The five-year long United Nations campaign for the reduction of greenhouse gases in the atmosphere culminated in the Kyoto protocol of 1997. Since this Kyoto conference attended by nearly 160 nations, sequestration of carbon dioxide from industrial flue gases and its storage and/or utilization have been receiving significantly enhanced attention. According to the US Department of Energy, very little research and development has been done in the United States on promising options that might address CO2 capture, reuse and storage technologies. An exception to this is the utilization of CO2 for enhanced oil recovery. Over a decade of industrial experience has accumulated at more than 70 enhanced oil recovery sites around the world where CO2 is injected to improve oil recovery from waterflooded reservoirs. The accumulated experience in the US, where about 32 million tons of CO2 per year are being utilized in EOR, has amply demonstrated that the retention of CO2 in the reservoir is very high when the original pressure is not exceeded. Thus, CO2 injected enhanced oil recovery presents itself as a mature field-tested technology for sequestering CO2 at a low net cost due to the revenues from recovered oil and gas.
Much of the CO2-EOR experience to date in the US involves the use of high-purity carbon dioxide for conducting miscible floods in conventional crude oil reservoirs. Due to the high costs associated with supplying high-purity CO2 to the reservoir, this process has seen limited commercial success. However, the past research at LSU and elsewhere has amply demonstrated that impure CO2 was also effective in enhancing oil recoveries. This makes the abundant supply of flue gases from fossil-fuel combustion operations a viable and cost-effective option without the need for separating CO2 from the flue gas mixtures. This paper attempts to review and synthesize the literature dealing with geologic sequestration of CO2 in EOR projects. The available data are analyzed both from EOR and CO2 sequestration points of view.