2024 Program

​The presentation by our colleagues from Terrensis highlighted the prospective interest in natural hydrogen in this specific area of the French Pyrenees. The aim of this new intervention will be to show that, in addition to its promising geological position, the "Grand Rieu" project, led by 45-8 Energy and Storengy, and more generally the projects in the area, are in a very favorable “Above Ground” situation.  The location encourage synergies between projects, at upstream and downstream levels as part of a particularly dynamic local and regional hydrogen ecosystem, supported by existing infrastructures or infrastructures already in project. It will facilitate concrete offtake opportunities for natural hydrogen and any associated co-products. We will also look at the production volumes that could be envisaged, the estimated production costs to date and the current timeline in order to fully materialize this promising project for the natural hydrogen industry in France and Europe.​

The Armorican Massif, Breton peninsula, is located in the far west of France. It consists of Proterozoic and Paleozoic sedimentary, magmatic and metamorphic formations that were deformed by the Cadomian and Variscan orogenies. It extends to the east under the Mesozoic and Cenozoic sedimentary series of the west of the Paris basin of which it constitutes the bedrock. Although lacking obvious targets (e.g. large mantle rock bodies), the variety of rocks that make up the Armorican basement and its high-density fault network of various age are worth exploring for the formation of hydrogen and its migration. The geochemical surveys we have carried out over the last two years highlighted hydrogen anomalies in soils. In the Brittany region, we will study the possible accumulation in the fractured basement. Further east, in the Paris Basin, hydrogen could have been trapped in the Mesozoic sedimentary reservoir formations (Lefeuvre et al., 2024).

Co-auteur : Christophe Rigollet, Vincent Roche, Nicolas Lefeuvre, Yannick Branquet, Eric Thomas, Jeanne Bride, Ulysse Froger

The research consortium associated with the REGALOR project (REssources GAzières de LORraine - FEDER/French State and Grand Est Region, 2018-2023) after having demonstrated the existence of natural hydrogen resources in the Lorraine carboniferous basin, has for the first time, specified the location of these resources within different geological formations. On the basis of SysMoGTM type probe technology (European Bureau Patent N°EP22210240.2 April 2023), the concentrations of dissolved gases (CO2, H2, CH4 and N2) and their isotopic signatures could be determined both in the Carboniferous sediments trough a vertical well (FOLS1A - Folschviller-France), between -600m and -1250m and directly in the coal seams abg trough 3 deviated flooded wells, at -925m (Well A), at -930m (Well B) and at -946 m (Well C).
In the Carboniferous sediments (vertical well FOLS1A), the concentrations at -1250 m in H2, CH4, N2 and CO2 are respectively 18.2, 7.4, 6.5, <0.05 mole%. On the contrary, measurements directly in the coal seams showed a very different relative proportion of these three gases, namely between 0.05 and 0.5 mole % for H2, between 87.0 and 96.0 mole % for CH4 , between 2.9 and 11.8 for N2 and between 0 .03 and 0.6 mole% for CO2. A high CH4 content (96 mole%) associated with a very low hydrogen content (<0.05%) in the coal veins, confirm the different origins for CH4 and H2. Moreover, the d13C-CH4 and Deuterium d2H-CH4 isotope data are similar for the FOLS1A, wells B and C. They vary between -43.8 and 39.9 ‰ for d13C-CH4 and between -238 and -208 ‰ for d2H-CH4. This shows that the methane contained in the coal seams and in the Carboniferous sediments are identical, thus reflecting a diffusion of CH4 from the coal seams (place of genesis) to the surrounding geological environment (additional storage zone). On the other hand, the absence of hydrogen in the tested coal veins can be limited by the following three hypotheses:
- a relative impermeability of coal deposits to hydrogen,
- a process of bio-physicochemical degradation within the veins,
- a mechanism of adsorption of H2 on the coal. In this case the concentration measured in the vein would be the equilibrium concentration of this process.
Because of the small hydrogen concentrations in the tested coal seams, isotopic analysis of H2 (for d2H-H2) could not be carried out. Nitrogen isotopia is inconclusive. The value of d15N is constant in the different boreholes studied at +1.5‰. It is located in the average of the d15N values described for global coals with reference to the publication by Quan and Adeboye (2021).
This research demonstrates that in a carboniferous context, the search for dissolved H2 must also be carried out outside of the coal seams, by targeting the surrounding submerged sediments, using exploration tools of SysMoGTM type. These results confirm the hypothesis of a production of H2 in deep conditions (>5 km), possibly from water-rock interaction, and the extremely low permeability of coal seams.

Philippe de DONATO1, Jacques PIRONON1, Raymond MICHELS1, Odile BARRES1,
Marie-Camille CAUMON1, Aurélien RANDI1, Catherine LORGEOUX1, Yves
GERAUD1, , Mathieu LAZERGES1, Vitaliy PRIVALOV1,5, Antoine FORCINAL2,
Fady NASSIF2, Médéric PIEDEVACHE3, Thomas FIERZ4, Yanick LETTRY4,
1Université
de Lorraine, CNRS, GeoRessources lab, F-54500 Vandœuvre-lès-Nancy,
France 2LFDE, Avenue du district – ZI Faulquemont, F-57380 Pontpierre,
France
3Solexperts France, 10, allée de la forêt de la Reine, F-54500
Vandœuvre-lès-Nancy, France 4Solexperts AG, Mettlenbachstrasse 25,
CH-8617 Mönchaltorf, Switzerland
5National Academy of Sciences of Ukraine, UA-03142 Kyiv, Ukraine

Introduction

In recent years, the world has witnessed a surge in research and development of renewable energy
technologies, ranging from solar and wind power to geothermal and biomass solutions. These
innovative approaches undoubtedly hold the key to reducing our carbon footprint, yet several of them
require the extraction and utilization of scarce minerals, leading to potential environmental
degradation and geopolitical complexities. A potentially game-changing alternative has emerged on
the horizon - Natural hydrogen. Mainly generated by geological processes, Natural H2 has been
observed with different degrees of purity as surface seepages or occasionally in wells targeting other
resources. Although some distinct natural processes are known to generate hydrogen, exploring for it
and understanding its presence remain a challenging task due the lack of geological models and
geophysical data.

