Jacques Pironon
Jacques PIRONON is Senior Research Fellow at the CNRS (French National Centre of Sciences). He is a specialist in geological fluids in sedimentary environments, he leads research projects to reduce the proportion of anthropogenic CO2 emissions in the atmosphere, to understand the formation of oil and gas deposits, to help monitor industrial sites and reduce the environmental impact of subsoil mining. He is a major player in partnership research, he leads research programs shared between industry and academia on underground exploration and exploitation. He develops sensors and techniques for measuring gas in deep boreholes for exploration and underground gas storage (CH4-H2-He-CO2-H2S) as well as experimental equipment for modeling deep environments in the laboratory. He founded the GeoRessources Research Laboratory at the Université de Lorraine in 2011, bringing together 200 people (researchers, technicians and administrative) to cover the entire cycle of raw materials from prospecting to recycling. With colleagues from CNRS, Université de Lorraine, FDE and Solexperts, he discovered the hydrogen deposit in Lorraine in 2022.
The Lorraine Carboniferous Basin is an ultra-deep sedimentary basin located on the border between France and Germany. Of Westphalian to Stephanian age, it is covered by the Mesozoic Paris basin.
Work combined petrographic observations with hydro-geochemical data in boreholes. For this, an innovative probe system (SysMoG™) for measuring dissolved gases, in-situ and continuously, was designed by the Solexperts company and the CNRS/University of Lorraine and deployed in the Folschviller stratigraphic borehole FOLS1A (Moselle-France) drilled in 2006 by Française De l’Energie. At the same time, rock samples were taken from neighboring core drillings. The siliciclastic sediments show pores and fractures that are cemented by diagenetic minerals whose typical paragenetic sequence is marked by the temporal succession: siderite, ankerite, quartz, dickite, sphalerite and barite.
CH4 dominates the gases of current fluids, resulting from the thermal maturation of coal over time. At a depth of 1250 m, H2 represents approximately 18% mol of the gas mixture and dissolved H2 concentration in waters is around 3.7 mg/L. The H2 concentration increases with depth giving hope for reaching concentration about 60% mol (30.8 mg/L) at 3 km depth. Siderite and ankerite (Fe(II)) may reduce water in hydrogen at deeper compartments of the Carboniferous. H2 genesis from coal is not excluded. These two hypotheses are temperature dependent and request more than 150°C, i.e. 5 km depth, for initiation. Measuring the drilling concentration makes it possible to estimate the contingent resources at around 34 Mt for the entire Lorraine carboniferous basin (16 000 km2).
In parallel, several methodologies for prospecting H2 emissions were deployed on the Folschviller site from the surface (-1m) to -100m. Thus, 4 vertical boreholes were the subject of occasional or continuous measurements. The FOLS1A borehole was measured at -100 m (SysMoG™ probe) where a hydrogen background of 400 ppm was detected in a gas mixture dominated by nitrogen. Environmental drilling at -24 m (SysMoG™ probe), almost 20 meters from FOLS1A, did not reveal traces of hydrogen during the ICP-MS measurement. Finally, two small boreholes 1 meter deep, located 30 meters from FOLS1A and equipped with two SurfMoG™ probes, revealed no trace of hydrogen during several months of recording.
We can conclude that the linear hydrogen concentration profile measured in the FOLS1A vertical borehole corresponds to a hydrogen diffusion profile whose source is probably more than 5 km deep. When we are far from FOLS1A, the detectors located at -24 m and -1 m depth do not detect hydrogen. These results show that prospecting for natural hydrogen cannot be limited to surface measurements and that exploratory drilling cannot be avoided.
Acknowledgments: This work was carried out by GeoRessources and LFDE as part of the REGALOR project supported by the Grand-Est Region and the FEDER.
Fig. 1: Folschviller (Moselle-France) site with the location of the different boreholes where hydrogen is measured.
Jacques PIRONON1, Philippe de DONATO1, Médéric PIEDEVACHE2, Odile BARRES1, Marie-Camille CAUMON1, Aurélien RANDI1, Catherine LORGEOUX1, Raymond MICHELS1, Mathieu LAZERGES1, Vitaliy PRIVALOV1,5, Antoine FORCINAL3, Fady NASSIF3, Thomas FIERZ4, Yanick LETTRY4
1Université de Lorraine, CNRS, GeoRessources lab, F-54500 Vandœuvre-lès-Nancy, France
2Solexperts France, 10, allée de la forêt de la Reine, F-54500 Vandœuvre-lès-Nancy, France
3LFDE, Avenue du district – ZI Faulquemont, F-57380 Pontpierre, France
4Solexperts AG, Mettlenbachstrasse 25, CH-8617 Mönchaltorf, Switzerland
5National Academy of Sciences of Ukraine, UA-03142 Kyiv, Ukraine
CNRS
Senior Research Fellow
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