Communication Dans Un Congrès Année : 2024

Localizing the major hydrogen resource in the Carboniferous Lorraine basin using down-whole gas monitoring and experimental organic geochemistry

Résumé

Natural gas has been classified by the European Union as a sustainable investment and recent events have highlighted how energy transition efforts can be compromised without a secure supply. In this context, the identification of local/regional decarbonized or low-carbon gas resources is important. The Lorraine Carboniferous Basin located in northeastern France is known to host sedimentary formations containing coal. Its main gas resource is coalbed methane for which the contingent resource estimate in the Française de l’Energie permit is 371 billion cubic meters. Estimates for larger parts of the basin are still ongoing. In order to predict gas quantities and geochemical compositions at different levels of maturity, an artificial maturation of coal was performed. Confined pyrolysis experiments thus document the gas formation stages as well as the evolution of the methane isotopic signature over a maturation range from 0.5 to 3.0% vitrinite reflectance. The development of SysMoG™, a new technology for monitoring gases at depths up to 1250m in the Folschviller scientific well (FOLS1A), has made it possible to establish a profile of the evolution of the dissolved gas content in the basin waters. Methane was recognized as the major constituent of dissolved gases. While it was absent at the shallowest measurement depth (100m), the hydrogen content of the dissolved gas mixture increased regularly with depth up to 20% at 1200m. This increase raised a double question: What is the mechanism of H2 formation? At what depth is the source of this hydrogen? To answer this second question, a first approach consisted in the extrapolation of the hydrogen enrichment profile observed in the scientific well. In addition, the isotopic compositions in carbon and hydrogen of the methane present in the dissolved gas of FOLS1A were compared to the trend of isotopic evolution obtained by artificial maturation experiments. It appears that the geochemical composition of methane can only be produced by coal having reached a vitrinite reflectance of about 1.4%. This level of thermal maturity of coal is currently observed at about 3000m depth. These two approaches are therefore convergent and indicate that the methane observed in the dissolved gas of FOLS1A between 800 and 1200m depth diffuses from coal bearing strata located at 3000m or below. We therefore suggest that this depth should be the target of future drilling campaigns that will be planned as part of the REGALOR II R&D project. This work was carried out by GeoRessources as part of the REGALOR project supported by the Grand-Est Region and the FEDER.

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Dates et versions

hal-05189440 , version 1 (28-08-2025)

Identifiants

  • HAL Id : hal-05189440 , version 1

Citer

Raymond Michels, Philippe De Donato, Jacques Pironon, Catherine Lorgeoux, Aurélien Randi, et al.. Localizing the major hydrogen resource in the Carboniferous Lorraine basin using down-whole gas monitoring and experimental organic geochemistry. Hydrogemm, Nov 2024, Paris, France. ⟨hal-05189440⟩
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