Understanding the Fate of H2S Injected in Basalts by Means of Time-Domain Induced Polarization Geophysical Logging
(2024) In Journal of Geophysical Research: Solid Earth 129(6).- Abstract
To help meet emission standards, hydrogen sulfide (H2S) from geothermal production may be injected back into the subsurface, where basalt offers, in theory, the capacity to mineralize H2S into pyrite. Ensuring the viability of this pollution mitigation technology requires information on how much H2S is mineralized, at what rate and where. To date, monitoring efforts of field-scale H2S reinjection have mostly occurred via mass balance calculations, typically capturing less than 5% of the injected fluid. While these studies, along with laboratory experiments and geochemical models, conclude effective H2S mineralization, their extrapolation to quantify mineralization and its... (More)
To help meet emission standards, hydrogen sulfide (H2S) from geothermal production may be injected back into the subsurface, where basalt offers, in theory, the capacity to mineralize H2S into pyrite. Ensuring the viability of this pollution mitigation technology requires information on how much H2S is mineralized, at what rate and where. To date, monitoring efforts of field-scale H2S reinjection have mostly occurred via mass balance calculations, typically capturing less than 5% of the injected fluid. While these studies, along with laboratory experiments and geochemical models, conclude effective H2S mineralization, their extrapolation to quantify mineralization and its persistence over time leads to considerable uncertainty. Here, a geophysical methodology, using time-domain induced polarization (TDIP) logging in two of the injection wells (NN3 and NN4), is developed as a complementary tool to follow the fate of H2S re-injected at Nesjavellir geothermal site (Iceland). Results show a strong chargeability increase at +40 days, interpreted as precipitation of up to 2 vol.% based on laboratory relationships. A uniform increase is observed along NN4, whereas it is localized below 450 m in NN3. Changes are more pronounced with larger electrode spacing, indicating that pyrite precipitation takes place away from the wells. Furthermore, a chargeability decrease is observed at later monitoring rounds in both wells, suggesting that pyrite is either passivated or re-dissolved after precipitating. These results highlight that a sequence of overlapping reactive processes (pyrite precipitation, passivation, pore clogging and possibly pyrite re-dissolution) results from H2S injection and that TDIP monitoring is sensitive to this sequence.
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- author
- Lévy, L. LU ; Ciraula, Daniel ; Legros, Bruno ; Martin, T. LU and Weller, A.
- organization
- publishing date
- 2024-06
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- borehole logging, gas storage, geothermal, H2S, pyrite, time-domain induced polarization
- in
- Journal of Geophysical Research: Solid Earth
- volume
- 129
- issue
- 6
- article number
- e2023JB028316
- publisher
- Wiley-Blackwell
- external identifiers
-
- scopus:85195269582
- ISSN
- 2169-9313
- DOI
- 10.1029/2023JB028316
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2024. The Author(s).
- id
- 93ec82cf-1ccf-44d7-b877-c7711f25d4cf
- date added to LUP
- 2024-06-15 16:18:38
- date last changed
- 2024-06-17 12:17:16
@article{93ec82cf-1ccf-44d7-b877-c7711f25d4cf,
abstract = {{<p>To help meet emission standards, hydrogen sulfide (H<sub>2</sub>S) from geothermal production may be injected back into the subsurface, where basalt offers, in theory, the capacity to mineralize H<sub>2</sub>S into pyrite. Ensuring the viability of this pollution mitigation technology requires information on how much H<sub>2</sub>S is mineralized, at what rate and where. To date, monitoring efforts of field-scale H<sub>2</sub>S reinjection have mostly occurred via mass balance calculations, typically capturing less than 5% of the injected fluid. While these studies, along with laboratory experiments and geochemical models, conclude effective H<sub>2</sub>S mineralization, their extrapolation to quantify mineralization and its persistence over time leads to considerable uncertainty. Here, a geophysical methodology, using time-domain induced polarization (TDIP) logging in two of the injection wells (NN3 and NN4), is developed as a complementary tool to follow the fate of H<sub>2</sub>S re-injected at Nesjavellir geothermal site (Iceland). Results show a strong chargeability increase at +40 days, interpreted as precipitation of up to 2 vol.% based on laboratory relationships. A uniform increase is observed along NN4, whereas it is localized below 450 m in NN3. Changes are more pronounced with larger electrode spacing, indicating that pyrite precipitation takes place away from the wells. Furthermore, a chargeability decrease is observed at later monitoring rounds in both wells, suggesting that pyrite is either passivated or re-dissolved after precipitating. These results highlight that a sequence of overlapping reactive processes (pyrite precipitation, passivation, pore clogging and possibly pyrite re-dissolution) results from H<sub>2</sub>S injection and that TDIP monitoring is sensitive to this sequence.</p>}},
author = {{Lévy, L. and Ciraula, Daniel and Legros, Bruno and Martin, T. and Weller, A.}},
issn = {{2169-9313}},
keywords = {{borehole logging; gas storage; geothermal; H2S; pyrite; time-domain induced polarization}},
language = {{eng}},
number = {{6}},
publisher = {{Wiley-Blackwell}},
series = {{Journal of Geophysical Research: Solid Earth}},
title = {{Understanding the Fate of H<sub>2</sub>S Injected in Basalts by Means of Time-Domain Induced Polarization Geophysical Logging}},
url = {{http://dx.doi.org/10.1029/2023JB028316}},
doi = {{10.1029/2023JB028316}},
volume = {{129}},
year = {{2024}},
}