| Title | Deep Roots of Geothermal Systems - a GEORG Collaborative Project |
|---|---|
| Authors | Ingólfsson, H P; Árnason, K; Axelsson, G; Franzson, H; Hreinsdóttir, S; Jónsson, M T; Sævarsdóttir, G A; Gunnarsson, G; Júlíusson, E; Podgorney, R P; Sigmundsson, F; Gardarsson, S M |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | Geothermal system, roots, intrusions, exploration, modelling, utilization, engineering, well design |
| Abstract | The nature of the heat source of volcanic geothermal systems and of the heat transfer within them is not accurately known. The heat transfer involves flow of magma, flow of fluids, heat exchange between rocks and fluids as well as thermo-elastic rock mechanics and chemical processes. Some decades ago a process termed convective downward migration (CDM) was proposed for the heat extraction and transfer mechanism. Recent modelling of silicic volcanic geothermal systems suggests a different heat transfer mechanism and much smaller shallow intrusions (dykes, sills, etc.) originating in deep magma chambers are also believed to play a primary role in the heat-source mechanism. In 2007-2008 IDDP-1 well was drilled in the Krafla geothermal field, NE Iceland. It was to be drilled to a depth of 4 to 5 km with the goal of encountering supercritical hydrothermal fluids. The well unexpectedly drilled into a high-silica rhyolite melt at approximately 2.1 km depth. IDDP-1 discharged superheated steam delivering power of about 30 MWe. This demonstrated that the deep roots of geothermal systems can be more complicated than anticipated and that huge amounts of energy can be harnessed by drilling close to (or into) magma. This experience has initiated scientific activities in Iceland towards an increased understanding of the deep roots of volcanic geothermal systems and how their energy can be tapped. On that basis the Deep Roots Geothermal (DRG) project was established. The project is managed within the Icelandic cluster cooperation of GEORG and is financially supported by GEORG, the government and main power companies of Iceland as well as the IDDP-Project. It is a comprehensive 3-year project with the overall aim to increase significantly the understanding of the relationship of water and magma in the roots of volcanoes and how heat is transferred into geothermal systems to maintain their energy as well as develop further the technology needed to harness geothermal energy at the high temperature and pressure involved. |