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Comparison of alternative approaches to modelling gas migration through a higher strength rock

Published online by Cambridge University Press:  05 July 2018

A. R. Hoch  and
M. James
A. R. Hoch*
Affiliation:
AMEC, Harwell Science and Innovation Campus, Didcot Oxfordshire OX11 0QB, UK
M. James
Affiliation:
AMEC, Harwell Science and Innovation Campus, Didcot Oxfordshire OX11 0QB, UK
*
*E-mail: andrew.hoch@amec.com
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Abstract

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The Radioactive Waste Management Directorate of the UK Nuclear Decommissioning Authority has prepared a generic disposal system safety case (DSSC) that covers a range of possible host rock environments. In many of the waste packages considered in the DSSC, the formation of gases by chemical and microbial processes is likely to occur. In order to demonstrate safety, it is necessary to understand the rates at which the gases are generated and their subsequent migration from a disposal facility after closure. This paper is concerned with modelling gas migration through a fractured higher strength host rock. A first set of simulations compares alternative approaches to modelling gas migration through a fractured rock. The approaches differ in their representation of the interaction between the fractures and the rock matrix. As expected, the gross features of many of the simulations are very similar, with a single continuum approach in which the porosity is set equal to either the fracture porosity or the matrix porosity providing the bounding cases. Gas migration is slower for those simulations where the gas can access more of the rock matrix. A final simulation, with a heterogeneous permeability field, is compared with the other simulations, again showing a very similar evolution.

Keywords

migrationfractured rockeffective continuumdouble continuummultiple interacting continuatough2
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 8 , December 2012 , pp. 3319 - 3326
Creative Commons
Creative Common License - CCCreative Common License - BY
© [2012] The Mineralogical Society of Great Britain and Ireland. This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY) licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2012

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