Wellbore Heat Transfer in CO2-Based Geothermal Systems

Abstract

Geothermal systems utilizing carbon dioxide as the subsurface heat exchange fluid in naturally porous, permeable geologic formations have been shown to provide improved geothermal heat energy extraction, even at low resource temperatures, compared to conventional hydrothermal and enhanced geothermal systems (EGS). Such systems, termed CO2 Plume Geothermal (CPG), have the potential to permit expansion of geothermal energy use while supporting rapid implementation. While most previous analyses have focused on heat transfer in the reservoir and surface components of CO2-based geothermal operations, here we examine wellbore 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 lifespan.