The ongoing structural change from the hydrocarbon industry towards sustainable green energy is one of the challenges Europe (and the world) faces recently. In Germany, there are approximately 15,000 boreholes with depths ≥ 400 m (deep wells). Transgeo, an Interreg funded transnational project aims at determining the potential of such boreholes for the extraction of Geothermal energy in Germany and 4 other Central European countries. During the 3 years of project duration, data of the deep drillings will be gathered, summarized in databases, and then fed into a web-based IT-tool, showing the potential of the deep wells for geothermal energy extraction. The information gathered and analyzed by the tool comprises not only aspects like the depth and the temperature gradient, but also geological, geophysical and technical information of the wells, as well as the local socioeconomic background and the legal situation. Within the project area, drill holes of the North German Basin, the Molasse Basin, the Vienna basin and the Pannonian basin will be taken into account. Within the North German Basin, about 1330 drillings lie in within the borders of the Brandenburg State. The purpose of these drillings was manifold and included hydrocarbon exploration (ca 50%), geological mapping (13%), underground storage (12%) and other mineral resource explorations (mainly coal, iron, copper, and uranium). Only about 2 percent of the drillings are still “open” (not plugged and/or cemented) and 9 percent count on temperature logs. Temperature gradients vary among the eastern North German basin, influenced mainly by Zechstein thickness.