A pre-injection assessment of CO2 and H2S mineralization reactions at the Nesjavellir (Iceland) geothermal storage site

Iwona Monika Galeczka; Andri Stefánsson; Barbara I. Kleine; Jóhann Gunnarsson-Robin; Sandra Ósk Snæbjörnsdóttir; Bergur Sigfússon; Sveinborg Hlíf Gunnarsdóttir; Tobias B. Weisenberger; Eric H. Oelkers

doi:10.1016/j.ijggc.2022.103610

A pre-injection assessment of CO₂ and H₂S mineralization reactions at the Nesjavellir (Iceland) geothermal storage site

Iwona Monika Galeczka
, Andri Stefánsson
, Barbara I. Kleine
, Jóhann Gunnarsson-Robin
, Sandra Ósk Snæbjörnsdóttir
, Bergur Sigfússon
, Sveinborg Hlíf Gunnarsdóttir
, Tobias B. Weisenberger
, Eric H. Oelkers

University of Iceland

Research output: Contribution to journal › Article › peer-review

Abstract

The injection of water dissolved CO₂ and H₂S into basalts into the Nesjavellir geothermal system (Iceland) is to begin in 2022. This study is a pre-injection investigation assessing the likely response of the fluid-rock system to the gas charged water injection. The target aquifer has a temperature of < 200 °C at the injection well, but the temperature increases to ∼300 °C towards the center of the geothermal field where the production wells are located. The aquifer has current in-situ pH values of 6.7–7.7 and CO₂ and H₂S concentrations of 30.1–1079 and 60.4–505 ppm, respectively. These pre-injection aquifer fluids are saturated with respect to numerous sulfide minerals but undersaturated with respect to the major carbonate minerals. The fluid during the anticipated pilot carbon and sulfur charged water injection is expected to have a temperature of ∼84 °C, a pH of ∼4.9 and dissolved CO₂ and H₂S concentrations of 1223 and 480 ppm, respectively. Geochemical modelling confirms that the injection of CO₂ and H₂S charged fluids will dissolve the altered basaltic host rock near the injection well followed by the precipitation of secondary minerals including sulfides and carbonates further from the well. Calculations suggest about 70% and 100%, respectively, of this injected CO₂ and H₂S will be mineralized between the injection and production wells. The increasing of the CO₂ and H₂S content of the injection fluid will increase mineralization efficiency if the increased acidity of this fluid increases the mass of basalt dissolution in the subsurface. Carbon, sulfur and helium isotope systematics and abundances imply that large part of CO₂ and H₂S emitted from the Nesjavellir powerplant, as well as those released from the geothermal fluids naturally originate from magmatic sources. Mass balance considerations suggest that the currently planned dissolved gas injection into the Nesjavellir system will negligibly affect the CO₂ and H₂S budget of the aquifer. However, efforts to maximize the mineralization efficiency when upscaling this carbon storage system should be made to limit possible increase in reservoir fluid CO₂ concentration.

Original language	English
Article number	103610
Journal	International Journal of Greenhouse Gas Control
Volume	115
DOIs	https://doi.org/10.1016/j.ijggc.2022.103610
Publication status	Published - 1 Mar 2022

Bibliographical note

Funding Information: The authors would like to thank the associate editor Charles Jenkins and the anonymous reviewers for their constructive comments. We also would like to acknowledge the colleagues at the Institute of Earth Sciences, University of Iceland, Iceland Geosurvey, CarbFix, and Reykjavik Energy for fruitful discussions. This work is part of the GECO project and has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 818169. Funding Information: The authors would like to thank the associate editor Charles Jenkins and the anonymous reviewers for their constructive comments. We also would like to acknowledge the colleagues at the Institute of Earth Sciences, University of Iceland, Iceland Geosurvey, CarbFix, and Reykjavik Energy for fruitful discussions. This work is part of the GECO project and has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 818169. Publisher Copyright: © 2022

Other keywords

Carbon dioxide (CO)
Geothermal
Hydrogen sulfide (HS)
Mineral storage
Reaction path modelling

Access to Document

10.1016/j.ijggc.2022.103610

Cite this

Galeczka, I. M., Stefánsson, A., Kleine, B. I., Gunnarsson-Robin, J., Snæbjörnsdóttir, S. Ó., Sigfússon, B., Gunnarsdóttir, S. H., Weisenberger, T. B., & Oelkers, E. H. (2022). A pre-injection assessment of CO₂ and H₂S mineralization reactions at the Nesjavellir (Iceland) geothermal storage site. International Journal of Greenhouse Gas Control, 115, Article 103610. https://doi.org/10.1016/j.ijggc.2022.103610

