Arnout Everts, Jos Bonnie, Ramon Loosveld

This paper proposes a broad classification of natural hydrogen occurrences from a viewpoint of not only exploration geology but also development-potential and ability to meet industrial needs. Conceptually, working subsurface “hydrogen systems” comprise the same key elements as their “petroleum system” counterparts namely: Source, Reservoir, Trap and Seal. Considering success or failure on these “system elements” and consequences for technical development-potential, this paper categorizes “finds” and prospects into three “hydrogen play types”: 1) “focussed seepage” plays where there is a hydrogen source but minimal trapping and where hydrogen concentrations reflect localized migration pathways, mostly of dissolved hydrogen; 2) “coal-bed hydrogen” plays where hydrogen is adsorbed on a molecular scale in coals; 3) “reservoir-trap-seal” plays with gaseous hydrogen columns trapped underneath an impermeable seal.

It appears that only “reservoir-trap-seal” hydrogen plays could potentially meet the supply needs of industrial facilities. To date, no accumulations of this type have unambiguously been discovered.