Constraints on the magnitude and rate of CO₂ dissolution at Bravo Dome natural gas field

Journal Article · Mon Oct 13 00:00:00 EDT 2014 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.1406076111· OSTI ID:1168277

Sathaye, Kiran J. ^[1]; Hesse, Marc A. ^[2]; Cassidy, M. ^[3]; Stockli, Daniel F. ^[1]

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1. Univ. of Texas, Austin, TX (United States). Jackson School of Geosciences, Dept. of Geological Sciences
2. Univ. of Texas, Austin, TX (United States). Jackson School of Geosciences, Dept. of Geological Sciences; Univ. of Texas, Austin, TX (United States). Inst. of Computational Engineering and Sciences
3. Univ. of Houston, TX (United States). Dept. of Earth and Atmospheric Sciences

The injection of carbon dioxide (CO₂) captured at large point sources into deep saline aquifers can significantly reduce anthropogenic CO₂ emissions from fossil fuels. Dissolution of the injected CO₂ into the formation brine is a trapping mechanism that helps to ensure the long-term security of geological CO₂ storage. We use thermochronology to estimate the timing of CO₂ emplacement at Bravo Dome, a large natural CO₂ field at a depth of 700 m in New Mexico. Together with estimates of the total mass loss from the field we present, to our knowledge, the first constraints on the magnitude, mechanisms, and rates of CO₂ dissolution on millennial timescales. Apatite (U-Th)/He thermochronology records heating of the Bravo Dome reservoir due to the emplacement of hot volcanic gases 1.2–1.5 Ma. The CO₂ accumulation is therefore significantly older than previous estimates of 10 ka, which demonstrates that safe long-term geological CO₂ storage is possible. Here, integrating geophysical and geochemical data, we estimate that 1.3 Gt CO₂ are currently stored at Bravo Dome, but that only 22% of the emplaced CO₂ has dissolved into the brine over 1.2 My. Roughly 40% of the dissolution occurred during the emplacement. The CO₂ dissolved after emplacement exceeds the amount expected from diffusion and provides field evidence for convective dissolution with a rate of 0.1 g/(m²y). Finally, the similarity between Bravo Dome and major US saline aquifers suggests that significant amounts of CO₂ are likely to dissolve during injection at US storage sites, but that convective dissolution is unlikely to trap all injected CO₂ on the 10-ky timescale typically considered for storage projects.

• Research Organization: Energy Frontier Research Centers (EFRC). Center for Frontiers of Subsurface Energy Security (CFSES)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Contributing Organization: CFSES partners with University of Texas at Austin (lead); Sandia National Laboratory
• Grant/Contract Number: SC0001114
• OSTI ID: 1168277
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Vol. 111, Issue 43; ISSN 0027-8424
• Publisher: National Academy of Sciences, Washington, DC (United States)
• Country of Publication: United States
• Language: English