Benchmark study of simulators for thermo-hydraulic modelling of low enthalpy geothermal processes

• Published in: Geothermics
• Main Authors: Mindel, Julian E., Alt-Epping, Peter, Les Landes, Antoine Armandine, Beernink, Stijn, Birdsell, Daniel T., Bloemendal, Martin, Hamm, Virginie, López, Simon, Maragna, Charles, Nielsen, Carsten M., Olivella Pastallé, Sebastià, Perreaux, Marc, Saaltink, Maarten Willem, Saar, Martin O., Van den Heuvel, Daniela, Vidal Montes, Rubén, Driesner, Thomas
• Other Authors: Universitat Politècnica de Catalunya. Departament d'Enginyeria Civil i Ambiental, Universitat Politècnica de Catalunya. Doctorat en Enginyeria del Terreny, Universitat Politècnica de Catalunya. MSR - Mecànica del Sòls i de les Roques, Universitat Politècnica de Catalunya. GHS - Grup d'Hidrologia Subterrània
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Àrees temàtiques de la UPC::Energies::Energia geotèrmica; Àrees temàtiques de la UPC::Enginyeria civil::Geotècnia::Mecànica de sòls; Geothermal resources; Energia geotèrmica; Iceland
• Online Access: http://hdl.handle.net/2117/355894; https://doi.org/10.1016/j.geothermics.2021.102130

In order to assess the thermo-hydraulic modelling capabilities of various geothermal simulators, a comparative test suite was created, consisting of a set of cases designed with conditions relevant to the low-enthalpy range of geothermal operations within the European HEATSTORE research project. In an effort to increase confidence in the usage of each simulator, the suite was used as a benchmark by a set of 10 simulators of diverse origin, formulation, and licensing characteristics: COMSOL, MARTHE, ComPASS, Nexus-CSMP++, MOOSE, SEAWATv4, CODE_BRIGHT, Tough3, PFLOTRAN, and Eclipse 100. The synthetic test cases (TCs) consist of a transient pressure test verification (TC1), a well-test comparison (TC2), a thermal transport experiment validation (TC3), and a convection onset comparison (TC4), chosen to represent well-defined subsets of the coupled physical processes acting in subsurface geothermal operations. The results from the four test cases were compared among the participants, to known analytical solutions, and to experimental measurements where applicable, to establish them as reference expectations for future studies. A basic description, problem specification, and corresponding results are presented and discussed. Most participating simulators were able to perform most tests reliably at a level of accuracy that is considered sufficient for application to modelling tasks in real geothermal projects. Significant relative deviations from the reference solutions occurred where strong, sudden (e.g. initial) gradients affected the accuracy of the numerical discretization, but also due to sub-optimal model setup caused by simulator limitations (e.g. providing an equation of state for water properties). This work was supported by the HEATSTORE project. HEATSTORE (170153-4401) is one of nine projects under the GEOTHERMICA – ERA NET Cofund aimed at accelerating the uptake of geothermal energy in Europe. The project is subsidized through the ERANET cofund GEOTHERMICA (Project n. 731117) by the European Commission, RVO (the Netherlands), DETEC (Switzerland), FZJ-PtJ (Germany), ADEME (France), EUDP (Denmark), Rannis (Iceland), VEA (Belgium), FRCT (Portugal), and MINECO (Spain). More information is available via http://www.heatstore.eu. Peer Reviewed Postprint (published version)