modElliNg Gas INjection ExpERiments (ENGINEER)


In a geological repository for radioactive waste, the corrosion of the ferrous materials, radioactive decay of the waste, radiolysis of organic materials and water, and the microbial breakdown of organic materials will produce gas, the most important of which (by volume) is hydrogen. Depending on the repository concept, the production of these gases may span in excess of 100,000 years, following emplacement of the waste. As gas is produced, it will accumulate, moving away from its source through the combined processes of molecular diffusion and bulk advection. Understanding these processes, the long-term fate of the gas and its impact on the surrounding materials is therefore important in the development of a geological disposal facility (GDF) for radioactive waste.

The purpose of Task A in DECOVALEX-2019 is to better understand the processes governing the advective movement of gas in two low permeability materials: (i) one engineered (compacted bentonite) and (ii) one a potential, natural repository host rock (in this case the Callovo Oxfordian Claystone). Special attention is given to the mechanisms controlling factors such as gas entry and flow, as well as pathway stability and sealing, which will impact barrier performance. To underpin this task, new numerical representations for the quantitative prediction of gas fluxes will be developed. These will be tested against a series of controlled laboratory tests, in a staged manner, building in complexity (both in terms of the experimental and modelling approaches). It is anticipated that the development of these models will provide a valuable tool to assess the impact of gas flow on barrier and host materials, providing information which could be used to support future repository design.

In addition, experience gained through this task is of direct relevance to other clay-based engineering issues where advective gas flow is involved, including: shale gas, hydrocarbon migration, carbon capture and storage, gas storage and landfill design.

Mixed SE and BSE images showing a trail of aggregated gold nanoparticles trapped within the trace of a now closed pathway. The Au particles are trapped along what appears to be a healed pathway that is sub-orthogonal to the plane of the fracture surface. Taken from Harrington et al. (2012).

Experimental Data

Data from a series of flow tests performed on initially saturated samples will be made available to project participants. These long-term tests, performed under carefully controlled laboratory conditions, provide detailed datasets with which to examine gas migration behaviour under steady state conditions. As such, a number of test geometries have been used, ranging in complexity from relatively simple 1-dimensional flow tests (performed under constant volume conditions), to triaxial tests performed on natural samples of Callovo-Oxfordian claystone. To gain insights into the advective movement of gas through these materials, laboratory data will be used to guide and benchmark numerical model development in an iterative process, increasing in model complexity from one test stage to the next.

Propagation of a gas fracture in a clay paste.
general degassing of a Cox sample (1).
general degassing of a Cox sample (2).


The initial plan of the task includes 4 distinct stages:

  • Stage 0 (code development):
    • Initial aim is to understand and reflect on the apparent stochastic behaviour of all experimental data to be considered. References and publications will be made available and the teams will be asked to develop one or more modelling approaches.
  • Stage 1: 1D gas flow through saturated bentonite under controlled laboratory conditions
    • Data will be provided from a 1D gas flow test, performed on saturated bentonite subjected to a constant volume boundary condition.
  • Stage 2: 3D spherical gas flow under controlled laboratory conditions
    • A: spherical flow through saturated bentonite, under a constant volume boundary condition.
    • B (optional): a second dataset under the same experimental boundary conditions is also offered, against which the models can be tested.
  • Stage 3: Application of previous models to a natural clay-based system
    • A: triaxial test performed on a sample Callovo-Oxfordian claystone (Cox). This dataset comprises a number of stages including initial hydration, hydraulic testing and gas injection.
    • B (optional): gas flow through hydrated bentonite pellets under constant volume conditions. If appropriate, data from a long-term test performed by the Commission for Atomic Energy and Alternative Energies (CEA) will be made available for Teams participating in this task.

Participating Groups

  • UK: British Geological Survey (Task Leader).
  • UK: Quintessa
  • Germany: Bundesanstalt für Geowissenschaften und Rohstoffe (BGR)
  • Germany: Helmholtz-Centre for Environmental Research (UfZ)
  • USA: Sandia National Laboratory
  • USA: Lawrence Berkley National Laboratory
  • France: Institut de Radioprotection et de Sûreté Nucléaire (ISRN)
  • Korea: Korea Atomic Energy Research Institute (KAERI)
  • Canada: Canadian Nuclear Safety Commission (CNSC)
  • Spain: Universitat Politècnica de Catalunya (UPC)
  • Taiwan: Taiwan Power Company (Taipower)

Further Information

For further information, please contact the task leader, Jon Harrington.


