Corinne Arrouvel

Since the singular case study in Bourakebougou (Mali) by an accidental discovery of a hydrogen reservoir, geological hydrogen is today considered renewable and exploitable locally. An increasing interest for mapping reservoirs worldwide started chasing indices to localize accumulation of geological H2. Brazil has been one of promising countries with hydrogen structures on the soil surface, called Fairy circles or more recently denominated as circular depressions (in particular in Roraima, Minas Gerais, Ceará, Tocantins). Recent discoveries of major reservoirs have been found by chance (e.g. Lorraine-France, Bulqizë-Albania) manifesting other patterns, with a probable deeper formation and diffusion through faults. In the present investigation, the best regions for hydrogen prospection have been proposed considering some proxies accessible thought satellite images, topographic data (such as fairy circles, fractures/faults), magnetic and gamma anomalies and visual observation on-field. In São Paulo, Rio de Janeiro and Espírito Santo states of Brazil, we have detected high concentrations at less than 1 m of depth in the soil (>1% in volume of H2, detected using a semiconductor detector, Variotec). From those preliminary results, we couple mineral dataset with thermodynamic simulations to support the mechanisms involved during its formation. The highest values have been reported close to faults and fractures. Hypotheses about its accumulation are under investigation, requiring other techniques such as seismic studies. Acknowledgment: Arrouvel is grateful FAPESP 2022/12650-9 for financial support, ICMBio at the Ipanema National Forest and the biological reserve of Union in the state of Rio de Janeiro, Vanea Nogueira Oliveira for her technical support.

Co-authors : Leonardo Silva de Oliveira (LENEP-UENF) and Alain Prinzhofer (GEO4U)