2024 Posters

Since the initial tests and proof of concept of the Hydrogen Eval, numerous experiments have been conducted on iron-rich samples. While pure iron is rarely found in nature, it serves as a valuable model for understanding how iron materials can gain mass through redox reactions with water. This research also highlights the impact of granulometry on the analysis results. Additionally, extensive work has been carried out to elucidate hydrogen generation from the siderite mineral. Results from studies on Banded Iron Formations (BIF) will also be presented.

Jérémie Ammouial

Research engineer in geochemistry

Vinci Technologies

Can we imitate the natural production of hydrogen from rocks? Can we improve this production? Can we produce industrial volumes? How can we limit energy consumption for this production? What are the most favorable rock types? 

All those questions are the basics of the challenge of this new subject: the Artificial Production of Hydrogen from Rocks. 

The recent call of ARPA-E (USDOE) has lunched the building of a community dedicated to this topic with 16 projects. If we limit this subject to chemical processes only, we need to identify the reduced elements constitutive of minerals that will be able to scavenge oxygen from the water and then release H2. Among these, ferrous iron is a very good candidate, as it is one of the 5 major elements in the Earth's composition. Other metals (Cu, Cr, Zn, Pb…) in their reduced forms could be very interesting but will be restricted to abnormal accumulations, where mining activities take place. If ferrous iron is the main target for artificial production of H2, other metals should be studied in more details. Fe(II) bearing phases are therefore of prime importance. 

A relative abundant literature exists for olivine and pyroxene and the process of serpentinization is thought as well known. However, in their exhaustive review, Barbier et al. (2020) show that only pressure and temperature are well-controlled parameters. The role of chemistry is unclear and for example the presence of carbon can play catalytic role (Andreani et Menez, 2019) but can also be a H2-killer by producing methane as by-product. Carbon poor system could be then be recommended. If H2 production has been observed experimentally with siderite, Milesi et al., (2015) show all the carbonaceous by-products that could polluted the H2-production. 

The quest for low-cost efficient catalysts of Olivine/Pyroxene is launched with some first results with aluminum (Andréani et al., 2013). Nickel appears to be promising (Barbier, 2022), but excess of catalysts can also be a H2-killer. From our provisional findings, it seems that stimulating H2 production with both timing and quantities can be very beneficial, but really fine-tuning will be needed to avoid undesirable phases and secondary hydrogen consumption. 

References: Andreani, M., et al.. (2013). Aluminum speeds up the hydrothermal alteration of olivine. Am. Mineral. 98, 1738–1744. doi: 10.2138/am.2013.4469 Andreani, M., and Ménez, B. (2019). “New perspectives on abiotic organic synthesis and processing during hydrothermal alteration of the oceanic lithosphere,” in Deep Carbon, eds B. Orcutt, I. Daniel, and R. Dasgupta, (Cambridge University Press), 447–479. Barbier, S., et al., (2020). A Review of H2, CH4, and Hydrocarbon Formation in Experimental Serpentinization Using Network Analysis. Frontiers in Earth Science, 8. Barbier S., (2022). PhD Thesis. UCBL Lyon, France. www.theses.fr/2022LYSE1099/document Milesi, V., et al., (2015). Formation of CO2, H2 and condensed carbon from siderite dissolution in the 200-300°C range and at 50MPa. Geochimica et Cosmochimica Acta, 154, 201-211.

Co-auteur : Barbier, Samuel; Andreani, Muriel; Gaucher, Jean, L.

Eric Gaucher

CEO

LAVOISIER H2 GEOCONSULT

Authors: U. Geymond^1,2, O. Sissmann², A. Vindret², T. Briolet², E. Ramanaidou³, I. Moretti⁴

Corresponding author: geymond@ipgp.fr

¹ Institut de physique du globe de Paris, CNRS, Université Paris Cité, Paris, France ;

² IFP Energies Nouvelles (IFPEN), Rueil-Malmaison, France ;

³ Commonwealth Scientific and Industrial Research Organisation (CSIRO), Kensington, WA 6151, Australia ;

⁴ Laboratoire des fluides complexes et de leurs réservoirs, CNRS, Université de Pau et des Pays de l’Adour, Pau, France ;

Abstract:

Substantial accumulations of geological hydrogen (H₂) are now being tracked worldwide as a potential new, clean energy source for the ecological transition. However, the transportation of hydrogen over long distances presents challenges in both profitability and technology, casting (or raising) doubt on the feasibility of using H₂ far from its production site [1]. Similarly, H₂ generation through stimulation must be conducted close to energy consumers. At least in the short term, producing H₂ for local needs appears to be a more practical solution.

Mining companies face two main daily challenges [2]: (i) reducing their environmental footprint such as by recycling waste, and (ii) supplying energy to their mines, particularly in isolated locations. Combining these concerns, it is tempting to explore geo-inspired H₂ generation by using mine tailings to produce a low-carbon and low-cost energy source directly on site.

The desertic Hamersley Province in Western Australia hosts the largest Banded Iron Formations (BIF) deposit in the world, far from common human activities. These Fe-rich rocks from the Precambrian period contain up to 40 wt% Fe_total (mainly Fe^II) when preserved from surficial alteration, distributed among Fe-oxide, Fe-carbonate, and Fe-silicate [3]. In some locations, BIF underwent significant iron enrichment and oxidation, favoring (or enhancing) their exploitability, which results in numerous assets in the region.

In recent months, a series of experiments was conducted on a BIF sample from a drill core of the Brockman Formation, one of the main Fe-rich horizons in Hamersley [4]. The sample was powdered to mimic mine tailings and reacted with O₂ -free water at temperatures between 40°C and 90°C. Isotherms of H₂ generation were constructed by monitoring H₂ levels in experimental reactors over several days. Results indicate that up to a few mmol/kg of rock can be produced from the starting material, with kinetics highly dependent on temperature. Although further investigation is needed, this study represents a promising first step towards a decarbonized and decentralized energy supply for mining companies, potentially reducing both their energy costs and environmental impact.

[1] Lapi, T., Chatzimpiros, P., Raineau, L., & Prinzhofer, A. (2022). System approach to natural versus manufactured hydrogen: An interdisciplinary perspective on a new primary energy source. International Journal of Hydrogen Energy, 47(51), 21701-21712.

[2] Carvalho, M., Romero, A., Shields, G., & Millar, D. L. (2014). Optimal synthesis of energy supply systems for remote open pit mines. Applied thermal engineering, 64(1-2), 315-330.

[3] Klein, C. (2005). Some Precambrian banded iron-formations (BIFs) from around the world: Their age, geologic setting, mineralogy, metamorphism, geochemistry, and origins. American Mineralogist, 90(10), 1473-1499.

[4] Ewers, W. E., & Morris, R. C. (1981). Studies of the Dales Gorge member of the Brockman iron formation, Western Australia. Economic Geology, 76(7), 1929-1

Ugo Geymond

Phd Student

IPGP

Authors:

Anton Kaiser, Qingwang Yuan, and Mohamed Mehana

Natural and stimulated geologic hydrogen has the potential to emerge as a new, clean energy source. Understanding the mechanisms of hydrogen generation in natural settings and stimulated conditions is crucial to evaluating and optimizing the potential of a source rocks. Most of the research focuses on the closed system, there is a lack of a model for simulating hydrogen production and evaluating it in an open system. The goal of this study is to provide reliable geochemical models for hydrogen production from serpentinization of mafic and ultramafic rocks in closed and open systems. In this work, two geochemical models were created that allow to estimate the potential volume of hydrogen produced for a given volume of rock and its variations with time for different conditions.

Geochemical program PHREEQC is used in this study to model kinetic reaction rates and thermodynamic equilibrium conditions for serpentinization. Based on experimental conditions, two models were created: 1) a kinetic reaction model for hydrogen generation and rock alteration over time; and 2) a thermodynamic model showing hydrogen generation at equilibrium conditions. After achieving a good match to experimental results, the model was used to test sensitivities of hydrogen production to various factors: temperature, pressure, rock composition, and pH. Running the models as open and closed systems allows to assess the increase of generated hydrogen from a source rock as well as the impacts of changing parameters that control the reactions and equilibrium.

The results from validated models show how all different factors affect hydrogen generating reactions. Temperatures above 400°C and a pH above 8 stopped all hydrogen production. Specifically, rock composition has a major impact on hydrogen production when temperature varies. Lower Fe(II) bearing rocks (Fo70 and above), higher temperatures around 300°C are required to maximize hydrogen production as Mg(II) consuming reactions that do not produce H₂ are favored otherwise. This leads to low Fe(II) bearing rocks only generating significant volumes in a small temperature region. Rocks with Fe(II) bearing components above 30% yield best results at temperatures around 150°C. Extracting hydrogen from the system (i.e., an open system) showed that that hydrogen generation can be increased by a factor of more than 2 compared to that of a closed system, and generation rate is accelerated by up to 6 times. Enabling an open system towards stimulation conditions, higher hydrogen yields are also observed at lower temperatures than its closed system counterpart. Peak hydrogen generation is observed at 500bar with reactions stopping at pressures around 800 to 950bar depending on initial rock composition.

The work provides reliable geochemical models for analyzing, assessing, and optimize hydrogen production that is not available previously. Adjusting both pressure and temperature can significantly increase the total hydrogen yield and generation rate. Even for iron-rich rocks with low Fe(II) content, hydrogen production can be increased by more than 10 times at optimized pressure and temperature conditions. These findings provide important insights for analyzing the potential hydrogen generating source rocks in natural settings and the possibility of increasing hydrogen yield through stimulation.

