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| Titel |
Multicomponent geothermometry applied to a medium-low enthalpy carbonate-evaporite geothermal reservoir |
| VerfasserIn |
Maria Battistel, Maurizio Barbieri, Shaul Hurwitz, William Eavans, Giovanni Chiodini |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093661
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| Publikation (Nr.) |
 EGU/EGU2014-8595.pdf |
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| Zusammenfassung |
| In order to improve the knowledge of the thermal state of medium to low-enthalpy thermal systems hosted in carbonate-evaporite rocks, a mineral-solution equilibrium model was compared to other theoretical geothermoters. We use the GeoT code (Spycher et al., 2014) which calculates reservoir temperatures based on a statistical evaluation of mineral saturation indices.
The calculations were applied to study the medium and low enthalpy geothermal systems in the Tyrrhenian-Apennine area (central Italy). The study area is mainly characterized by Paleozoic metamorphic basement and a Mesozoic carbonate–evaporite sequence overlain by Oligocene–Mid Miocene flysch formations and Quaternary volcanic complexes associated with crustal extension in the Tyrrhenian area. A regional aquifer is hosted in the carbonate-evaporate formations, and smaller aquifers are hosted in the volcanic rocks.
For reservoir temperature calculations the chemical composition of 58 springs and wells with a temperature between 22° and 65°C was taken into account. The waters are classified as Ca-HCO3 waters with low TDS, Ca-SO4 waters with high TDS and few HCO3-NaK type waters.
The calculated reservoir temperatures of the medium-low enthalpy hydrothermal systems in Tyrrhenian-Apennine area range between 40 and 100°C. As expected, cation geothermometers provide unrealistic values of equilibrium temperature. Calculations based on the chalcedony geothermeter provide more realistic temperatures than the quartz geothermometers because silica solubility at temperatures <180°C is controlled by amorphous silica or chalcedony. GeoT simulation results show that all the considered mineral phases are either near saturation or oversaturated and the equilibrium temperatures range between 48° and 116°C. The statistical approach of “best clustering minerals”, used in this model, solves the problems related to cation or single component geothermometers. For these cases, multicomponent geothermometry coupled with optimization provides a reliable approach to reconstruct fluid composition at depth and estimate reservoir temperatures.
Spycher, N. et al (2014), Integrated multicomponent solute geothermometry, Geothermics, 51, 113-123. |
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