Project Schwerin Geothermal DH
Residents of Schwerin, Germany can look forward to an emissions-free heat source in their district heating network. The first well in the Schwerin-Lankov geothermal couple has already exceeded all expectations. The newly drilled reinjection well was tested with very positive results. Geothermal consultants at GTN, the German subsidiary of Manvit, are excited about the results.
“The Schwerin geothermal project is an important milestone for the transition towards a carbon-neutral heat supply in northern Germany,” said Dr. Peter Seibt, Managing Director of GTN on the GTN website, when asked about the latest drilling results, “The Schwerin geothermal project is an important milestone for the transition towards a carbon-neutral heat supply in northern Germany. We are very proud to have been part “From this lighthouse project from the beginning. The project shows that even shallow reservoirs can be a possible option for geothermal supply.” Several projects in Germany target reservoirs deeper than 3,000 metres. The project in the capital of the German state of Mecklenburg-Vorpommern uses the Postera sandstone, which is already accessible at an altitude of 1,200 metres. Drilling costs are significantly reduced due to the shallow depth and result, despite low temperatures, in high economic feasibility.
The temperature of the thermal water is 56°C, and at the beginning of 2022, the Stadtwerke Schwerin (Schwerin municipal utility) expects to start using it to provide an environmentally friendly heat source. Before supplying heat to the district heating network, the temperature is raised to 80°C through high-temperature heat pumps. About 10% of Schwerin’s thermal demand will be covered by the new geothermal heating plant. With additional projects, a total of 60% could be possible.
Deviated injection well
In contrast to the vertical production well, the injection well near “Sportpark Lankow” in Schwerin was drilled as an S-shaped skew well. This allowed a subsurface distance of 1,100 meters between the ends of the two wells, which is required for sustainable use of the reservoir. At a depth of 410 m, the well deviated from perpendicular to an angle of 30 degrees. After an additional 550 m, the angle was smoothly dropped again until the well returned to a vertical path. The target layer was reached at a vertical depth of 1220 m. Successful directional drilling is achieved through careful planning and the use of specialized drilling equipment.
The targeted Postera sandstone dates back to the Upper Triassic (ca. 200-205 million years ago). The thick layers of sand were deposited within a vast river plain that extended over large parts of today’s northern Germany. At the site of Schwerin, there are remains of this river system over 40 m thick sandstones. The fine to medium-grained Postera sandstones are poorly compacted and offer the most favorable hydraulic properties, which are essential for effective geothermal energy extraction.
Reservoir exploration at Schwerin-Lankow was carried out using the so-called “Sandsteinfazies” approach. This new exploration technology was developed by the University of Göttingen and GTN in the context of several R&D projects funded by BMWi (German Federal Ministry for Economic Affairs and Energy). A key outcome of these research projects is a set of high-resolution maps showing subsurface facies, sandstone thickness and reservoir quality.