Abstract
AbstractContinental crust at temperatures > 400 °C and depths > 10–20 km normally deforms in a ductile manner, but can become brittle and permeable in response to changes in temperature or stress state induced by fluid injection. In this study, we quantify the theoretical power generation potential of an enhanced geothermal system (EGS) at 15–17 km depth using a numerical model considering the dynamic response of the rock to injection-induced pressurization and cooling. Our simulations suggest that an EGS circulating 80 kg s−1 of water through initially 425 ℃ hot rock can produce thermal energy at a rate of ~ 120 MWth (~ 20 MWe) for up to two decades. As the fluid temperature decreases (less than 400 ℃), the corresponding thermal energy output decreases to around 40 MWth after a century of fluid circulation. However, exploiting these resources requires that temporal embrittlement of nominally ductile rock achieves bulk permeability values of ~ 10–15–10–14 m2 in a volume of rock with dimensions ~ 0.1 km3, as lower permeabilities result in unreasonably high injection pressures and higher permeabilities accelerate thermal drawdown. After cooling of the reservoir, the model assumes that the rock behaves in a brittle manner, which may lead to decreased fluid pressures due to a lowering of thresholds for failure in a critically stressed crust. However, such an evolution may also increase the risk for short-circuiting of fluid pathways, as in regular EGS systems. Although our theoretical investigation sheds light on the roles of geologic and operational parameters, realizing the potential of the ductile crust as an energy source requires cost-effective deep drilling technology as well as further research describing rock behavior at elevated temperatures and pressures.
Publisher
Springer Science and Business Media LLC
Reference105 articles.
1. Armstead HCH, Tester JW. Heat mining. New York: Methuen Inc.; 1987.
2. Asanuma H, Mogi T, Tsuchiya N, Watanabe N, Naganawa S, Ogawa Y, et al. Japanese supercritical geothermal project for drastic increase of geothermal power generation in 2050. In: Proceedings World Geothermal Congress 2020+1. 2021.
3. Axelsson G, Egilson T, Gylfadóttir S. Modelling of temperature conditions near the bottom of well IDDP-1 in Krafla, Northeast Iceland. Geothermics. 2014;49:49–57. https://doi.org/10.1016/j.geothermics.2013.05.003.
4. Bailey RC. Trapping of aqueous fluids in the deep crust. Geophys Res Lett. 1990;17:1129–32. https://doi.org/10.1029/GL017i008p01129.
5. Beentjes I, Bender JT, Tester JW. Dissolution and thermal spallation of barre granite using pure water hydrothermal jets. Rock Mech Rock Eng. 2019;52:1339–52. https://doi.org/10.1007/s00603-018-1647-2.
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