Efforts to release pressure of geothermal well in Basel successful
Basel city view (source: flickr/ Maria Grazia Montagnari, creative commons)
Alexander Richter
3 Nov 2017
Efforts to release pressure of the existing well drilled during the abandoned geothermal project in Basel/ Switzerland have been successfully concluded.
Earlier this week, Basler Zeitung – a local paper in Basel/ Switzerland reported that the gradual opening of the geothermal well in the city, due to an increase in micro-earthquakes, has been completed. The pressure in the borehole is completely reduced.
During opening, there were no noticeable earthquakes and very few and very weak microquakes, as stated in a statement from the Department of Health Basel-City and the Industrial Works Basel (IWB) on Wednesday. The strongest earthquake since autumn 2016 has reached a magnitude of 1.9.
To prevent a repressurization, the hole is now left open, as it is called. Next, a concept for the long-term protection of the borehole will be created. The basis for this is the findings of the opening phase.
Noticeable earthquake possible
The opening of the borehole was ordered at the end of March 2017 by the health department of Basel-Stadt. The reason was an increase in as yet unrecognizable micro-earthquakes due to the increase in pressure under the lid of the closed geothermal well.
With the pressure reduction now completed, those in charge want to reduce the likelihood of a noticeable quake. However, the experts do not rule out that an earthquake that can be felt by the population can occur in the next few years. However, according to current estimates, a damage quake remains “unlikely”.
The borehole had been created as part of a Basel geothermal experiment. The drilling began in 2006 after several years of preparation. The “Deep Heat Mining” project wanted to heat up cold water in the plutonic rock and use the heat at the top, for which in advance the rock below should be permeable by water pressure.
However, this process triggered tremors. On December 8, 2006, a clearly noticeable 3.4 magnitude earthquake shook the region, marking the end of the $100 million project. Since 2012, the Swiss Seismological Service monitors the location on behalf of the city canton.
Source: Basler Zeitung
