Reactivity of micas and cap-rock in wet supercritical CO2 with SO2 and O2 at CO2 storage conditions

Pearce, Julie K., Dawson, Grant K. W., Law, Alison C. K., Biddle, Dean and Golding, Suzanne D. (2016) Reactivity of micas and cap-rock in wet supercritical CO2 with SO2 and O2 at CO2 storage conditions. Applied Geochemistry, 72 59-76. doi:10.1016/j.apgeochem.2016.06.010

Author Pearce, Julie K.
Dawson, Grant K. W.
Law, Alison C. K.
Biddle, Dean
Golding, Suzanne D.
Title Reactivity of micas and cap-rock in wet supercritical CO2 with SO2 and O2 at CO2 storage conditions
Formatted title
Reactivity of micas and cap-rock in wet supercritical CO2 with SO2 and O2 at CO2 storage conditions
Journal name Applied Geochemistry   Check publisher's open access policy
ISSN 0883-2927
Publication date 2016-07-01
Sub-type Article (original research)
DOI 10.1016/j.apgeochem.2016.06.010
Open Access Status Not Open Access
Volume 72
Start page 59
End page 76
Total pages 70
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon Press
Collection year 2017
Language eng
Formatted abstract
Seal or cap-rock integrity is a safety issue during geological carbon dioxide capture and storage (CCS). Industrial impurities such as SO2, O2, and NOx, may be present in CO2 streams from coal combustion sources. SO2 and O2 have been shown recently to influence rock reactivity when dissolved in formation water. Buoyant water-saturated supercritical CO2 fluid may also come into contact with the base of cap-rock after CO2 injection. Supercritical fluid-rock reactions have the potential to result in corrosion of reactive minerals in rock, with impurity gases additionally present there is the potential for enhanced reactivity.

The first observation of mineral dissolution and precipitation on phyllosilicates and CO2 storage cap-rock (siliciclastic reservoir) core during water-saturated supercritical CO2 reactions with industrial impurities SO2 and O2 at simulated reservoir conditions is presented. Phyllosilicates (biotite, phlogopite and muscovite) were reacted in contact with a water-saturated supercritical CO2 containing SO2-, or SO2 and O2, and were also immersed in the gas-saturated bulk water. Secondary precipitated sulfate minerals were formed on mineral surfaces concentrated at sheet edges. SO2 dissolution and oxidation resulted in solution pH decreasing to 0.74 through sulfuric acid formation. Phyllosilicate dissolution released major, minor, and trace elements to solution with ∼50% Fe mobilized. Geochemical modelling was in good agreement with experimental water chemistry. New minerals nontronite (smectite), hematite, jarosite and goethite were saturated in models. A cap-rock core siltstone sample from the Surat Basin, Australia, was also reacted in water-saturated supercritical CO2 containing SO2 or in pure supercritical CO2. In the presence of SO2, siderite and ankerite were corroded, and Fe-chlorite altered by the leaching of mainly Fe and Al. Corrosion of micas in the cap-rock was however not observed as the pH was buffered by carbonate dissolution. Ca-sulfate, and Fe-bearing precipitates were observed post SO2-CO2 reaction, mainly centered on surface cracks and an illite rich illite-smectite quantified. Water saturated impure super critical CO2 was observed to have reactivity to rock-forming biotite, muscovite and phlogopite minerals. In the cap-rock core however carbonates and chlorite were the main reacting minerals showing the importance of assessing actual core
Keyword Mineral dissolution
Geological carbon dioxide capture
Seal integrity
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Publications
School of Chemical Engineering Publications
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Created: Mon, 18 Jul 2016, 10:05:17 EST by Dr Julie Pearce on behalf of School of Earth Sciences