Enhancing Geothermal Reservoirs

Schulte, Thomas; Zimmermann, Günter; Vuataz, F.; Portier, Sandrine; Tischner, Torsten; Junker, Ralf; Jatho, Reiner; Huenges, Ernst

doi:10.1002/9783527630479.ch4

Cited by 17 publications

(13 citation statements)

References 81 publications

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“…In crystalline rocks characterized by low matrix porosity, the main flow channeling occurs in permeable and connected fractures [ Evans et al ., ]. Thus, projects based on EGS technology require good knowledge of the fracture network to understand flow distribution at depth and to design borehole trajectories according to the geometrical properties of the fracture network [ Schulte et al ., ]. In France, the first industrial geothermal project aiming to produce overheated water from a geothermal resource in a fracture network at the sediment‐basement interface was initiated in 2004 at Rittershoffen (Figure b) [ Baujard et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Permeable fracture zones in the hard rocks of the geothermal reservoir at Rittershoffen, France

Vidal

Genter²,

Chopin

2017

JGR Solid Earth

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Fluid circulation in zones of fractures are a key challenge to exploit deep geothermal heat from natural reservoir. At Rittershoffen (Upper Rhine Graben, France), two geothermal boreholes, GRT‐1 and GRT‐2, were drilled in 2012 and 2014, respectively. They targeted the local Rittershoffen normal fault, which strikes N‐S and dips westward. In this study, major natural fractures were observed in the open holes of both wells from acoustic image logs correlated with other standard geophysical logs (gamma ray, neutron porosity, and caliper). Their permeability was evaluated at the borehole scale from temperature logs, mud losses, and gas surveys. One originally permeable (OP) fracture zone was observed in the granite of GRT‐1. In GRT‐2, four OP fracture zones were observed in the granite and two in sandstones. In GRT‐2, fracture zones are composed by several fluid pathways that could explain the higher natural permeability than in GRT‐1. All OP fractures are associated with positive temperature anomaly, interpreted as circulation of hot geothermal water through the permeable fracture, or negative one, interpreted as the cooling of a porous, altered and fractured zone around the permeable fracture after drilling operations. Permeability of natural fracture oriented N170° seems to be intimately linked to the secondary mineral deposits resulting from paleocirculations. The geometrical fracture model along the wellbore suggests that the inclined trajectory of GRT‐2 increases the connection between the borehole and the nearly vertical fracture network associated to the local fault. A good characterization of zones of fractures in a targeted natural reservoir allows an optimal exploitation of geothermal resource.

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Section: Introductionmentioning

confidence: 99%

Permeable fracture zones in the hard rocks of the geothermal reservoir at Rittershoffen, France

Vidal

Genter²,

Chopin

2017

JGR Solid Earth

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“…Table 3 summarizes key information including ranges of depth, thickness, temperature, and hydraulic conductivity for different petrothermal reservoirs. A crucial factor in the production of geothermal energy is related to the large uncertainty of effective porosity/permeability and transmissivity/transmissibility values, which directly influence the achievable flow rates and thus doublet power in petrothermal systems (e.g., Schulte et al 2010). Actively deforming areas characterized by extensional and strike-slip settings are favorable for EGS (Cloetingh et al 2010).…”

Section: Petrothermal Reservoirsmentioning

confidence: 99%

“…Hydrothermal systems are systems of warm or hot water present in deep aquifers or hydraulically conductive fault zones (Muffler and Cataldi 1978). Where natural permeability is too low for economic-technical use of geothermal energy, natural joints can be hydraulically stimulated or new fractures formed by injecting pressurized water to enhance permeability and create a heat exchanger, a procedure designated by EGS (Breede et al 2013;Held et al 2014;Huenges 2010). These are called petrothermal systems, unconventional geothermal resources or hot-dry rock (HDR) systems (Breede et al 2013;ENGINE Coordination Action 2008).…”

