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 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

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, Yannick Branquet, Eric Thomas, Jeanne Bride, Ulysse Froger

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.

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

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

This study investigates the properties of natural hydrogen (H2) in two geothermal wells, PX1 and PX2, in the Pohang enhanced geothermal system (EGS) in the Korean Peninsula. Well PX1 has a steady H2 concentration level of ~30 ppm, whereas well PX2 has much higher levels, 6000 ppm at depths of 45 m and increasing at a rate of ~130 ppm/m with depth of 1–45 m. The H2 flux in PX2 is ~871 g/m2/day. Possible source rocks for the generation of H2 include gabbroic amphibolite xenoliths within granodiorite and ultramafic rocks. Thermodynamic modeling yields estimated maximum concentrations of H2 of ~120 ppm and ~900 ppm in the xenoliths and ultramafic rocks, respectively. The difference in H2 concentrations between PX1 and PX2 is ascribed to the different locations of the wells with respect to the position and geometry of the causative fault of the Pohang earthquake. PX1 is located in the hanging wall, whereas PX2 cuts the fault and penetrates the hanging wall and footwall. The impermeable gouge layer(s) and permeable damage zone of the fault are inferred to have sealed and facilitated the migration of H2, respectively. The H2 trap in the Pohang EGS site formed in response to activity along the causative fault and antithetic normal faults that developed during the evolution of the Pohang Basin. The occurrence of H2 reservoirs controlled by fault structures (i.e., structural traps), as observed at the EGS site, should be considered during exploration for economic accumulations of H2.

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

Objectives

The serpentinization of the mafic and ultramafic rocks is one of the most significant mechanisms for producing natural hydrogen in the subsurface. The northern part of Borneo is notable for its complex regional geology, particularly regarding Fe-rich rocks in the ophiolite zone of Sabah. This article discusses the mineralogy of ophiolites in Sabah, which could lead to the natural hydrogen feasibility via serpentinization processes.

Methods

Fieldwork was conducted in selected outcrops to investigate the presence of ophiolites, and standard petrography and x-ray diffraction (XRD) analyses were performed on the mineral composition and composition of the rocks. The investigation area includes the ophiolites found in Ranau, Telupid and Lahad Datu, these ophiolites are composed of crystalline basement and ultramafic- serpentinite rocks that are of Triassic to Early Tertiary age.

Results, Observations, Conclusions

The rock samples consist mainly of serpentinite with some basalt, dolerite and amphibolite. These rocks are unconformably overlain by younger sedimentary rocks, including the Eocene-Oligocene Crocker Formation and the Paleocene-Eocene Trusmadi Formation in northern Sabah. In central Sabah, the ophiolite is overlain by the Eocene-Oligocene Crocker Formation and the Kulapis Formation, while the ophiolite in southern Sabah is overlain by the Oligocene-Middle Miocene mélange sequence such as the Kuamut, Ayer and Kalumpang Formations. The results of the geochemical and mineralogical investigations show that the serpentinite samples contain a considerable amount of serpentine minerals (Figure 1) such as antigorite, cronstedtite and lizardite as well as some unaltered ultramafic/mafic minerals (e.g. forsterite, fayalite, pyroxene and hornblende) and traces of secondary minerals (such as magnetite, chromite, hematite, siderite and pyrite). The degree of serpentinization in the serpentinite samples ranges from 25% to 79% by volume, with most samples exceeding 45%. The degree of serpentinization gradually increases from North Sabah (average 45%) to Central Sabah (average 59%) and South Sabah (average 74%). Other rock types such as basalt, dolerite and amphibolite show a lower degree of serpentinization, ranging from 2% to 20%. The laboratory analyses indicate that significant serpentinization processes have occurred along the ophiolite zone of Sabah, which could yield significant amounts of hydrogen gas through the geochemical reactions below:

1.     3Fe₂SiO₄ (fayalite) + 2H₂O → 2Fe₃O₄ (magnetite) + 3SiO₂ (quartz) + 2H₂

1. 6Fe₂SiO₄ (fayalite) + 7H₂O → 3Fe₃Si₂O₅(OH)₄ (serpentine) + Fe₃O₄ (magnetite) + H₂

The overlying sedimentary rock formations could provide reservoir and seal traps for the hydrogen gas accumulation. These results give new insight into potential natural hydrogen resources in Sabah’s ophiolite zone; however, more detailed investigations are needed for further evaluation. Limited subsurface data is a major challenge in studying the entire natural subsurface hydrogen system along the ophiolite zone in Sabah.

Novel/Additive Information

The study provides fresh insights and new information about the potential of natural hydrogen in the Sabah’s ophiolite zone, Malaysia.

