Rigollet Christophe, Aubourg Charles, Bader Anne-Gaëlle, Dupuy Johann, Fargetton Tiphaine, Gal Frederick, Gaucher Eric C., Hauville Benoit, Lefeuvre Nicolas, Loiseau Keanu, Martelet Guillaume, Moretti Isabelle, Portier Eric, Rosanne Maria, Thomas Eric
Natural hydrogen is an alternative to manufactured hydrogen and does not emit CO2. This new sector is, however, less mature than other means of producing hydrogen and there is only one exploited deposit, in Mali.
As part of the H2NA project, based on existing data and field investigations, we have conceptualized the different potential hydrogen systems on the scale of the Nouvelle Aquitaine Region.
• The geology of the Massif Armoricain and the Massif Central is favorable to the production of natural hydrogen by serpentinization of mafic formations or by radiolysis of water in granites. In the absence of sedimentary cover, the question of possible accumulations in fracture systems arises.
• The Seuil du Poitou presents both a potential deep source (the extension of the Hercynian massifs) and a Jurassic sedimentary cover with reservoir formation – cover formation couples.
• In the Permian Quercy graben, hydrogen could come from the radiolysis of water in the uranium-bearing Permian sandstones or from the serpentinization of Hercynian mafic rocks. Lias evaporites are a potential cover.
• The serpentinization of the deep gabbros of the Aquitaine Basin (ophites), accessible to outcrop in the Pyrenees, could be a source of natural hydrogen with possibilities of accumulation in the Jurassic sedimentary series.
• The Parentis Basin also presents a favorable configuration with a mantle rise in the axis of the rift which could be serpentinized and several possibilities of accumulation in pre-salt and post-salt cover reservoir couples.
• The Pyrenees, here also with a mantle rise in the process of serpentinization with circulations along the large Pyrenean structures and possible accumulations (1) in the folds and scales of the northern Pyrenean zone, (2) in the deep scales and the filling of the foreland basin, or (3) associated with salt structures.
The evaluation of the geological risk associated with each of these hypotheses will make it possible to prioritize the cases with a view to more in-depth investigations for the next months.
The H2NA collaborative project is supported by the Nouvelle Aquitaine Regional Council and brings together the consulting company CVA, the potential operators 45-8, ENGIE and Storengy, the UPPA university and the BRGM (French geological survey).