Context and survey location

Natural hydrogen gas emanations have been observed and measured along the North Pyrenean Frontal
Thrust and other related faults rooted in the mantle body (Lefeuvre et al, 2021). These results,
together with a promising geological setting and evidence of fluid migration at depth, suggest that H2
may be sourced from mantle rocks serpentinization and carried to the surface along major thrusting
faults. To test this theory, CNRS, university of Toulouse and Stryde have collaborated to acquire a
passive seismic data on a 3d grid using the latest generation of compact autonomous nodes, usually
used for very dense active seismic surveys in O&G exploration. Given the very difficult access terrain
and the size of the area to survey, the use of such technology was a major enabler in this project.

Data acquisition and analysis

900 autonomous nodes were deployed over a 10x10km area, plus an additional 2d line along a road
with 100 stations. Each station was made of 3 single sensor nodes (Figure 1). The nodes were left to
record continuously for 1 month and were retrieved during the 2nd week of October 2022. 550 events
were recorded during this period, half of them directly below the grid with magnitudes varying
between -2.1 and 2.3.

Results

The north Pyrenean fault can clearly be identified on the event localization graph (Figure 2). Using
these picks, a local earthquake tomography (LET) of the upper crust was performed. The tomography
velocity model in shows two domains separated by an isovelocity of 5.6 km/s for P waves and 3.3
km/s for S waves (Figure2). Low velocities, characteristic of sedimentary rocks (smaller than 5.6
km/s) represents the decollement level of the Aquitaine Basin. Beneath we observe a Vp between 6.0
and 6.4 km/s, characteristic of hercynian basement rocks. We do not observe any high velocity
anomaly that could suggest the presence of serpentinized mantle in the shallow crust even though this
hypothesis cannot be excluded in the case of a completely serpentinized mantle body which would
have physical properties close to those of a normal upper crust.

Conclusions

We show that passive seismic can be significantly enhanced using a much denser grid of receiver
made possible by the latest generation of autonomous nodes.

In this project, the tomography doesn’t seem to support the presence of serpentinized mantle in the
shallow crust which raises new questions about the origin of natural hydrogen observed at the surface.
Natural hydrogen exploration is at its early stages of development and requires the utilization of
variety of geophysical techniques and instruments for establishment. Similar to the Oil & Gas sector,
which has significantly benefited from geophysical tools, employing these technologies promises

enhanced efficiency and vital data acquisition for the success of natural hydrogen exploration and
renewable energy industries in general. This convergence highlights the potential for leveraging
established methodologies to bolster advancements in these evolving sectors.

Exploration of natural hydrogen in various geological contexts (ophiolites, cratons, superficial macro-seeps and subsurface accumulations discovered through drilling) gives today a decent geochemical database on gas concentrations (hydrogen, nitrogen methane, helium and other noble gases), as well as isotopic ratios (Hydrogen, carbon, nitrogen, noble gas isotopes).
Several fundamental questions related to natural hydrogen are still under discussion:
- Is a hydrogen system a renewable system at human time scale?
- Why nitrogen and helium are always associated with hydrogen in various proportions, whereas their generation is generally not related to the hydrogen generation as understood today?
- How to quantify the interest of a hydrogen system, in terms of future production?
- While hydrogen fields will be produced, will the gas composition remain constant through time, or could occur a shift of gas composition versus the amount of produced gas?
Fossil noble gas isotopes (20Ne, 36Ar, 84Kr for example) are present in the Earth atmosphere, and in aquifers equilibrated with the air concentrations (ASW). They represent very simple geochemical natural tracers in gas phases, as their sources are very well characterized, as well as their physical properties. As they are chemically inert, any observed fractionation needs to be related to physical processes as phase exchanges (in our case, only water and vapor phases), diffusion and adsorption/desorption on solid surfaces. Radiogenic noble gas isotopes as 4He and 40Ar, which amounts are increasing with time, present chronometers associated with the geological fluids.
Fossil isotopes, measured in various geological occurrences of natural hydrogen, present a good consistency, and indicate clearly that they suffered large physical fractionations, which cannot be related to any simple mixing process between geological reservoirs. Their behavior is very different than when associated with hydrocarbon accumulations. We demonstrate that they suffered a fractionation linked to their extraction from aquifer water and desorption from solid surfaces into a gas phase (hydrogen blend gas), and that this extraction is occurring in an open system for natural hydrogen systems, whereas it occurs in an almost closed system in petroleum systems.
A simple modelling allows to confirm the open dynamics of hydrogen gas in geological formations, where accumulations are related to bottleneck effect rather than to a complete sealing process. It was also possible to compare the efficiency of this steady-state accumulation in various case studies, as well as the efficiency of hydrogen generation for various geological hydrogen systems.

Hydrogen, whether produced from renewable energies, through stimulating serpentinization, or harvested from natural geological reservoirs, represents a key energy vector and source for the ecological transition toward a net-zero carbon society. Molecular hydrogen is also a key electron donor in diverse microbial metabolisms, and many microorganisms use it as an energy source and convert it into a variety of compounds. Over the last decades of research, we have discovered that subsurface environments harbor a diverse microbial community capable of interacting with hydrogen and other volatiles. These communities are present in virtually all rock types and extend to depths of 5 kilometers or more. The storage of hydrogen underground, whether natural or engineered, presents several challenges, primarily due to its interaction with a diverse and ubiquitous subsurface biosphere. In this talk, I will review our current understanding of the microbiology of natural hydrogen and underground hydrogen storage, highlighting the existing gaps in our knowledge and identifying areas to focus basic and industrial research to make a hydrogen-based society a reality. While natural hydrogen prospecting, orange hydrogen, and underground hydrogen storage have diverse challenges, their microbiology is deeply intertwined and can inform each other reciprocally. I will present new, unpublished microbiology data from hundreds of natural hydrogen springs sampled globally and compare their microbiology with that of porous reservoirs and laboratory experiments, integrating efforts across geosciences, biosciences, and engineering.