Anton Kaiser

Research

Texas tech University

The co-authors and their affiliations are the following:

Andrew C. Turner, affiliation: Central Energy Resources Science Center, U.S. Geological Survey, Denver, CO 80225 USA

Markus Bill, affiliation: Energy Geosciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 USA 

Daniel A. Stolper, affiliation: Department of Earth and Planetary Science, University of California, Berkeley, CA 94720 USA and Energy Geosciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 USA 

Molecular hydrogen (H2) is found in a variety of settings on and in the Earth from low-temperature sediments to hydrothermal vents and is actively being considered as an energy resource for the transition to a green energy future. When examining H2 in the environment, it is important to constrain its origins. One way to do this is measure its stable isotopic composition, given as the deuterium/hydrogen [D/H] ratio or 𝛿D. In nature, the 𝛿D of molecular hydrogen (𝛿DH2) varies by hundreds of per mil from ~-800‰ in hydrothermal and sedimentary systems to ~+440‰ in the stratosphere. This range reflects a variety of processes, including kinetic isotope effects associated with formation and destruction and equilibration with water, the latter proceeding at fast (order year) timescales even at low temperatures (<100°C; e.g., Pester et al., 2018). In hydrothermal and sedimentary systems, H2 is commonly assumed to be at equilibrium with local fluids. At isotopic equilibrium, the D/H fractionation factor between liquid water and hydrogen (D𝛼H2O(l)-H2(g)) is a function of temperature and can thus be used as a geothermometer for H2 formation and re-equilibration temperatures. In order to use values of 𝛿DH2 for geothermometry, it is necessary that D𝛼H2O(l)-H2(g) as function of temperature be known accurately over the range of environmentally relevant temperatures where liquid water is present. Multiple studies have produced theoretical calculations for hydrogen isotopic equilibrium between hydrogen gas and liquid or vapor water. However, only three published experimental calibrations exist in the H2O-H2 system: two between 51 and 742°C for H2O(g)-H2(g) (Suess, 1949; Cerrai et al., 1954), and one in the H2O(l)-H2(g) system for temperatures <100°C (Rolston et al., 1976). Evaluation of the accuracy of these calibrations is difficult as both the measurement techniques and standardization procedures do not follow modern practices. Indeed, many studies use theoretical calculations over experimental calibrations to estimate D𝛼H2O(l)-H2(g).
Here we present a new experimental calibration of the equilibrium hydrogen isotopic fractionation factor for liquid water and hydrogen gas (D𝛼H2O(l)-H2(g)) from 3 to 90°C, measured and standardized using modern techniques. Equilibration was achieved using platinum catalysts and verified via experimental bracketing by approaching final D𝛼H2O(l)-H2(g) values at a given temperature from both higher (top-bracket) and lower (bottom-bracket) initial D𝛼 values. Final D𝛼H2O(l)-H2(g) values representing the equilibrium, given by averaged top- and bottom-brackets are in general agreement with previous experimental data and theoretical calculations. We will discuss the implications of this work on the estimation of formation and re-equilibration temperatures of H2 in low-temperature settings on Earth.

Flora Hochscheid

Postdoctoral Researcher

University of California Berkeley

Keanu Loiseau^1,2, Charles Aubourg¹, Pierre Camps³, Christophe Rigollet²

¹ Université de Pau et des Pays de l’Adour, Laboratoire des Fluides Complexes et leurs Réservoirs, 64000 Pau, France

² CVA-Engineering, 64000 PAU, France

³ Géosciences Montpellier Université de Montpellier et CNRS, 34090 Montpellier, France

The production of hydrogen during oxidation of olivine (serpentinization) of mantle rocks is a known process in the temperature range of about 300°C. Serpentine and magnetite, both carriers of Fe2+ (and Fe3+), are by-products of serpentinization. The magnetite can oxidize and produce H2 at temperatures as low as 100°C (Geymond et al., 2023, Frontiers).  In this work we show that further oxidation of the serpentinite produces also magnetite, this reaction is fast whatever the temperature from 100 to 300°C and is speed up by the magnetite content itself. We studied it through the evolution in laboratory of various samples within a hydrated atmosphere.

In the Pyrenees, direct access to these mantle rocks, here lherzolites, is made possible by numerous exhumed mantle bodies, some of which are almost kilometers in size providing access to a unique and ideal collection of fresh samples. In addition, an active H₂ system is functioning and the generating rocks are supposed to be the same mantle rocks present from about 8-10 km depth.

Coupled with the density, the magnetic signal allows to quantify the level of serpentinization of these rocks (Loiseau et al., 2024, Geoenergy). The 7 studied lherzolite samples showed a serpentinization ranging from a few % to 100% (density of 2.4 to 3.4), corresponding to magnetite concentrations from a few hundred ppmv up to around 10%. Some of these lherzolites show low temperature alteration processes with carbonation without excluding the presence of stoichiometric magnetite.

This variety of properties has allowed us to monitor magnetite production in the laboratory on solid natural samples. Our approach involves heating samples with different degrees of serpentinization (0 to 100%) at different temperatures (100°C, 200°C and 300°C) in a hydrated atmosphere while applying a magnetic field of 100 µT. The experimental design makes it possible to qualify the magnetic minerals newly formed during 24 hours of heating. With this technique, concentrations as low as a few ppbv can be identified. Longer trials were originally carried out, but data showed that the full response is achieved in less than 1 day.

Our results demonstrated the formation of magnetite in all samples and at all temperatures. Neoformed magnetite has all the characteristics of stoichiometric magnetite, with sizes in excess of several tens of nanometres. The most remarkable feature of our study is that it shows:

1)     Fully serpentinized samples still generate magnetite in presence of hot water and air.

2)     The kinetics of this magnetite generation are temperature dependent (one order of magnitude more between 100-200°C and 300°C).

3)     A strong correlation between magnetite production and the quantity of initial magnetite. This means that presence of magnetite speeds up production of magnetite, in other words, that magnetite stimulates the processes of Fe2+ oxidation to Fe3+.

Our study indicates a catalytic role for the magnetite and suggests that fully serpentinized zones could still play a significant role in hydrogen production at low temperature context such as mantle bodies at shallow depth (from about 3km).

Keanu Loiseau

Research

Université de PAU et des Pays de l'Adour

Interest in natural hydrogen (H2) has rapidly increased in recent years due to its potential as an alternative low-carbon source of energy. However, identifying locations and mechanisms of natural hydrogen generation and accumulation in the subsurface remains a challenge. Searching for and studying surface seeps is an important first step in natural hydrogen exploration, one which many groups have begun to work on. The primary method which has been used to identify and characterize seeps in recent work has been the concentration of hydrogen in soil gases at the surface. While this strategy has had success, issues such as varying temporal and environmental conditions limit interpretation of data. A central question is whether hydrogen measured in soil gas is produced locally by biological processes or in the subsurface by geologic mechanisms. This is difficult to definitively answer with surface soil gas hydrogen concentration measurements alone. To better characterize sources of hydrogen seeps, other techniques must be used in conjunction with hydrogen concentration measurements. Examining the concentrations of additional gases, such as methane and other hydrocarbons, carbon dioxide, nitrogen, and noble gases can help to place a particular hydrogen observation within a framework of potential gas sources. Hydrogen produced by different mechanisms has different characteristic associated gases, which we are beginning to characterize and catalogue in soil gases. Bulk isotopic compositions of hydrogen, as well as the other associated gases mentioned above, can provide another layer of information. Some isotopic signatures are suggestive of biological origin (e.g., potentially highly depleted methane or hydrogen isotopic compositions), and indirect evidence for differing generation mechanisms may be inferred from formation or re-equilibration temperatures. As gases move towards the surface, they may interact with other species encountered along migration pathways, and their isotopic compositions might be altered. Isotopic compositions of different molecules can be assessed together through apparent fractionation factors, providing information on the relationship between different gas species. For example, hydrogen-bearing species such as methane or water are known to interact with hydrogen, and equilibration or partial equilibration of the isotopic composition of hydrogen with these species is possible and could overprint a signal of the pathway that gases take from subsurface to surface in the isotopic compositions of the gases themselves. Finally, clumped isotopes of hydrogen, methane, carbon dioxide, and potentially other novel techniques may provide yet another dimension to understand the formation and migration of gases from the subsurface to the surface. We will discuss the utility and potential for measurements of isotopic compositions and concentrations of hydrogen and associated species in soil and subsurface (e.g., dissolved in groundwater) gases to contribute to our understanding of natural hydrogen surface seeps and their potential connection to subsurface sources.

Co-authors : Andrew G. Hunt, Geoffrey S. Ellis

Andrew Turner

United States Geological Survey

One of the most important research questions regarding natural hydrogen (H2) as a prospective energy source is whether it can be considered a renewable resource on the human time scale, which would necessitate relatively rapid generation processes (dynamic short-term system logic), or whether its presence in reservoir rocks, observed in several cases, is the consequence of accumulations over long geological time scales, similar to hydrocarbon systems (natural gas system logic). Some peer-reviewed and unreviewed articles, reports, commentaries, and websites suggest or claim that naturally occurring H2 is ""renewable"" and ""fresh"" due to its rapid production. However, there is no scientific evidence demonstrating that natural H2 is really a renewable gas at human time scale.

