Effect of sedimentary heterogeneities in the sealing formation on predictive analysis of geological CO2 storage

Michael U. Onoja, John D.O. Williams, Hayley Vosper, Seyed M. Shariatipour

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    9 Citations (Scopus)
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    Numerical models of geologic carbon sequestration (GCS) in saline aquifers use multiphase fluid flow-characteristic curves (relative permeability and capillary pressure) to represent the interactions of the non-wetting CO2 and the wetting brine. Relative permeability data for many sedimentary formations is very scarce, resulting in the utilisation of mathematical correlations to generate the fluid flow characteristics in these formations. The flow models are essential for the prediction of CO2 storage capacity and trapping mechanisms in the geological media. The observation of pressure dissipation across the storage and sealing formations is relevant for storage capacity and geomechanical analysis during CO2 injection. This paper evaluates the relevance of representing relative permeability variations in the sealing formation when modelling geological CO2 sequestration processes. Here we concentrate on gradational changes in the lower part of the caprock, particularly how they affect pressure evolution within the entire sealing formation when duly represented by relative permeability functions. The results demonstrate the importance of accounting for pore size variations in the mathematical model adopted to generate the characteristic curves for GCS analysis. Gradational changes at the base of the caprock influence the magnitude of pressure that propagates vertically into the caprock from the aquifer, especially at the critical zone (i.e. the region overlying the CO2 plume accumulating at the reservoir-seal interface). A higher degree of overpressure and CO2 storage capacity was observed at the base of caprocks that showed gradation. These results illustrate the need to obtain reliable relative permeability functions for GCS, beyond just permeability and porosity data. The study provides a formative principle for geomechanical simulations that study the possibility of pressure-induced caprock failure during CO2 sequestration.

    Original languageEnglish
    Pages (from-to)229-243
    Number of pages15
    JournalInternational Journal of Greenhouse Gas Control
    Early online date23 Jan 2019
    Publication statusPublished - 1 Mar 2019

    Bibliographical note

    NOTICE: this is the author’s version of a work that was accepted for publication in
    International Journal of Greenhouse Gas Control. Changes resulting from the
    publishing process, such as peer review, editing, corrections, structural formatting,
    and other quality control mechanisms may not be reflected in this document.
    Changes may have been made to this work since it was submitted for publication.
    A definitive version was subsequently published in International Journal of
    Greenhouse Gas Control, [[82], (2019)] DOI: 10.1016/j.ijggc.2019.01.013
    © 2019, Elsevier. Licensed under the Creative Commons AttributionNonCommercial-NoDerivatives 4.0 International


    • Capillary pressure
    • Geologic carbon sequestration
    • Numerical simulation
    • Pressure evolution
    • Relative permeability

    ASJC Scopus subject areas

    • Energy(all)
    • Industrial and Manufacturing Engineering
    • Management, Monitoring, Policy and Law
    • Earth and Planetary Sciences(all)


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