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Title: Observational evidence confirms modelling of the long-term integrity of CO2-reservoir caprocks

Storage of anthropogenic CO2 in geological formations relies on a caprock as the primary seal preventing buoyant super-critical CO2 escaping. Although natural CO2 reservoirs demonstrate that CO2 may be stored safely for millions of years, uncertainty remains in predicting how caprocks will react with CO2-bearing brines. The resulting uncertainty poses a significant challenge to the risk assessment of geological carbon storage. We describe mineral reaction fronts in a CO2 reservoir-caprock system exposed to CO2 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 ~105 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 CO2.
 [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
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
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
54 ENVIRONMENTAL SCIENCES; carbon storage; SANS; pore size distribution; reactive transport
OSTI Identifier: