St.Gallen / St.Galler Stadtwerke
City’s public utility company under public law, 100% owned by the City of St.Gallen (Switzerland); Self-organized branch within the municipality / administration; Working in the fields of electricity (production and grids), water (grids), natural gas (grids), district heating (production and grids), optical fibre broadband (grids) and energy related services for its customers and third parties (other energy companies, municipalities, etc.); about 300 employees, 5 employees within the department of “Innovation”, whereas 1 employee in charge of the coordination/project management of the planning, realisation and resulting assets (managing of existing geothermal well, data, samples and documentations) of the former geothermal project (2010-2014, project haltet since 2014, details below) with technical/geological background.
Role in the Project
The geothermal project undertaken by the city of St.Gallen (Switzerland) and operated by the St.Galler Stadtwerke was based on a large-scale 3D seismic survey in 2010. The survey led to drilling of the geothermal well, “St.Gallen GT-1”, to a measured depth of 4450 m MD across Tertiary and Mesozoic rock formations as well as extensive scientific and technical analysis, and well completion aimed at geothermal use. After complications occurred during well stimulation and testing in July 2013 (a gas kick and seismic events up to ML 3.5 as a consequence of killing the well) the project was temporarily stopped. In October 2013 the project was resumed with a modified drill stem test producing gas and water and collection of a comprehensive data set on the developed jointed aquifer within the regionally prominent St.Gallen Fault Zone.
The well has since been temporarily shut-in, and is being pressure monitored from surface as well as monitored using a passive seismic network. Because of very low hot water flow rates, yet high natural gas rates produced and associated high risks for felt induced seismicity, the geothermal project has been halted in May 2014 (see also www.geothermie.stadt.sg.ch for project facts and history). Since then, St.Galler Stadtwerke has started to search for an ultimately commercially viable alternative use of this geothermal well and define the conditions for a definitive well abandonment in the medium-term.
In the course of this analysis, St.Galler Stadtwerke have invited E&P companies as well as the science and technology community to engage in the discussion with a view towards collecting ideas and concepts for the future use of the geothermal well with a scientific focus.
The S4CE St.Gallen project team is made up of only one team member at the moment – project manager Thomas Bloch. Thomas studied Geology at University of Heidelberg (GER), Lund University (S) and Karlsruher Institut für Technologie – KIT (GER), graduating in 2006 within the field of hydrogeology / geothermal. After having gained working experience in different fields of geothermal with different employers in Karlsruhe and Stuttgart (Germany) since 2006, Thomas has been in charge at St.Galler Stadtwerke for the project management of the drilling campaign for the former Geothermal Project St.Gallen and subsequent evaluations (e.g. natural gas and scientific aspects) since the year 2010. Since 2017, Thomas – being a team member of the department of Innovation within the St.Galler Stadtwerke – is also involved within S4CE managing all aspects of St.Gallen field site.