Haute-Sorne, Switzerland geothermal project given go-ahead for stimulation tests
The drilling rig at the site of the Haute-Sorne geothermal project, Switzerland (source: Geo-Energie Jura)
Carlo Cariaga
17 Jun 2025
With the approval of canton authorities, the geothermal project in Haute-Sorne in Jura, Switzerland will proceed with stimulation tests starting July 2025.
Approval has been granted to start the stimulation tests for the much-anticipated geothermal project in Haute-Sorne in the canton of Jura in Switzerland.
Stimulation testing is scheduled to begin by the 7th of July. Stimulation tests will happen over one to two weeks, while the entire process is expected to take about a month and a half. The operations will conclude with the installation of seismic sensors in the well for long-term monitoring.
Being developed by Geo-Energie Jura AG, drilling of a geothermal well to 4000 meters depth was completed at the Haute-Sorne site in August 2024. The project is a major milestone for geothermal in the region, as it is the first well drilled in the Jura Arc, between Geneva and Basel, that completely penetrates the sediments and reaches the crystalline basement. A series of geophysical measurements had been completed since then to better understand the Jura geology. A leak test of the borehole had also been completed as part of the preparation for hydraulic stimulation.
The authorization is issued following verification by the cantonal authorities, with the support of their experts, of Geo-Energie Jura’s detailed work program.
Supervised stimulation protocol
The stimulation tests will be carried out in the exploratory well, at a depth of approximately 3,800 meters. The tests involve injecting water from the municipal network, in stages and without the addition of chemicals, sand or solids, up to a maximum flow rate of 60 L/min.
A sophisticated seismic monitoring system will enable precise monitoring of the microseismicity deliberately induced by these operations. The seismograms will be published and available in near real time. The data will be available on the Swiss Seismological Service (SED) website during the stimulation phase.
The operator’s work program provides for the temporary interruption of injections for analysis if the local magnitude reaches 0.3. Moreover, stimulation tests will end if the magnitude reaches 1.5. The local magnitude values will be determined independently and bindingly by the SED under ETH Zurich. The latter will also be responsible for defining within 48 hours whether the earthquakes are induced by tests or are natural.
A decision on the future of the project
Analysis of the results of the stimulation tests will be crucial in determining the future of the project.
After analysis, the operator will transmit the results of the exploratory phase to the Canton of Jura, including an update of the risk analysis and the geological model. This data, as well as its integration into the general plan for the next phase, will allow the competent services to assess the compliance of the second stage of the project. The Independent Expert Group (GEI), mandated to provide scientific monitoring related to the risk of induced seismicity, will support this analysis and then formulate recommendations to the Government.
Based on the assessment by the cantonal services and the recommendations of the GEI, the Government may then validate or not the continuation of the project, specifying, where applicable, the authorization framework. As long as an authorization condition is not respected or if the risk level is not acceptable, the continuation of the project will not be authorized.
RELATED: Positive conclusions on Haute-Sorne geothermal project reported by federal committee
Source: Canton of Jura, RFJ, and Geo-Energie Jura