In this respect, it is crucial to examine the H2 generation rates (in terms of kg of H2 produced per year per m3 of rock) provided by laboratory experiments and models. These rates should be compared to the measured H2 flow (for example, in kg per year) in several surface gas manifestations, which have been shown to be continuous and long-lasting. Here, this exercise is provided for two major H2 generating processes, radiolysis and serpentinization, based on the latest published experimental and theoretical H2 generation rates. The generation rates are being compared to several H2 fluxes observed in seeps and springs in ultramafic rock systems. The simultaneous presence of H2 with other non-renewable crustal gases is also discussed

Giuseppe Etiope

Senior Researcher

Istituto Nazionale di Geofisica e Vulcanologia

Exploring the clumped isotope composition of gases such as hydrogen (H₂) or methane (CH₄) opens new frontiers in gas resource development. This study presents pioneering measurements of the clumped isotope composition of molecular hydrogen from natural geological settings using the Thermo 253 Ultra high-resolution mass spectrometer. Our findings from submarine hydrothermal vents and a continental reservoir reveal significant insights into the biogeochemical cycling of hydrogen. Our research focuses on natural hydrogen samples collected from high and low-temperature submarine hydrothermal vents (Lost City, Rainbow, Ashadze) and an intracontinental reservoir in Mali. By measuring the clumped isotope composition (ΔDD) of H₂, we can infer the temperatures of fluid venting and long-term storage. The ΔDD values of these samples ranged from 225 to 72 ‰, corresponding to temperatures from 27 to 375 °C. These measurements closely align with known environmental temperatures (storage or venting), primarily due to rapid isotopic re-equilibrium between hydrogen and water in near surface condition. Our study also underscores the importance of clumped isotope analysis in understanding biogeochemical processes. Experiments with methanogen cultures revealed that metabolic 'back reaction' progressively drives the ΔDD values of residual H₂ towards equilibrium with environmental temperatures. This insight into microbial activity provides valuable information on the subsurface microbial consumption of hydrogen, impacting the isotopic signatures detected in geological settings. Furthermore, the applicability of clumped isotope analysis is beyond hydrogen. Clumped isotope measurements of co-associated gases like methane and nitrogen can similarly reveal the thermal and chemical processes affecting the gases mixture. For instance, methane's clumped isotope composition can indicate its formation temperature and distinguish between biogenic, abiotic and thermogenic sources. Coupling clumped isotope analysis across multiple gases enhances our ability to better trace complex geochemical processes and improve our understanding of Earth's subsurface complexe gas systems. Our preliminary results also pave the way for several promising avenues of future research. Detailed studies on the rates of isotope exchange between H₂ and H₂O, both intramolecularly and with other hydrogen-bearing compounds, are essential to refine our understanding on the formation condition of natural hydrogen (temperature, depth, timing). Investigating the clumped isotope composition of other gases associated with H₂ in various geological settings can provide comprehensive insights into their formation and transformation/alteration processes. Moreover, expanding the application of clumped isotope analysis to industrial processes, such as hydrogen storage and commercial production, could improve the efficiency and sustainability of these technologies. Clumped isotope may also serve as a new tracer of H2 origin, i.e., distinguishing between sources such as methane steam reforming and water electrolysis, and help in making gas certificat of origin.

Co-auhors: Hao Xie, Antoine Crémière, Thomas Giunta, Marvin Lilley, Olivier Sissmann, Victoria Orphan, Arndt Schimmelmann, Eric Gaucher, Jean-Pierre Girard, John Eiler

Xavier MANGENOT

Expert Geochemist

The Lorraine coal basin is an intra-mountain Carboniferous basin located in north-eastern France and is the SW extension of the Saar-Nahe basin of Germany. Coal exploitation from the 19th century to 2004 was complemented from the 1990’s until recently by gas exploration (CBM and conventional) throughout the basin. Most recent exploration of la Française de l’Energie focused on the former coal exploitation sector in the east and revealed the presence of economic interesting CBM reserves. Scientific investigation by the Regalor project aimed to study the nature, origin, occurrence and abundance of gas. The detection of gas dissolved in the formation waters revealed at depth >800m the presence of a mixture dominated by methane and hydrogen (up to 18mol% at 1250m). In order to improve the interpretation of the observed gas, experimentation was conducted in the laboratory on coal using artificial maturation. Since gas generation from coal is a kinetic driven reaction and samples in the basin have experienced a minimum thermal maturity of vitrinite reflectance 0.70%, experiments were conducted at temperature between 300 to 470°C from 24h to 1 week in order to in order to cover the first stages of gas generation up to the gas window stage. The experiments designs and procedures used have proved their ability to provide geochemical data in accordance with kerogen evolution as observed in sedimentary basins. For each experiment, gas samples were collected and analyzed for their composition and C as well as H isotopes on individual constituents. From 300 to 350°C, gas is dominated by CO2 (87 to 64 mol%). At this stage methane generation corresponds to early stage. Gas generation with methane as dominant constituent (gas stage) occurs at T>350°C and represents 91mol% of hydrocarbons at 470°C. The carbon (‰PDB) and hydrogen (‰ SMOW) isotopic compositions of methane respectively evolve from -33.3 ‰/-211‰ at 300°C to a minimum of -37.7‰/-221‰ at 350°C and increased steadily up to -28.7‰/-143‰ at 450°C. The methane dissolved in the formation waters of the Folschviller 1A (FOLS1A) well presents isotopic characteristics between -43.8 and 39.9 ‰ PDB for -238 and -208 ‰SMOW. These values are in the range of the lightest observed in our experiments and obtained at 350°C (vitrinite reflectance equivalence of 1.4%). This suggests that the methane that accompanies hydrogen in the FOLS1A well originates from coal seams currently located at about 3000m depth. Molecular hydrogen was also generated from coal in our experiments. Preliminary data indicate that within the time/temperature range investigated up to 20mol% of hydrogen was generated in the hydrocarbon gas. Acknowledgments: This work was carried out by GeoRessources as part of the REGALOR project supported by the Grand-Est Region and the FEDER.

Co-authors: Salim ALLOUTI, Catherine LORGEOUX, Aurélien RANDI, Vitaliy PRIVALOV, Antoine FORCINAL, Fady NASSIF, Jacques PIRONON, Philippe de DONATO.

Raymond Michels

Chargé de recherche

GeoRessources

The transformation between iron oxide minerals is a topic of interst in many different fields: From high-temperature conversion of hematite to magnetite to metallic iron in steel production, to natural ore formation in e.g. hydrothermal systems and a multitude of oxidation-reduction reactions in the soil system. For steel manufacturing usually a gas phase-solid system at ambient pressure is investigated, for the hydrothermal/groundwater system studies a liquid-solid system. However, for both the subsurface storage of molecular hydrogen and the formation, transport or accumulation of natural hydrogen, a gas-fluid-solid system must be considered. Considering porous rocks for subsurface storage, mineralogical investigations have revealed that many possible formations in Germany contain hematite – in low amounts, but as a reactive surface that could oxidize molecular hydrogen in the storage complex. Unlike the gas-solid phase reactions in steel manufacturing, the processes involved in the transformation of hematite to magnetite and vice versa in liquid water remain unclear, with various theories proposed. Many researchers [e.g. 2] favour the reduction of surficial ferric iron in the crystal lattice during oxidation of dissolved H2 adsorbed onto the surface, and subsequent migration of either ferrous iron into the lattice or oxygen out of the lattice - for production of water as oxidation product of H2 during the processes However, Otake et al. [3] and others [4] suggest a non-redox process driven by hematite’s interaction with dissolved iron, where hematite transforms to magnetite through a dissolution and reprecipitation-driven replacement mechanism. Evidence is mounting for the attainment of partial (local) equilibria in the evolving system during the redox reactions. In the context of subsurface hydrogen storage in the project BiMiAb_H2 we investigated the reactions of molecular hydrogen with hematite and magnetite in the aqueous system near in situ conditions, i.e., at temperatures of 80-200°C and a pressure of 120-200 bar in high pressure reactors for up to four weeks. We used sealed gold capsules with natural hematite or magnetite, water (H2O) and H2 as starting material and quantified the conversion of H2 to H2O as well as the reduction of hematite to magnetite or the back reaction by X-ray diffraction and Raman spectroscopic analyses. In addition, we employed isotope tracer techniques to assess the contribution of oxygen from the hematite to the water by using mass spectrometry and Raman microscopy. The rate of H2 oxidation could not be described by a simple first-order reaction. For high-resolution insights, X-ray microscopy and TEM analyses on FIB sections were used to investigate the reaction progress within the grains at various locations. By examining the unique features at different structural locations on a single grain and by using Raman spectroscopy to analyse isotope label incorporation, we explored various theories on how hematite is replaced by magnetite in water. This includes considering whether the process is a solid-state reaction or driven by dissolution-reprecipitation, potentially involving tiny clusters of amorphous iron oxide [5]. References: [1] Abd Elhamid et al. (1996) J Solid State Chem 123:249-254 [2] Hallström et al. (11) Acta Mater 59: 53-60 [3] Otake et al. (2007) EPSL 257: 60-70 [4] Yin et al. (2022) EPSL 577: 117282 [5] Sun et al. (2007) Angew. Chem. 56: 4042-4046

This study investigates natural hydrogen seepage in the Yilgarn Craton of Western Australia, focusing on the FF4 site where long-term autonomous monitoring was conducted. The Wongan Hills area, characterized by Archean metamorphosed basalts, gabbros, chlorite schists, serpentinites, and banded iron formations, adjacent to vast Archean granitoid terrains, provides an ideal geological setting for studying natural hydrogen emissions. Data were collected across three distinct seasons to understand the relationship between hydrogen concentrations and groundwater levels. The results show significant seasonal fluctuations in hydrogen emissions, with high concentrations recorded after dry summers and reduced levels following rainfall due to increased groundwater presence. The monitoring revealed that hydrogen seepage is significantly influenced by seasonal groundwater levels. During dry periods, hydrogen concentrations reached peaks of >500 ppm, while post-rainfall periods saw a decline in hydrogen emissions, attributed to increased groundwater acting as a barrier to seepage. This correlation suggests that groundwater saturation may inhibit hydrogen escape through the near subsurface, leading to potential false negatives in soil gas surveys conducted after rainfall. Additionally, the study observed the effects of barometric pressure pumping on hydrogen soil gas fluctuations. Variations in atmospheric pressure were found to impact the diffusion of hydrogen gas to the surface, with pressure drops enhancing seepage rates and pressure increases reducing them. This phenomenon further complicates the detection and monitoring of hydrogen emissions, necessitating consideration of barometric pressure trends alongside hydrological conditions. These findings highlight the need for careful timing of soil gas sampling for hydrogen exploration to account for seasonal environmental conditions. The data highlight the importance of repeat monitoring in the accurate detection of natural hydrogen seeps and contribute to the broader understanding of subsurface hydrogen dynamics, essential for advancing natural hydrogen exploration and exploitation.

