Exploration Methods

Bruhn, David; Manzella, Adele; Vuataz, F.; Faulds, James E.; Moeck, Inga; Erbas, Kemal

doi:10.1002/9783527630479.ch2

Cited by 11 publications

(5 citation statements)

References 123 publications

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“…Exploration of geothermal energy systems consists in the identification of hot reservoirs where fluids circulate naturally, and where best economical conditions are met. Apart from the required socioeconomic studies, characterization of a geothermal reservoir can be achieved with geological studies, geochemical analyses and geophysical field surveys (see the recent review of various methods by Bruhn et al, 2010). In addition, the understanding of fluid dynamics in anomalously hot fractured area could also help in the identification of a potential reservoir (McKenna and Blackwell, 2004;Oliver et al, 2006;Kuhn et al, 2006;.…”

Section: Introductionmentioning

confidence: 99%

Structure of hydrothermal convection in the Upper Rhine Graben as inferred from corrected temperature data and basin-scale numerical models

Guillou-Frottier

Carré

Bourgine

et al. 2013

Journal of Volcanology and Geothermal Research

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International audienceGeothermal anomalies in sedimentary basins are strongly controlled by fluid circulation within permeable zones. This study presents a new compilation of newly corrected bottom-hole temperature data in the French part of the Upper Rhine Graben, where the Soultz-sous-Forêts temperature anomaly is locked beneath a local horst structure. After a geostatistically constrained interpolation procedure, maps and cross-sections are extracted from the 3D thermal block, together with the associated standard deviations. Thermal anomalies are preferentially associated with the thickest zones of the permeable fractured Buntsandstein (sandstones) formation, in apparent contradiction with previous models where two major fault zones were suggested to control fluid flow. The underlying fractured granitic basement hosts fluid circulation patterns which are apparently controlled at large-scale by the inclined basement-sediments interface. Based on these observations, numerical models of hydrothermal convection including an inclined basement-sediments interface, a local horst structure, and realistic petrophysical properties have been carried out. The depth-decrease of permeability, the inclination of the interface and the fixed heat flow condition at the base of the model, explain why only a few upwellings can be triggered. Thermal anomalies and a measured temperature profile can be reproduced when fault permeability equals 10-14 m². Interestingly, structure of convective patterns also exhibits a second hotter upwelling, 8 km east of the Soultz-sous-Forêts upwelling zone, where another geothermal exploration project is now underway. The understanding of hydrothermal convection with realistic fluid and rock properties clearly appears as a predictive tool for geothermal exploration strategie

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Section: Introductionmentioning

confidence: 99%

Structure of hydrothermal convection in the Upper Rhine Graben as inferred from corrected temperature data and basin-scale numerical models

Guillou-Frottier

Carré

Bourgine

et al. 2013

Journal of Volcanology and Geothermal Research

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“…Based on the difference in the resistivity distribution, this layer was divided into a "more compact" and a "more fractured" part (i.e., layer 3a and 3b, respectively) with higher (70-150 Ωm) and lower (20-30 Ωm) resistivity values, respectively. The resistivity of carbonate rocks is generally higher than 800 Ωm [18]. On the other hand, the resistivities measured in layer 3 are much lower for both the compact and fractured parts.…”

Section: Discussionmentioning

confidence: 87%

“…Layer (1) was interpreted as the Quaternary alluvial cover composed of interchanging clays, sands, and gravels. Clay sediments generally show low resistivities (10-100 Ωm; [18]), while sands and gravels have higher resistivity (>200 Ωm; [60]). Considering the wide range of resistivity in granular materials, relatively low resistivity values were observed in layer 1.…”

Section: Discussionmentioning

confidence: 99%

“…Geothermal systems are dominantly controlled by systems of fault and fractures [11][12][13][14], since faults and their highly permeable damage zone are preferential pathways for the circulation of thermal fluids and their uprising [15][16][17]. Among the methods for geological reconstruction and subsurface modeling, geophysical methods can be used to measure the spatial and/or temporal variations in the physical properties of the subsurface, obtaining a quantitative model that completes the geological interpretation [18][19][20]. In particular, they represent the best approach for geological reconstruction where thick unconsolidated sediments cover the bedrock, limiting the possibility of direct measurements to a few stratigraphic logs.…”

