- Copyright ©2008. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.
The Citronelle Dome is a giant, salt-cored anticline in the eastern Mississippi Interior Salt Basin of southern Alabama that is located near several large-scale, stationary, carbon-emitting sources in the greater Mobile area. The dome forms an elliptical, four-way structural closure containing opportunities for CO2-enhanced oil recovery (CO2-EOR) and large-capacity saline reservoir CO2 sequestration.
The Citronelle oil field, located on the crest of the dome, has produced more than 169 million bbl of 42–46° API gravity oil from sandstone bodies in the Lower Cretaceous Rodessa Formation. The top seal for the oil accumulation is a thick succession of shale and anhydrite, and the reservoir is underfilled such that oil-water contacts are typically elevated 30–60 m (100–200 ft) above the structural spill point. Approximately 31–34% of the original oil in place has been recovered by primary and secondary methods, and CO2-EOR has the potential to increase reserves by up to 20%.
Structural contour maps of the dome demonstrate that the area of structural closure increases upward in section. Sandstone units providing prospective carbon sinks include the Massive and Pilot sands of the lower Tuscaloosa Group, as well as several sandstone units in the upper Tuscaloosa Group and the Eutaw Formation. Many of these sandstone units are characterized by high porosity and permeability with low heterogeneity. The Tuscaloosa-Eutaw interval is capped by up to 610 m (2000 ft) of chalk and marine shale that are proven reservoir seals in nearby oil fields. Therefore, the Citronelle Dome can be considered a major geologic sink where CO2 can be safely stored while realizing the economic benefits associated with CO2-EOR.
Richard Esposito is a research geologist with Southern Company in Birmingham, Alabama, and holds an M.S. degree in geology from Auburn University and an M.S. degree in environmental management from Samford University. His research interests are electrical utility carbon capture-storage and CO2-enhanced oil recovery. Richard is a candidate to graduate with a Ph.D. in environmental health engineering from the University of Alabama at Birmingham, with emphasis on carbon management.
Jack Pashin heads the energy program at the Geological Survey of Alabama and holds a Ph.D. from the University of Kentucky. He has authored numerous publications on sedimentary geology, petroleum geology, and carbon sequestration. Jack has been an AAPG Distinguished Lecturer, serves on the AAPG Publications Committee, and is an associate editor of the AAPG Bulletin.
Peter Walsh is a research professor in the Department of Mechanical Engineering at the University of Alabama at Birmingham. His research interests are in control of emissions from combustion in electric utility boilers and industrial furnaces. Peter graduated from Cornell University in 1977 and has worked in combustion research groups at Sandia National Laboratories, Pennsylvania State University, Massachusetts Institute of Technology, and Princeton University.