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Geochemical Impact on the Caprock Porous Structure during CO2 Geological Storage : A Laboratory and Modeling Study

Abstract : CO2 storage is envisioned as a technique which reduces large quantities of CO2 rejected in the atmosphere because of many human activities. The effectiveness of this technique is mainly related to the storage capacity as well as its safety. The safety of this operation is primarily based on the conservation of petro-physical properties of the caprock, which prevents the transport of CO2 towards the surface. However when CO2 reaches the reservoir/caprock interface due to buoyancy effects, the interaction between interstitial fluid and injected fluid creates a serie of dissolution/precipitation reactions affecting the properties of containment of the caprock, which is generally characterized by low transport properties. This study aims to assess the impact caused by CO2/interstitial fluid interaction on the nanostructure of a caprock under geological storage conditions. In order to do this, degradation experiments at high pressure of CO2 (88 bar) and isothermal (55°C) conditions have been conducted using batch reactors for 3.5 months. The sample used for these experiments is a well characterized shale, from the Tournemire formation (Aveyron-France). Porosity evolution has been followed by using volumetric adsorption at low pressure, from advanced NLFDT and classical theories based on the micropores filling, and capillary condensation phenomena. Results showed a slight variation in both mesopores and micropores size distributions, as a result of dissolution processes, which dominated at laboratoty time scale. Furthermore, chemical analysis from the water sampled showed an overall increase in Ca,Mg,K,Si,Na. The results obtained by physical adsorption and water chemistry analysis were consistent, with geochemical modeling, which suggested reaction paths with calcite dissolution as the main mineral, by producing porosity at short term and (clays, feldspars) dissolution of aluminosilicates dominating at long term.
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https://hal-ineris.archives-ouvertes.fr/ineris-00971238
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Submitted on : Wednesday, April 2, 2014 - 3:59:18 PM
Last modification on : Friday, March 6, 2020 - 2:17:02 AM

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  • HAL Id : ineris-00971238, version 1
  • INERIS : EN-2013-407

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David Ricardo Rhenals Garrido, Stéphane Lafortune, Hanène Souli, Philippe Dubujet. Geochemical Impact on the Caprock Porous Structure during CO2 Geological Storage : A Laboratory and Modeling Study. AGU Fall Meeting 2013, Dec 2013, San Francisco, United States. ⟨ineris-00971238⟩

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