Nagra TBO

Hydraulic tests in deep boreholes, complete hydraulic characterisation of the subsurface

A sound knowledge of the hydrogeological conditions in the subsurface is of great importance for the safety of a deep geological repository, and is an important criterion when comparing possible sites for a deep geological repository. The hydraulic tests in the deep boreholes were used to investigate the hydrogeology of the subsurface of the siting areas in detail, thus significantly completing the overall geological picture.

Solexperts carried out the hydraulic tests in the deep boreholes over a period of three years from 2019 to 2021. The focus was on the Opalinus Clay, which is to be investigated in more detail as the host rock for the deep repository for radioactive waste. Using our HDDP (Heavy Duty Double Packer) system, which we developed and produced ourselves, borehole sections were isolated and examined for their geohydraulic properties. Pulse tests, slug tests and pumping tests were carried out and evaluated analytically and numerically with the help of our subcontractor AFRY.

Gas tests

In a deep repository, gas is produced over time by various processes, e.g. corrosion of steel. An important goal of the investigation campaign was to determine the in-stu gas entry pressure into the Opalinus Clay layers at the different sites. Solexperts modified their test equipment accordingly so that successful gas tests could be carried out. 

Deflected well

The over 1000 m deep deviated borehole in Rheinau was also a technical challenge. With a large amount of material and the appropriate modifications to the test equipment, hydraulic tests and gas tests could be successfully performed.

Downloads

Heavy-Duty Double Packer System, China, BRIUG

Hong Kong Dilatometer 72 mm

Lyss - hydrogeological investigation

Brenner Base Tunnel, thermal leakage detection

Hanchurch Service Reservoir - Fibre optic joint monitoring

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