​Geological environments associated with the generation of natural hydrogen include Precambrian crystalline shields, greenstone and ophiolite belts and crustal suture zones associated with plate tectonic collisions. The serpentinization of ultramafic/mafic rocks such as basalt and peridotite in those environments is a metamorphic process that is effective in generating natural hydrogen in the subsurface through the hydration of ferrous iron present in minerals such as olivine. The global distribution of those mafic hydrogen source rocks is a result of the differentiation of the crust and plate tectonic activity during Precambrian and Phanerozoic supercontinent and tectonic cycles. Understanding the evolution of those crustal events and their relationship to the distribution of mafic rocks in suture zones, greenstone belts and Precambrian crystalline shields provides a first order view of the locations for natural hydrogen resources.

Analysis of supercontinent tectonic cycles from the Paleoproterozoic (1.6 Ga), Mesoproterozoic (1.2 Ga), Neoproterozoic (800 Ma) and Phanerozoic (200 Ma) and the resultant distribution of Precambrian crystalline shields and greenstone and ophiolite belts that contain iron-rich ultramafic/mafic rocks provides insights about distribution of hydrogen source rocks on modern continents. Greenstones and ophiolites consist of ultramafic/mafic rocks such as basalt, gabbro and peridotite while Precambrian crystalline shields have higher ultramafic/mafic composition than younger crust. These rock types are present in the subsurface and outcrops in Africa, Australia, North America, South America and SE Asia. Outcrops of suture zones and ophiolites in Malaysia indicate that conditions are favorable for the generation of natural hydrogen.

Three major supercontinents have been identified in the last 2 Ga: 1) Pangea, forming at 300 Ma, 2) Rodina forming at 1.3 to 0.8 Ga and 3) Columbia forming at 1.8 to 1.5 Ga. Mantle convection forced their breakup resulting in the current distribution of the Precambrian crustal blocks and greenstone belts of interest as potential hydrogen source rocks. Tectonic events in SE Asia during the Permo-Trassic and Jurassic also resulted in regional suture zones and ophiolite belts with the potential for hydrogen generation.

Analysis of geologic maps of Africa shows the presence of Archean and Proterozoic continental blocks in North Africa near Mali where natural hydrogen has been discovered and is being produced. These Birimian (2.5 Ga) ultramafic/mafic rocks form parts of the basement in the Taoudeni basin and are likely sources of natural hydrogen. Likewise, mafic rocks in South Australia associated with Proterozoic island arc convergence may be source rocks for natural hydrogen. Triassic-Jurassic ophiolites in SE Asia along the Bentong-Raub suture zone also have mineral compositions consistent with natural hydrogen source rocks.

This study provides fresh insights into the global distribution of natural hydrogen source rocks and the potential for hydrogen generation via serpentinization of mafic greenstone and ophiolite belts and Precambrian continental crust.​

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.

Hydrogen accumulation in the subsurface relies on an effective "hydrogen system," sharing elements of "hydrocarbon system," such as reservoir and seal (Prinzhofer et al., 2018). Therefore, seismic exploration is useful for detecting and evaluating hydrogen plays. Understanding the physical properties of hydrogen-bearing reservoirs is essential for seismic-based evaluation, but research in this area is limited. Hydrogen's ultra-light density and small molecular size create knowledge gaps in how these gases affect the elastic properties of gas-bearing rocks. Questions about distinguishing hydrogen from other reservoir fluids (e.g., gas and brine) using seismic methods remain unanswered. This study utilizes laboratory rock physics high-frequency measurements and modelling to investigate hydrogen gas's impact on sandstone's elastic properties under varying temperatures and pressures. The same procedure is applied to methane and brine for comparison. Helium and Nitrogen are used as proxies for hydrogen and methane due to their non-reactive and non-absorbing properties, allowing the study of gas effects without chemical reactions. These tests provide insights into rock behavior under pore-pressure changes caused by ultra-light gases. Specialized equipment is needed for prolonged experiments with fluids at high temperatures and pressures. The rock mechanics testing system was modified to contain nitrogen, helium, and brine without leaks. This system includes a servo-mechanical frame press that can reach 250,000 lbf within a temperature-controlled enclosure, a pump for applying up to 15,000 psi of confining pressure and 10,000 psi of pore pressure, and high-resolution pumps for handling supercritical fluids and monitoring volume for saturation estimates. Berea sand cores, simulating high-quality clean sand reservoirs, were used as test samples. The test matrix was designed to replicate hydrogen accumulation scenarios at shallow and intermediate depths with varying pore pressures. Laboratory testing began with fully brine-saturated samples. For shallow depth intervals, effective pressure was initially set at 5 MPa and increased to 14 MPa at 50°C. For intermediate depth intervals, effective pressure started at 10 MPa and increased to 30 MPa at 100°C. This process was repeated with helium- and nitrogen-saturated sands. Additionally, conceptual rock physics modelling based on measured data investigated the applicability of the Mavko-Jizba squirt flow model for rocks saturated with ultra-light gases at high frequencies. Laboratory measurements revealed that brine-saturated rocks exhibited the highest P-velocity and density, followed by nitrogen and helium-saturated cases, as brine's density and incompressibility facilitate effective P-wave transmission. Helium-saturated rocks showed the highest shear velocity due to the lower density effect of ultralight gases, which reduces pore pressure and increases effective stress. There is separation between elastic properties of Helium and Nitrogen saturated rock, suggesting the potential of using seismic for natural hydrogen exploration. Rock physics modelling results indicated that while the common approach could accurately model the density of fluid-saturated rocks, it showed significant variances for P-wave and S-wave velocity modelling in nitrogen and helium-saturated cases, highlighting its inadequacy for ultra-light gases. These findings are crucial for developing adaptive rock physics models for rocks saturated with ultra-light gases, enhancing the use of seismic data for natural hydrogen exploration and storage evaluation.

