Purity is not proof: an air-corrected mud-gas hydrogen purity alone cannot demonstrate a natural hydrogen accumulation

Six natural hydrogen wells have been announced with headline purities of 73% to 97%, each from gas released during drilling, with air, or oxygen and nitrogen, removed by calculation; two operators say testing is still needed. A purity records composition, not quantity or source, so alone it cannot show a recoverable accumulation. In the contractor’s public records, the interval behind Ramsay 2’s 86% is one the contractor labelled a “Likely artefact”, just below a casing shoe; its hydrogen before air correction (0.98%), its purity (86.26%) and a relative per-rock index match or exceed two events it attributed to the formation. At Ramsay 1 the real-time log at the 73.3% depth was at background. A drilling study’s carbonate samples, re-analysed, held at most 249 ppmv of drilling-made hydrogen, which reads up to 82% with oxygen and nitrogen excluded but under 1% on an oxygen-based correction. Coding of the 20 announcing documents finds confirmation or discovery wording in 14 of 20 headlines, attached mostly to presence and purity and never to a quantity. Gas rates since reported for two headline wells, about 3 to 360 m3 a day, come from other or wider intervals, so no headline interval yet has a hydrogen rate; on a six-tier evidence ladder the headline figures are Tier 1, a show in drilling returns. The paper does not argue that these wells lack accumulations, only that their purities cannot tell; a registered forecast expects their first flow tests to give under 1,000 m3 of hydrogen a day.