Donato Giovannelli, Martina Cascone, Guillermo Climent Gargallo, Gabriella Gallo, Angelina Cordone, Marco Moracci, Davide Iacopini, Mariano Parente, Danilo Russo, Maria Portapillo, Giuseppina Luciani, Almerinda di Benedetto, Alberto Vitale Brovarone

Geological Hydrogen exploration is a complex process that involves understanding both mineral and hydrocarbon systems. This includes the mineral content, fluid conduits, as well as the generation, migration, and trapping of hydrogen gas. To successfully explore for H2 systems, we need to integrate knowledge from these different branches of geosciences.

Xcalibur, having conducted extensive airborne surveys for both sectors, is uniquely positioned to apply its existing Airborne Geophysical tools to aid in the search for geological hydrogen. Currently, the Falcon Gravity Gradiometer Technology is being extensively used to map and evaluate the geology, thereby identifying potential locations for Hydrogen exploration.

However, while the current generation of Airborne Gravity Gradiometer (AGG) systems is well-suited to mapping the vital structural boundaries, faults, structure and basement geology which are critical to Hydrogen systems, their sensitivity and resolution are not sufficient to image more subtle geological features. These features may be crucial at the prospect scale when evaluating H2 accumulation or migration pathways at the prospect/Exploration & Production (E&P) scale.

To address this, Xcalibur and Lockheed Martin are developing the next-generation gravity gradiometer, known as the Condor Airborne Laplacian Gradiometer. This instrument is designed to directly measure the Gravity Tensor at a single point in space, eliminating the need for measurements in a rotating reference frame. With the sub-systems validation component of the program concluded, there is high confidence that the desired performance will be achieved. Modelling has shown that the Condor has the potential to provide low noise data to such an extent that instrumentation noise becomes irrelevant. Condor should provide better quality gravity data than all other airborne and marine and moving-base ground sensor technology.

As a button on to either FALCON or CONDOR, or as a standalone system, Xcalibur has progressed with the development of H-MAS, a Hydrogen Raman Spectrometer. Designed to measure the concentration of atmospheric Hydrogen just above the earth’s surface, H-MAS will be capable of measuring concentrations to a few parts per million. The primary goal of H-MAS is to measure H2 concentrations, it can also be configured to measure methane and a few other gases that exhibit Raman scattering. The recipient of a Curtin University Trailblazer grant to commercialise the technology, the technology, proven in the lab, is moving rapidly to becoming a deployable instrument.

Xcalibur believes that this combination of very high-resolution gravity measurements and the simultaneous deployment of the H-MAS spectrometer provides a unique and powerful tool in the search for Geological Hydrogen

Co-authors; Daniel Palmowski, Adrian Kleine, Thomas Hantschel

Terranta GmbH, Aachen, Germamy

Exploration activity for natural hydrogen has grown significantly in recent years. The geologic concepts and processes required for natural hydron to produce economic hydrogen accumulations are being more and more refined to support the efforts to explore for geologic hydrogen resources. The hydrogen system concept, adopted from the petroleum system approach, is now being applied for many exploration projects around the world. New and effective tools to model the hydrogen system are being developed. Adopting some of the workflows form hydrocarbon and combining them with those of mineral exploration, two- and three-dimensional reactive transport modeling offers an effective approach to test our hypothesis and concepts for consistency and efficiency. The modeling of hydrogen generation, migration and accumulation requires however several new modeling technologies and as well as a better understanding of how the generated hydrogen migrates through the subsurface.

Any “working” hydrogen system requires efficient hydrogen expulsion from a source rock. Generation via serpentinization or radiolysis can only lead to efficient hydrogen expulsion if the generated hydrogen is transported out of the source rock to prevent a thermodynamic equilibrium situation within the source rock. Therefore, the key to modeling hydrogen systems is describing and quantifying the flow of water in the subsurface. Water accessibility is critical for the generation processes (serpentinization or radiolysis), the water-flow rate is critical to understand the transport of hydrogen and hence the effective expulsion from the source rocks.

An extension to the simple Darcy flow formulation of the water flow is required to address the complexity of flow drivers (density driven flow/convection) and the complexity of hydrogen transportation and migration (advective and diffusive transport, free-phase flow). To solve such problems using numerical methods requires smart and efficient grids, to not only deliver the numerical base for solving complex differential equations. The grids need to be capable of representing the needed geometric complexity of the geological models. Additionally, the modeling of convection and advective transport adds new and different scales, in both space and time, to the model.

We will present and illustrate the status quo of Hydrogen Systems Modeling based on real case studies. Modeling the flow rates of water in the subsurface on the needed scales and accuracies the combination with reactive flow modeling capabilities opens the capabilities to quantitatively assess hydrogen systems to de-risk exploration projects.

