Investigation report released on Vendenheim geothermal project in France

Drilling rig on site of Vendenheim project, Alsace/ France (source: Fonroche)

A report commissioned by the Bas-Rhin prefecture, we reported on its establishment, has found a “bundle of clues” as to the responsibility of Georhin (formerly Fonroche Geothermal) in the earthquake north of Strasbourg/ France in November 2019. The operator disputes this position.

A “cluster of clues to establish the link between the injections […] and the activation of the Strasbourg/Robertsau area”. According to an expert report posted online – for its public version – on May 5, 2022 by the Bas-Rhin prefecture, the geothermal company Georhin (formerly Fonroche Géothermie) would be at the origin of the earthquake of magnitude 3.1 felt on November 12, 2019 north of Strasbourg. Until then, the two wells in Vendenheim (Bas-Rhin) drilled by Georhin had only been formally questioned – including by the operator – for the tremors that followed in 2020 and 2021. One of them having also led the prefect to pronounce the definitive stop of the installation, before the administrative court found her wrong.

In its report published on Wednesday May 4, the committee of experts – made up of researchers from various universities, the National Institute for the Industrial Environment and Risks and the Bureau of Geological and Mining Research – set up by the prefecture in February 2021, estimates that the “continuous pressurization” in one of the two wells, as well as “the accumulation of volumes injected (in particular from August 2020)” has indeed led to the instability of the faults nearby of the site. A second phase, “postponed to a later framework to be defined”, should “provide independent analyzes to verify the results of Fonroche Geothermal”, write the experts.

Lack of hard data

The general approach of the operator is called into question. Among the points underlined by the experts: the “lack of solid data for the construction of a geological model”, resulting in “a poor knowledge of the structure of the reservoir and a poor assessment of the risk of seismicity”. Or again, operational procedures which “have always been placed in favourable scenarios” leading to “underestimating the risks”.

Jean-Philippe Soulé, CEO of Georhin, believes that scientific uncertainty persists about the origin of the 2019 earthquake. He considers the body of evidence “unsubstantiated”, although accepting certain other criticisms of the report. For him, the experts’ analysis marks above all an “acknowledgment of failure” of the methods of cooperation between industrialists and scientists on this type of project. “The subjects raised by the committee are precisely those on which we have worked together over the past ten years,” he says. The company intends to provide a “point by point” review of the work of the committee of experts in the coming months.

As for the drilled wells, the experts go in the direction of the operator so that they are not filled up, for monitoring purposes.

Source: Les Echos