The World’s First Deep Borehole Dedicated to Natural Hydrogen Confirms Significant H₂ Enrichment in the Lorraine Carboniferous Basin (France)
PresentationBreaking News from the Natural H2 World
2026-11-03 | 09:15 AM - 09:30 AM | Conference Room 1
Abstract
The Lorraine Carboniferous Basin in northeastern France has recently emerged as a major target for natural hydrogen exploration. During the H-NAT 2023 conference in Perth, Australia, Solexperts reported the first detection of hydrogen in a pre-existing 1,300 m-deep borehole located at Folschviller (Moselle, France). Hydrogen was identified as dissolved gas within Carboniferous formations of the Saar–Lorraine Basin and quantified using the SysMoG™ downhole gas monitoring technology. These pioneering observations suggested the presence of a previously unrecognized deep hydrogen system and provided the basis for the first resource assessment of the basin.
Building on these encouraging results, and supported by the Grand Est Region, the European Union (ERDF–Just Transition Fund), and the French State through the Trois Évêchés exploration permit and drilling authorization, La Française de l’Énergie (FDE) initiated and financed the deepest borehole in the world specifically designed to investigate a natural hydrogen accumulation. The PTH-2 borehole was drilled in late 2025 at Pontpierre (Moselle, France) using a water-based drilling system and reached a measured depth referenced to the rotary table (MDRT) of 3,662 m in March 2026.
The well intersects Triassic formations of the Paris Basin, residual Permian units, and the Carboniferous Westphalian D and C sequences down to the upper part of the Westphalian B. Several fault zones and intervals displaying variable fracture intensity were encountered, providing valuable information regarding potential fluid migration pathways and reservoir compartmentalization. The borehole was cased and cemented to 1,960 m MDRT and subsequently screened to total depth to enable direct sampling of formation fluids and dissolved gases using a new-generation SysMoG™ probe.
Continuous monitoring of gases in the drilling mud confirmed the presence of hydrogen and methane as the predominant gases. The presence of helium was also detected. Ten days after completion of drilling operations, the SysMoG™ tool, was successfully deployed to a depth of 2,928 m MDRT, representing the deepest direct investigation of a natural hydrogen-bearing aquifer performed to date. Multi-analytical investigations conducted by the GeoRessources laboratory (Université de Lorraine) measured hydrogen concentrations reaching 49.6 mol%, together with helium concentrations ranging from 0.1 to 0.2 mol%.
The measurements further demonstrated a rapid re-establishment of hydrogen-rich conditions within the Carboniferous aquifer following drilling-induced disturbance, indicating active recharge and dynamic replenishment processes. These observations provide strong evidence for the persistence and stability of the hydrogen system at depth. The new dataset independently confirms the previously estimated resource potential of approximately 34 Mt of natural hydrogen derived from the Folschviller discovery well.
The Lorraine Basin currently represents the only proven deep natural hydrogen accumulation documented worldwide. These results constitute a major milestone for the emerging natural hydrogen sector, validate exploration concepts developed by the international scientific community, and demonstrate the effectiveness of dedicated downhole gas characterization technologies. The success of the PTH-2 borehole opens the way for the next phase of the REGALOR II program, coordinated by FDE in partnership with Saint-Gobain Recherche, which will focus on testing production concepts and evaluating the commercial development potential of this unique hydrogen resource.
Authors: Antoine FORCINAL (La Française de l’Energie-FDE, Pontpierre, France)
Fady NASSIF (La Française de l’Energie-FDE, Pontpierre, France)
Philippe de DONATO (CNRS-Université de Lorraine/GeoRessources lab, Nancy, France)
Jacques PIRONON (CNRS-Université de Lorraine/GeoRessources lab, Nancy, France)
Médéric PIEDEVACHE (Solexperts France, Vandœuvre-lès-Nancy, France)
Frédéric MATHURIN (BRGM, Orléans, France)
