A Review of Self-Sealing Mechanisms in Fine-Grained Sedimentary Rocks
in the context of
Geological Disposal of Radioactive Waste
WEBINAR
By Tom Berry (Leader Rock Engineering Group, Jacobs Engineering)
27th April 2023 19:00 BST
ABSTRACT
Self-sealing of fine-grained sedimentary rocks (c.f. mudstones and shales) is an important mechanism for many engineering applications including tunnelling (Armand, et al., 2013), (Bock, et al., 2010), through to (Zhang, 2011), mining (Nagra, 2022), hydrocarbon extraction (Fisher, et al., 2013) and so on. Of particular relevance to many European countries[1], self-sealing has long been an important factor in the suitability of fine grained sedimentary rocks as a potential host rock for a geological disposal of higher-activity radioactive waste, along with very low material permeability, transport by diffusion, strong retention capacity and relative homogeneity continuity of deposits. (Norris, 2019).
Peterborough Member of the Oxford Clay Formation (Image used with the kind permission of Forterra).
A preliminary review has been carried out to assess the current state of knowledge regarding self-sealing in theory and self-sealing in practice to understand the nature and extent of self-sealing in fine grained (lower strength) sedimentary rocks.
Self-sealing in fine grained sedimentary rocks has been an active research area for the last 40 years, this talk introduces the nature of fine grained sedimentary rocks and the formation of discontinuities therein before discussing in detail self-sealing processes and mechanisms in fine grained sedimentary rocks. The theoretical discussion of self-sealing of fine grained rocks is supplemented with selected examples of natural analogues and self-sealing from engineering practice. For completeness we will present a summary of self-sealing processes and mechanisms in other rock types. Finally we summarise the experiments that have demonstrated self-sealing in fine grained sedimentary rock carried out in boreholes, laboratory experiments and in situ from underground research laboratories
[1] Nagra proposes “Nördlich Lägern” as the site for a repository | Nagra and The Siting Process for a Geological Disposal Facility (GDF) - GOV.UK (www.gov.uk)
BIOGRAPHY
Tom is an engineering geologist with nearly 30 years’ experience in the UK and overseas. He has provided engineering geological input for major clients and projects including for Nuclear Waste Services, UU HARP tunnelling project, California High Speed Train Project, Lake Mead Third Intake tunnel, Forth Replacement Crossing, the Øresund Link and so on. Tom leads Jacobs’ Rock Engineering Group in Europe and is a part-time postgraduate research student at the University of Leeds. He combines his time between thought and technical leadership, technical delivery and as often as he can, field work. He is often called upon to provide specialist engineering geological input to projects as well as conferences, publications and statutory / industry guidance.
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