Investigative report published on the Vendenheim geothermal project in France

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

The initial investigation report points to some responsibility in the seismic events that led to the shutdown of the Vendenheim geothermal project in Alsace/France, an assertion which the promoter considers to be unfounded.

A report commissioned by the Bas-Rhin prefecture, which we reported on when it was set up, found a “bundle of clues” as to the responsibility of Georhin (formerly Fonroche Géothermie) in the earthquake north of Strasbourg/ France in November 2019. The operator disputes this item.

A “cluster of clues to establish the link between the injections […] and the activation of the Strasbourg/Robertsau zone”. According to an expert report posted online – for its public version – on May 5, 2022 by the prefecture of Bas-Rhin, the geothermal company Georhin (formerly Fonroche Geothermie) would be at the origin of the magnitude 3.1 earthquake 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. they also led the prefect to pronounce the final shutdown of the installation, before the administrative court found him wrong.

In its report published on Wednesday 4 Maythe committee of experts – made up of researchers from various universities, the National Institute for the Environment and Industrial Risks and the Bureau of Geological and Mining Research – set up by the prefecture in February 2021, considers that the “continuous pressurization” in one of the two wells, as well as “the accumulation of injected volumes (in particular from August 2020)” has indeed led to the instability of the faults near 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 “poor knowledge of the structure of the reservoir and a poor appreciation of the risk of seismicity”. Or again, operational procedures which “have always been placed in favorable 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 all the evidence to be “unsubstantiated”, while accepting some 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 for the past ten years,” he explains. The company intends to take stock “point by point” 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, for monitoring purposes.

Source: The echoes

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