Numerical simulation of sedimentary basins (Schneider et al, 2000) has been developed to assist the geoscientist in building consistent integrated models of the deep subsurface over geologic time and in predicting petroleum systems. Beyond these applications, it seems interesting to ask whether it can also help to address the challenges of hydrogen systems. In this communication, we present some recent developments in numerical basin modeling that tentatively address some of these challenges. A demonstration case is presented and several scenarios about natural hydrogen migration and alteration are considered. To be able to model natural H2 systems, we had to extend and develop new functionalities to simulate migration processes that are usually neglected when considering hydrocarbons: 1. Although already designed for two-phase flow simulation, we needed to implement the exchange of hydrogen between the vapor phase and the aqueous phases. To do this, we rely on an analytical formulation of H2 solubility as a function of salinity, pressure, and temperature, and which was calibrated against the equation of state of Sørreide and Whitson (1992). Using this functionality, H2 exsolution or dissolution along flow paths as thermodynamic conditions change is well represented. 2. Dissolved hydrogen diffusion is also simulated with a diffusion coefficient that depends on porosity, temperature, and facies tortuosity. 3. To model possible influx of H2 by hydrothermal flow, we are now able to impose the influx rate at deep fault roots as well as its dissolved hydrogen concentration. Classical gas production by an order-one degradation process of a source material using an Arrhenius degradation rate is also available in predefined lithologies. 4. Since the degradation kinetics of H2 is also expected to be orders of magnitude faster than that of hydrocarbons, a basic degradation model based on an order-1 process has been implemented according to the model proposed by Rosso (1993), where the degradation occurs only in a temperature range. 5. Finally, our detailed modeling of flow in fault zones which simulates the flow in damage zone cells and across the fault gouge using different discretization cells is particularly well suited to simulating H2 migration which is believed to be largely controlled by flow along faults. Using this updated version of our basin simulator, we developed a demonstration case slightly modified from a 2D section of the Perth Basin in Australia (Frery et al, 2017). This demonstration case shows that predicting hydrogen migration is far from intuitive as it is controlled by many factors, including regional-scale hydrodynamics and thermodynamic conditions, the latter controlling the depth and location of exsolution. This makes basin modeling an essential tool to address natural H2 systems.

Co-auteur : Marie-Christine Cacas-Stentz*, Benjamin Braconnier*, Francesco Patacchini*, Clémentine Meiller*, Arnaud Pujol*, Adriana Traby*, Françoise Willien*, Sylvie Wolf*

Hydrogen directly coming from the Earth could represent an alternative source of decarbonized hydrogen and potentially provide the opportunity to rapidly scale up green hydrogen production for domestic use and export. Exploration programs aiming to find natural H₂ reserves at economic scale are now active worldwide, but the geological contexts favourable to generate and accumulate such gas at depth remain poorly constrained. Hydrogen can be naturally produced by various processes in the subsurface. Here, we review and discuss the generation processes as well as the elements of the hydrogen system through recently investigated case studies located in South Australia and Western Australia.

These case studies, including the well-known Gold Hydrogen Ramsey prospect, integrated new datasets acquired: 1) in the field with soil-gas surveys and ground water analyses around potential natural seeps, and 2) in the laboratory on samples from historic well cores and cuttings to investigate the subsurface geofluid paleo-migrations, the oxidation processes, the generation potential and characterise the geomechanical and transport properties of selected potential sources, reservoirs and seals. Finally, conceptual geological models of hydrogen prospectivity were developed to discuss the weight of each generation process and to integrate the elements of the system at a regional scale. 

Co-authors: Dr. Ema Frery¹, Dr. Julien Bourdet³, Dr. Claudio Delle Piane¹, Dr. Melissa Duque NK¹, Krista Davies^1,2, Dr. Charles Heath¹, Dr. Se Gong¹, Dr. Bhavik Lodhia¹, Dr. Jelena Markov¹, Dr. Mustafa Sari¹, Dr Siyumini Perera¹, Dr. Joel Sarout¹, Dr. Julian Strand¹

1. CSIRO Energy
2. 2. ECU
3. Rocks and Bubbles

The Paleozoic ophiolite massifs are widely distributed in Kazakhstan and present a part of the Central Asian Orogenic Belt (CAOB). These ophiolites consist mainly of ultramafic-mafic units, volcano-sedimentary sequences, and basaltic and doleritic lavas. In Western Kazakhstan, the Kempirsai peridotite massif is one of the largest in the south Urals. It contain several mines for podiform chromite ores which are associated with ultramafic lithotypes (dunite and Harzburgite). This study is focused on Khromtau mine in Aktobe region in northwestern Kazakhstan to investigate the distribution of the different peridotite lithotype. The mineralogical and geochemical composition of the peridotite lithotypes were studied in order to define the type and relative abundance of Fe-, mg-bearing minerals as well as the extent of serpentinization and its byproducts (e.g. magnetite, serpentine, brucite) . The investigated peridotite rocks consist mainly chromite- rich dunite enriched in fayalite and forsterite minerals and clinopyroxene. Tiny magnetite crystals are also reported growing on the fayalitic olivine. Lizardite and Fe-brucite are dominant mineral phases observed in the studied peridotite rocks. Mineralogical and geochemical composition of the studied peridotite reveal their significant potential for natural H2 generation via serpentinization. Batch reactor experiment will be conducted to investigate potential hydrogen generation from the Aktobe peridotite at temperatures less than 100°C.

Authors: Mahmoud Leila1,2, Randy Hazlett1, George Mathews1, Milovan Fustic1 1School of mining and Geosciences, Nazarbayev University, Astana, Kazakhstan 2Faculty of Science, Mansoura University, Mansoura, Egypt

The Carpathian Foredeep is an asymmetric foreland basin formed at the front of the Carpathians as a result of the northward thrusting of the orogen. The substrate of the basin comprises rocks from the Epivariscan Platform along with its Permian-Mesozoic cover. The basin is filled with Miocene sediments, which are the primary target for oil and gas exploration in this region. By 2005, more than 70 natural gas fields had been discovered in the Carpathian Foredeep.

In the context of hydrocarbon exploration within this basin, eight areas were examined using a surface geochemical method based on analyzing the molecular composition of soil gas samples. Samples were collected from a depth of 1.2 meters using a patented probe and sampling set. The analysis included concentrations of light alkanes and alkenes, as well as hydrogen and carbon dioxide. The laboratory analyses of the molecular composition of the collected samples were performed using gas chromatography with FID and TCD detectors.

Generally, hydrogen was not always included in soil gas analyses. When hydrogen was measured, its interpretation was often limited to minor mentions supplementing analysis of anomalous concentrations of alkanes, and alkenes in the context of hydrocarbon accumulation exploration. This study aims to analyze the variations in hydrogen concentrations identified in 2964 soil gas samples from the Polish part of the Carpathian Foredeep, assess the relationships between hydrogen and light hydrocarbons, and interpret the concentration distributions integrated with geological-seismic model.

