Characterising brines in deep Mesozoic sandstone reservoirs, Denmark
The Danish subsurface contains several sandstone units, which represent a large geothermal resource (Vosgerau et al. 2016). Currently, only three geothermal plants are operating in Denmark, but several exploration licences are expected to be awarded in 2019. Geothermal energy is exploited from deepl...
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Geological Survey of Denmark and Greenland
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Online Access: | https://doi.org/10.34194/GEUSB-201943-01-04 |
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doaj-6eb088398609413380156c9ee90763d42020-11-25T03:21:22ZengGeological Survey of Denmark and GreenlandGeological Survey of Denmark and Greenland Bulletin1604-81562019-07-0143e201943010410.34194/GEUSB-201943-01-04Characterising brines in deep Mesozoic sandstone reservoirs, DenmarkHanne D Holmslykke0Niels H Schovsbo 1Lars Kristensen2Rikke Weibel3Lars H Nielsen4Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, DenmarkGeological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, DenmarkGeological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, DenmarkGeological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, DenmarkGeological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, DenmarkThe Danish subsurface contains several sandstone units, which represent a large geothermal resource (Vosgerau et al. 2016). Currently, only three geothermal plants are operating in Denmark, but several exploration licences are expected to be awarded in 2019. Geothermal energy is exploited from deeply buried porous sandstones by bringing warm formation water (brine) to the surface, extracting the heat and returning the cooled water to the same sandstones. The reduced temperature of the brine during this process implies a risk of scaling, which may reduce reservoir permeability and hence injectivity. Predicting the chemical composition of formation waters, however, could help to reduce the risk associated with scaling in planned geothermal facilities. Here, we present a regional overview of the geochemistry of brines from deep Mesozoic sandstones in the Danish Basin and North German Basin that supplements previous studies, notably by Laier (2002, 2008). The brine composition at shallow burial typically reflects the original (connate) formation water chemistry, which is determined by the original depositional environment of the sandstone, for example fluvial or marine. However, the mineralogical composition of the sandstone changes during burial, whereby some minerals may dissolve or precipitate when exposed to higher temperatures. These mineral changes are reflected in the brine composition, which typically becomes more saline with increased burial (e.g. Laier 2008; Kharaka & Hanor 2003). The brine chemistry reported here shows a distinct depth trend, which reflects original connate formation waters that are modified through burial diagenesis. We have classified the brines into brine types, which are shown to be related to their depositional environment, depth, geological formation and geographical domains. https://doi.org/10.34194/GEUSB-201943-01-04DenmarkSandstoneMesozoicGeothermal energyBrine chemistry |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Hanne D Holmslykke Niels H Schovsbo Lars Kristensen Rikke Weibel Lars H Nielsen |
spellingShingle |
Hanne D Holmslykke Niels H Schovsbo Lars Kristensen Rikke Weibel Lars H Nielsen Characterising brines in deep Mesozoic sandstone reservoirs, Denmark Geological Survey of Denmark and Greenland Bulletin Denmark Sandstone Mesozoic Geothermal energy Brine chemistry |
author_facet |
Hanne D Holmslykke Niels H Schovsbo Lars Kristensen Rikke Weibel Lars H Nielsen |
author_sort |
Hanne D Holmslykke |
title |
Characterising brines in deep Mesozoic sandstone reservoirs, Denmark |
title_short |
Characterising brines in deep Mesozoic sandstone reservoirs, Denmark |
title_full |
Characterising brines in deep Mesozoic sandstone reservoirs, Denmark |
title_fullStr |
Characterising brines in deep Mesozoic sandstone reservoirs, Denmark |
title_full_unstemmed |
Characterising brines in deep Mesozoic sandstone reservoirs, Denmark |
title_sort |
characterising brines in deep mesozoic sandstone reservoirs, denmark |
publisher |
Geological Survey of Denmark and Greenland |
series |
Geological Survey of Denmark and Greenland Bulletin |
issn |
1604-8156 |
publishDate |
2019-07-01 |
description |
The Danish subsurface contains several sandstone units, which represent a large geothermal resource (Vosgerau et al. 2016). Currently, only three geothermal plants are operating in Denmark, but several exploration licences are expected to be awarded in 2019. Geothermal energy is exploited from deeply buried porous sandstones by bringing warm formation water (brine) to the surface, extracting the heat and returning the cooled water to the same sandstones. The reduced temperature of the brine during this process implies a risk of scaling, which may reduce reservoir permeability and hence injectivity. Predicting the chemical composition of formation waters, however, could help to reduce the risk associated with scaling in planned geothermal facilities.
Here, we present a regional overview of the geochemistry of brines from deep Mesozoic sandstones in the Danish Basin and North German Basin that supplements previous studies, notably by Laier (2002, 2008). The brine composition at shallow burial typically reflects the original (connate) formation water chemistry, which is determined by the original depositional environment of the sandstone, for example fluvial or marine. However, the mineralogical composition of the sandstone changes during burial, whereby some minerals may dissolve or precipitate when exposed to higher temperatures. These mineral changes are reflected in the brine composition, which typically becomes more saline with increased burial (e.g. Laier 2008; Kharaka & Hanor 2003).
The brine chemistry reported here shows a distinct depth trend, which reflects original connate formation waters that are modified through burial diagenesis. We have classified the brines into brine types, which are shown to be related to their depositional environment, depth, geological formation and geographical domains. |
topic |
Denmark Sandstone Mesozoic Geothermal energy Brine chemistry |
url |
https://doi.org/10.34194/GEUSB-201943-01-04 |
work_keys_str_mv |
AT hannedholmslykke characterisingbrinesindeepmesozoicsandstonereservoirsdenmark AT nielshschovsbo characterisingbrinesindeepmesozoicsandstonereservoirsdenmark AT larskristensen characterisingbrinesindeepmesozoicsandstonereservoirsdenmark AT rikkeweibel characterisingbrinesindeepmesozoicsandstonereservoirsdenmark AT larshnielsen characterisingbrinesindeepmesozoicsandstonereservoirsdenmark |
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