Co-author: Emanuelle Frery, Lionel Esteban, Alireza Keshavarz, Stefan Iglauer

Krista Davies

Phd Candidate

EDITH COWAN UNIVERSITY

The Lorraine Carboniferous Basin is an ultra-deep sedimentary basin located on the border between France and Germany. Of Westphalian to Stephanian age, it is covered by the Mesozoic Paris basin.

Work combined petrographic observations with hydro-geochemical data in boreholes. For this, an innovative probe system (SysMoG™) for measuring dissolved gases, in-situ and continuously, was designed by the Solexperts company and the CNRS/University of Lorraine and deployed in the Folschviller stratigraphic borehole FOLS1A (Moselle-France) drilled in 2006 by Française De l’Energie. At the same time, rock samples were taken from neighboring core drillings. The siliciclastic sediments show pores and fractures that are cemented by diagenetic minerals whose typical paragenetic sequence is marked by the temporal succession: siderite, ankerite, quartz, dickite, sphalerite and barite.

CH₄ dominates the gases of current fluids, resulting from the thermal maturation of coal over time. At a depth of 1250 m, H₂ represents approximately 18% mol of the gas mixture and dissolved H₂ concentration in waters is around 3.7 mg/L. The H₂ concentration increases with depth giving hope for reaching concentration about 60% mol (30.8 mg/L) at 3 km depth. Siderite and ankerite (Fe(II)) may reduce water in hydrogen at deeper compartments of the Carboniferous. H₂ genesis from coal is not excluded. These two hypotheses are temperature dependent and request more than 150°C, i.e. 5 km depth, for initiation. Measuring the drilling concentration makes it possible to estimate the contingent resources at around 34 Mt for the entire Lorraine carboniferous basin (16 000 km²).

In parallel, several methodologies for prospecting H₂ emissions were deployed on the Folschviller site from the surface (-1m) to -100m. Thus, 4 vertical boreholes were the subject of occasional or continuous measurements. The FOLS1A borehole was measured at -100 m (SysMoG™ probe) where a hydrogen background of 400 ppm was detected in a gas mixture dominated by nitrogen. Environmental drilling at -24 m (SysMoG™ probe), almost 20 meters from FOLS1A, did not reveal traces of hydrogen during the ICP-MS measurement. Finally, two small boreholes 1 meter deep, located 30 meters from FOLS1A and equipped with two SurfMoG™ probes, revealed no trace of hydrogen during several months of recording.

We can conclude that the linear hydrogen concentration profile measured in the FOLS1A vertical borehole corresponds to a hydrogen diffusion profile whose source is probably more than 5 km deep. When we are far from FOLS1A, the detectors located at -24 m and -1 m depth do not detect hydrogen. These results show that prospecting for natural hydrogen cannot be limited to surface measurements and that exploratory drilling cannot be avoided.

Acknowledgments: This work was carried out by GeoRessources and LFDE as part of the REGALOR project supported by the Grand-Est Region and the FEDER.

Fig. 1: Folschviller (Moselle-France) site with the location of the different boreholes where hydrogen is measured.

Jacques PIRONON¹, Philippe de DONATO¹, Médéric PIEDEVACHE², Odile BARRES¹, Marie-Camille CAUMON¹, Aurélien RANDI¹, Catherine LORGEOUX¹, Raymond MICHELS¹, Mathieu LAZERGES¹, Vitaliy PRIVALOV^1,5, Antoine FORCINAL³, Fady NASSIF³, Thomas FIERZ⁴, Yanick LETTRY⁴

¹Université de Lorraine, CNRS, GeoRessources lab, F-54500 Vandœuvre-lès-Nancy, France

²Solexperts France, 10, allée de la forêt de la Reine, F-54500 Vandœuvre-lès-Nancy, France

³LFDE, Avenue du district – ZI Faulquemont, F-57380 Pontpierre, France

⁴Solexperts AG, Mettlenbachstrasse 25, CH-8617 Mönchaltorf, Switzerland

⁵National Academy of Sciences of Ukraine, UA-03142 Kyiv, Ukraine

Jacques Pironon

Senior Research Fellow

CNRS

Michael Langford*3, Tayo Fagade1, , Dora Piedrahita 1,
Nicolas Camelo 1, Elkin Colorado1, Cesar Patino2
 
1Expro, Broadfield Blvd.  Houston, 77084. USA & Expro, Bogota, Colombia   
2Ecopetrol, Bogota, Colombia
3 Expro, UK
 
 
Abstract:
 
We present a comparison of different sample containers for soil vapor sampling for subsequent hydrogen analysis, during exploration for white hydrogen resources across Colombia.
 
Using real-world data obtained during sampling campaigns carried out across Ecopetrol assets in Colombia, we evaluate hydrogen recovery rates between low-pressure aluminum sample cylinders (110cc) and larger, higher-pressure stainless-steel cylinders (300-500cc). Laboratory measurements are compared with those obtained in the field using portable equipment. A description of the novel sampling process is also described. Further comparison is made with existing published literature.
 
Our work shows that the smaller aluminum cylinders are at least as effective as the stainless-steel vessels in capturing and preserving hydrogen samples, contrary to some previously published work. However, the lower sample volume (especially at low pressure) proved limiting when extensive analysis programs were required.
 
Whilst the study uses data obtained from soil vapor sampling, it is relevant to all hydrogen sampling operations and should be considered when designing sampling and analysis programs for future work.
 
 
* Corresponding Author and Speaker. Email: Michael.langford@expro.com

Michael Langford

Technical advisor

Expro

L. Gerbaud², D. Strąpoć¹

¹SLB, Clamart, France ; ²MINES ParisTech, Fountainebleau & Pau, France

Drillbit metamorphism (DBM) can generate gaseous products, including hydrogen from the decomposition of drilling fluids: oil-based mud (OBM), water-based mud (WBM), and even pure water, due to intense interaction at the drillbit-rock interface. Here for the first time, we study this phenomenon by varying only one parameter at a time and observe properties of the generated gases in an indoor rig floor facility. We derive correlations of drillbit-energy and vibrations proxies with amounts of generated gases, depending on mud type, and including alkenes, alkanes, hydrogen, and carbon monoxide.

Drilling was performed using one of a kind controlled-environment indoor-rig-floor with closed mud-loop connected to a gas logging equipment. The set up simulates drilling conditions down to 5 km using 0.5-m long rock samples. Controllable drilling parameters are weight on bit (WOB), rpm, mud flow rate, rock type (sandstone, granite, and basalt), drillbit type (several types of PDC bits with different cutter designs and level of wear, and different drilling fluids (OBM, WBM, pure water). A mud degasser was connected to the mud flow loop and mud gas analysis while drilling: i) gas chromatography (GC) for gaseous alkanes and alkenes, ii) mass spectrometry (MS) for H₂, CO₂ and hydrocarbons, iii) electrochemical for H₂. Additional spot samples were taken for detailed laboratory analyses. Subsequently, gas and drilling data, including torque variability and vibrations (triaxial accelerometer) were correlated.

Progressive and stepwise gas generation increases were observed in response to modulated drilling parameters, e.g., stepwise increase of rpm or WOB. We performed over 30 runs modulating an individual drilling parameter and using different drill bits with different levels of wear and different drilling fluids. In-depth data analysis shows that inefficient drilling, e.g., using a worn drill bit is prone to high heat generation, especially when increasing rpm, while newer harder drill bits tend to generate increased gas via higher levels of vibrations. In OBM gas molecular and isotopic data proves systematic cracking of base oil and generation of gaseous products, H₂ as the main one followed by methane, carbon monoxide, ethene, ethane, propene, etc. Moreover, these gaseous products tend to maintain constant molecular and isotopic ratios in individual runs and enable DBM-correction of naturally encountered C₁-C₅ alkanes and H₂ in exploration wells drilled with OBM. Additionally, we studied different heat-proxies using available drilling parameters, e.g., power input (torque multiplied by rpm) or high frequency torque oscillations, and vibrations, that influence quantities of DBM-generated gases, even when drilling with pure water. In the latter case only elevated H₂ was observed with traces of C₁, only when polymer mud additives were added to water. It is the first to date proof that pure water can be decomposed to H₂ by the act of drilling. Specifically using PDC drill bits on granite or basalt, and more so when increasing WOB causing enhanced vibrations. That implies that the water molecules can be split into H₂ via the act of extreme friction, high frequency impacts, mineral crushing, resembling the natural process of cataclasis known for natural H₂ generation during rock crushing at the activated fault zones.

The proven existence of the DBM gas by-products can flag and de-risk crucial mud gas logs for critical subsequent sampling, testing and completions decisions during hydrocarbons and H­₂ exploration. These successful experiments pave the way for systematic investigation of the DBM process to a wide extent, as a cautionary tale about practices used during exploration for petroleum and natural hydrogen.

​

Dariusz Strapoc

Principal Geology and Fluids SME

The transition to a sustainable, low-carbon energy future is gaining increasing attention due to the imperative to reduce greenhouse gas emissions and address problems caused by climate change. In this situation, Hydrogen, as the most energy-rich of gases, is currently considered a promising candidate to replace fossil fuels. But all of the current methods are as yet too expensive to compete with fossil fuels. This is because the production of hydrogen, a secondary energy source produced by combining different energy sources, has a fundamental flaw. To overcome these limitations, Natural Hydrogen that is buried on Earth, such as fossil fuels, provide a way around these restrictions.

 Natural hydrogen is hydrogen gas that occurs naturally underground in the Earth’s subsurface, within geologic formations and the mantle. In this work, we conduct research on process design to produce natural hydrogen underground and use it as an energy source.

We collect data on gas composition from the literature. According to the results, natural hydrogen reserves exhibit a diverse composition, including light and heavy hydrocarbons, nitrogen, carbon dioxide, oxygen, etc.       

Based on this data, this study proposes a new natural hydrogen production process, which was developed by applying the existing natural gas production process. This natural hydrogen production process is validated by developing process simulation model with proven thermodynamics.

Additionally, Exergy and Techno-economic Analyses will be conducted to assess differences compared to current hydrogen production process (green and blue). Based on this, it is intended to show that the natural hydrogen production process is a commercially realistic and economical method.