The maximum recorded hydrogen concentration in the samples was 2320 ppm. The average hydrogen concentration in the soil gas across the entire Carpathian Foredeep is about 70 ppm, which is five times higher than the median value. Additionally, hydrogen concentrations show a strong correlation with ethane and the total alkanes C₂-C₅, with Pearson correlation coefficients of 0.49 and 0.52, respectively. Previous studies have shown that heavier alkanes cannot form in significant quantities in the near-surface zone, suggesting that the presence of these components in soil gas is due to microseepage and migration from deep accumulations or hydrocarbon generation zones. Therefore, the correlation between hydrogen and the total alkanes C₂-C₅ may indirectly indicate a geological origin for the hydrogen.

Noteworthy is the Brzesko-Wojnicz area, where the highest hydrogen concentration in the entire basin was recorded. Elevated concentrations of this gas correlate with zones where the Miocene bedrock lies relatively shallow. Additionally, the Miocene of this area is drilled by numerous wells, which may facilitate hydrogen migration from deeper horizons.

The conducted studies have shown that the hydrogen concentrations in soil gas in the Carpathian Foredeep area exhibit significant variability. The research indicates that hydrogen may have a deep origin, likely migrating to the surface from the Miocene substrate along fault zones and fractures. However, at this stage of research, it is difficult to definitively determine whether the mapped zones of anomalous hydrogen concentrations result from its dispersion from deep accumulations.

The research project was supported by program “Excellence initiative – research university” IDUB for the AGH University of Krakow (project number 6237).

Anna Twaróg¹, Henryk Sechman¹

¹AGH University of Krakow, Faculty of Geology, Geophysics and Environmental Protection,
al. A. Mickiewicza 30, 30-059 Krakow, Poland.

​

An estimated 40 start-up companies are now exploring for natural hydrogen globally. Therefore, natural (white) hydrogen is seen as a new alternative net zero emission energy resource within the future energy system. Despite the fact, that natural hydrogen was already found and produced in 1910 in the Leopoldshall salt mine near Stassfurt in Germany, for 4.5 years, no further follow-up work was undertaken until recent exploration successes in Mali, Kansas, Southern Australia and other areas highlighted the abundance of hydrogen in the subsurface and in surface emanations globally. The performed reviews of these global natural hydrogen occurrences illustrate a vast range of geological settings in which natural hydrogen is present. From such natural hydrogen occurrences and their various possible sources, ten different exploration play concepts were developed (Grötsch, 2023) which aim at focusing further research in yet unexplored areas - like Germany and beyond. To address the wide range of possible options within Germany, a multi-disciplinary research consortium was formed between FAU, Frauenhofer-IEG, RWTH, LIAG, GFZ and KIT end of 2023. Aim is to address common data acquisition in the field and lab, create a digital GIS data repository for the whole of Germany, characterize each play concept with actual examples, define the end-to-end play-based exploration workflow for natural hydrogen and to identify viable prospects which are considered material for future development as decentralized energy solutions. For this purpose, key areas within Germany were high-graded and mapped for further study which comprise highly metamorphic complexes, ore deposits, major deep-routed structural lineaments and thrust sheets, organic rich formations, former coal mining locations, volcanic areas, rift grabens and aquifers. The presentation will introduce players and play-concepts of the NHEG-project.

Co-author: Peter Achtziger-Zupančič, Operational Manager Fraunhofer IEG & Lecturer RWTH Aachen, Germany

Natural hydrogen (also known as geological and/or ‘white’ hydrogen) is currently receiving a huge boost in scientific and commercial interest. To aid the understanding and to ultimately support the ranking of differing geological prospectivity, it helps to classify components of these systems into analytical stages based on source, migration, reservoir, trap and seal (as is done in mineral and petroleum systems). There are several formation processes (e.g. redox reactions between iron-rich rocks and water, radiolysis, pyrolysis of organic matter) which form the main ‘source rock’ targets. Serpentinization possesses a much quicker reaction rate of hydrogen generation relative to other formation processes, meaning that source rocks such as ultramafic (mantle) suites within ophiolites are considered prime targets for investigation. Given the expected high values of density and susceptibility within these iron-rich ultramafic rock types, we can use our gravity and magnetic data to map their surface and subsurface extents, model their properties and quantify possible variations in the degree of serpentinization laterally and/or with depth. This may predict specific locations hosting relatively ‘fresh’, unreacted mantle rocks which could still yield further natural hydrogen production. Furthermore, we can use these same potential fields data to map and model granitic bodies for potential of radiolysis. We can also leverage Getech’s predicted total organic carbon (TOC) models through geological history to assess the natural hydrogen potential derived through the heating/maturation of organic matter.

The Vardar Zone (which is separated into Eastern (EVZ) and Western (WVZ) branches) represents the closure of the Vardar Oceanic Basin and the subsequent obduction of two ophiolitic suites from the Late Jurassic until the Early Cretaceous (Schmid et al., 2020). We have focussed on an area broadly covering Bosnia & Herzegovina, Serbia, Montenegro, Kosovo, Albania, and North Macedonia. Recent studies (Lévy et al., 2023) have investigated the spatial link between elevated hydrogen concentrations at surface and their proximity to outcropping EVZ and WVZ units, primarily attributing them to serpentinization of ultramafic rocks. This process is believed to be primarily taking place at depths of ~2 km through analysis of hydrogen isotopes (Lévy et al., 2023), which is also suggested by results of Getech’s magnetic vector inversion (MVI) over this region. The MVI models the 3D distribution of magnetisation amplitude and orientation which prove very illustrative when interpreting the subsurface distributions and varying degrees of serpentinization progress within these target ultramafic rocks. A 2D gravity and magnetic model has also been produced across this study area and provides further detail on the subsurface nature of this complex geological region. Source rock predictions (of ultramafics as well as other formation processes considered) can then be located within their geothermal regime setting to estimate their hydrogen generation potential. We can also incorporate fault dilatancy tendencies to model comparative fluid migration routes between different structures. All of these findings can be combined to map the predicted favourability of natural hydrogen systems which will further de-risk natural hydrogen exploration across the Balkans, and this workflow is replicable anywhere on the globe.

