The Soultz-sous-Forêts’ Enhanced Geothermal System: A Granitic Basement Used as a Heat Exchanger to Produce Electricity

Ledésert, Béatrice; Hébert, Ronan

doi:10.5772/34276

Cited by 4 publications

(3 citation statements)

References 22 publications

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“…Both types are classified under Enhanced (or Engineered) Geothermal Systems (EGS) (e.g. Genter et al 2010;Ledesert and Hebert 2012;Olasolo et al 2016;Lu 2018;Norbeck et al 2018). Other crystalline-hosted geothermal systems also contain mineralised fractures, which are indicative of paleogeothermal fluid migration in the past (e.g.…”

Section: Implications For Reservoir Volumementioning

confidence: 99%

“…Other crystalline-hosted geothermal systems also contain mineralised fractures, which are indicative of paleogeothermal fluid migration in the past (e.g. Aquilina et al 1997;Dezayes et al 2005;Ledesert and Hebert 2012;Holl 2015). Consequently, it is likely that there will be some amount of hydrothermal alteration in the surrounding rock mass, as observed in the Carnmenellis Granite.…”

Section: Implications For Reservoir Volumementioning

confidence: 99%

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Reservoir properties of fault-related hydrothermally altered granites in Cornwall: Implications for geothermal energy prospectivity

Inskip,

Harpers,

Shail

et al. 2023

Preprint

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Granite based geothermal systems are currently being explored in Cornwall for their potential to decarbonise energy production. Fault structures, known locally as cross-courses, are being targeted due to their potential to both host fluids at depth and create zones of enhanced permeability through fault related fractures. These structures have been transmissive in the past, evidenced by mineral veins, and surrounding host rock alteration. Hydrothermal alteration has the potential to affect the petrophysical properties of a rock, however these effects on potential geothermal systems has received little attention to date. In this study we measure the tensile strength, porosity and permeability of samples of Carnmenellis Granite which have been hydrothermally altered to different amounts. We find that hydrothermal (argillic) alteration leads to a weaker, more porous and permeable rock, which has implications both in terms of reservoir volumes and fluid production rates. The alteration of feldspars into clay minerals leads to microporous regions that are connected throughout the material, and consequently an increase in total porosity by an order of magnitude and matrix permeability by up to 4 orders of magnitude. However, fractures hosted in the altered material are more likely to close under higher effective stress than those hosted in comparatively unaltered material, which leads to a lower fracture permeability. Finally, we demonstrate that hydrothermally altered zones have the potential to host significantly greater amounts of accessible fluid than the fractures alone, and that they should be considered when assessing reservoir volumes in these types of geothermal systems.

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Section: Implications For Reservoir Volumementioning

confidence: 99%

Section: Implications For Reservoir Volumementioning

confidence: 99%

Reservoir properties of fault-related hydrothermally altered granites in Cornwall: Implications for geothermal energy prospectivity

Inskip,

Harpers,

Shail

et al. 2023

Preprint

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“…Such level of power production has been a longstanding goal of EGS-type technologies. In nearly all the recent field experiments, however, injectivity, tracer return, and/or pressure support rather than rock to fluid heat transfer is all that has been attained or proven (e.g., Rose et al, 2006Rose et al, , 2012Sanjuan et al, 2010;Ledésert and Hébert, 2012;Mills and Humphrey, 2013;Ayling et al, 2016;Benato and Taron, 2016;Bradford et al, 2016;Cladouhos et al, 2016), and this is in contrast to modest successes at the Fenton Hill hot-dry rock site where relatively short period outputs of 3-10 MW th were achieved (Kelkar et al, 2016). One constraint is that fracture-controlled networks are prone to confined fluid flows and short circuiting (e.g., National Research Council, 1996;Tester et al, 2006), and this minimizes effective rock to fluid heat exchange and sustained geothermal energy production (e.g., Grant, 2016).…”

