Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland
Abstract Continuous high-resolution gravimetry is increasingly used to monitor mass distribution changes in volcanic, hydrothermal or other complex geosystems. To quantify the often small target signals, gravity contributions from, e.g. atmospheric mass changes, global and local hydrology should be...
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ftdoajarticles:oai:doaj.org/article:8f9398ec86734f54b933e68dae549a3e 2023-05-15T16:52:07+02:00 Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland Florian Forster Andreas Güntner Philippe Jousset Marvin Reich Benjamin Männel Jacques Hinderer Kemal Erbas 2021-12-01T00:00:00Z https://doi.org/10.1186/s40517-021-00208-w https://doaj.org/article/8f9398ec86734f54b933e68dae549a3e EN eng SpringerOpen https://doi.org/10.1186/s40517-021-00208-w https://doaj.org/toc/2195-9706 doi:10.1186/s40517-021-00208-w 2195-9706 https://doaj.org/article/8f9398ec86734f54b933e68dae549a3e Geothermal Energy, Vol 9, Iss 1, Pp 1-28 (2021) Geothermal monitoring Superconducting gravimetry Time-series analysis Gravity reduction Þeistareykir Renewable energy sources TJ807-830 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.1186/s40517-021-00208-w 2022-12-31T05:48:31Z Abstract Continuous high-resolution gravimetry is increasingly used to monitor mass distribution changes in volcanic, hydrothermal or other complex geosystems. To quantify the often small target signals, gravity contributions from, e.g. atmospheric mass changes, global and local hydrology should be accounted for. We set up three iGrav superconducting gravity meters for continuous monitoring of the Þeistareykir geothermal field in North Island. Additionally, we installed a set of hydrometeorological sensors at each station for continuous observation of local pressure changes, soil moisture, snow and vertical surface displacement. We show that the contribution of these environmental parameters to the gravity signal does not exceed 10 µGal (1 µGal = 10–8 m s−2), mainly resulting from vertical displacement and snow accumulation. The seasonal gravity contributions (global atmosphere, local and global hydrology) are in the order of ± 2 µGal at each station. Using the environmental observations together with standard gravity corrections for instrumental drift and tidal effects, we comprehensively reduced the iGrav time-series. The gravity residuals were compared to groundwater level changes and geothermal mass flow rates (extraction and injection) of the Þeistareykir power plant. The direct response of the groundwater levels and a time-delayed response of the gravity signal to changes in extraction and injection suggest that the geothermal system is subject to a partially confined aquifer. Our observations indicate that a sustainable “equilibrium” state of the reservoir is reached at extraction flow rates below 240 kg s−1 and injection flow rates below 160 kg s−1. For a first-order approximation of the gravity contributions from extracted and injected masses, we applied a simplified forward gravity model. Comparison to the observed gravity signals suggest that most of the reinjected fluid is drained off through the nearby fracture system. Article in Journal/Newspaper Iceland Directory of Open Access Journals: DOAJ Articles Þeistareykir ENVELOPE(-16.951,-16.951,65.880,65.880) Geothermal Energy 9 1 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geothermal monitoring Superconducting gravimetry Time-series analysis Gravity reduction Þeistareykir Renewable energy sources TJ807-830 Geology QE1-996.5 |
spellingShingle |
Geothermal monitoring Superconducting gravimetry Time-series analysis Gravity reduction Þeistareykir Renewable energy sources TJ807-830 Geology QE1-996.5 Florian Forster Andreas Güntner Philippe Jousset Marvin Reich Benjamin Männel Jacques Hinderer Kemal Erbas Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland |
topic_facet |
Geothermal monitoring Superconducting gravimetry Time-series analysis Gravity reduction Þeistareykir Renewable energy sources TJ807-830 Geology QE1-996.5 |
description |
Abstract Continuous high-resolution gravimetry is increasingly used to monitor mass distribution changes in volcanic, hydrothermal or other complex geosystems. To quantify the often small target signals, gravity contributions from, e.g. atmospheric mass changes, global and local hydrology should be accounted for. We set up three iGrav superconducting gravity meters for continuous monitoring of the Þeistareykir geothermal field in North Island. Additionally, we installed a set of hydrometeorological sensors at each station for continuous observation of local pressure changes, soil moisture, snow and vertical surface displacement. We show that the contribution of these environmental parameters to the gravity signal does not exceed 10 µGal (1 µGal = 10–8 m s−2), mainly resulting from vertical displacement and snow accumulation. The seasonal gravity contributions (global atmosphere, local and global hydrology) are in the order of ± 2 µGal at each station. Using the environmental observations together with standard gravity corrections for instrumental drift and tidal effects, we comprehensively reduced the iGrav time-series. The gravity residuals were compared to groundwater level changes and geothermal mass flow rates (extraction and injection) of the Þeistareykir power plant. The direct response of the groundwater levels and a time-delayed response of the gravity signal to changes in extraction and injection suggest that the geothermal system is subject to a partially confined aquifer. Our observations indicate that a sustainable “equilibrium” state of the reservoir is reached at extraction flow rates below 240 kg s−1 and injection flow rates below 160 kg s−1. For a first-order approximation of the gravity contributions from extracted and injected masses, we applied a simplified forward gravity model. Comparison to the observed gravity signals suggest that most of the reinjected fluid is drained off through the nearby fracture system. |
format |
Article in Journal/Newspaper |
author |
Florian Forster Andreas Güntner Philippe Jousset Marvin Reich Benjamin Männel Jacques Hinderer Kemal Erbas |
author_facet |
Florian Forster Andreas Güntner Philippe Jousset Marvin Reich Benjamin Männel Jacques Hinderer Kemal Erbas |
author_sort |
Florian Forster |
title |
Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland |
title_short |
Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland |
title_full |
Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland |
title_fullStr |
Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland |
title_full_unstemmed |
Environmental and anthropogenic gravity contributions at the Þeistareykir geothermal field, North Iceland |
title_sort |
environmental and anthropogenic gravity contributions at the þeistareykir geothermal field, north iceland |
publisher |
SpringerOpen |
publishDate |
2021 |
url |
https://doi.org/10.1186/s40517-021-00208-w https://doaj.org/article/8f9398ec86734f54b933e68dae549a3e |
long_lat |
ENVELOPE(-16.951,-16.951,65.880,65.880) |
geographic |
Þeistareykir |
geographic_facet |
Þeistareykir |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Geothermal Energy, Vol 9, Iss 1, Pp 1-28 (2021) |
op_relation |
https://doi.org/10.1186/s40517-021-00208-w https://doaj.org/toc/2195-9706 doi:10.1186/s40517-021-00208-w 2195-9706 https://doaj.org/article/8f9398ec86734f54b933e68dae549a3e |
op_doi |
https://doi.org/10.1186/s40517-021-00208-w |
container_title |
Geothermal Energy |
container_volume |
9 |
container_issue |
1 |
_version_ |
1766042248277917696 |