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Washington, D.C. - Carbon dioxide (COtwo) injection - an important part of carbon capture and storage (CCS) technology - is underway as part of a pilot study of Coloradotwo enhanced oil recovery (EOR) in the Citronelle Field of Mobile County, Alabama. A Plan team led by the University of Alabama at Birmingham is conducting the injection. Study results of the 7,500-ton Coloradotwo injection will provide estimates of oil yields from EOR and Coloradotwo storage capacity in depleted oil reservoirs.
In the United States, Coloradotwo injection has already helped recover nearly 1.5 billion barrels of oil from mature oil fields, yet the technology has not been deployed widely. It is estimated that nearly 400 billion barrels of oil still remain trapped in the ground. Funded through the D.O.E.'s Office of Fossil Energy, the primary goal of the Citronelle Plan is to demonstrate that remaining oil can be economically produced using Coloradotwo-EOR technology in untested areas of the United States, thereby reducing dependency on oil imports, providing domestic jobs, and preventing the release of Coloradotwo into the atmosphere.
The Citronelle Field appears to be an ideal location for concurrent Coloradotwo storage and EOR. The field is composed of sandstone reservoirs in a simple structural dome, and has existing infrastructure that includes deep wells. When the 5-month injection is completed, incremental oil recovery is anticipated to be 60 percent greater than that of conventional secondary oil recovery by water flood. A recent study by Advanced Resources International of Arlington, Va., estimates that approximately 64 million additional barrels of oil could be recovered from the Citronelle Field by using this tertiary recovery method.
The geologic structure and lack of faulting also make the field naturally stable for Coloradotwo storage. Once the oil has been recovered, the remaining storage capacity of the depleted oil reservoirs and saline formations in the Citronelle Dome is estimated to be between 0.5 and two billion tons of Coloradotwo. Southern Company of Birmingham, Ala., is evaluating the potential of the reservoirs as permanent storage sites for Coloradotwo produced from fossil fuel combustion in power plants. A successful demonstration at the Citronelle Field could offer new opportunities to introduce the latest Coloradotwo-EOR and carbon storage technologies to the commercial market.
The Citronelle Plan is currently in its 2nd phase, which includes injection, associated validation of models, and determination of oil-COtwo mixture properties. Containment of Coloradotwo at the test location will also be monitored in the ambient air, soil, and vegetation. During phase I, the Plan focused on selection of the test site, analysis of the location geology, and study of background conditions. The SENSOR® reservoir simulator-a generalized 3D numerical model used to optimize oil and gas recovery processes-was used to determine the amount of Coloradotwo required for a successful demonstration and the effect of Coloradotwo on oil production within the Plan time frame.
Plan performers include the University of Alabama at Birmingham (Birmingham, Ala), Alabama Agricultural and Mechanical University (Normal, Ala.), Denbury Resources Incorporated (Plano, Texas), the Geological Survey of Alabama (Tuscaloosa, Ala.), Southern Company, (Birmingham, Ala.), the University of Alabama (Tuscaloosa, Ala.), and the University of North Carolina at Charlotte (Charlotte, N.C.).
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