Postgraduate research opportunities Colloidal Silica for Well Stabilisation during Borehole Sealing

This project is investigating the use of colloidal silica grout (which forms a hydrogel) in the long-term sealing of boreholes in the ground, to prevent subsequent upward fluid migration from rocks at depth to the surface.

Successful borehole sealing is vital in many industries, including:

• deep borehole disposal of radioactive waste
• oil and gas production and well decommissioning
• carbon capture and storage
• hydrogen storage

For UK radioactive waste disposal, the preferred option for borehole sealing is backfilling with compacted bentonite, a clay which swells to form a tight, strong seal upon wetting. Prior to bentonite emplacement, it is necessary for the steel borehole casing to be removed.

Recent field trials have exposed a problem with this method in weak or damaged rocks, where the borehole walls can collapse before the compacted bentonite is emplaced. This PhD project will investigate the potential for colloidal silica grout to provide short-term stabilisation of these weak rocks, prior to the bentonite emplacement.

This PhD will use similar silica injection and imaging techniques. The final repaired rock will be investigated to optimise strength and durability.  This project will suit a student interested in geotechnics, rock mechanics, geochemistry and/or material science using experimental techniques. You will learn basic laboratory techniques and will be trained on regularly used analytical equipment.

As a PhD student at the University of Strathclyde, you will also complete the University of Strathclyde’s acclaimed Researcher Development Programme, acquiring cross-disciplinary skills to broaden career prospects in various industries.

The candidate will also undertake a short secondment to gain work experience at Nuclear Waste Services Ltd.

The project will be largely experimental, using equipment in the University of Strathclyde’s geotechnical laboratories. Colloidal silica will be injected into samples of damaged mudstone and the resulting material will be tested for shear strength, erosion resistance and unconfined compressive strength. The chemical and physical interactions between the colloidal silica and the bentonite will also be investigated to determine any long-term impacts on seal performance. Investigations will make use of the University of Strathclyde’s Advanced Materials Research Laboratory, which hosts equipment such as Scanning Electron Microscopy, X-Ray Diffraction facilities and Micro X-Ray Computer Tomography.