Section: Research Papermentioning

confidence: 99%

Interpretation of hydrothermal conditions, production-injection induced effects, and evidence for enhanced geothermal system-type heat exchange in response to >30 years of production at Roosevelt Hot Springs, Utah, USA

et al. 2021

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The Roosevelt Hot Springs hydrothermal system is located at the base of the Mineral Mountains in southwestern Utah on the eastern side of the Basin and Range. Hydrothermal activity is related to relatively recent bimodal magmatism, and the system is hosted in coarsely crystalline rock made of Oligocene–Miocene granitoids and Precambrian gneiss. The hydrothermal plume covers ∼5 km2, with a maximum temperature of 268 °C at ∼750 m depth, and a vertically extensive fault-fracture mesh east of the Opal Mound fault controls the upflow of hydrothermal fluids. Power generation (currently 38 MWe gross) began in 1984, and up through 2016, four wells were used for fluid production, and three wells were used for edge-field injection. Chemical analyses of produced fluids show that modern reservoir fluid compositions are similar to but more concentrated than those at the start of production, having near-neutral pH, total dissolved solids of 7000–10,000 mg/kg, and ionic ratios of Cl/HCO3 ∼50–100, Cl/SO4 ∼50–100, and Na/K ∼4–5. Chemical geothermometers indicate equilibration temperatures that mainly range between 240° and 300 °C. Early production induced a steep drop in pressure (∼3.0–3.5 MPa), which was accompanied by a 250–300 m lowering of piezometric levels in wells and development of a shallow steam zone across the system. Hydrothermal fluid compositions evolved continuously in response to production-related steam-loss and injection breakthrough, which is reflected by gradual increases in chloride of up to 35% and stable isotope ratios of up to ∼2‰δ18O and ∼10‰δD. Simple mixing model calculations suggest that there has been a significant amount, ∼10–20 MWth, of sustained multi-decadal heat mining and enhanced geothermal system (EGS)–type heat transfer by the injectate as it returns to the production zone. Overall, the two factors that have sustained long-term power production (currently 38 MWe gross) are the increased upflow of deep chloride water and, to a lesser extent, the mining of heat at <1 km depth.

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Guangdong, a Potential Province for Developing Hot Dry Rock Geothermal Resource

Wang¹,

Sun²,

Hu³

et al. 2014

AMM

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In the past decades, the study on Hot Dry Rock (HDR) geothermal resource has been a hot topic. A large number of investigations confirm that electricity power generated from HDR is feasible and suggest that HDR geothermal source is a kind of local and renewable energy. Up no now, many countries have carried out HDR experiments. As a large energy consumption country, China will also develop HDR geothermal energy in the near future. In the present study, our preliminary data potentially suggest that Guangdong province have great potential to develop HDR geothermal applications.

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The Soultz-sous-Forêts’ Enhanced Geothermal System: A Granitic Basement Used as a Heat Exchanger to Produce Electricity

Cited by 4 publications

References 22 publications

Reservoir properties of fault-related hydrothermally altered granites in Cornwall: Implications for geothermal energy prospectivity

Reservoir properties of fault-related hydrothermally altered granites in Cornwall: Implications for geothermal energy prospectivity

Interpretation of hydrothermal conditions, production-injection induced effects, and evidence for enhanced geothermal system-type heat exchange in response to >30 years of production at Roosevelt Hot Springs, Utah, USA

Guangdong, a Potential Province for Developing Hot Dry Rock Geothermal Resource

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The Soultz-sous-Forêts’ Enhanced Geothermal System: A Granitic Basement Used as a Heat Exchanger to Produce Electricity

Cited by 4 publications

References 22 publications

Reservoir properties of fault-related hydrothermally altered granites in Cornwall: Implications for geothermal energy prospectivity

Reservoir properties of fault-related hydrothermally altered granites in Cornwall: Implications for geothermal energy prospectivity

Interpretation of hydrothermal conditions, production-injection induced effects, and evidence for enhanced geothermal system-type heat exchange in response to &gt;30 years of production at Roosevelt Hot Springs, Utah, USA

Guangdong, a Potential Province for Developing Hot Dry Rock Geothermal Resource

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Product

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Interpretation of hydrothermal conditions, production-injection induced effects, and evidence for enhanced geothermal system-type heat exchange in response to >30 years of production at Roosevelt Hot Springs, Utah, USA