Organic H₂ formation at atomic to basin scales: predictions and ground-truthing

This study investigates the abiotic formation of organic dihydrogen (H₂ORG) using analytical, experimental and modelling techniques. In a petroleum context, H₂ORG's bulk precursor is mainly “dead carbon”, and thus anthracite is the most inherently prolific source lithofacies. The demonstrated growth of aromatic rings at elevated maturity is conjectured to generate hydrogen radicals which combine to form H₂ORG, and/or react with pre-formed methane to generate ethane. Molecular modelling predicts mineral catalysis enhances aromatisation. In the Shahezi Formation (Songliao Basin), methane retention accompanies precursor depletion, whereas H₂ORG occurs only sparsely despite quantitatively significant precursor degradation. Expulsion into known potential carrier systems, and/or reaction losses are invoked. Fluid inclusions confirm that H₂ is scarce in source facies, exemplified by Westphalian anthracite (L.Saxony Basin), and that there are lateral H₂ORG-migration routes away from source strata in the Cooper Basin. It is concluded that the commercial exploitation of in-situ H₂ORG from source rocks is unlikely.