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title = "A pre-injection assessment of CO2 and H2S mineralization reactions at the Nesjavellir (Iceland) geothermal storage site",

abstract = "The injection of water dissolved CO2 and H2S into basalts into the Nesjavellir geothermal system (Iceland) is to begin in 2022. This study is a pre-injection investigation assessing the likely response of the fluid-rock system to the gas charged water injection. The target aquifer has a temperature of < 200 °C at the injection well, but the temperature increases to ∼300 °C towards the center of the geothermal field where the production wells are located. The aquifer has current in-situ pH values of 6.7–7.7 and CO2 and H2S concentrations of 30.1–1079 and 60.4–505 ppm, respectively. These pre-injection aquifer fluids are saturated with respect to numerous sulfide minerals but undersaturated with respect to the major carbonate minerals. The fluid during the anticipated pilot carbon and sulfur charged water injection is expected to have a temperature of ∼84 °C, a pH of ∼4.9 and dissolved CO2 and H2S concentrations of 1223 and 480 ppm, respectively. Geochemical modelling confirms that the injection of CO2 and H2S charged fluids will dissolve the altered basaltic host rock near the injection well followed by the precipitation of secondary minerals including sulfides and carbonates further from the well. Calculations suggest about 70\% and 100\%, respectively, of this injected CO2 and H2S will be mineralized between the injection and production wells. The increasing of the CO2 and H2S content of the injection fluid will increase mineralization efficiency if the increased acidity of this fluid increases the mass of basalt dissolution in the subsurface. Carbon, sulfur and helium isotope systematics and abundances imply that large part of CO2 and H2S emitted from the Nesjavellir powerplant, as well as those released from the geothermal fluids naturally originate from magmatic sources. Mass balance considerations suggest that the currently planned dissolved gas injection into the Nesjavellir system will negligibly affect the CO2 and H2S budget of the aquifer. However, efforts to maximize the mineralization efficiency when upscaling this carbon storage system should be made to limit possible increase in reservoir fluid CO2 concentration.",

keywords = "Carbon dioxide (CO), Geothermal, Hydrogen sulfide (HS), Mineral storage, Reaction path modelling",

author = "Galeczka, \{Iwona Monika\} and Andri Stef{\'a}nsson and Kleine, \{Barbara I.\} and J{\'o}hann Gunnarsson-Robin and Sn{\ae}bj{\"o}rnsd{\'o}ttir, \{Sandra {\'O}sk\} and Bergur Sigf{\'u}sson and Gunnarsd{\'o}ttir, \{Sveinborg Hl{\'i}f\} and Weisenberger, \{Tobias B.\} and Oelkers, \{Eric H.\}",

note = "Funding Information: The authors would like to thank the associate editor Charles Jenkins and the anonymous reviewers for their constructive comments. We also would like to acknowledge the colleagues at the Institute of Earth Sciences, University of Iceland, Iceland Geosurvey, CarbFix, and Reykjavik Energy for fruitful discussions. This work is part of the GECO project and has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 818169. Funding Information: The authors would like to thank the associate editor Charles Jenkins and the anonymous reviewers for their constructive comments. We also would like to acknowledge the colleagues at the Institute of Earth Sciences, University of Iceland, Iceland Geosurvey, CarbFix, and Reykjavik Energy for fruitful discussions. This work is part of the GECO project and has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 818169. Publisher Copyright: {\textcopyright} 2022",

year = "2022",

month = mar,

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doi = "10.1016/j.ijggc.2022.103610",

language = "English",

volume = "115",

journal = "International Journal of Greenhouse Gas Control",

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Galeczka, IM, Stefánsson, A, Kleine, BI, Gunnarsson-Robin, J, Snæbjörnsdóttir, SÓ, Sigfússon, B, Gunnarsdóttir, SH, Weisenberger, TB & Oelkers, EH 2022, 'A pre-injection assessment of CO₂ and H₂S mineralization reactions at the Nesjavellir (Iceland) geothermal storage site', International Journal of Greenhouse Gas Control, vol. 115, 103610. https://doi.org/10.1016/j.ijggc.2022.103610

TY - JOUR

T1 - A pre-injection assessment of CO2 and H2S mineralization reactions at the Nesjavellir (Iceland) geothermal storage site

AU - Galeczka, Iwona Monika

AU - Stefánsson, Andri

AU - Kleine, Barbara I.

AU - Gunnarsson-Robin, Jóhann

AU - Snæbjörnsdóttir, Sandra Ósk

AU - Sigfússon, Bergur

AU - Gunnarsdóttir, Sveinborg Hlíf

AU - Weisenberger, Tobias B.

AU - Oelkers, Eric H.