Salt caverns offer a promising option owing to their low investment cost, high sealing potential and low cushion gas requirement. In Italy, natural gas storage in underground reservoir has been practiced for decades but the hydrogen storage is still at its infancy as currently no sites for hydrogen storage exist in Italy. In this contribution we explore the option of salt caverns across the territory. Messinian evaporitic units scattered across the Apennine represent the best option and therefore we do explore the feasibility of hydrogen storage in salt caverns in (active or dismantled) onshore salt mines. We do analyse the structural and stratigraphy and mineralogical context of the Messinian evaporitic units across selected onshore subsurface salt mines (Southern Italy), with a focus to the pure Halite units and mixed Halite/ Kainite Units with thickness 200 m and at depth range of 200-600 m. For the suitable sites we discuss the various site, their energy densities (cavern storage potential divided by the volume) and their relevance for hydrogen storage potential.

Co-auteur : Iacopini D. 1 , Anzelmo G. , Edlmann K. , Cascone M. , Russo G. 1 Maniscalco R. , Parente M. 1 , Sabatino C. , Di Benedetto C. , , Colella A. 1 , Balassone P., Cappelletti, P , Giovannelli , D., Simili M.

The exploration of sustainable hydrogen production is increasingly focused on geological hydrogen, particularly through stimulated processes, as a promising avenue. This paper discusses our initiative to establish the first test bed site for geological hydrogen production in Oman’s Samail Ophiolite. The Samail Ophiolite, an extensive formation of ultramafic rocks rich in Fe(II)-bearing minerals, presents an ideal geological setting for hydrogen generation through water-rock interactions. Geological hydrogen production exploits natural exothermic reactions between water and Fe(II)-bearing rocks, leading to hydrogen generation and the formation of Fe(III)-bearing minerals. This process, known as serpentinization, is especially effective in peridotites and gabbros, which are abundant in the Samail Ophiolite. Previous studies have documented significant hydrogen concentrations in groundwater and surface seeps within this formation, highlighting its potential for in-situ hydrogen generation. The project encompasses a multi-phase exploration study to evaluate and establish a pilot site for geological hydrogen production. The initial phase involves a comprehensive desktop study to assess existing geologic and hydrogeologic data, field mapping, and sample collection. This phase aims to identify and characterize prospective pilot sites based on their geological potential for hydrogen generation, considering factors such as the presence of ultramafic rocks with minimal metamorphic and alteration overprints and the geochemical suitability of groundwater. Following the desktop study, geologic surveying and coring will be conducted to collect detailed subsurface data, which will be analyzed for their petrophysical characteristics, mineralogy, and hydrogen generation potential. Hydrogeologic assessments will measure groundwater chemistry and dissolved gas composition to establish baseline conditions and identify suitable sites for water injection and hydrogen recovery. Environmental assessments will ensure sustainability and adherence to regulatory standards, evaluating potential impacts on air and water quality, biodiversity, and local communities. This initiative positions us at the forefront of global hydrogen exploration, with significant scientific and environmental implications for sustainable energy production.

Coming soon

The Semail Ophiolite, renowned for its exceptional preservation, provides a rare geological snapshot of oceanic lithosphere rocks at the surface. Extensive studies in the southern region, particularly within the Sultanate of Oman, have shed light on active serpentinization processes and the associated natural hydrogen (H2) production. However, the northern section of the ophiolite remains underexplored. This study aims to fill this knowledge gap by investigating the potential for Natural H2 resources in Ras Al Khaimah and in the Northern UAE. Our research involved comprehensive surface gas measurements to construct an H2 distribution map, examining the correlation between gas emissions and lithological variations from the metamorphic sole to various mantle peridotites and crustal upper gabbros. Major structural features were also assessed. Findings indicate that structural windows exposing the metamorphic sole are key areas for locating higher H2 concentration measurements. Additionally, prominent structural lineaments between the layered and upper gabbros represent potential migration pathways for H2 from the underlying peridotites. Sampling of gas bubbling zones provided encouraging outcomes, mirroring results observed in the blue pools in the southern massifs of the ophiolite. Repetitive samplings on the same area over periods of time reveal large variations in gas readings that require further evaluation. These new measurements emphasize the northern Semail Ophiolite's potential as a valuable natural H2 province, highlighting its importance for future energy exploration and exploitation in Ras Al Khaimah and in the Northern UAE.

Co-auteur : Gabriel Pasquet, Keanu Loiseau, Mohamed Diatta, Giacomo Firpo, Paul Swire, Andrew Amey, Thibaut Burckhart, Isabelle Moretti

In 2024 the Advanced Research Projects Agency of the US Department of Energy (ARPA-E) kicked off an exploratory program in geologic hydrogen to rapidly answer the question – can we develop engineering solutions that will harness the massive potential that lays beneath our feet as a new primary energy? The program aims to unleash American ingenuity to assess the challenges and opportunities through the funding of 18 integrated projects that bring together 6 US DOE National Labs, 20 Universities and 10 companies. In addition to the science/engineering development the program seeks to create an ecosystem that enables the fast deployment of the technology, addresses risks and develops mitigation strategies early on. 

The presentation will give an overview of how the program will begin to address the vast challenge that comes with operating within a white space. A specific focus will be on are the emerging initial results indicating that a more expansive development program is in order.