Junseok Kim

Graduate student

KENTECH

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

Ema Frery

Senior research scientist

CSIRO

1South of Brazil, the Uruguayan territory contains various promising rocks for H2 generation. An Archean Craton (Rio de la Plata), of from Montevideo, and some Neoproterozoic terranes north of Punta del Este. Such a craton has been proven to be a good H2 generating rock in Brazil and the Neoproterozoic formations, especially the BIF, generate H2 in Namibia. This country is located on the conjugated margin of Atlantic. Based on these promising correlations, Nativo Energy, a startup dedicated to natural H2 exploration, was created to look for natural H2 potential in Uruguay. The H2 exploration did not start yet in the country but the law doesn’t preclude it. In addition, the country has a H2 road map through which production, use and exportation of H2 have been already framed.

The first field campaign took place in April 2024, soil gas measurement, gas and rock sampling and later GC gas analyses were carried out. The 2 founders of Nativo Energy, 2 postgraduate students from the La Republica University, and 3 French experts were present. Results confirmed the presence of high H2 content in the soil, the key role of the suture zone as H2 migration pathway; they allow us to be very optimistic about Uruguay natural H2 potential. They are currently confidential but will be shown next November

·       Co-auteur Ricardo Bertolloti and Juan Negro:  Nativo Energy:

·       Isabelle Moretti, Alain Prinzhofer, Vincent Roche

·       Marcos Sequeira Callazo and Facundo Plenc Universidad de la Republica

Isabelle Moretti

Researcher

E2S UPPA - FRENCH TECHNOLOGY ACADEMY

The geologic and geophysical inputs necessary for the favorability mapping of geologic hydrogen systems are presented here in support of the U.S. Geological Survey's efforts to create the first map of geologic hydrogen prospectivity in the conterminous United States. The geologic hydrogen system model has several components that are required for a viable accumulation: 1) a source of natural hydrogen, 2) a reservoir to store hydrogen in the subsurface, and 3) a competent seal to retain the hydrogen and prevent leakage to the Earth’s surface. In total, there are 21 geologic layers in the model and the distribution of chance of success values are assigned to each layer based on our interpretation of the geologic hydrogen model and our comprehensive knowledge of the United States’ geology.

The geologic hydrogen source component is divided into three sub-components comprising serpentinization-type water reduction sources (SP), radiolysis of water sources (RD), and deep mantle sources (DP). Layers within the SP sub-component include: 1) an area defined by a magnetic anomaly in the offshore, eastern United States, 2) onshore areas where ultramafic rocks are present at the surface, and are inferred to extend into the subsurface, and 3) deep subsurface areas that have high-amplitude, positive magnetic and gravity anomalies. Layers within the RD sub-component include 1) areas with known uranium deposits, 2) areas that are favorable for the concentration of uranium, 3) areas underlain by the Precambrian cratonic platform, and 4) areas that are underlain by accreted terranes and contain Phanerozoic-age granitic rocks at the surface. Layers within the DP sub-component include 1) areas of mapped, km-depth scale surface faults, 2) areas of Paleoproterozoic-age suture zones, and 3) areas of modeled, deep crustal boundaries interpreted from geophysical data. Finally, migration pathways were applied to specific source component layers. Regional-scale hydrogen migration pathways are derived from the basement topography, and consumption of hydrogen during migration is accounted for by diminished prospectivity with increased migration distance.

The reservoirs and seal components are split between sedimentary (e.g., siliciclastic, carbonate) and crystalline rocks (e.g., igneous, metamorphic) based on high-resolution, surface geologic maps of the United States. An additional seal layer accounts for areas where salt is present within the subsurface. A final layer includes areas where sedimentary basins contain thick (i.e., >1,000 feet) accumulations of both porous reservoir rocks and impermeable rocks for geologic hydrogen storage and seal, respectively.

Collectively, these layers comprise the geologic inputs for the first edition of a natural hydrogen prospectivity map of the conterminous United States.

Jane Hearon¹, Sarah Gelman¹, Scott Kinney¹, Robert Miller¹, Christopher Skinner¹_, and Geoffrey S. Ellis¹

¹U.S. Geological Survey, Central Energy Resources Science Center, Denver, CO

Jane Hearon

Geologist

U.S. Geological Survey

​Colombia has a number of geological contexts that could be favorable for the production of natural hydrogen. This is the case in the Cordillera Occidental, more specifically in the Cauca-Patía basin and in the southern part of the Sinu-San Jacinto basin, as well as in the southern part of the Lower Magdalena Valley basin. The Cauca-Patía basin shows an extension of the Cretaceous ophiolites, which lie beneath the folded sedimentary and volcanic-sedimentary sequence that extends into the eastern part of Cali. The basin is bounded on the east and west by ophiolites outcropping from the central and western cordilleras, in the northern and southern parts of these ranges. Northward, the lower Sinú-San Jacinto basin and the lower Magdalena valley feature Jurassic ophiolites, including two ultramafic bodies: Cerro Matoso and San José de Uré. Cerro Matoso is one of Colombia's largest ferronickel mines, and the Porvenir gabbro, an Upper Jurassic mafic-ultramafic body. The Moho transition has been described as a=outcropping in this area A geospatial analysis of the ophiolites of western Colombia was carried out, where with the help of Landsat and Sentinel sensors, vegetation anomalies, known as "fairy circles", were identified. These vegetation anomalies are usually smaller and the vegetation appears different compared to the fairy circles identified in other countries, but natural hydrogen is still present. In this area an additional peculiarity is added to these anomalies, in the bamboo crops the growth of this plant is affected, with a reduced height in the areas of H2 emanation, suggesting that H2 may be affecting the growth of this plant. In addition, gas measurements were also made on major faults, where the highest H2 concentrations (GA5000 saturation, i.e. 1000 ppm) were found, specifically on the Guabas Pradera fault, in the southern part of the Ginebra ophiolitic complex (Carrillo et al., 2023). The H2 potential in Colombia may be promising, as Cretaceous sediments are present above bedrock, where traps, deposits and seals are likely to be present. For example, in the Cauca Patia basin there are several batholiths that could possibly serve as traps for hydrogen accumulation and in the north there may be a constant generation of hydrogen as it is a hydrated and fractured zone. Carrillo Ramirez, A.; Gonzalez Penagos, F.; Rodriguez, G.; Moretti, I. Natural H2 Emissions in Colombian Ophiolites: First Findings. Geosciences 2023, 13, 358. https:// doi.org/10.3390/geosciences13120358​

Alejandra Carillo Ramirez

PhD student researcher

Université de PAU et des Pays de l'Adour

Natural, or geologic, hydrogen may be a future low-carbon subsurface energy resource. To assess the potential for geologic hydrogen throughout the conterminous United States, the U.S. Geological Survey has developed a methodology to model subsurface hydrogen systems. Following a similar method developed for petroleum systems, Chance of Success (COS) is defined here as a fractional probability that a viable accumulation of natural hydrogen can exist in the subsurface. Several components make up the geologic hydrogen system model and are required for viable accumulations: 1) a source of natural hydrogen, 2) a reservoir to store hydrogen, and 3) a competent seal to retain hydrogen and prevent mechanical or capillary leakage to the Earth’s surface. The geologic characterization of these components is described in a companion abstract (Hearon et al., this conference), while the motivation and broad-scale results are discussed in another companion abstract (Ellis et al., this conference). This contribution will focus on the quantitative methods developed to model hydrogen systems, its components, sub-components, and COS analysis, ultimately generating the first edition of a natural hydrogen prospectivity map of the conterminous United States. Lateral migration of hydrogen in the subsurface is presumed to be possible, analogous to the migration of other buoyant subsurface fluids (i.e., oil and gas). While migration can occur in both sedimentary and non-sedimentary settings, migration pathways likely follow stratigraphic boundaries in sedimentary settings. In contrast, fractures likely dictate flow in crystalline rocks and would be difficult to predict on a large scale. Here, we limit our initial focus to only sedimentary migration pathways. Using a continental-scale map of total sedimentary thickness to generate an elevation map of the top of basement (or the floor of sedimentary rocks), we calculate fluid flow paths. When potential sources of geologic hydrogen occur under or within sedimentary basins, hydrogen is presumed to migrate laterally and up-dip following the contours of basement topography, allowing an area of broad spatial extent to have exposure to migrating hydrogen. Our methodology further considers the potential for a reduction in hydrogen access as distance increases away from possible sources due to consumption by biotic and abiotic processes. The geologic hydrogen system COS is calculated by multiplying the individual component COS values (source including migration, reservoir, and seal) which were generated from a series of 21 geologic sub-components (see Hearon et al., this conference) and their individual COS values. Since sub-components may overlap spatially (for example, a source of hydrogen due to serpentinization, and a source due to radiolysis), the sub-components are combined by multiplying chances of failure, rather than chances of success, ultimately increasing the component COS due to this overlap. Finally, uncertainty is quantified by assigning low, mid, and high cases to create distributions of sub-component COS values, which are then propagated in a Monte Carlo method to generate stochastic outcomes where the final results are presented as P90, P50, and P10 maps for geologic hydrogen prospectivity.

