title: Observational evidence confirms modelling of the long-term integrity of CO2-reservoir caprocks.
abstract: 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. This uncertainty poses a significant challenge to the risk assessment of geological carbon storage. Here 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. 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 CO2.
authors.affiliation: Shell Global Solutions International, Kessler Park 1, 2288 GS Rijswijk, The Netherlands.|Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
authors.forename: N
authors.initials: N
authors.lastname: Kampman
authors.affiliation: Shell Global Solutions International, Kessler Park 1, 2288 GS Rijswijk, The Netherlands.
authors.forename: A
authors.identifier: 0000-0002-3279-5202
authors.initials: A
authors.lastname: Busch
authors.affiliation: Clay and Interface Mineralogy, RWTH Aachen University, Bunsenstrasse 8, 52072 Aachen, Germany.
authors.forename: P
authors.identifier: 0000-0003-1770-412X
authors.initials: P
authors.lastname: Bertier
authors.affiliation: Shell Global Solutions International, Kessler Park 1, 2288 GS Rijswijk, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Snippe
authors.affiliation: High Pressure and Temperature Laboratory, Utrecht University, PO Box 80 021, 3508 TA Utrecht, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Hangx
authors.affiliation: Jülich Centre for Neutron Science (JCNS), Forschungszentrum Jülich GmbH, Outstation at Heinz Maier-Leibnitz Zentrum (MLZ),1 Lichtenbergstrasse, 85747 Garching, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Pipich
authors.affiliation: Jülich Centre for Neutron Science (JCNS), Forschungszentrum Jülich GmbH, Outstation at Heinz Maier-Leibnitz Zentrum (MLZ),1 Lichtenbergstrasse, 85747 Garching, Germany.
authors.forename: Z
authors.initials: Z
authors.lastname: Di
authors.affiliation: Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: G
authors.initials: G
authors.lastname: Rother
authors.affiliation: British Geological Survey, Environmental Science Centre, Keyworth, Nottingham NG12 5GG, UK.
authors.forename: J F
authors.initials: JF
authors.lastname: Harrington
authors.affiliation: Department of Geology, Utah State University, 4505 Old Main Hill, Logan, Utah 84322-4505, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Evans
authors.affiliation: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
authors.forename: A
authors.initials: A
authors.lastname: Maskell
authors.affiliation: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
authors.forename: H J
authors.initials: HJ
authors.lastname: Chapman
authors.affiliation: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Bickle