Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approach

Abstract The potential of underground $$\hbox {CO}_2$$ CO 2 storage relies on the sealing efficiency of an overlaying caprock that acts as a geological barrier. Shales are considered as potential caprock formations thanks to their favourable hydro-mechanical properties. In this work the sealing capa...

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Main Authors: Eleni Stavropoulou, Lyesse Laloui
Format: Article
Language:English
Published: Nature Portfolio 2022-06-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-022-14793-8
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author Eleni Stavropoulou
Lyesse Laloui
author_facet Eleni Stavropoulou
Lyesse Laloui
author_sort Eleni Stavropoulou
collection DOAJ
description Abstract The potential of underground $$\hbox {CO}_2$$ CO 2 storage relies on the sealing efficiency of an overlaying caprock that acts as a geological barrier. Shales are considered as potential caprock formations thanks to their favourable hydro-mechanical properties. In this work the sealing capacity of Opalinus Clay shale to $$\hbox {CO}_2$$ CO 2 injection is studied by means of capillary entry-pressure and volumetric response. The overall objective of this work is to contribute to the safe design of a $$\hbox {CO}_2$$ CO 2 injection strategy by providing a better understanding of the geomechanical response of the caprock material to $$\hbox {CO}_2$$ CO 2 injection and eventual breakthrough at different scales. This is achieved by relating lab-measured hydro-mechanical properties of the studying caprock material (porosity, permeability, volumetric response) to field-related parameters (effective stress, injection pressure). A number of $$\hbox {CO}_2$$ CO 2 breakthrough tests is performed in Opalinus Clay samples under two different scales, meso and micro. At the meso-scale, $$\hbox {CO}_2$$ CO 2 injection is performed in oedometric conditions under different levels of axial effective stress in both gaseous or liquid phase. In parallel, the material’s transport properties in terms of water permeability are assessed before $$\hbox {CO}_2$$ CO 2 injection at each corresponding level of effective stress. The impact of $$\hbox {CO}_2$$ CO 2 phase and open porosity on the material’s $$\hbox {CO}_2$$ CO 2 entry pressure are demonstrated. The correlation between measured entry pressure and absolute permeability is discussed. A second testing campaign at a smaller scale is presented where $$\hbox {CO}_2$$ CO 2 breakthrough is for the first time identified with in-situ X-ray tomography. $$\hbox {CO}_2$$ CO 2 injection is performed under isotropic conditions on an Opalinus Clay micro-sample (micro-scale), and $$\hbox {CO}_2$$ CO 2 breakthrough is identified through quantitative image analysis based on the measured localised volumetric response of the material. This innovative methodology provides important insight into the anisotropic response of this complex material that is indispensable for its representative modelling in the context of safe geological $$\hbox {CO}_2$$ CO 2 storage.
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spelling doaj.art-ad683a9f17794a41970ae4a04db9b65a2022-12-22T00:32:58ZengNature PortfolioScientific Reports2045-23222022-06-0112111910.1038/s41598-022-14793-8Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approachEleni Stavropoulou0Lyesse Laloui1Laboratory for Soil Mechanics (LMS), EPFL-ENAC-LMS, Ecole Polytechnique Fédérale de Lausanne (EPFL)Laboratory for Soil Mechanics (LMS), EPFL-ENAC-LMS, Ecole Polytechnique Fédérale de Lausanne (EPFL)Abstract The potential of underground $$\hbox {CO}_2$$ CO 2 storage relies on the sealing efficiency of an overlaying caprock that acts as a geological barrier. Shales are considered as potential caprock formations thanks to their favourable hydro-mechanical properties. In this work the sealing capacity of Opalinus Clay shale to $$\hbox {CO}_2$$ CO 2 injection is studied by means of capillary entry-pressure and volumetric response. The overall objective of this work is to contribute to the safe design of a $$\hbox {CO}_2$$ CO 2 injection strategy by providing a better understanding of the geomechanical response of the caprock material to $$\hbox {CO}_2$$ CO 2 injection and eventual breakthrough at different scales. This is achieved by relating lab-measured hydro-mechanical properties of the studying caprock material (porosity, permeability, volumetric response) to field-related parameters (effective stress, injection pressure). A number of $$\hbox {CO}_2$$ CO 2 breakthrough tests is performed in Opalinus Clay samples under two different scales, meso and micro. At the meso-scale, $$\hbox {CO}_2$$ CO 2 injection is performed in oedometric conditions under different levels of axial effective stress in both gaseous or liquid phase. In parallel, the material’s transport properties in terms of water permeability are assessed before $$\hbox {CO}_2$$ CO 2 injection at each corresponding level of effective stress. The impact of $$\hbox {CO}_2$$ CO 2 phase and open porosity on the material’s $$\hbox {CO}_2$$ CO 2 entry pressure are demonstrated. The correlation between measured entry pressure and absolute permeability is discussed. A second testing campaign at a smaller scale is presented where $$\hbox {CO}_2$$ CO 2 breakthrough is for the first time identified with in-situ X-ray tomography. $$\hbox {CO}_2$$ CO 2 injection is performed under isotropic conditions on an Opalinus Clay micro-sample (micro-scale), and $$\hbox {CO}_2$$ CO 2 breakthrough is identified through quantitative image analysis based on the measured localised volumetric response of the material. This innovative methodology provides important insight into the anisotropic response of this complex material that is indispensable for its representative modelling in the context of safe geological $$\hbox {CO}_2$$ CO 2 storage.https://doi.org/10.1038/s41598-022-14793-8
spellingShingle Eleni Stavropoulou
Lyesse Laloui
Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approach
Scientific Reports
title Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approach
title_full Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approach
title_fullStr Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approach
title_full_unstemmed Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approach
title_short Evaluating $$\hbox {CO}_2$$ CO 2 breakthrough in a shaly a caprock material: a multi-scale experimental approach
title_sort evaluating hbox co 2 co 2 breakthrough in a shaly a caprock material a multi scale experimental approach
url https://doi.org/10.1038/s41598-022-14793-8
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