Co-authors: Jane S. Hearon, Scott A. Kinney, Robert F. Miller, Christopher C. Skinner, and Geoffrey S. Ellis

Sarah Gelman

Geologist (Basin Modeler)

Us Geological Survey

Since the singular case study in Bourakebougou (Mali) by an accidental discovery of a hydrogen reservoir, geological hydrogen is today considered renewable and exploitable locally. An increasing interest for mapping reservoirs worldwide started chasing indices to localize accumulation of geological H2. Brazil has been one of promising countries with hydrogen structures on the soil surface, called Fairy circles or more recently denominated as circular depressions (in particular in Roraima, Minas Gerais, Ceará, Tocantins). Recent discoveries of major reservoirs have been found by chance (e.g. Lorraine-France, Bulqizë-Albania) manifesting other patterns, with a probable deeper formation and diffusion through faults. In the present investigation, the best regions for hydrogen prospection have been proposed considering some proxies accessible thought satellite images, topographic data (such as fairy circles, fractures/faults), magnetic and gamma anomalies and visual observation on-field. In São Paulo, Rio de Janeiro and Espírito Santo states of Brazil, we have detected high concentrations at less than 1 m of depth in the soil (>1% in volume of H2, detected using a semiconductor detector, Variotec). From those preliminary results, we couple mineral dataset with thermodynamic simulations to support the mechanisms involved during its formation. The highest values have been reported close to faults and fractures. Hypotheses about its accumulation are under investigation, requiring other techniques such as seismic studies. Acknowledgment: Arrouvel is grateful FAPESP 2022/12650-9 for financial support, ICMBio at the Ipanema National Forest and the biological reserve of Union in the state of Rio de Janeiro, Vanea Nogueira Oliveira for her technical support.

Co-authors : Leonardo Silva de Oliveira (LENEP-UENF) and Alain Prinzhofer (GEO4U)

Corinne Arrouvel

Lecturer / Researcher

When studying a hydrogen system, it is often difficult to access and characterize the source rocks. In this sense, the greater Münchberg Massif area offers a unique opportunity. East of the Franconian Line, the serpentinites are exposed and easily accessible. West of the Franconian Line, the serpentinites most likely continue and are buried under a thick pile of sediments. In this study, we focus on the area east of the Franconian Fault System. With an interdisciplinary approach, using geology, petrology, geophysics and numerical modelling methods, we aim to characterize the hydrogen source rock in the context of a hydrogen system. The Münchberg Massif – a stack of nappes formed during the Variscan orogeny – consists of stratigraphically inverted metamorphic layers, where the degree of metamorphism decreases with depth. Serpentinites are part of the Prasinit-Phyllit-Serie and are accessible at the outer rim of the Massif. Geological models, seismic and magnetic data suggest that the Prasinit-Phyllit-Serie is present at about 3 km depth throughout the Massif and was partly uplifted by several fault zones in the south. The fault zones in the Münchberg Massif also provide potential pathways for fluid flow. We collected 17 geological samples of the outcropping serpentinites at two locations (Peterleinstein and Zell), about 20 km apart. The results of the petrological analyses (polarization microscope, X-ray diffraction, raman spectroscopy, major and trace element analytic) reveal different degrees of serpentinisation for the two locations. At Peterleinstein, the samples are completely serpentinized with main mineral components of lizardite, magnetite and chlorite. In contrast, the Zell samples are only partly serpentinized with main components of antigorite, magnetite and partly forsterite and clinopyroxene. The chemical composition of the serpentinites is similar at both locations and hints at a depleted mantle protolith. The analyses suggest slightly different serpentinization conditions and degrees of serpentinization throughout the Münchberg Massif. A possible cause for this might be different fluid availability at the locations due to heterogeneities in permeability. It is therefore possible that a residual potential for serpentinization and thus hydrogen formation still exists locally at depth. To get a better understanding of a possible hydrogen system in the subsurface and to illustrate the potential transport processes and pathways, we implemented our results in numerical finite element models using the software package TerrantaLab and TerrantaFlow. We calculated hydrogen flow in a 2D cross-section of the Münchberg Massif, where the Prasinit-Phyllit-Serie was implemented as a hydrogen generating source rock. We performed different scenarios with variations of hydrogen generation rates as well as variations of the petrophysical properties of the geological layers and fault zones. We studied advective and diffusive hydrogen transport (dissolved in water) as well as variations of hydrogen amounts emanating at the surface in these scenarios. Combining outcrop data, laboratory measurements, geophysical data and numerical modelling, contributes to deciphering the hydrogen system and its potential role in the energy system.

Co-authors : Meike Bagge, Peter Klitzke, Maximilian Hasch, Nikola Koglin, Rüdiger Lutz, Andreas Bahr, Daniel Palmowski

Meike Bagge

Research Scientist

Federal Institute for Geosciences and Natural Resources (BGR)

How fast do hydrogen consuming microbial organisms grow in geological hydrogen systems that reside within the temperature limits of life (e.g. <121oC), and what is their impact on the steady-state abundance of hydrogen in the subsurface? There is currently a lack of data regarding the abundance of microbial life in geological hydrogen source and reservoir rocks, and how fast these organisms grow, which has significantly implications for calculating whether hydrogen can accumulate or will be substantially consumed. We will share new methods and spectroscopic tools we are developing that can be used to quantify the rates of microbial activity in hydrogen-bearing rocks and fluids. We then apply these tools to rocks and fluids obtained from partially-serpentinized peridotite aquifers in Oman, as well as generate data from experiments designed to more generally apply to hydrogen systems. The new data being produced shows many orders of magnitude variability in microbial hydrogen-dependent activity rates depending upon the mineralogy, salinity, pH and abundance of oxidants that can then be better integrated into emerging models of natural and stimulated hydrogen systems.

Co-auteurs : Srishti Kashyap, Tristan Caro, Carson Cucarola, Eric Ellison

Alexis Templeton

Professor

University of Colorado

Hydrogen is a fundamental electron donor in several microbial metabolisms and is considered to be an important energy currency available to microbial communities in anaerobic environments. Hydrogen, produced naturally by geological processes and industrially via water hydrolysis, represents one of the key steps to the transition to a greener energy society. Geological hydrogen emissions are widespread and can be produced by diverse processes, including microbial fermentation of organic matter, radiolysis of water, water rock interactions in hydrothermal systems and hydration of iron-rich ultramafic rocks. When hydrogen is released at depth, it can travel towards the surface, traversing a large subsurface ecosystem. Subsurface microbial communities can use hydrogen as an energy source, coupling its oxidation to the reduction of a variety of different compounds, through a diverse group of enzymes called hydrogenases. These diverse enzymes use tangled organometal complexes built around a binuclear Ni-Fe, Fe-Fe or Fe center, with bound CO and CN(-) groups, as well as multiple FeS centers. Understanding the diversity of hydrogenases in the subsurface and the role of trace elements’ availability in controlling their spatial distribution is crucial to quantify the subsurface microbial utilization of molecular hydrogen derived from geological reactions. Here, we will present data on the diversity of hydrogenases from over 180 deeply-sourced springs located in diverse tectonic settings worldwide. By coupling metagenomic data with high resolution geochemical analysis, we inferred how the different geochemical landscapes found in the different settings sampled, shape the distribution of hydrogenases in natural ecosystems. This, in turn, will help to establish the baseline of hydrogenotrophic metabolisms in the subsurface, complementing our knowledge of the microbial influence on hydrogen cycling in various geological settings. Our study deepens our understanding of subsurface hydrogen and its relationship with the deep biosphere, aiding both natural hydrogen exploration as well as geological hydrogen storage.

Martina Cascone1, Davide Corso1, Gabriella Gallo1, Flavia Migliaccio1, Matteo Selci1, Deborah Bastoni1, Francesco Montemagno1, Bernardo Barosa1, Annarita Ricciardelli1, Feliciana Oliva1, Luciano di Iorio1, Monica Correggia1, Angelina Cordone1, Alessia Bastianoni1,2, Ilaria Pietrini2, Elisabetta Franchi2, Giovanna Carpani2, Rebecca L. Tyne3, Peter H. Barry4, Karen G. Lloyd5, Gerdhard L. Jessen6, Agostina Chiodi7, J. Maarten de Moor8,9, Carlos J. Ramirez10, Matt Schrenk11, Almerinda di Benedetto12, Giuseppina Luciani12, Giuseppina Anzelmo13, David Iacopini13, Mariano Parente13, Alberto Vitale Brovarone14,15,16, Marco Moracci1, Donato Giovannelli1,4,17,18,19


1. Department of Biology, University of Naples Federico II, Naples, Italy
2. Eni S.p.A R&D Environmental & Biological Laboratories, San Donato Milanese MI), Italy
3. University of Manchester, UK
4. Woods Hole Oceanographic Institution, Woods Hole, MA, USA
5. Microbiology Department, University of Tennessee, Knoxville, TN, USA
6. Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile & Center for Oceanographic Research COPAS COASTAL, Universidad de Concepción, Valdivia, Chile
7. Instituto de Bio y Geociencias del Noroeste Argentino (IBIGEO, CONICET-UNSa), Salta, Argentina
8. Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional, Heredia, Costa Rica
9. Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, USA
10. Servicio Geológico Ambiental, Heredia, Costa Rica
11. Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
12. Department of Chemical Engineering, Materials and Industrial Productions, University of Naples Federico II, Naples, Italy

13. DISTAR, Naples, Italy

14. Dipartimento di Scienze Biologiche, Geologiche e Ambientali (BiGeA), Alma Mater Studiorum Università di Bologna, Bologna, Italy
15. Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD UR206, 75005 Paris, France
16. Institute of Geosciences and Earth Resources, National Research Council of Italy, Pisa, Italy
17. Institute of Marine Biological Resources and Biotechnologies, National Research Council, Ancona, Italy
18. Earth-Life Science Institute, Tokyo Institute for Technology, Tokyo, Japan
19. Department of Marine and Coastal Science, Rutgers University, New Brunswick, NJ, USA

Martina Cascone

Research

University of Naples

Serpentinization is commonly presented as the main source of natural hydrogen (H2) in the continental domains. However, recent works in Australia and Brazil showed that Archean– Paleoproterozoic banded iron formations could be another natural source of H2 gas. Although the reaction that produces hydrogen is similar (Fe2+ oxidation - H2O reduction process), the iron content may be higher in banded iron formations than in mafic igneous lithologies, potentially generating H2 more efficiently. Here, we present structural evidence that reported H2 emissions from Waterberg Basin, Namibia, are associated with underlying Neoproterozoic banded iron formations - the Chuos Formation. The subcircular depressions are numerous in this basin (> 2200) and cover an area of 4,000 square kilometers. The highest density occurs in the central basin a few kilometers away from Waterberg Plateau. Overall, however, the subcircular depressions distribution appears to be random. Magnetite, a known H2‑generating mineral, is ubiquitous and accompanied by other suspected H2‑generating minerals (biotite and siderite) in Chuos Formation. Wherever, Chuos Formation is deformed and metamorphosed as evidenced by the presence of biotite. Magnetite occurs either as pervasive cm to dm continuous metamorphic laminations in foliation and fractures planes and/or diffusely disseminated in metachert and metacarbonate levels. From this, we infer that metamorphism does not negatively affect the Fe2+ content that is required to generate hydrogen. Based on the magnetic response map of the different lithologies around Waterberg Basin, the spatial distribution of Chuos Formation is inferred to underlie much if not most of Waterberg Basin. At some places, Chuos Formation continuously outcrops over several kilometers (>150 km) with an estimated thickness of several hundreds of meters, which is consistent with our field observations. We assume that H2 measurements in Waterberg Basin may be associated to an active H2‑generating system by oxidation of banded iron formations in subsurface. In addition, magmatic dolerite sills are also present in the basin, and may in parallel act as seals to allow accumulation of H2 like in Mali. The banded iron formations that constitute more than 60% of global iron ore reserves, should be targeted for H2 exploration.