Co-auteur : Hongwen Zhao, Ernest Austin Jr Jones

Eden has signed an agreement with the Oman Ministry of Energy and Minerals (MEM) to develop the first international concession for stimulated GeoH2 production in Oman’s Samail Ophiolite. This project will focus on mapping peridotite heterogeneity and assessing GeoH2 resource potential. Key objectives include identifying an optimal location for the concession based on stimulated hydrogen production potential and utilizing Eden’s Electrical Reservoir Stimulation (ERS) technology to experimentally demonstrate over a 10^5× increase in H2 production rates compared to base rates. The project will use techno-economic analysis and reservoir models to validate that field-scale H2 production can achieve costs of less than $1/kg at the wellhead. The Samail Ophiolite, as one of the largest Fe(II)-bearing rock formations accessible at the surface, provides a unique advantage due to low operational costs and fewer regulatory barriers, allowing for expedited project progression. The primary challenge in GeoH2 production is the inherently low reaction rates and limited reaction surface area required for mineralogical transformations. Eden’s ERS technology addresses these challenges by providing mechanical and thermal stimulation to increase rock reaction surface area and formation temperatures. ERS can enhance H2 reaction rates by over five orders of magnitude above base rates through controlled high-power electrical treatment. The project will be executed in several phases. Initially, a comprehensive desktop study will evaluate existing geological and hydrogeological data, incorporating magnetotelluric surveys to map subsurface conductivity structures, followed by field mapping and sample collection. Next, geologic surveying and coring will be conducted to gather detailed subsurface data, involving drilling operations to obtain rock core samples up to 1000 meters deep. These samples will be analyzed for their petrophysical characteristics, mineralogy, and hydrogen generation potential. Concurrent hydrogeologic assessments will measure groundwater chemistry and dissolved gas composition to establish baseline conditions and identify suitable sites for water injection and hydrogen recovery. In the subsequent phase, ERS technology will be piloted within selected wells to experimentally demonstrate increased hydrogen production rates and to optimize stimulation parameters. This phase will involve drilling a total of three wells, each 1 km deep, including one monitoring well, and will integrate electrical resistivity surveys to enhance the understanding of subsurface properties. The ERS technology works by applying high-voltage electrical pulses to the subsurface, creating micro-fractures in the rock and increasing the surface area available for water-rock reactions. This stimulation not only enhances permeability but also raises the formation temperature, accelerating the hydrogen production process. Laboratory experiments have shown that ERS can sustain these enhanced conditions over extended periods, making it a promising technique for continuous hydrogen generation. Environmental assessments will ensure sustainability and adherence to regulatory standards, evaluating potential impacts on air and water quality, biodiversity, and local communities. The successful demonstration of the ERS technology at this site aims to validate the method and demonstrate that stimulated GeoH2 production can be a viable and cost-effective source of hydrogen. The establishment of this demonstration site in Oman’s Samail Ophiolite represents a pioneering effort in GeoH2 research, with significant scientific and environmental implications, potentially positioning Oman at the forefront of the global hydrogen economy.

