CO2 flooding is one of an arsenal of enhanced oil recovery (EOR) methods used to wring oil from older fields. Thermal strategies, such as steam injection, are popular in low-gravity oils. Injections of CO2 or nitrogen work with lighter gravities. At present, some 643,000 barrels of oil a day are pumped from EOR projects in the U.S. That’s down from peak levels achieved in 1992, when 761,000 barrels were made each day. The drop comes from the decline in oil produced from thermal methods, which has fallen from 480,000 barrels a day in 1986 to around 273,000 a day in 2008. The method on the rise is CO2 miscible flooding. Its production has been growing steadily, and volumes reached 240,000 barrels a day in 2008, a tenfold increase from 28,000 barrels a day in 1986. In addition to its efficacy as an oil-recovery technology, CO2 flooding can deliver tremendous environmental benefits. That’s because CO2 can be sequestered in depleted oil reservoirs. Indeed, old oilfields could be used to permanently store considerable volumes of CO2 beyond those needed for oil recovery. It’s an area where the expertise of the oil industry intersects with the world’s growing desire to reduce levels of CO2 emitted to the atmosphere. --by Peggy Williams, Senior Exploration Editor, Oil and Gas Investor