Carbon dioxide (CO2) injection has proven to be one of the most efficient EOR methods since it was first tried in 1972 in Scurry County, Texas. Since then, CO2 injection has been used successfully throughout the Permian Basin of West Texas and eastern New Mexico (where about half of all the CO2 floods in the world are located), as well as in Louisiana, Mississippi, Wyoming, Oklahoma, Colorado, Utah, Montana, Alaska, and Pennsylvania.