Results of 2nd exploration well for Geneva geothermal project encouraging

Results of 2nd exploration well for Geneva geothermal project encouraging Lully drilling site, Geneva, Switzerland (source: SIG/ © Magali Girardin 1_0)
Alexander Richter 7 Jan 2021

The actors of the geothermal project of Geneva, Switzerland report encouraging results of the second exploration well drilled at Lully.

As reported by Geothermies, the joint project of municipality of Geneva in Switzerland and its local utility SIG, the second exploration well drilled at medium depth has shown encouraging results.

The results of the Lully drilling confirm that the subsoil is saturated with water, but that seismic data acquisition campaigns must be continued in order to be able to place the wells with more precision, where the flows are high.

The actors of the GEothermies program comment on the results of the Lully drilling (all in French):

The Lully borehole, like the previous one in Satigny, is rich in experience and contributes to the skills development of local actors. Eventually, geothermal energy will be able to heat greenhouses, businesses or even municipalities.

Lully drilling: 2nd exploratory drilling and the deepest ever drilled in Geneva! 

Geneva relies on geothermal energy to heat the canton with renewable and local heat. The geological conditions of the township are promising, but must be clarified through an exploration program. The Lully borehole is the second medium-depth exploration borehole in the GEothermies program after that carried out in 2018 at Satigny. It aims to better understand the Bernese subsoil, in a geological context a little different from that of Satigny, and to assess whether it is just as favorable to the development of geothermal energy. This second pilot project will also make it possible to benefit from the technical and administrative experience feedback from such operations for the next drilling.

The first drilling carried out at Satigny in 2018 confirmed the forecasts made during the prospecting phase since it found, between 420 and 744 meters deep, water at a temperature of 33 ° C which naturally rises. at the surface with a flow rate of more than 50 liters per second. In Lully, the presumed fault zones affecting the limestone layers are of another type and this context should be explored to assess whether it is just as favorable to natural hot water circulation. The Lully borehole with a depth of 1,456 meters  is deeper than that of Satigny.

In order to capitalize on the lessons learned from the first Satigny drilling, the same machine was used and the same teams were mobilized. The selected drilling rig is significantly lighter than the rigs usually used for deeper wells, while having all the safety features required for such operations, such as well plugging blocks (BOP) installed. at the top of the structure in order to ensure its watertightness by its immediate closing in the event, in particular, of strong inflows of water. This type of drilling is similar to a traditional site, without any particular nuisance and in accordance with the legislation in force.