The layered model of the Copahue geothermal reservoir, Argentina
An exhaustive review of the available data related to the reservoir of the volcano-hosted Copahue geothermal system is presented. Reservoir interpretation to date suggests a vapor-dominated nature. However, the review provided reveals the limitations of this model, regarding the transition from shal...
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2019
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_21959706_v7_n1_p_Barcelona http://hdl.handle.net/20.500.12110/paper_21959706_v7_n1_p_Barcelona |
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paper:paper_21959706_v7_n1_p_Barcelona2023-06-08T16:35:08Z The layered model of the Copahue geothermal reservoir, Argentina Copahue geothermal field Exploration Geothermal reservoir Liquid-dominated Vapor-dominated Clay alteration Electric conductivity Geothermal wells Kaolinite Natural resources exploration Petroleum prospecting Silicate minerals Volcanoes Well logging Zeolites Copahue Exploration drilling Geothermal reservoir High-electrical resistivities Isothermal segments Tectonic deformations Temperature profiles Vapor dominated Geothermal fields An exhaustive review of the available data related to the reservoir of the volcano-hosted Copahue geothermal system is presented. Reservoir interpretation to date suggests a vapor-dominated nature. However, the review provided reveals the limitations of this model, regarding the transition from shallow argillic to deep propylitic alteration zones, gas geothermometers calibrated to near-neutral pH environment, production tests, and low recharge of the feed zone, among the other features. We propose that a layered model with a shallow vapor zone above a fluid pressurized reservoir better accounts for the known features of the geothermal reservoir. Temperature profiles define the 800-m-thick upper thermal boundary that includes the impermeable clay cap. An argillic alteration layer (smectite + chlorite + illite + kaolinite) with low electric resistivity response, consistent with the presence of smectite, composes the clay cap. A shallow steam cap develops immediately below the impermeable layer. This vapor zone has 200–215 °C, low seismic activity, and high electrical resistivity, and is highlighted by the isothermal segment of the well logs. The bottom part of the reservoir is subjected to controversy because of the lack of direct measurements. The deep liquid-dominated reservoir has a temperature of ~ 280 °C, develops below 1500 m depth under near-neutral pH condition, and probably has a pervasive propylitic alteration, and wairakite + laumontite + chlorite + epidote + prehnite + actinolite is the likely mineral assemblage. Pressure collapse might trigger the development of the shallow steam cap during deflation–inflation volcanic cycles or Pleistocene-to-recent tectonic deformation. This work points out the main weak points of the previous conceptual model, providing an alternative one based on the first comprehensive compilation of data of the Copahue reservoir. Further research, including a deep exploration drilling stage, is required to establish the physicochemical reservoir state precisely and to validate the proposed layered model. © 2019, The Author(s). 2019 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_21959706_v7_n1_p_Barcelona http://hdl.handle.net/20.500.12110/paper_21959706_v7_n1_p_Barcelona |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Copahue geothermal field Exploration Geothermal reservoir Liquid-dominated Vapor-dominated Clay alteration Electric conductivity Geothermal wells Kaolinite Natural resources exploration Petroleum prospecting Silicate minerals Volcanoes Well logging Zeolites Copahue Exploration drilling Geothermal reservoir High-electrical resistivities Isothermal segments Tectonic deformations Temperature profiles Vapor dominated Geothermal fields |
| spellingShingle |
Copahue geothermal field Exploration Geothermal reservoir Liquid-dominated Vapor-dominated Clay alteration Electric conductivity Geothermal wells Kaolinite Natural resources exploration Petroleum prospecting Silicate minerals Volcanoes Well logging Zeolites Copahue Exploration drilling Geothermal reservoir High-electrical resistivities Isothermal segments Tectonic deformations Temperature profiles Vapor dominated Geothermal fields The layered model of the Copahue geothermal reservoir, Argentina |
| topic_facet |
Copahue geothermal field Exploration Geothermal reservoir Liquid-dominated Vapor-dominated Clay alteration Electric conductivity Geothermal wells Kaolinite Natural resources exploration Petroleum prospecting Silicate minerals Volcanoes Well logging Zeolites Copahue Exploration drilling Geothermal reservoir High-electrical resistivities Isothermal segments Tectonic deformations Temperature profiles Vapor dominated Geothermal fields |
| description |
An exhaustive review of the available data related to the reservoir of the volcano-hosted Copahue geothermal system is presented. Reservoir interpretation to date suggests a vapor-dominated nature. However, the review provided reveals the limitations of this model, regarding the transition from shallow argillic to deep propylitic alteration zones, gas geothermometers calibrated to near-neutral pH environment, production tests, and low recharge of the feed zone, among the other features. We propose that a layered model with a shallow vapor zone above a fluid pressurized reservoir better accounts for the known features of the geothermal reservoir. Temperature profiles define the 800-m-thick upper thermal boundary that includes the impermeable clay cap. An argillic alteration layer (smectite + chlorite + illite + kaolinite) with low electric resistivity response, consistent with the presence of smectite, composes the clay cap. A shallow steam cap develops immediately below the impermeable layer. This vapor zone has 200–215 °C, low seismic activity, and high electrical resistivity, and is highlighted by the isothermal segment of the well logs. The bottom part of the reservoir is subjected to controversy because of the lack of direct measurements. The deep liquid-dominated reservoir has a temperature of ~ 280 °C, develops below 1500 m depth under near-neutral pH condition, and probably has a pervasive propylitic alteration, and wairakite + laumontite + chlorite + epidote + prehnite + actinolite is the likely mineral assemblage. Pressure collapse might trigger the development of the shallow steam cap during deflation–inflation volcanic cycles or Pleistocene-to-recent tectonic deformation. This work points out the main weak points of the previous conceptual model, providing an alternative one based on the first comprehensive compilation of data of the Copahue reservoir. Further research, including a deep exploration drilling stage, is required to establish the physicochemical reservoir state precisely and to validate the proposed layered model. © 2019, The Author(s). |
| title |
The layered model of the Copahue geothermal reservoir, Argentina |
| title_short |
The layered model of the Copahue geothermal reservoir, Argentina |
| title_full |
The layered model of the Copahue geothermal reservoir, Argentina |
| title_fullStr |
The layered model of the Copahue geothermal reservoir, Argentina |
| title_full_unstemmed |
The layered model of the Copahue geothermal reservoir, Argentina |
| title_sort |
layered model of the copahue geothermal reservoir, argentina |
| publishDate |
2019 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_21959706_v7_n1_p_Barcelona http://hdl.handle.net/20.500.12110/paper_21959706_v7_n1_p_Barcelona |
| _version_ |
1768544978406998016 |