Geothermal systems utilizing carbon dioxide as the subsurface heat exchange fluid in naturally porous, permeable geologic formations have been sho wn to provide improved geothermal heat energy extraction, even at low resource temperature s, compared to conventional hydrothermal and enhanced geothermal systems (EGS). Such systems , termed CO 2 Plume Geothermal (CPG), have the potential to permit expansion of geotherma l energy use while supporting rapid implementation. While most previous analyses have f ocused on heat transfer in the reservoir and surface components of CO 2 -based geothermal operations, here we examine wellb ore heat transfer. In particular, we explore the hypothesis that wellbore flow can be assumed to be adiabatic for the majority of a CPG facility's life span.