Clay interaction with liquid and supercritical CO 2: The relevance of electrical and capillary forces

D. Nicolas Espinoza*, Juan Carlos Santamarina

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Caprocks with significant clay content are candidate seal layers for CO 2 geological storage. Changes in electrical and capillary forces are expected when CO 2 invades the water saturated pore space. Sedimentation experiments conducted to explore the response of kaolinite and montmorillonite to deionized water, brine, heptane, liquid CO 2 and supercritical CO 2 show that both montmorillonite and kaolinite aggregate when submerged in CO 2 and the final porosity in CO 2 is smaller than in brine. Differences in dielectric properties between CO 2 and water, and ensuing implications on van der Waals attraction and double layer repulsion explain the observed phenomena. On the other hand, capillary effects induced by the water-CO 2 interface are corroborated by clay-water paste desiccation experiments conducted using supercritical CO 2: water dissolution into the surrounding CO 2 causes suction and capillary contraction, the invasion of the CO 2-water interface into the sediment, and the formation of desiccation cracks. Volume contraction and crack initiation are consistent with the sediment response within an effective stress framework. Altered electrical forces and emergent capillary forces lead to coupled chemo-hydro-mechanical phenomena in seal layers that could facilitate CO 2 breakthrough and advection through high porosity caprocks; related phenomena are identified in the reservoir rock. Additional studies are needed to further assess coupled phenomena when the interparticle distance is a few monolayers of water.

Original languageEnglish (US)
Pages (from-to)351-362
Number of pages12
JournalInternational Journal of Greenhouse Gas Control
StatePublished - Sep 1 2012


  • Cap rock
  • Carbon geological storage
  • Desiccation crack
  • Mineral fluid interaction
  • Phyllosilicates
  • Sealing capacity
  • Swelling pressure

ASJC Scopus subject areas

  • Pollution
  • Energy(all)
  • Industrial and Manufacturing Engineering
  • Management, Monitoring, Policy and Law


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