N1 - Funding Information: The authors would like to thank the associate editor Charles Jenkins and the anonymous reviewers for their constructive comments. We also would like to acknowledge the colleagues at the Institute of Earth Sciences, University of Iceland, Iceland Geosurvey, CarbFix, and Reykjavik Energy for fruitful discussions. This work is part of the GECO project and has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 818169. Funding Information: The authors would like to thank the associate editor Charles Jenkins and the anonymous reviewers for their constructive comments. We also would like to acknowledge the colleagues at the Institute of Earth Sciences, University of Iceland, Iceland Geosurvey, CarbFix, and Reykjavik Energy for fruitful discussions. This work is part of the GECO project and has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 818169. Publisher Copyright: © 2022

PY - 2022/3/1

Y1 - 2022/3/1

N2 - The injection of water dissolved CO2 and H2S into basalts into the Nesjavellir geothermal system (Iceland) is to begin in 2022. This study is a pre-injection investigation assessing the likely response of the fluid-rock system to the gas charged water injection. The target aquifer has a temperature of < 200 °C at the injection well, but the temperature increases to ∼300 °C towards the center of the geothermal field where the production wells are located. The aquifer has current in-situ pH values of 6.7–7.7 and CO2 and H2S concentrations of 30.1–1079 and 60.4–505 ppm, respectively. These pre-injection aquifer fluids are saturated with respect to numerous sulfide minerals but undersaturated with respect to the major carbonate minerals. The fluid during the anticipated pilot carbon and sulfur charged water injection is expected to have a temperature of ∼84 °C, a pH of ∼4.9 and dissolved CO2 and H2S concentrations of 1223 and 480 ppm, respectively. Geochemical modelling confirms that the injection of CO2 and H2S charged fluids will dissolve the altered basaltic host rock near the injection well followed by the precipitation of secondary minerals including sulfides and carbonates further from the well. Calculations suggest about 70% and 100%, respectively, of this injected CO2 and H2S will be mineralized between the injection and production wells. The increasing of the CO2 and H2S content of the injection fluid will increase mineralization efficiency if the increased acidity of this fluid increases the mass of basalt dissolution in the subsurface. Carbon, sulfur and helium isotope systematics and abundances imply that large part of CO2 and H2S emitted from the Nesjavellir powerplant, as well as those released from the geothermal fluids naturally originate from magmatic sources. Mass balance considerations suggest that the currently planned dissolved gas injection into the Nesjavellir system will negligibly affect the CO2 and H2S budget of the aquifer. However, efforts to maximize the mineralization efficiency when upscaling this carbon storage system should be made to limit possible increase in reservoir fluid CO2 concentration.

AB - The injection of water dissolved CO2 and H2S into basalts into the Nesjavellir geothermal system (Iceland) is to begin in 2022. This study is a pre-injection investigation assessing the likely response of the fluid-rock system to the gas charged water injection. The target aquifer has a temperature of < 200 °C at the injection well, but the temperature increases to ∼300 °C towards the center of the geothermal field where the production wells are located. The aquifer has current in-situ pH values of 6.7–7.7 and CO2 and H2S concentrations of 30.1–1079 and 60.4–505 ppm, respectively. These pre-injection aquifer fluids are saturated with respect to numerous sulfide minerals but undersaturated with respect to the major carbonate minerals. The fluid during the anticipated pilot carbon and sulfur charged water injection is expected to have a temperature of ∼84 °C, a pH of ∼4.9 and dissolved CO2 and H2S concentrations of 1223 and 480 ppm, respectively. Geochemical modelling confirms that the injection of CO2 and H2S charged fluids will dissolve the altered basaltic host rock near the injection well followed by the precipitation of secondary minerals including sulfides and carbonates further from the well. Calculations suggest about 70% and 100%, respectively, of this injected CO2 and H2S will be mineralized between the injection and production wells. The increasing of the CO2 and H2S content of the injection fluid will increase mineralization efficiency if the increased acidity of this fluid increases the mass of basalt dissolution in the subsurface. Carbon, sulfur and helium isotope systematics and abundances imply that large part of CO2 and H2S emitted from the Nesjavellir powerplant, as well as those released from the geothermal fluids naturally originate from magmatic sources. Mass balance considerations suggest that the currently planned dissolved gas injection into the Nesjavellir system will negligibly affect the CO2 and H2S budget of the aquifer. However, efforts to maximize the mineralization efficiency when upscaling this carbon storage system should be made to limit possible increase in reservoir fluid CO2 concentration.

KW - Carbon dioxide (CO)

KW - Geothermal

KW - Hydrogen sulfide (HS)

KW - Mineral storage

KW - Reaction path modelling

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U2 - 10.1016/j.ijggc.2022.103610

DO - 10.1016/j.ijggc.2022.103610

M3 - Article

SN - 1750-5836

VL - 115

JO - International Journal of Greenhouse Gas Control

JF - International Journal of Greenhouse Gas Control

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