Section: Introductionmentioning

confidence: 99%

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Reconstruction of Fault Architecture in the Natural Thermal Spring Area of Daruvar Hydrothermal System Using Surface Geophysical Investigations (Croatia)

et al. 2023

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The sustainable utilization of geothermal energy mostly depends on the characteristics of the geothermal resource from which it is extracted. Among others, detailed geological modeling is a key factor for estimating the potential of a geothermal resource. This research focuses on the modeling and reconstruction of the geological setting of the Daruvar thermal spring area using geophysical techniques. An integrated geophysical approach based on electrical resistivity tomography (ERT) and both active and passive seismic (MASW and HVSR) methods was used. Based on ERT results and the stratigraphic logs of the wells in Daruvar, three resistivity layers/geological units were identified. The deepest layer with resistivity < 150 Ωm is the Triassic carbonate that constitutes the thermal aquifer. Sharp lateral variations in the resistivity distributions within the bedrock were interpreted as fault damage zones saturated with thermal waters. Integrating the results of the seismic methods, the thickness of the first seismic layer that corresponds to the Quaternary cover was estimated from 5 to 20 m. Here, results of the geophysical investigations were combined into a 3D geological model highlighting the occurrence of subvertical N-S and E-W trending faults in the Daruvar spring area. The N-S-trending fault was interpreted as a fault plane parallel to the regionally mapped Daruvar fault. This fault juxtaposes the Triassic carbonate complex of the thermal aquifer with a Neogene sedimentary sequence of significantly lower permeability. Neogene–Quaternary tectonic activity further increased the fracturing and the permeability field in the Daruvar spring area, as proven by the smaller scale E-W faults and the well logs. This fracture network permits a quick upwelling of thermal fluids resulting in thermal springs with temperatures up to 50 °C. This work proves that the construction of a detailed geological model is crucial for assessing the reservoir and fault geometries in thermal systems hosted in fractured carbonate rocks.

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“…Hydrogeochemical methods are an effective tool to determine the origin of the geothermal fluid, the interaction with the aquifer, aquifer equilibrium temperature, water mean residence time, and possible mixing processes [16][17][18]. Geophysical methods can be used to reconstruct the geological and structural settings in the subsurface assessing the volume of the aquifer and the geometry of the fault network that drives the fluid flow [19][20][21]. In addition, the management of the geothermal aquifer requires an assessment of the hydrogeological parameters of an aquifer, such as hydraulic conductivity, transmissivity, and porosity.…”

Section: Introductionmentioning

confidence: 99%

Multidisciplinary Research of Thermal Springs Area in Topusko (Croatia)

et al. 2023

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Topusko is the second warmest natural thermal water spring area in Croatia, located at the southwest edge of the Pannonian Basin System. Due to favourable geothermal properties, these waters have been used for heating and health and recreational tourism since the 1980s. Thermal springs with temperatures up to 50 °C are the final part of an intermediate-scale hydrothermal system. However, systematic research on the Topusko spring area has not been conducted to lay the foundation for sustainable resource utilisation. Multidisciplinary research including the hydrogeochemical characterisation of naturally emerging thermal water, an electrical resistivity tomography (ERT) investigation conducted to reconstruct the subsurface geology, and hydrogeological parametrisation of the geothermal aquifer was carried out to refine the existing local conceptual model. The results show Ca-HCO3 facies of Topusko thermal waters, which get heated in a Mesozoic carbonate aquifer. The water equilibrium temperature in the geothermal aquifer is estimated to be 78 °C based on the SiO2-quartz geothermometer. The fault damage zone, which enables the upwelling of thermal water, was identified by ERT investigations. The transmissivity values of the aquifer derived from the results of step-drawdown tests range from 1.8 × 10−2 to 2.3 × 10−2 m2/s. Further multidisciplinary research is necessary to improve the existing conceptual model of the Topusko hydrothermal system.

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Exploration Methods

Cited by 11 publications

References 123 publications

Structure of hydrothermal convection in the Upper Rhine Graben as inferred from corrected temperature data and basin-scale numerical models

Structure of hydrothermal convection in the Upper Rhine Graben as inferred from corrected temperature data and basin-scale numerical models

Reconstruction of Fault Architecture in the Natural Thermal Spring Area of Daruvar Hydrothermal System Using Surface Geophysical Investigations (Croatia)

Multidisciplinary Research of Thermal Springs Area in Topusko (Croatia)

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