Large amounts of oil and gas were produced in Central Europe from thousands of deep wells, but after decades of production many of the hydrocarbon wells are abandoned or must soon be abandoned. The declining hydrocarbon industry leaves behind an enormous infrastructure and thousands of highly skilled workers, especially in rural areas facing multiple economic and social challenges. Instead of abandoning unused wells, they can be used for geothermal energy production and heat storage to support local communities and industries in the energy transition. However, this potential is largely underutilised due to economic uncertainties and non-technical barriers. The overall objective of TRANSGEO is to enable a structural change from a fossil-fuel producing hydrocarbon industry towards sustainable green energy provision from geothermal energy sources within Central Europe with focus on rural areas. Our approach of applying established geothermal technologies and workflows to the conditions of existing hydrocarbon infrastructure and matching it with local energy demand and heating networks is highly innovative. The main outputs include a transnational well repurpose potential assessment, site-specific feasibility studies, validated well repurpose methodologies, a web-based tool for assessment of well repurpose potential, and a transnational strategy and action plan.