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List of co-authors:

Stephan Séjourné (1-2)

Félix-Antoine Comeau (2)

Maria Luisa Moreira dos Santos (2)

Geneviève Bordeleau (2)

Maxime Claprood (3)

Pascal Mouge (4)

Valentin Mulliez (4)

Michel Malo (2)

Bernard Giroux (2)

Erwan Gloaguen (2)

Jasmin Raymond (2)

(1) Enki GeoSolutions, Montréal, QC, Canada

(2) Institut national de la recherche scientifique, Centre Eau Terre Environnement (INRS-ETE), Québec, QC, Canada

(3) Centre d’études sur les ressources minérales, Université du Québec à Chicoutimi (UQAC), Saguenay, QC, Canada

(4) Novatem, Mont-Saint-Hilaire, QC, Canada

The availability of accurate national and regional-scale maps of prospective areas for geologic hydrogen resources is invaluable to the energy industry as a guide for exploration activities. Knowledge of the potential distribution of geologic hydrogen resources is also critical for policymakers at the federal, state, and local levels. Geologic hydrogen resources likely occur in places that historically have not experienced natural resource extraction. To gain societal acceptance, the development of any discovered resources will need to be done responsibly. If not already in place, appropriate regulations to protect environmental health and ensure safety will need to be enacted. Furthermore, understanding the distribution of potential resources is essential for the decision-making process for infrastructure development. Previous efforts to assess prospectivity for geologic hydrogen resources have been limited in the spatial scale and/or the extent to which contributing factors are accounted for. To address this need, the U.S. Geological Survey has developed a methodology for determining the relative prospectivity of geologic hydrogen resources. This method has been applied to the onshore regions of the conterminous United States. The approach is based on a conceptual geologic hydrogen system model, analogous to the petroleum system, comprising sources, migration pathways, reservoirs, traps, and seals, as well as consideration for preservation of geologic hydrogen accumulations. Geologic, geochemical, and geophysical datasets were identified as proxies for the essential components that are required for an effective geologic hydrogen system. Individual input data sets were assigned weightings (i.e., chance of success) derived from interpretations of published literature and then integrated to determine net prospectivity for specific regions. The integration methodology was primarily based on geologic inference. Given our nascent understanding of the geologic hydrogen system model and the limited amount of data that are available from known accumulations, there is a high degree of uncertainty associated with the model and the significance of the input data. This uncertainty is accounted for by employing a range of weightings for each of the model inputs and then applying a Monte Carlo approach to calculate probabilistic distributions for prospectivity values. Accounting for the three-dimensional nature of geologic hydrogen accumulation potential when mapping in two dimensions remains a challenge. Maps of discrete prospectivity probabilities (e.g., P10, P50, P90, etc.) have been produced. The results indicate that areas of known ultramafic and radiogenic hydrogen source rocks are highly prospective, but the potential for effective reservoirs, traps, and seals also substantially impacts resource prospectivity. The resultant maps will be available to the public in an interactive, online format, which allows for an in-depth examination of the controls on geologic hydrogen accumulation potential but emphasizes the high degree of uncertainty. This effort represents the first attempt to assess geologic hydrogen resource prospectivity at the national scale using a holistic geologic approach. The details of the methodology will also be made available and can readily be applied to other locations at broader (e.g., international) and more local (e.g., regional) scales.

Co-authors : Sarah E. Gelman, Jane S. Hearon, Robert F. Miller, Scott A. Kinney, and Christopher C. Skinner

Geologic hydrogen can provide a pathway to achieve the net-zero energy transition. Initial estimates suggest that geologic hydrogen resources can be massive with some suggesting about 23 Tg of total hydrogen flow annually, corresponding to >7.5GWh/yr of energy potential. Fundamental research on geologic hydrogen, however, is still evolving, with several unknowns. In this research, we investigate the occurrence and availability of geologic hydrogen regionally near the Albuquerque basin in New Mexico, United States. We have curated evidence of hydrogen shows from several historical oil, gas, and water wells across New Mexico. We investigate the geology surrounding the wells with high hydrogen production with the largest one located in Cibola County, New Mexico, showing ~32% of hydrogen. In addition, we reveal the interplay of key components, including the availability of source rocks conducive to geologic hydrogen generation, an active fault structure near the source, and a reasonable seal rock that allows for accumulation of the occurring hydrogen. Moreover, we consider potential loss pathways and by integrating these components, we develop a basin model for the Albuquerque basin to quantify the potential of geologically occurring hydrogen in this region. We also conduct a sensitivity analysis on key generation, accumulation, and loss parameters to account for the inherited heterogeneity of the subsurface systems and quantify the uncertainty associated with geologic hydrogen potential. Our research provides a methodology for prospect identification and quantification for geologic hydrogen in a specific region with a demonstrable example from New Mexico.

Located in a Brazilian craton, the São Francisco Basin (SFB) presents a proven natural hydrogen (H2)
system, evidenced by high H2 concentrations in boreholes and numerous surface H2 emanations, some
already long-term monitored. Despite over six years of study, no detailed research has been carried
out to correlate these superficial observations with subsurface geological features. Therefore, this
study aims to evaluate the elements of the H2 system, including generating rocks, reservoirs, traps,
and seals, focus on the central and southern parts of the SFB, using public geophysical and well data
previously acquired by the oil and gas industry.

Wells drilled in structural traps contain natural gas and H2 at various depths, from 300 m to almost 4
km, particularly in Neoproterozoic units. The H2 rich layers exhibit very low permeability, classifying
them as tight reservoirs. The H2 amounts vary from a few percent to 41%. These intervals can be
identified using neutron log, especially where the H2 concentration exceeds that of CH4. Overlapping
impermeable zones within the same lithostratigraphic units act as a caprock. These seals seem to be
efficient to stopping or delaying the H2 flux, since the H2-hosting wells do not coincide with areas of
high density of the sub-circular depressions (SCD), which are typically associated with surface H2
emanation. Alternatively, the absence of SCD may be attributed to soil characteristics that are not
favorable for their formation, since we noticed the SCD are predominantly found in soft sediments of
the Cenozoic cover of the SFB.

