The cost of geothermal wells for co-generation of electricity and district heating system is about 40-50% of the total investment cost of the energy production (Sveinbjörnsson et al. 2014). The single most failure mechanism for high-temperature geothermal wells according to study in the H2020 project GeoWell (Sveinbjörnsson et al. in preparation) is buckling and mechanical overload of the casing string in the well due to constrained thermal expansion. In addition, for medium enthalpy geothermal wells, it is known that temperature and pressure cycles above 100°C during construction, operation and shut-in phases have the potential to severely deteriorate the integrity of the cemented annulus (e.g. Goodwin and Crook, 1992; De Andrade et al., 2015). The GeConnect project proposal aims at increasing the reliability of the downhole construction of geothermal wells beyond the state of the art, using new innovative technology of flexible couplings ...additional information