a function of how CO2 interacts with oil which is determined by the property of miscibility, when multiple liquids can mix together completely becoming one homogenous liquid. For example, water and vinegar are completely miscible. By contrast, water and oil are immiscible; they do not combine at any proportion. CO2 at a supercritical pressure and temperature is completely miscible with oil; it will combine completely.
“An analogous example of how this process works in oil production could be a frying pan coated in grease. When the pan is rinsed with water, some of the oil remains because oil and water are immiscible. If a solvent, such as dish soap, is applied to the pan, the solvent combines with the grease and the grease is more completely removed from the pan. In CO2 EOR, the CO2 combines with the oil and helps move it through the rock pore spaces, enabling greater recovery of the oil in place.”
A 2011 Department of Energy report estimates that CO2 EOR could provide 137 billion barrels of additional technically recoverable domestic oil, of which 67 billion barrels are economically recoverable at an oil price of $85 per barrel.
Kinder Morgan is carrying out an expanded evaluation program of the St. Johns field in preparation for producing CO2 and shipping it east via pipeline.