High temperature geothermal wells are constructed of several concentric steel casings that are fully cemented up to the surface. The structural integrity of such casings is essential for the utilization of wells. The casing is subjected to multiple thermo-mechanical loads that can cause casing failures. Thermal expansion generates thermal stresses in the casings and causes the wellhead to rise slightly during discharge. In this paper, a nonlinear structural finite-element model of the cased section of a geothermal well is presented and validated. The numerical results show good agreement with wellhead displacement measurements of 5 different wells in Iceland. (C) 2015 Elsevier Ltd. All rights reserved.