Swelling‐induced changes in coal microstructure due to supercritical CO2 injection

Abstract Enhanced coalbed methane recovery and CO2 geostorage in coal seams are severely limited by permeability decrease caused by CO2 injection and associated coal matrix swelling. Typically, it is assumed that matrix swelling leads to coal cleat closure, and as a consequence, permeability is redu...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Yihuai Zhang, Maxim Lebedev, Mohammad Sarmadivaleh, Ahmed Barifcani, Stefan Iglauer
Format: Article
Language:English
Published: Wiley 2016-09-01
Subjects:
CO2 geosequestration
enhanced coalbed methane recovery
coal swelling
microstructure
permeability drop
Online Access:https://doi.org/10.1002/2016GL070654
Description
Summary:Abstract Enhanced coalbed methane recovery and CO2 geostorage in coal seams are severely limited by permeability decrease caused by CO2 injection and associated coal matrix swelling. Typically, it is assumed that matrix swelling leads to coal cleat closure, and as a consequence, permeability is reduced. However, this assumption has not yet been directly observed. Using a novel in situ reservoir condition X‐ray microcomputed tomography flooding apparatus, for the first time we observed such microcleat closure induced by supercritical CO2 flooding in situ. Furthermore, fracturing of the mineral phase (embedded in the coal) was observed; this fracturing was induced by the internal swelling stress. We conclude that coal permeability is drastically reduced by cleat closure, which again is caused by coal matrix swelling, which again is caused by flooding with supercritical CO2.
ISSN:0094-8276
1944-8007

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