Section: Background On Different Types Of Geothermal Utilizationsmentioning

confidence: 99%

“…Subsurface temperatures represent important information for the identification of geothermal reservoirs because the temperature domain determines the types of geothermal energy use and applications that can be implemented. Hydraulic properties, notably permeability and the associated transmissibility, are crucial parameters because they dictate the technical feasibility of specific applications by directly influencing achievable flow rates and thus power output of a geothermal plant (e.g., Schulte et al 2010). In hydrothermal as well as petrothermal reservoirs, the crustal stress field influences or controls the creation and evolution of faults, fractures, and joints, thus permeability, and therefore is particularly important for site selection for geothermal exploration and development of Enhanced Geothermal Systems (Cloetingh et al 2010).…”

Section: Geothermal Explorationmentioning

confidence: 99%

“…The Lower Devonian basement therefore forms the impermeable base of the Buntsandstein aquifer where the Rotliegend is absent (LGB and LUWG 2010;Lucius 1948). Compact sedimentary rock can be used to create artificial heat exchangers using EGS technology (Breede et al 2013;Schulte et al 2010;Tester et al 2006;Zimmermann et al 2011). Lower Devonian lithologies best suited for geothermal exploitation are deep-lying, thick, and laterally persistent layers with a high proportion of sandstone and/or quartzite with a possible fracture porosity/permeability.…”

Section: Hydrogeology Of the Rotliegendmentioning

confidence: 99%

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Exploration for deep geothermal reservoirs in Luxembourg and the surroundings - perspectives of geothermal energy use

Schintgen

2015

Geotherm Energy

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Background: The aim of this paper is to combine different types of information necessary for a first rather qualitative assessment of deep geothermal reservoirs in the region of Luxembourg. Within the geological framework, the study area encompasses Luxembourg and the surrounding areas of Belgium, Germany, and France. On the one hand, the focus is laid on low-enthalpy hydrothermal reservoirs in Mesozoic aquifers in the Trier-Luxembourg Embayment. On the other hand, petrothermal reservoirs in the Devonian basement of the Ardennes and Eifel regions are considered for exploitation by Enhanced/Engineered Geothermal Systems (EGS). Methods: For geothermal exploration and exploitation purposes, geological, thermal, hydrogeological and structural data are necessary. Results: Among the Mesozoic aquifers, the Buntsandstein aquifer characterized by temperatures of up to 50°C is a suitable hydrothermal reservoir that could be exploited by means of heat pumps or provide direct heat for various applications. The most promising area is the zone of the SE-Luxembourg Graben. The aquifer is the warmest underneath the upper Alzette valley and the limestone plateau in Lorraine, where the Buntsandstein aquifer lies below a thick Mesozoic cover. At the base of an inferred Rotliegend graben in the same area, temperatures of up to 75°C are expected. However, geological and hydraulic conditions are uncertain. In the Lower Devonian basement, thick sandstone-/quartzite-rich formations with temperatures >90°C are expected at depths >3.5 km and likely offer the possibility of direct heat use. The setting of the Südeifel (South Eifel) region, including the Müllerthal region near Echternach, as a tectonically active zone may offer the possibility of deep hydrothermal reservoirs in the fractured Lower Devonian basement. Based on recent data on the structure of the Trier-Luxembourg Basin, the new concept presents the Müllerthal-Südeifel Depression as a Cenozoic tectonic structure that is still mobile and relevant for geothermal exploration. Conslusion: Beyond direct use of geothermal heat, the expected modest temperatures at 5 km depth (about 120°C) and increased permeability by EGS in the quartzite-rich Lochkovian could prospectively enable combined geothermal heat production and power generation in Luxembourg and the western realm of the Eifel region.

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Study of Geothermal Energy Potential with Geothermal Doublet: A Case Study for Puga Valley Ladakh

Jha

Puppala

2017

Water Science and Technology Library

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Enhancing Geothermal Reservoirs

Cited by 17 publications

References 81 publications

Permeable fracture zones in the hard rocks of the geothermal reservoir at Rittershoffen, France

Permeable fracture zones in the hard rocks of the geothermal reservoir at Rittershoffen, France

Exploration for deep geothermal reservoirs in Luxembourg and the surroundings - perspectives of geothermal energy use

Study of Geothermal Energy Potential with Geothermal Doublet: A Case Study for Puga Valley Ladakh

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