CSIRO result sharpens Prominence’s Eyre hydrogen drilling targets

Hydrogen detected across all analysed samples

Prominence Energy Limited (ASX:PRM) has received a significant exploration result from a CSIRO study of its Eyre Peninsula project: hydrogen was detected in all 28 successfully analysed rock samples. The gases were released by crushing fluid inclusions, providing evidence consistent with past circulation of hydrogen-bearing fluids through the investigated geological system.

The strongest reading was 7.72 millimoles of hydrogen per kilogram of rock, recorded in a quartz vein from the Tunkillia Suite. That result does not establish a present-day free-gas accumulation, recoverable volumes or commercial potential. The timing of the hydrogen-bearing fluid circulation also remains unknown.

The study adds geological support to the company’s exploration thesis without converting it into a discovery. Prominence had previously outlined an Eyre resource framework covering 202.8 billion cubic feet of unrisked 2U prospective hydrogen across 15 leads, but those volumes remain undiscovered and exploratory.

Two potential hydrogen source mechanisms identified

CSIRO identified uranium- and thorium-enriched felsic rocks of the Hiltaba Suite, particularly the Cultana Subsuite, as candidates for radiolytic hydrogen generation. The tested Cultana samples contained uranium concentrations of up to 50.9 parts per million and thorium concentrations of up to 142.5 parts per million.

A second possible mechanism involves reactions between water and reduced iron in rocks. A Sleaford Complex chlorite schist contained 8.39% ferrous iron by weight, while Tunkillia dolerites and Hiltaba-associated metagabbros also showed reduced-iron potential. The study did not quantify current hydrogen generation rates, and future generation would depend on suitable geological conditions and access to water.

Potential seal evidence rests on one sample

CSIRO also identified faults and fracture networks as possible migration pathways, with several higher hydrogen measurements occurring near major structural intersections. The report stops short of establishing a direct link to active hydrogen migration.

A single Gawler Range Volcanics rhyolite sample provided preliminary evidence of a possible sealing unit. It recorded connected porosity of about 1.2% and very low gas permeability under laboratory conditions, including no measurable permeability perpendicular to the rock fabric. The result is encouraging for further testing, but one sample cannot establish the thickness, continuity or regional integrity of a seal.

Target ranking moves towards mid-2027 drilling

Prominence plans to combine source-rock characteristics, structural pathways, reservoir indications and possible seals to rank prospects within PEL 803. Follow-up work under consideration includes expanded testing of volcanic cover, further investigation of hydrogen-bearing fluid inclusions, sampling of accessible deeper fluids and selection of an integrated target for potential exploration or stratigraphic drilling.

The company is targeting a multi-well helium and natural hydrogen drilling campaign from mid-2027, a plan previously described in its mid-2027 drilling plan. The program remains conditional on technical results, approvals and funding, while Prominence has also begun updated drilling engineering, cost assessment and farm-out discussions.