The injection of carbon dioxide (CO2) to enhance oil recovery (EOR), a key component of carbon capture and storage (CCS) technology, is undergoing a mid-scale study at the Citronelle field in Mobile County, Alabama, on March 2, 2010. The University of Alabama-led project team is working on an injection of 7,500 tons of CO2 that will provide real-world data on enhanced oil recovery and CO2 storage capacity from depleted reservoirs.

      In the United States, carbon dioxide (CO2) injection has helped recover nearly 1.5 billion barrels of oil from some mature fields as of February 2010, but the technology has not yet been widely deployed. It is estimated that up to 400 billion barrels of oil could still be collected from the ground.

      The primary objective of the Citronelle project, funded by the Department of Energy's Office of Fossil Energy, is to demonstrate the economics of CO2 enhanced oil recovery (EOR) production in untested areas of the United States.

      The Citronelle field is an ideal location for CO2 sequestration and enhanced oil recovery (EOR). The field consists of sandstone deposits in a single structural field and the existing infrastructure contains deep Wells. When the five-month injection is completed, it is expected to provide a 60 percent increase in oil recovery compared to conventional secondary recovery using water injection. A study by Advanced Resources International of Arlington, Va., estimates that an additional 64 million barrels of oil could be recovered from the Citronelle field using the triple-recovery technology.

      The geological structure and few faults also allow the field to be used for natural and stable CO2 sequestration. Once the oil is recovered, the remaining storage capacity of the depleted oil reservoir and the brine formation formed during the Citronelle field validation is estimated to be between 500 million and 2 billion tons of CO2. Southern Company of Birmingham, Ala., is evaluating these stores as permanent stores of CO2 from the burning of fossil fuels in some power plants. The successful validation of the Citronelle field will provide opportunities for new CO2-EOR and carbon sequestration applications in the commercial market.

      The Citronelle field validation project was a two-phase project that included model-related CO2 injection and the determination of the properties of the oil-CO2 mixture. The CO2 tolerability of air, soil, and new plants at the site will also be monitored. The SENSOR storage simulator is a three-dimensional model applied to optimize the oil and gas recovery process to determine the amount of CO2 required for successful verification and the impact of CO2 on oil production over the time period of the project.

      Participants in the project include the University of Alabama in Birmingham, Alabama Agricultural and Mechanical University, Denbury Resources, Alabama Geological Survey, Southern Company in Birmingham, the University of Alabama in Tuscaloosa, and the University of North Carolina at Charlotte.