Meeting future net-zero carbon energy needs: Improved borehole sealing using compacted bentonite and silica grout.

Borehole decommissioning and abandonment requires the long-term sealing of potential fluid migration pathways. Recent field trials at Harwell by Nuclear Waste Services revealed a tendency of adjacent walls collapsing into the borehole before sealing materials are emplaced. This project seeks to provide a solution by investigating new technologies for borehole sealing to prevent upward leakage of fluids that are stored at-depth in the ground.
The research focuses on the potential for silica-based grouting materials in conjunction with bentonite to stabilise and seal off boreholes in weak and/or fractured rock columns. Through experimentation, the research seeks to optimise the colloidal silica grout composition, as well as, investigate any chemical and physical interactions at the interface between the bentonite and the colloidal silica grout. The output will thus provide data and models of long-term borehole seal performance to inform the Environmental Safety Case for a Geological Disposal Facility.