Ragnarsson, ArniArniRagnarssonDurst, PierrePierreDurstRandeberg, ErlendErlendRandebergReinsch, ThomasThomasReinschThorbjornsson, IngolfurIngolfurThorbjornssonWollenweber, JensJensWollenweberJong, Willem deWillem deJongSørlie, Carsten F.Carsten F.SørlieSigurdsson, OmarOmarSigurdssonVercauteren, FrankFrankVercauterenSkúlason Kaldal, GunnarGunnarSkúlason Kaldal2023-07-052023-07-052021https://publica.fraunhofer.de/handle/publica/417896This paper describes the main results of the GeoWell research project, which was running in the period 2016-2019. It was funded through the EC-Horizon 2020 programme addressing various aspects of new and enhanced technology for the design and operation of high-temperature geothermal wells. These include cement slurry design, casing material selection, coupling of casings, downhole temperature and strain measurements in real time using fibre optic technologies as well as novel methods for risk assessment with respect to well planning, design and operation of geothermal wells. The research focused on both conventional geothermal production wells and deeper wells where the operation pressure is as high as 150 bar and temperatures can exceed 400°C. The technology developments of the project and material candidates were tested under downhole conditions in laboratories and partly in-situ in existing geothermal environment.enconference paper