Coming soon

We present the latest results of play-based natural hydrogen exploration in the Semail Ophiolite of northern UAE, Ras al Khaimah. The study area constitutes the RAK South area which overlies the Aswad Block of the Semail ophiolite. The geological and geophysical database for the study area combines the results of geological fieldwork and sample analysis with regional and local potential field and seismic data. The geophysical database includes full tensor gradiometry (FTG) and aeromagnetic data acquired over RAK South in 2016 and re-processed in 2022. The FTG data have formed the basis for integrated interpretation and modelling resulting in a 3D static, spatial model for the ophiolite in RAK South. This forms the end-point for a geodynamic model that begins with ophiolite formation in the Mid-Cretaceous, obduction during the late Cretaceous/early Tertiary and post-obduction compressional tectonics in the Oligo-Miocene. The model depicts an overall folded geometry for the ophiolite imposed by post-obduction, out-of-sequence sub-ophiolite thrust reactivation. Internal structure is dominated by a network of vertical shear zones and faults formed initially during the high-temperature conditions of accretion and then by solid-state deformation during cooling associated with ophiolite detachment and emplacement (obduction). In order to maximise hydrogen generation from the source protolith the exploration philosophy adopted works on the basis of ‘high-temperature serpentinization’ (200 to 320OC). In the geodynamic history of the ophiolite two key scenarios are identified for hydrogen systems resulting from high-temperature serpentinization: - ‘Late’-phase Low-temperature serpentinization and hydrogen generation is known to be taking place in the Semail ophiolite by the action of meteoric water on ultramafic mantle rocks. For ‘high-temperature’ serpentinization to occur circulating groundwater needs to penetrate via faults or shear zones to mantle ophiolite at depths of at least 8km. Play elements for this hydrogen system have been derived from the static model. - ‘Early’-phase Earlier serpentinization and hydrogen generation was activated in the lower part of the ophiolite by water derived from de-hydration/metamorphism of subducting oceanic crust and/or de-watering of sub-ophiolite sediments. Play elements for this hydrogen system have been derived from the late Cretaceous thermal and structural history encompassed in the geodynamic model. The derived play elements have been analysed within the established geological and geophysical framework to define play fairways for focussing ongoing exploration efforts. Some of the key issues affecting the exploration and future exploitation of natural hydrogen in ophiolites will be highlighted.

Co-auteur : Paul Swire (RAK Gas), Ian Hutchinson (NHSG), Steve Lawrence (NHSG), Jonathan Watson (Metatek), Andy Barnicoat (NHSG)).

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.

The Emirate of Ras Al Khaimah (RAK) in the United Arab Emirates (UAE) is well placed to take a leading role in the decarbonisation of the gulf region. The Semail Ophiolite in the southern area of RAK provides the potential for both natural hydrogen exploration and carbon capture via mineralisation projects. What gives RAK a competitive advantage in the eventual commercialisation of these projects is a unique combination of Federal commitment to decarbonisation, Emirate level regulations creating a framework for investment and a proximity to heavy industry and potential consumers with multiple transport and off-take options that will simplify project ramp-up and enhance overall project economics. The RAK Petroleum Authority (RAKPA) will soon be able to administer hydrogen licenses in Ras Al Khaimah alongside traditional oil and gas licenses. RAKPA has been working with several technical and commercial consultancies to enhance our understanding of the natural hydrogen system but also develop a regulatory and commercial framework to give investors’ confidence to invest in projects under a variety of contractor friendly commercial arrangements. In conjunction with hosting COP28 the UAE launched an ambitious plan to decarbonise its industries which includes significant plans for both Green and Blue hydrogen. Whilst facing their own challenges, these technologies are, with federal support, likely to facilitate the initial conversion of key industries like steel and cement to develop a local UAE hydrogen market of around 1.4 MTPA by 2031 and expanding to 15 MTPA by 2050. We believe having RAK natural hydrogen enter an existing hydrogen ecosystem will significantly reduce the time required to get any discovered volumes to market. Ultimate recovery (UR) per well has a major impact on project economics. Encouragingly our models show that even with low UR/well natural hydrogen can compete favourably with green hydrogen in the UAE and with rates equivalent to a “typical shale gas well” we can expect natural hydrogen to displace blue hydrogen and compete with grey hydrogen on a price per kg basis. Distances within the UAE are short compared to many global natural hydrogen projects so lower pipeline capex will enhance project economics. Additionally there may be options for early production of smaller volumes during project ramp up through either blending hydrogen within existing gas pipelines to RAK industrial hubs or utilising the recently completed Emirates rail line that connects major industrial centers in Dubai and Abu Dhabi with the Ophiolite belt in RAK South. With two separate R&D projects underway in RAK South we expect to be de-risking natural hydrogen play types with drilling in late 2024 and 2025.Co-auteur : Andrew Amey, Philip MacLean