CO₂-mineral reaction in a natural analogue for CO₂ storage-implications for modelling

Wilkinson, M., Haszeldine, R.S., Fallick, A.E., Odling, N., Stoker, S.J. and Gatliff, R.W. (2009) CO₂-mineral reaction in a natural analogue for CO₂ storage-implications for modelling. Journal of Sedimentary Research, 79(7), pp. 486-494. (doi: 10.2110/jsr.2009.052)

Abstract

Geochemical models of CO₂ injection into reservoir sandstones often predict the growth of minerals that will permanently store the CO₂ in solid form, and injection experiments record significant fluctuations in porewater chemistry on a short time scale. Yet the proportion of CO₂ reaction may be small, even over geological time scales. A southern North Sea (UK) gas accumulation with a high natural CO2 content (c. 50%) forms a natural analogue to engineered storage, and provides a calibration point for geochemical models of CO₂-rock reaction. In the analogue site, the carbonate mineral dawsonite has formed in only trace amounts (0.4 ± 0.3% solid volume) despite exposure to high levels of CO₂ for 50 Myr or more. It is calculated that only 2.4 (± 0.9)% of the CO₂ present within the structure is currently locked up as dawsonite, and a similar quantity in solution in the porewaters. Comparison of stable O and C isotopes with a neighbouring field with low CO₂ content gas suggests that up to 0.7 (± 2)% solid volume dolomite cement is associated with the CO₂ charge, equivalent to 0-25% of the total CO₂. The remaining 70-95% of the CO₂ is present as a free phase, after tens of millions of years. Consequently, geological storage of anthropogenic CO₂ in reservoirs similar to the Rotliegend Group must rely on physical containment and not mineral sequestration. The Rotliegend Group is still and excellent candidate for a CO₂ storage reservoir, though using physical trapping mechanisms and not chemical ones.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fallick, Professor Anthony
• Authors: Wilkinson, M., Haszeldine, R.S., Fallick, A.E., Odling, N., Stoker, S.J., and Gatliff, R.W.
• Subjects: Q Science > QE Geology; G Geography. Anthropology. Recreation > GE Environmental Sciences
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Journal of Sedimentary Research
• Publisher: Society for Sedimentary Geology
• ISSN: 1527-1404