CO2 geological storage: Hydro-chemo-mechanical analyses and implications

Seunghee Kim*, Juan Carlos Santamarina

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The injectivity of CO2 and the integrity of the reservoir-caprock system are affected by CO2 invasion, water-CO 2-mineral reactions, and ensuing mineral dissolution and precipitation. We identify different zones around an injection well and investigate the effects of these hydro-chemo-mechanical interactions. Geochemical analyses combine a comprehensive mass balance formulation with chemical calculations using published equations and PHREEQC. This analysis framework is used to assess near-well, pool, and far-field conditions, and to determine species concentrations, pH, changes in brine density, and changes in mineral and fluid volume in the reservoir. Results show that the brine density may increase by as much as 1.2% and can sustain convective flow of CO 2 dissolved brine; the characteristic time scale for convection can be as short as a few years in some permeable formations currently being considered for storage. The precipitation of secondary minerals near the injection well increases the mineral volume by a maximum of 5%, yet, only a minor decrease in CO2 permeability is anticipated. Dissolution may result in unsupported caprock (the span should not exceed 20% of the caprock thickness to prevent failure), and may cause compaction-driven shear failure of the reservoir. Finally, the analysis of lateral capillary trapping shows that the CO2 pool is only a few meters thick in leveled caprock interfaces and in the absence of geometric traps.

Original languageEnglish (US)
Pages (from-to)528-543
Number of pages16
JournalGreenhouse Gases: Science and Technology
Volume4
Issue number4
DOIs
StatePublished - Jan 1 2014

Keywords

  • carbonate reservoir
  • hydro-geomechanical implication
  • mass balance formulation
  • mineral dissolution
  • mineral precipitation

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry

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