  1. Cuss, R.J., Harrington, J.F., Noy, D.J., Graham, C.C., and Sellin, P. (2014). Evidence of localised gas propagation pathways in a field-scale bentonite engineered barrier system; results from three gas injection tests in the Large scale gas injection test (Lasgit). Applied Clay Science, 102, pp.81-92, doi:10.1016/j.clay.2014.10.014.
  2. Cuss, R.J., Harrington, J.F., Giot, R., and Auvray, C. (2014) Experimental observations of mechanical dilation at the onset of gas flow in Callovo-Oxfordian claystone. In: Clays in Natural and Engineered Barriers for Radioactive Waste Confinement; Norris, A., Bruni, J., Cathelineau, M., Delage, P., Fairhurst, C., Gaucher, E.C., Hohn, E.H., Kalinichev, A., Lalieux, P, and Sellin, P. (Eds), 400, Geological Society Special Publications: London, United Kingdom, Geological Society of London, pp. 507-519, doi:10.1144/SP400.26
  3. Cuss, R.J., Harrington, J.F., Noy, D.J., Wikman, A., and Sellin, P (2011). Large scale gas injection test (Lasgit): Results from two gas injection tests. Physics and Chemistry of the Earth. 36, pp.1729-1742. DOI: 10.1016/j.pce.2011.07.022
  4. Cuss, R.J., Harrington, J.F., and Noy, D.J. (2010). Large scale gas injection test (Lasgit) performed at the Äspö Hard Rock Laboratory. Summary report 2008. Svensk Kärnbränslehantering AB (SKB) Technical Report TR-10-38, SKB, Stockholm, Sweden. Pp.109.
  5. Cuss, R.J. and Harrington, J.F. (2011). Update on dilatancy associated with onset of gas flow in Callovo-Oxfordian claystone; Progress report on test SPP_COx-2. British Geological Survey Commissioned Report, CR/11/110. 34pp.
  6. Graham, C.C., Harrington, J.F., Cuss, R.J., and Sellin, P. (2012) Gas migration experiments in bentonite: implications for numerical modelling. Mineralogical Magazine. December 2012, Vol. 76(8), pp.3279-3292. DOI: 10.1180/minmag.2012.076.8.41
  7. Harrington, J.F., Graham, C.C., Cuss, R.J. and Norris, S. (in prep). Stress coupling during advective gas flow in compact bentonite: impact on gas breakthrough behaviour.
  8. Harrington, J.F., de La Vaissiere, Noy, D.J., Cuss, R.J., and Talandier, J. (2012) Gas Flow in Callovo-Oxfordian Clay (COx): Results from Laboratory and Field-Scale Measurements. Mineralogical Magazine. December 2012, Vol. 76(8), pp.3303-3318. DOI: 10.1180/minmag.2012.076.8.43
  9. Harrington, J.F., Milodowski, A.E., Graham, C.C., Rushton, J.C., and Cuss, R.J. (2012) Evidence for gas-induced pathways in clay using a nanoparticle injection technique. Mineralogical Magazine. December 2012, Vol. 76(8), pp.3327-3336. DOI: 10.1180/minmag.2012.076.8.45.
  10. Harrington, J.F. and Horseman, S.T. (2003). Gas migration in KBS-3 buffer bentonite: Sensitivity of test parameters to experimental boundary conditions. Report TR-03-02. Svensk Kärbränslehantering AB (SKB), Stockholm, Sweden.
  11. Harrington, J.F. and Horseman, S.T. (1999). Gas transport properties of clays and mudrocks. In: Muds And Mudstones: Physical And Fluid Flow Properties (eds A.C.Aplin, A.J. Fleet, and J.H.S. Macquaker). Geological Society of London, Special Publication No. 158, 107-124.
  12. Horseman, S.T., Harrington, J.F. and Sellin, P. (2004) Water and gas flow in Mx80 bentonite buffer clay. In: Symposium on the Scientific Basis for Nuclear Waste Management XXVII (Kalmar), Materials Research Society, Vol. 807. 715-720.
  13. Horseman, S.T., Harrington, J.F. and Sellin, P. (1999). Gas migration in clay barriers. Engineering Geology, Vol. 54, 139-149.