Chemical reactions of portland cement with aqueous CO2 and their impacts on cements mechanical properties under geologic CO2 sequestration conditions

Qingyun Li, Yun Mook Lim, Katharine M. Flores, Kelly Kranjc, Young Shin Jun

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

To provide information on wellbore cement integrity in the application of geologic CO2 sequestration (GCS), chemical and mechanical alterations were analyzed for cement paste samples reacted for 10 days under GCS conditions. The reactions were at 95 °C and had 100 bar of either N2 (control condition) or CO2 contacting the reaction brine solution with an ionic strength of 0.5 M adjusted by NaCl. Chemical analyses showed that the 3.0 cm × 1.1 cm × 0.3 cm samples were significantly attacked by aqueous CO2 and developed layer structures with a total attacked depth of 1220 μm. Microscale mechanical property analyses showed that the hardness and indentation modulus of the carbonated layer were 2-3 times greater than for the intact cement, but those in the portlandite-dissolved region decreased by ∼50%. The strength and elastic modulus of the bulk cement samples were reduced by 93% and 84%, respectively. The properties of the microscale regions, layer structure, microcracks, and swelling of the outer layers combined to affect the overall mechanical properties. These findings improve understanding of wellbore integrity from both chemical and mechanical viewpoints and can be utilized to improve the safety and efficiency of CO2 storage.

Original languageEnglish
Pages (from-to)6335-6343
Number of pages9
JournalEnvironmental Science and Technology
Volume49
Issue number10
DOIs
Publication statusPublished - 2015 May 19

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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