April 2021 - Second stimulation of the DESTRESS project

After first stimulations in November 2020, in the next days, Geo-Energie Suisse (GES) will perform another set of high-pressure injections at the BedrettoLab using a multi-packer-system. Packers are large rubber sleeves that are lowered into the borehole to divide it into several sections. They allow to stimulate the different sections separately with exactly the pressure and the amount of water needed. This method aims at enhancing the permeability per section in a controlled way while minimizing induced seismicity. GES conducts the so far largest stimulation test at BedrettoLab as part of the DESTRESS project.

For these stimulation tests, GES will use a set of 14 packers (see illustration showing the concept) that are mounted at fixed intervals of 12 to 25 meters. This means, that a larger rock volume will be stimulated than in November, when the packers were installed at narrower intervals. The packers are placed at depths of about 250 to 400 meters in the borehole ST1, whereby only the lowest sections will be stimulated. The goal is to observe how the packer system behaves as a whole and if the packers succeed in separating the sections allowing targeted stimulations.

As for all activities in the BedrettoLab, safety is the top priority also for these stimulations. For this reason, GES and ETH Zurich closely monitors the preparation and implementation of the stimulations. The chances are very small that these stimulations will cause damage to the tunnel (a probability of less than 1 in 10’000)  and even smaller that they will cause earthquakes large enough to be felt or cause damage in nearby villages (a probability of less than 1 in 10 million).