The Archean and Paleoproterozoic basement containing ferrous and radioactive rocks, as well as the
Cretaceous ultramafic intrusions, are the main candidates for the H2 generation rocks. These units
mostly outcrop around the basin, such as the Banded Iron Formation from the Quadrilátero Ferrífero
(QF) in the southeast, and the ultramafic Alto do Paranaíba Igneous Province (APIP), in the southwest.
Significant magnetic anomalies observed in and around the basin may indicate potential H2 kitchens,
as they can be considered indirect indicators of ferrous bodies. Among them, it must be highlighted
the Pirapora Anomaly, in the central part of the basin, and anomalies beneath the APIP and QF,
extending to the internal part of the basin. These areas may correspond to the main generating rocks
of the basin, even if a large distance from the H2 evidences is required. Furthermore, the contribution
of radiolysis cannot be excluded.

The multiphase structural history of the SFB allows gas migration over short and long distances, which
may have enabled the widespread H2 occurrences in the basin, originated by multiple generating rocks
both inside and outside he basin.

In summary, the presence of all the elements of the H2 system in the central and southern SFB makes
it a proxy area for H2 attractive discoveries. Additionally, the existing gas pipeline network to major
population centers can promote a future H2 production and distribution.

​Co-authors: ​
Vivian Azor de Freitas, Alain Prinzhofer, João Batista Françolin, Francisco José Fonseca Ferreira and
Isabelle Moretti

Olivier Lhote, Tiphaine Fargetton, Catherine Formento, Stephane Galibert and Tiphayne Tual

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Affiliation:  Storengy-ENGIE, Bois-Colombes, Île-de-France, France

The growing interest in Natural Hydrogen Gas (H2) is spurring a new wave of exploration due to its potential as a clean energy source. We investigate the highest concentration of natural  H2 found in Brazil, specifically in the Rio Grande do Sul and Santa Catarina states. Our research identifies free H2 occurrences within the intracratonic Paraná Basin, revealed through formation tests in historic exploratory wells. The H2 concentrations in these tests varied from 0.14% to 8.79%, although associated with non-commercial natural gas volumes (CH4, varying from 87.68% to 98.61%, and He from below detection limit to 1.03%). The He content in the formation tests is inversely proportional to H2 content, suggesting a non-mantellic source. However, He isotope analyses are necessary to determine the relation between these gasses and their source conclusively.  On the other hand, rock alteration, such as biotite hydration did not explain the relation between H2 and natural gas. Although H2 and oil & gas systems can be independent, the probability of the existence of two unrelated systems is statistically more improbable. Due to this, we speculate that the anomaly is related to organic matter maturation, this could explain the natural gas and H2 coexistence in a single system. This model has some issues, as the anomalies are below the levels richer in organic matter, such as coals. However, organic-rich shales exist below the anomaly identified in the well. In addition, this region is known for the existence of reservoir rocks (sandstones with good porosity) and seals (thick basalt layers, sills, and continental flood basalt spills). This study underscores the necessity for comprehensive exploration to realize the economic potential of H2 in Southern Brazil. Our findings lay the groundwork for future research, particularly in understanding the geological conditions conducive to hydrogen accumulation and migration. By highlighting the geological frameworks and potential sources of hydrogen, we aim to contribute to the growing body of knowledge on natural hydrogen systems and support the development of renewable energy resources in South America. The Paraná Basin shows all the elements necessary to host the economic accumulation of natural  H2. For now the southmost of the basin is the best target for hydrogen gas prospecting in Brazil. This research advocates for strategic sampling and detailed geological analysis to harness natural H2 , fostering a sustainable energy future.

Serratt, H., - Henrique Serratt (1)(2)(3)
Cupertino, J.A., - José Antonio Cupertino (1)
Cruz, M.F., - Matheus Fernandez Cruz (1)
Teixeira, C.D., - Claudia Domingues Teixeira (1)
Oliveira, H.O.S., - Helder Osvaldo Samucuta de Oliveira (1)
Lehn, I., - Ilana Lehn (1)
Girelli., T.J., - Tiago Jonathan Girelli (1)
Rizzi, M.A.M., - Monique Aparecida Marchese Rizzi (1)
Augustin A.H. - Adolpho Herbert Augustin (1)
Bonato. J.  - Juliano Bonato (1)
Chemale Jr, F. - Farid Chemale Junior (1)

affiliations :

(1) Programa de Pós-Graduação em Geologia, Universidade do Vale dos Sinos, São  Leopoldo, Brazil 

(2) Instituto de Geociências, Universidade de Brasília, 70910-900, Brasília, DF, Brazil 

(3) UMR CNRS-IFREMER-CNRS-UBS 6538 Geo-Ocean, IUEM, Université de Bretagne Occidentale, France

Located in the northeast of Brazil, Maranhão has a GDP around 23 billion dollars, and an important need of energy for industry (20% of the GDP) and agriculture (12.6%). Steel mill, cellulose factory, beverage factory, ethanol factory, chemical products factory and alumina factory, as well as field irrigation uses today a significant amount of energy. Another important aspect to highlight is that Maranhão is a large exporter of iron ore, grains, alumina and cellulose, due to the fact that it has an access channel to the ports with a natural depth of approximately 23 meters. Expectation for new sources of energy exploited locally and with low carbon emissions is high, and natural hydrogen may be considered as a promising option. A first attempt for exploring this natural resource has been performed, and the surface measurements are encouraging in several areas of the state. The main geological formation outcropping in Maranhão is the Paleozoic basin of Parnaiba, covering an Archean basement. A lot of fairy circles could be observed in the Eastern part of the state and in the center of the basin. These structures are aligned along large lineation, including the continental sized TransBrasiliana tectonic suture. Some of these structures present weak hydrogen signal in soils. But other ones, mainly located along the Parnaiba River, show concentrations higher than 1000 ppm, and a recharge in hydrogen after several minutes, indicating that hydrogen is actively seeping, and does not correspond to human artefact. Areas with extremely soft soils present also hydrogen anomalies, whereas the weakness of sandy soils prevents generally any hydrogen preservation. More studies are now necessary to confirm the potential of this area. Other surface measurements as gamma spectrometry and radar interferometry may add valuable insights for the recognition of the natural hydrogen potential in Maranhão.