Recent Geothermal Exploration for Deep Seated Sources in Sweden

Abstract

Exploration and production drilling activities for Geothermal Energy was more or less dormant in Sweden for almost a couple of decades. Then in the beginning of 2000 and 2001 two activities started in Malmö and Lund, both in southernmost Sweden. In Lund a different approach for geothermal energy utilisation took form at the Department of Engineering Geology (DEG), Lund University. After a comprehensive seismic exploration programme and evaluations of the complex local tectonic features along the so-called Tornquist deformation zone a site for exploration drilling was defined. Late 2002 the deep drilling project started. The aim was to drill deep into the crystalline basement rocks associated with the deformation zone thereby penetrating a number fracture zones hopefully providing a geothermal fluid above 100°C. The local energy operator in Lund intended to use the hot water for direct heat in the district heating net. Unfortunately it was concluded that the deformation zone in basement was tight. Due to the results from the test of the basement the second option was activated. The option was to perforate the casings along the sedimentary section above 1950 m. Thereby the prime goal with direct heat was changed to a geothermal heat pump application. Based on the achievements from the testing of the sedimentary section a second well was drilled 1500 m away to a depth of 1927 m. The final medium long term test of the second well unfortunately revealed that the aquifer properties did not comply with the energy demands set up by the Energy Company. The project was sadly enough stopped when it was clear that only about one third of the capacity might be at hand.