The GRE GEO Project – Development of Corrosion-Resistant Casing System - GRE based well Design and Qualification Procedures for Geothermal Wells - Keywords: corrosion-resistant, fiberglass, GRE, glassfiber, scaling, materials qualification, four-quadrant design envelope, well design, casing system, geothermal wells, glass fiber reinforced epoxy casing system The European funded GEOTHERMICA GRE-GEO project rallies a multinational consortium of geothermal experts to develop a new glass fiber reinforced epoxy casing system for geothermal wells. Such a system would solve the corrosion and scaling challenges of conventional steel based well designs. Glass Reinforced Epoxy (GRE) tubular are already being used for decades in highly corrosive oil wells (e.g. H2S, CO2, Sulfide Reducing Bacteria based corrosion). However, the industry-standards describing such tubular are missing and design envelopes representing their load capacities have not been verified. This presently limits the down-hole use of GRE tubular. One of the objectives of the project is the development of product qualification procedures to provide the basis for the construction and verification of a final product suitable for installation in the conventionally used well designs.