Drilling of an exploratory geothermal borehole, led by Geological Survey of North Rhine-Westphalia (GD NRW), has officially started in the Dellbrück district of Cologne in North Rhine-Westphalia (NRW), Germany. The well will be drilled to a depth of up to 1000 meters as a means to determine whether the limestone layers beneath Cologne are suitable for as a geothermal reservoir.
The research borehole is part of the exploration and drilling program “Geothermal Energy – We Explore North Rhine-Westphalia,” commissioned by the Ministry of Economic Affairs, Innovation, Digitalization and Energy (MWIKE) as part of the NRW Geothermal Master Plan.
The drilling work and the subsequent measurements and tests are expected to take three to four months. The plan is to extract core samples of the complete stratigraphic sequence of the Massenkalk limestone formation. Following the drilling, a pumping test will be conducted to determine if and how much water is contained within the limestone layer. After the Kohlenkalk, which has been successfully explored in Krefeld in 2025, this could be another geothermal reservoir that boosts interest in geothermal energy use in NRW.
“The Massenkalk is interesting because natural cavities have formed within it near the Earth’s surface. The caves in the Bergisches Land region, such as those in Ennepetal and Attendorn, are all located in the Massenkalk. We will now investigate whether it also contains cavities and fissures at depth where warm water could be present,” further explained Project manager Ingo Schäfer.
“The results are relevant for the entire region,” emphasizes Schäfer. “We are making the data available to the city of Cologne as well as to the general public, so that municipalities and public utilities can build on it and utilize the heat potential beneath their feet.”
Source: Geowärme NRW
