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Title: Observational evidence confirms modelling of the long-term integrity of CO 2-reservoir caprocks

Storage of anthropogenic CO 2 in geological formations relies on a caprock as the primary seal preventing buoyant super-critical CO 2 escaping. Although natural CO 2 reservoirs demonstrate that CO 2 may be stored safely for millions of years, uncertainty remains in predicting how caprocks will react with CO 2-bearing brines. The resulting uncertainty poses a significant challenge to the risk assessment of geological carbon storage. We describe mineral reaction fronts in a CO 2 reservoir-caprock system exposed to CO 2 over a timescale comparable with that needed for geological carbon storage. Moreover, the propagation of the reaction front is retarded by redox-sensitive mineral dissolution reactions and carbonate precipitation, which reduces its penetration into the caprock to ~7 cm in ~10 5 years. This distance is an order-of-magnitude smaller than previous predictions. The results attest to the significance of transport-limited reactions to the long-term integrity of sealing behaviour in caprocks exposed to CO 2.
Authors:
 [1] ; ORCiD logo [2] ; ORCiD logo [3] ;  [2] ;  [4] ;  [5] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [9] ;  [9]
  1. Shell Global Solutions International, Rijswijk (Netherlands); Univ. of Cambridge (United Kingdom)
  2. Shell Global Solutions International, Rijswijk (Netherlands)
  3. RWTH Aachen Univ. (Germany)
  4. Univ. of Utrecht (Netherlands)
  5. Julich Research Centre (Germany)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. British Geological Survey, Nottingham (United Kingdom)
  8. Utah State Univ., Logan, UT (United States)
  9. Univ. of Cambridge (United Kingdom)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; NE/F004699/1; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; carbon storage; SANS; pore size distribution; reactive transport
OSTI Identifier:
1279389