Vincent Roche

Associate professor

University of Le Mans

The HyAfrica project proposes a first step in the understanding of the extraction and utilisation possibilities of natural hydrogen in a set of African countries. Its objective is to assess the resources of natural hydrogen in promising regions of Morocco, Mozambique, South Africa and Togo and to evaluate its social- economic impact, if deployed for power production in standalone or mini-grid systems. Moreover, HyAfrica will allow regional and national authorities in the target countries to increase the share of renewables in the energy mix by developing roadmaps and action plans to pursue strategies for exploiting this renewable energy source and include it in their energy systems. The ultimate aim is to building capacity within the local communities.

A regional scale methodology has been adopted to study the target areas at different strategic levels of importance for natural hydrogen prospection and exploration. These levels range from mapping natural hydrogen occurrences to the business models for energy production. Stakeholders, including regulatory agencies, are also addressed in order to identify the existing bottlenecks to natural hydrogen exploration and to feed the development of roadmaps to bypass them in the future. 

The procedure of mapping natural hydrogen is based on a synergy between field work, geological analysis and geophysical modelling. Field work, conducted by local teams, performs in situ probing of hydrogen at shallow depths with dedicated sensors. Geological and geophysical analysis infer the presence of any deep-level geological controls that may govern the occurrence of natural hydrogen seeps on a regional level, the analysis of geophysical data provides a qualitative characterization of prospective areas and the development of geophysical models produce quantitative conceptual geological models. Besides the mapping of natural hydrogen resources socio-economical evaluations are also conducted. Stakeholders are identified and invited to participate in workshops that allow to disseminate the project results and to collect feedback on regulatory and policy issues and use opportunities for natural hydrogen. The stakeholders feedback is then considered as the first step in the development of exploitation roadmaps and business cases that are some of the project main outcomes.

Hundreds of field measurements were executed in the South African target area with the results showing numerous locations with existence of hydrogen at concentrations above expected values. The geological and geophysical analysis are studying both serpentinization of iron-rich rocks and natural radiolysis as possible hydrogen sources, and the faults and lineaments of the region as structural control for the hydrogen ascension to the surface.

This work will present the preliminary integrated results for the HyAfrica South Africa target region, focusing on mapping the natural hydrogen occurrence, stakeholders engagement process, regulatory issues and potential use cases and business models.

Authors list: P. Mesquita¹, J. Carneiro¹, A. Bumby², A. Smit², N. Hammond³, S. Masango³, N. Gumede², S. Huggins², T. Mokobodi³, N. Kotsedi³, R. Christiansen⁴, G. Gabriel⁴, S. Mondlane⁵, E. Duque⁶,  A. Barkaoui⁷

¹ CONVERGE, Lda, Portugal

² University of Pretoria, South Africa

³ University of Limpopo, South Africa

⁴ Leibniz Institute for Applied Geophysics, Germany

⁵ Universidade Eduardo Mondlane, Mozambique

⁶  Fraunhofer IEE, Germany

⁷ Université Mohammed Premier, Morocco

Rodolfo Christiansen¹, Mohamed Sobh¹, Alae-Eddine Barkaoui², David Tierney³, Gerald Gabriel^1,4

¹ LIAG Institute for Applied Geophysics, Hannover, Germany

²  Université Mohammed Premier, Oujda, Maroc

³ GETECH, Leeds, United Kingdom

⁴ Leibniz University Hannover, Institute of Earth System Sciences (IESW), Hannover, Germany

This study explores a multidisciplinary approach to characterize geological conditions for advancing the understanding and quantification of natural hydrogen production in the Tendrara Basin, eastern Morocco. This region exhibits surface evidence of natural hydrogen systems through the presence of sub-circular depressions. Inspection of gravity and magnetic anomalies point to the subsurface presence of ultramafic lithologies, assumed to relate to ophiolitic suites associated with the Atlas compressional system. Our methodology spans from initial data acquisition to complex geological modelling and numerical analyses. The first stage involves establishing a comprehensive database of petrophysical, geochemical, hydrogeological, and geophysical data. This includes compiling and statistically analysing diverse datasets from various sources to ensure their accuracy and reliability. Different techniques are employed to visualize and interpret trends within the data, which is essential for deeper analysis. The next phase involves constructing detailed 3D geological models, starting from basic configurations based on geological structures and units. Advanced geostatistical methods refine these models to build detailed fault networks and geological interfaces, which are validated against empirical data from boreholes and seismic sections to improve accuracy. This modelling provides a robust framework for analysing reservoir seals and gas migration routes, which is essential for evaluating exploration potential. Subsequently, we simulate temperature distributions in the study area, crucial for assessing the potential for natural hydrogen generation. We then use a sophisticated approach to geophysical inversion to accurately determine the volumes of source rocks –serpentinized (ophiolitic) rocks in this case. Our technique integrates geological and petrophysical data, enhancing the interpretability of geological models and distinguishing between different rock types such as peridotites and host rocks based on their unique petrophysical properties. The final and most critical component of our research focuses on quantifying hydrogen production, which is important for constraining transport models and for decision makers. This involves the application of computational models that integrate critical petrophysical and geochemical data to simulate the chemical reactions and physical transformations occurring within source rocks during serpentinization. An algorithm is used to determine daily hydrogen production, adapting parameters to the unique characteristics of the study area, such as the degree of serpentinization and varying temperature windows from 100 to 400°C. In these simulations, we employ gravity and magnetic data to calculate the present-day extent of serpentinization and its impact on decreased rock density and increased magnetic susceptibility. We examine different serpentinization rates, a key parameter influencing the volume and quality of hydrogen production. These rates help estimate the velocity of the serpentinization front, a crucial factor in determining how quickly hydrogen can be produced in situ. By integrating laboratory data and historical serpentinization rates, our models provide detailed insights into the distribution of hydrogen-rich zones, and production rates. Integrating this data with 3D geological and transport models enables dynamic assessment of potential hydrogen extraction sites, ensuring well targeted and feasible exploration efforts.

Rodolfo Christiansen

Scientific Researcher

Leibniz Institute for Applied Geophysics (LIAG)

The kingdom of Morocco is engaged in an energy strategy that supports the country’s transition to different source of renewable energy. The National Office of Hydrocarbon and Mines (ONHYM) saw the opportunity that natural hydrogen offers to diversify the national renewable energy mix with low cost and environmental impact. ONHYM started the assessment of the Moroccan geology by collecting and interpreting the available geoscientific data to identify the most promising targets for natural hydrogen exploration. The reconnaissance works carried out confirmed the presence of natural hydrogen emission with some of the target showing the presence of circular depressions. More detailed work were carried out focused on the two main targets at the coastal meseta and the southern provinces, it included geological and geophysical reconnaissance, in-situ measurements, gas sampling for chemical and isotopic analysis.

Co-authors : Nour Eddine BERKAT, Alae Eddine BARKAOUI, Yassine Zarhloule, Othman SADKI, Mustapha CHAIB, Júlio F.CARNEIRO, Paulo Mesquita

Reda EN NABBADI

Onhym

The study highlights the promising potential of natural hydrogen as a renewable energy source in Morocco, warranting further research and investment to support the country's energy transition. It explores the potential of natural hydrogen in the southern provinces of Morocco, specifically focusing on Tarfaya, Laâyoune, and Boujdour. Conducted by Moroccan National Office of Hydrocarbon and Mines, the study aims to identify hydrogen sources, assess their viability, and propose future action plans. The research is divided into two phases: identifying promising target areas and characterizing these targets through fieldwork and laboratory analysis. The methodology includes using geological, structural, hydrogeological, geochemical, and geophysical data, conducting in situ hydrogen measurements, and developing conceptual models to understand hydrogen migration. Significant hydrogen concentrations were detected at sites like Sebkha Oum Dba’ (1.77% H2) and Daoura, confirming natural hydrogen seepages. Geological models indicate that graben structures and deep faults are preferential pathways for hydrogen migration. Proposed actions include geophysical surveys, thermal flux measurements, and exploratory drilling to measure hydrogen beneath sebkha salt layers.

