H2 dynamics in the soil of a H2-emitting zone (São Francisco Basin, Brazil): Microbial uptake quantification and reactive transport modelling

Myagkiy, Andrey; Brunet, Fabrice; Popov, Claudia; Krüger, Ricardo Henrique; Guimaraes, Helena; Sousa, Rafaella Silveira; Charlet, Laurent; Moretti, Isabelle

doi:10.1016/j.apgeochem.2019.104474

Cited by 26 publications

(21 citation statements)

References 59 publications

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“…A sensor installed in the center of the structure for few months recorded only a few H 2 concentration pulses but most of the time had a signal close to 0 (Prinzhofer and Engie's Team personal communication). The 24 h period is not yet fully understood (Myagkiy et al, 2020) nor the gap, or delay, between the highly emitting area and the other ones. However, the fact that the H 2 concentration in the soil, near the surface, is changing with time along the day is shown by all data.…”

Section: Time-resolved H 2 -Concentration Measurements Within the Faimentioning

confidence: 99%

“…The effect, on H 2 diffusive transport, of bacterial activity has already been investigated on soils from the same structure of the São Francisco basin (Myagkiy et al, 2020). The kinetics of H 2 consumption by the bacteria present in the soil, which was calibrated in laboratory experiments, is proved to be very large and may reduce or even completely hide the deeper H 2 flows.…”

Section: Time-resolved H 2 -Concentration Measurements Within the Faimentioning

confidence: 99%

“…Two types of calculation were performed, namely with and without H 2 bacterial consumption, for a comparison. The details of its measurements can be found in Myagkiy et al (2020). The model assumes a constant gradient in bacteria distribution; the maximum value of bacterial consumption activity is assumed to appear at the surface and reaches zero at the bottom of the model.…”

Section: Physical Governing Equations and Assumptionsmentioning

confidence: 99%

“…The impact of water saturation degree in the soil is not regarded in this study but can have an important impact on hydrogen characteristic transport time in porous media (see e. g. Myagkiy et al, 2020). High water content in the soil reduces its effective porosity and restricts the diffusion and advection of H 2 into the soil.…”

Section: Physical Governing Equations and Assumptionsmentioning

confidence: 99%

“…Bacterial activity: the impact of this parameter has already been discussed in a previous paper (Myagkiy et al, 2020), so we will incorporate this effect in the discussion but the impact of the variation of the quantity of bacteria and kinetic of the H 2 consumption will not be discussed here in detail.…”

Section: Boundary Conditionsmentioning

confidence: 99%

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Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Myagkiy

Moretti

Brunet

2020

BSGF - Earth Sci. Bull.

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Natural H2 emissions from the ground have now been measured in many places worldwide. These emissions can be localized on faults or be more diffuse in some sedimentary basins, usually of Proterozoic age. In such a case, emanation zones are often visible from aerial images or on high-resolution topographic maps since they correspond to slight depressions of circular to elliptic shape. Furthermore, the rounded depressions are covered with a scrubby vegetation which often contrasts with the surrounding vegetation. Although the emission structure displays a very regular shape, the distribution of H2 concentration in the first meter of soil in such a structure does show a clear pattern. For example, the maximum concentration is almost never measured in the center of the structure and the few time-resolved data show that the soil H2 concentration is variable with time. Here, the time and space evolution of H2 concentration is simulated using a 2-D advective-diffusive model of H2 transport in porous media. Several parameters have been tested as the depth and periodicity of the H2 point source (pulsed), bacterial H2 consumption and permeability heterogeneities of the soil. The radius of the structure is linked to the time spent by the H2 in the soil that depends on the soil permeability, the depth of the gas leakage point and the pressure of the bubble. To account for field observations, the case of a shaly, less permeable, heterogeneity in the center of the structures has been modeled. It resulted in an increase of the concentration toward the rim of the structure and a close to zero signal in its center. If the deep signal is periodic with a frequency smaller than a few hours, H2 concentration within the soil is almost constant; in other cases, the near surface concentration wave reflects the concentration periodicity of the source with a delay (in the range of 12 h for 30 m of soil) and so the near surface H2 concentration values will be highly dependent on the time at which the measurement is performed. H2 monitoring through a sensor network is thus mandatory to characterize the H2 dynamics in the soil of fairy circles.

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Section: Time-resolved H 2 -Concentration Measurements Within the Faimentioning

confidence: 99%

Section: Time-resolved H 2 -Concentration Measurements Within the Faimentioning

confidence: 99%

Section: Physical Governing Equations and Assumptionsmentioning

confidence: 99%

Section: Physical Governing Equations and Assumptionsmentioning

confidence: 99%

Section: Boundary Conditionsmentioning

confidence: 99%

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Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Myagkiy

Moretti

Brunet

2020

BSGF - Earth Sci. Bull.

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Modeling deep control pulsing ﬂux of native H2 throughout tectonic fault-valve systems

Donzé

Bourdet

Truche

et al. 2022

Preprint

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Pulsing seepages of native hydrogen (H2) have been observed at the surface on several emitting structures. It is still unclear whether this H2 pulsed flux is controlled by deep migration processes, atmosphere/near-surface interactions or by bacterial fermentation. Here, we investigate mechanisms that may trigger pulsating fluid migration at depth and the resulting periodicity. We set up a numerical model to simulate the migration of a deep constant fluid flow. To verify the model's formulation to solve complex fluid flows, we first simulate the morphology and amplitude of 2D thermal anomalies induced by buoyancy-driven water flow within a fault zone. Then, we simulate the H2 gas flow along a 1-km draining fault, crosscut by a lower permeable rock layer to investigate the conditions for which a pulsing system is generated from a deep control. For a constant incoming flow of H2 at depth, persistent bursts at the surface only appear in the model if: (I) a permeability with an effective-stress dependency is used, (II) a strong contrast of permeability exists between the different zones, (III) a sufficiently high value of the initial effective stress state at the base of the low permeable layer exists, and (IV) the incoming and continuous fluid flow of H2 at depth remains low enough so that the overpressure does not "open" instantly the low permeability layer. The typical periodicity expected for this type of valve-fault control of H2 pulses at the surface is at a time scale of the order of 100 to 300 days. Hosted fileessoar.10512945.1.docx available at https://authorea.com/users/527803/articles/611174modeling-deep-control-pulsing-%EF%AC%82ux-of-native-h2-throughout-tectonic-fault-valvesystems Modeling deep control pulsing flux of native H 2 throughout tectonic fault-valve systems

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Origin of continuous hydrogen flux in gas manifestations at the Larderello geothermal field, Central Italy

et al. 2021

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H2 dynamics in the soil of a H2-emitting zone (São Francisco Basin, Brazil): Microbial uptake quantification and reactive transport modelling

Cited by 26 publications

References 59 publications

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Modeling deep control pulsing ﬂux of native H2 throughout tectonic fault-valve systems

Origin of continuous hydrogen flux in gas manifestations at the Larderello geothermal field, Central Italy

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H2 dynamics in the soil of a H2-emitting zone (São Francisco Basin, Brazil): Microbial uptake quantification and reactive transport modelling

Cited by 26 publications

References 59 publications

Space and time distribution of subsurface H2concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Space and time distribution of subsurface H2concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Modeling deep control pulsing ﬂux of native H2 throughout tectonic fault-valve systems

Origin of continuous hydrogen flux in gas manifestations at the Larderello geothermal field, Central Italy

Contact Info

Product

Resources

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Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model