The Soultz-sous-Forêts site is the world's only operational pilot plant producing electricity via EGS technology (Enhanced Geothermal Systems) (NE France, 2005). © BRGM

Geothermal energy: measurement campaigns in Alsace and Auvergne

02.22.2017
The Géodénergies scientific interest group is currently running two projects on deep geothermal heat extraction. Several geophysical measurement campaigns are under way at Riom in the Massif Central and Vendenheim and Eckbolsheim in Alsace.

A convoy of vibrator trucks will be circulating for about a month in the Riom sector.  Every 20m, the convoy comes to a halt, deploys plates on the ground and emits a vibration. Geophones record the duration of travel of the vibrations, producing a "sonogram" of the subsoil that reflects its geological structure. This campaign is part of the Reflet project on characterisation of deep geothermal reservoirs in fault zones. The knowledge produced by these measurements, followed by drilling and digital simulations, will reduce uncertainties about the sources of geothermal heat in question, i.e., fluids circulating at temperatures above 150°C and at a rate of up to 350m/hour, which would be used to power electricity and/or heat production plants. Three sites in three different rift areas (grabens) in the Alsace, Auvergne and Rhône-Alpes regions, are now being investigated with a view to developing a theoretical model of geothermal reservoirs in fault zones.

A convoy of vibrator trucks will be circulating for about a month in the Riom sector.

"Listening" to fault zones

The second project, Temperer, complements the first by focusing on the collapse basins of the Rhine and Limogne rift zones. In this case, the aim is to record very low magnitude micro-tremors (<2, at the threshold of human perception) before, during and after drilling of the production and injection wells. The aims are to ascertain the initial behaviour of the faults, monitor changes during the course of the geothermal project and, in general, gain more accurate knowledge of the reservoir's characteristics. Four geophones - instruments that record seismic waves - were installed in the spring of 2016 at Vendenheim (Alsace) at a depth of a few metres. In April 2017, they will be moved to a deeper level. Four other geophones will be placed at the same time at a neighbouring site in Eckbolsheim.

Four geophones - instruments that record seismic waves - were installed in the spring of 2016 at Vendenheim (Alsace) at a depth of a few metres.  

The Reflet and Temperer projects started in 2015 and will continue for 4.5 years. Like all Géodénergies projects, these are applied research projects that closely involve the industrial companies concerned, in this case Fonroche Géothermie and Electerre de France.

Towards more widespread geothermal heat extraction from deep rock formations

Much of current scientific research on geothermal applications is focused on the new Enhanced/Engineered Geothermal Systems (EGS technologies). The aim is to enable direct heat extraction from relatively impermeable rocks deep below the surface, in any geological context, to produce heat and electricity. The research began over thirty years ago at the scientific pilot facility at Soultz-sous-Forêts (Alsace), which has demonstrated the feasibility of extracting heat (at up to 200°C) from relatively impermeable granite formations at depths of 4,500 to 5,000 metres.

About GEODENERGIES

As a partnership that builds on the strengths of its 17 members, which include 9 companies, 7 public research organisations and 1 competitiveness cluster, GEODENERGIES works as a scientific interest group aiming to lead the field in technological development and high added value integrated services in the field of zero-carbon energy involving uses of the subsoil. The target areas for development are:

  • underground storage of CO2 to reduce the adverse climate impacts of fossil fuel use,
  • energy storage in different forms (heat, electricity in the form of compressed air, hydrogen) to expand the deployment of wind, solar and other forms of renewable energy,
  • geothermal applications for direct production of non-intermittent heat and "green" electricity.

GEODENERGIES works at the interface between scientific and economic players in these sectors, to encourage their involvement and combine their efforts in projects that will boost their growth and consolidate France's technological advance on these markets of the future. Géodénergies is anticipating innovative and practical solutions for its partner industries to consolidate their national and international successes. Funding from the "Investing for the Future" scheme is supporting the industrial research projects conducted by Géodénergies, which is aiming to become an Institute for the Energy Transition (ITE) by 2019.

Since the creation of Géodénergies, 5 projects lasting two to four years have been launched, each with a budget of 1 to 8 million euros and involving five to six partners.

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