HR: 1340h
AN: B33A-1010    [Abstracts]
TI: Potential of Basalt Aquifers for the Permanent Sequestration of Anthropogenic Carbon Dioxide
AU: * Matter, J M
EM: jmatter@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Geoscience 105B 61 Route 9W, Palisades, NY 10964 United States
AU: Goldberg, D S
EM: goldberg@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Borehole Research 61 Route 9W, Palisades, NY 10964 United States
AU: Takahashi, T
EM: taka@ldeo.columbia.eu
AF: Lamont-Doherty Earth Observatory, Geoscience 105B 61 Route 9W, Palisades, NY 10964 United States
AB: Injection of anthropogenic CO₂ into deep geological formations is one of the promising storage techniques being considered. The retention time and environmental safety of the CO₂ storage depend on the chemical reactions between the injected CO₂, the reservoir fluid and the host rocks. The pH buffer capacity of aquifer fluids and the acid neutralization potential of the reservoir rocks are important factors for stabilization of the injected CO₂. Mafic rocks such as basalt, which are made primarily of silicate minerals of Mg, Ca, Fe and Al, provide earth-alkaline metals (Ca²⁺, Mg²⁺), which neutralize carbonic acid and form solid carbonate phases. The carbonate minerals thus formed sequester CO₂ in a chemically stable and environmentally benign form. We explore the scientific and technical potential of deep basalt formations for long-term storage of CO₂ as an alternative to the more common sedimentary reservoir rocks. The significant global storage capacity onshore as well as offshore located on the major mid-oceanic ridges and the high potential for secure and permanent sequestration as stable (Ca, Mg, Fe)CO₃ minerals demonstrate the importance of basalt as a potential sequestration target. To better understand this carbon sequestration scheme in an industrial scale, dissolution / precipitation reactions and reactions rates must be evaluated by in situ experiments in the field. We have carried out short-term, small-scale CO₂ injection experiments as single-well push-pull tests within a diabase sill using a 1000 ft deep experimental borehole on the Lamont campus. CO₂-saturated water (PCO₂ of 20 atm) was injected into a hydraulically isolated interval first, and fluid samples were retrieved by pumping several days after the injection to monitor the release rate of earth-alkaline metals under natural conditions. First order reaction rates have been established and the field results will be compared with the results of the laboratory experiments. Their implication for CO₂ sequestration within basaltic rocks will be discussed.
DE: 0428 Carbon cycling (4806)
DE: 1011 Thermodynamics (0766, 3611, 8411)
DE: 1012 Reactions and phase equilibria (3612, 8412)
DE: 3612 Reactions and phase equilibria (1012, 8412)
SC: Biogeosciences [B]
MN: Fall Meeting 2005