Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

• Main Author: Schrag, Daniel P.
• Other Authors: United States. Department of Energy.
• Format: Report
• Language: English
• Published: Harvard College 2006
• Subjects: Sea Bed; Carbon Dioxide; Site Selection; Dissolution; Mathematical Models; Hydrates; Carbon Sequestration; Carbonic Acid; Calcium Carbonates; Economic Analysis; Permeability; 54 Environmental Sciences; Carbonic acid; North Atlantic
• Online Access: https://doi.org/10.2172/895621; https://digital.library.unt.edu/ark:/67531/metadc888490/

Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. The results of our modeling efforts were published this past summer in the Proceedings of the National Academy of Sciences. We are expanding on that work through a variety of laboratory and modeling efforts. In the laboratories at Columbia and at Harvard, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. We are currently preparing the results of these findings for publication. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but might also provide an upper seal in the sediment-pore fluid system, preventing release of CO{sub 2} into the deep ocean, particularly if depth and temperature at the injection point rule out immediate hydrate formation. This is done by injecting liquid CO{sub 2} into various types of porous media, and then monitoring the changes in permeability. Finally, we are performing an economic analysis to estimate costs of drilling and gas injection, site monitoring as well as the availability of potential disposal sites with particular emphasis on those sites that are within the 200-mile economic zone of the United States. We present some preliminary results from these analyses. A paper discussing the site selection based on data from the Ocean Drilling Program and Deep Sea Drilling Program is currently in preparation.