| Title | Low temperature systems in Kjalarnes Iceland, exploration using gradient wells |
|---|---|
| Authors | Sigurður Garðar. Kristinsson, Auður Agla Óladóttir |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Geothermal research and utilization near Kjalarnes in SW-Iceland has a long history, with drilling activity dating back to 1952. Geological mapping has identified two eroded central volcanoes, including the Viðey-Kjalarnes and Stardalur systems. Geophysical surveys have revealed a large low-resistivity zone south of Kjalarnes. Magnetic and gravity surveys support the presence of a volcanic center offshore Kjalarnes. Several shallow geothermal wells were drilled between 1952 and the late 1970s, with limited success. Renewed interest in the area in 1978 led to drilling of a 637 m deep well in 1979, which showed a temperature gradient of 230°C/km and a peak temperature of 128°C. From 2022 to 2025, 28 temperature gradient wells were drilled across Kjalarnes by Reykjavik Energy, significantly expanding the geothermal knowledge and subsequently, two deeper production wells (~ 900 m) were drilled in a previously unknown systems. In 2025, six new gradient wells were drilled at Esjuberg, revealing unusually high temperature gradients—up to 430°C/km in EB-10, which does not align with results from earlier data. Measured temperatures reached nearly 90°C at just 200 m depth. These values strongly suggest an active geothermal system, likely controlled by fractures and dike intrusions observed in the nearby Esja mountain. Comparisons with other wells at Brimnes and Vallá indicate that Esjuberg shows the highest geothermal gradients in the region, with potential reservoir temperatures exceeding 100°C. Continued exploration and deep drilling are recommended to confirm the extent and capacity of this promising geothermal resource. |