Co-authors: Reda EN NABBADI, Yassine Zarhloule, Alae Eddine BARKAOUI, Othman SADKI, .Júlio F.CARNEIRO, Mustapha CHAIB

Nour Eddine Berkat

Senior Geophysicist

Onhym

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Fariba Kohanpour1, Margaux Le Vaillant1, Ema Frery2
1: Commonwealth Scientific and Industrial Research Organisation (CSIRO), Mineral Resources, 26 Dick Perry Avenue, Kensington,
WA 6151, Australia
2: Commonwealth Scientific and Industrial Research Organisation (CSIRO), Energy, 26 Dick Perry Avenue, Kensington, WA 6151,
Australia
The purpose of this study is to identify the key processes involved in the formation and
preservation of a hydrogen system using a mineral systems approach. This involves mapping the
geological proxies of key parameters and integrating them using a GIS-based prospectivity
modelling technique to identify regions with the highest hydrogen-resource potential. The work
addresses the following questions: (1) What are the main geological processes or critical factors
for natural hydrogen generation and endowment? and (2) Where are the prospective zones for
natural hydrogen exploration?
To fulfil these objectives, a multi-stage approach was developed, leveraging advancements in
geodynamics, geophysical and geological interpretation for mineral systems analysis and
prospectivity modelling. Firstly, the project focused on a comprehensive literature review. We
aimed to identify the critical elements of the natural hydrogen system, leading to the formation
and preservation of hydrogen resources comparable to mineral systems components. The
primary outcome of this stage was recognising the key parameters of a natural hydrogen system,
including sources, generation kinetics, migration pathways, hydrogen reservoirs, and trap
locations. We then mapped and integrated the geological proxies of the hydrogen system’s key
parameters to create prospectivity models. This modelling requires input data from the first stage
of the project, i.e., an understanding of the different components of natural hydrogen systems
and their relative roles in the formation and preservation of hydrogen resources.
The modelling followed the following steps: (1) identification of mappable proxies for each key
component of the hydrogen system(s), (2) creation of predictor maps based on the identified
proxies, (3) classification and weighting of these maps along with a confidence factor, and (4)
generation of prospectivity models (potential maps) by overlaying the weighted predictor maps.
The results include a series of predictor maps for each component of the hydrogen system (i.e.
source, pathway, reservoir, trap), which are combined to estimate hydrogen potential across
Australia. This allows for the prioritization of critical elements and the application of different
scenarios in natural hydrogen targeting.



Fariba Kohanpour

Research Scientist, Mineral Systems Geologist

CSIRO

The natural hydrogen (also referred to as “white” or “geological” hydrogen) appears as the most promising candidate to achieve economically viable, stable, low-carbon footprint economy, compared to the non-homogeneous cost of synthetically-produced hydrogen. Naturally-occurring free hydrogen gas has been reported in multiple geological contexts since decades, such as serpentinized peridotite massifs, pre-Cambrian cratons, rift zones, geothermal and volcanic regions: these represent the most favorable and economically-viable geological settings for natural hydrogen generation, potential accumulation and preservation. Additionally, sedimentary basins may also be potential for natural hydrogen generation/accumulation when associated with specific geological environments and H2-generation mechanisms. The concept of “Favourability Maps” has been successfully applied in geothermal exploration. Our proposed workflow is based on the generation of “Natural Hydrogen Favourability Maps (NHFMs)”: a tool to support decision making in natural hydrogen exploration. These maps are the result of the overlap between surface and subsurface elements. The surficial indicators for hydrogen generation may include fairy cycles, hyper-alkaline springs in serpentinizied contexts and hydrogen surface measurements, while subsurface parameters involve the main hydrogen play elements. The hydrogen play elements of an area include multi-dimensional interaction of: 1) the geodynamic setting of a region and its controls on the spatial distribution of potential hydrogen-generation rock types (e.g. peridotite lithotypes, radioelement-rich rocks, etc.), 2) the hydrogen-generation rock types (mineralogy, rheology, weathering intensity, petrophysical properties, etc.), 3) the relationship between rock-types and hydrogen generation mechanisms (e.g. water/rock interactions), 4) the stratigraphic setting, 5) the reservoir characterization, 6) the tectonic setting and the link with the presence/absence of privileged migration paths, 7) the caprock characterization, 8) the thermal properties of the region (heat-flow, thermal gradient, etc.), and 9) the hydrogeological setting. The integration of all these key play elements allow the construction of HFMs to assist in the identification and characterization of potential hydrogen prospects, the creation of a project funnel for prospect ranking and providing more informed support for decision making. The concept of HFMs has been applied in several regions and different geological contexts around the globe and has proven to be very effective for locating potential natural hydrogen prospects. Additionally, these prospects were confirmed using highly innovative and advanced TERRA-A proprietary natural resources detection technology (e.g. natural hydrogen, helium, water etc.), thereby providing strong evidence for the efficacy of hydrogen-favorability maps as a promising tool for exploration and evaluation of natural hydrogen prospects.

Co-auteur : Grant Nicholas, Peter Seibert, Mahmoud Leila

Fiammetta Mondino

Senior geologist

 Introduction Energy transition from fossil fuels to renewable energy and hydrogen energy is believed to be one of key solutions to cope with decarbonization. Under this circumstance, natural hydrogen exploration (gold hydrogen) and Hydrogen production with subsurface simulation (orange hydrogen) gains more attentions due to its low cost and low carbon footprints as compared to manufactured hydrogen. However, there is no methodologies for hydrogen resource potential evaluation in place. This paper proposes a graph-based approach with constrains from mineralogy of source rocks and environmental conditions of serpentinization. The method can serve as a quick tool to do natural hydrogen potential estimation for any given Fe-rich rock bodies. 2. Methods Natural hydrogen generation has been attributed to a variety of generation mechanisms in which the hydration of Fe-rich ultramafic/mafic minerals (serpentinization) is considered as a major one responsible for hydrogen emissions found across the global. This method is to develop a series of templates quantitatively depicting the relationships among hydrogen gas yields, the content of Fe-bearing minerals in the source rocks, and the degree of serpentinization. For a given targeting area, the potential hydrogen generation can be evaluated based on 3 inputs:1) the volume of Fe-rich rocks which can be estimated on regional geological map and multiphysical data. 2) the content of Fe-bearing mineral, and 3) the degree of serpentinization can be inferred from XRD and petrography of the rock samples. 3. Results Serpentinization is a complex metamorphic process of ferromagnesian minerals characterized by the hydration and the oxidation of reduced iron species resulting in H2 generation. Geochemical modeling shows that various reaction pathways of serpentinization may take place, such as. 6Fe2SiO4 (fayalite) + 7H2O → 3Fe3Si2O5(OH)4 (chrysotile) + Fe3O4 (magnetite) + H2 (1) 3Fe2SiO4 (fayalite) + 2H2O → 2Fe3O4 (magnetite) + 3SiO2 + 2H2 (2) The controlling factors include mineral composition, temperature, pH values, water/rock ratio, reactive surface area and water compositions. Given that a) a rock body has a volume of 1.88E+08 cubic meters, b) composited dominantly of olivine with 10% of fayalite; 3) the degree of serpentinization varies between 0 to 100%. Two templates are created based on equation (1) and (2). The estimated H2 generation can be read on two graphs. For the lower case (equation 1), the potentially generated H2 range from 0 to 8.32E07 kg while the rock body is serpentinized between 0 to 100%. For an upper case, 0 to 3.7E08 kg of H2 would be generated while the serpentinization proceeded from 0 to 100%. 4. Conclusions This paper proposed an innovative tool to estimate the H2 generation potential of Fe-rich rocks during serpentinization, which provides critical information for the techno-economic analysis of gold hydrogen and orange hydrogen projects.

Co-auteur : Ernest Jones, Hasnol Hady Ismail

Hongwen Zhao

Petronas

Objectives of this study is to present a systematic workflow for geologic hydrogen exploration. The workflow is designed by considering, the characteristics of hydrogen play elements such as source, generation, migration, accumulation, and seal. Methods This study reviewed geologic hydrogen seepages found globally in Africa, Australia, Brazil, Europe, and USA and a discovery in the Bourabougou in Mali. This established that geologic hydrogen could generate, migrate, and accumulate in subsurface reservoirs analogous to hydrocarbon plays. However, distinct difference in geologic hydrogen play is its source rock (Fe-rich, radioactive hard rocks), geological conditions and physicochemical reactions based on this a detailed workflow developed and presented to explore geologic hydrogen, with following broad steps: 1. Hydrogen geology 2. Hydrogen subsurface modelling 3. Hydrogen prospecting Results, Observations, Conclusions Geologic hydrogen generation mechanism established by various studies and lab experiment included serpentinization and radiolysis other process like pyrolysis of organic matter and deep mantle de-gassing also suggested by few authors. This study focuses on serpentinization and radiolysis which are related to water rock reactions. The main outcome of this study is a stepwise workflow, 1. Hydrogen geology study which is the first step details out integration of available maps of surface lithology, mineral, ore and mining location, topography, structural and tectonics, gravity & magnetics data, and natural seepages in the area, if any. This integration delineates selected area for field survey and produce pre-field maps for outcrop geological investigation. Outcrop study produced protocols of rock, water and gas sample collection and gas measurements. Lab analyses workflows establish protocols for Rock, water, and gas analyses such as petrography, XRD, XRF, GC, stable isotopic analyses 2. Hydrogen subsurface modelling produced a workflow for geochemical modelling which uses mineralogical composition, water composition P/T condition to generate equilibrium batch and kinetic models. Reactive transport model entails earth model, porosity/permeability, and flow simulation. Reservoir modelling for reservoir properties modeling if accumulation is in porous reservoirs and fracture modeling in induced porosity. 3. Hydrogen prospecting elaborates hydrogen seepage detection of GSDs (Fairy circle) using remote sensing and AI-ML tools followed by hydrogen surface monitoring using handheld hydrogen sensors. Multiphysics data study like CSEM, gravity and magnetic integration with seismic which generates area of interest (AOIs) to test the site with R&D drilling and hydrogen measurements to establish the play presence. Prospect maturation workflow provides steps to derisk reservoir, trap, and seal and generated leads and prospect for exploratory drilling. Novel/Additive Information This workflow produces a multidisciplinary approach to discover geologic hydrogen play elements, source rock geochemistry of Fe rich rocks, multi-physics data applicability, automated GSDs interpretation using AI-ML, lab based and modeled quantification of geochemical potential of hydrogen.

Co-auteur : Ernest A Jones, Hongwen Zhao, Hasnol Hady Ismail, Seng Wah Tan, Junxiao Li and M Izzuljad B Ahmad Fuad

Seemant Rajput

Geoscientist

Petronas