AlNajdi, NA, Worden, RH 
ORCID: 0000-0002-4686-9428 and Utley, James EP ORCID: 0000-0003-0397-5607
(2024)
Compositional controls on the Lower Cretaceous Rodby Shale pore structure and surface area: a planned CCS top seal caprock for the Acorn storage site
International Journal of Greenhouse Gas Control, 137.
p. 104219.
ISSN 1750-5836, 1878-0148
Abstract
Fine-grained lithologies above CCS reservoirs cannot automatically be assumed to be mineralogically stable, or high quality top-seals to highly pressured CO<inf>2</inf> as saline aquifer have previously contained hydrostatically pressured water. We have investigated the mineralogy, pore systems and surface area characteristics of the Lower Cretaceous Rodby Shale, the caprock to the Captain Sandstone at the UK's planned Acorn/Goldeneye CCS site. Rodby Shale core was logged and analysed by XRD, light microscopy, and SEM. Grain size was measured using laser particle size analysis. Mercury intrusion porosimetry and nitrogen adsorption analysis were used to characterise the pore network. The Rodby is smectite-rich and contains abundant calcite as well as quartz silt with small quantities of chlorite and plagioclase. Calcite was sourced from benthic microfossils, locally recrystallised to create a pore-filling cement. The mean pore throat and pore body diameter are about 17 nm putting the Rodby in the mesopore range and suggesting a predominance of slit-like pores. There are three lithofacies in the Rodby Shale: (i) high surface area clay-rich shale, (ii) low surface area calcite-rich shale, (iii) intermediate surface area quartz-rich. if the second lithotype encountered CO<inf>2</inf>, then the resulting calcite dissolution would lead to increasing surface area of the remaining shale. The Rodby Shale has good potential to be an effective barrier for CO<inf>2</inf> escape, based on assessments of diffusion rate and post-breakthrough advection rate as well as stability and sealing assessments.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Caprock, Top-seal, Smectite, Calcite, Surface area, Pore throat diameter, Pore body size, Porosity, Permeability, Top-seal effectiveness, Top-seal quality |
| Divisions: | Faculty of Science & Engineering Faculty of Science & Engineering > School of Environmental Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 20 Sep 2024 15:31 |
| Last Modified: | 23 May 2026 09:13 |
| DOI: | 10.1016/j.ijggc.2024.104219 |
| Open Access URL: | https://doi.org/10.1016/j.ijggc.2024.104219 |
| Related Websites: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3184668 |
| Disclaimer: | The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate. |
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