The presence of natural molecular hydrogen found as a gas in the subsurface has been documented in many locations throughout the world (Zgonnik, 2020). In deference to man-made ‘green’ or ‘blue’ hydrogen naturally occurring hydrogen gas in the sub-surface has been termed either ‘white’ or ‘gold’ hydrogen (Ball and Czado, 2022). Given the extremely lightweight and highly reactive nature of hydrogen, its occurrence as a free molecule in nature is rare and requires specific subsurface conditions to be met:

• A source of natural hydrogen generation (biogenic, chemical, or radioactive),

• A reservoir rock,

• An impermeable ‘cap rock or seal’ to prevent hydrogen leakage via diffusion, and

• The absence of oxygen as this will react with the hydrogen creating water and leaving no trace hydrogen gas was ever present.

Significant hydrogen gas shows were documented in 1963 from the Triassic Bunter Sandstone interval in the Monzón-1 exploration well drilled in the Ebro Basin of northern Spain. The Bunter Sandstone reservoir lies on a well-defined basement closure and is sealed by a thick sequence of evaporite bearing Bunter shales at a depth greater than 3500 metres below the ground surface. The geology documented in the Monzón-1 well perfectly matches the sub-surface conditions thought to be required for the entrapment and concentration of natural gold hydrogen. Despite good petrophysical indications of trapped gas presence, the well was not flow tested at the time of drilling. The intriguing conclusion is that an accumulation of gold hydrogen awaits re-discovery and it is Helios Aragon’s plan to do just that and re-drill and test the Monzón structure.

https://eurogeologists.eu/efg-webinar-natural-hydrogen-in-the-monzon-1-well-ebro-basin-northern-spain/