Enhanced heat recovery in CO₂-enhanced geothermal systems: A temperature-sensitive proppant approach

Enhanced Geothermal Systems using supercritical CO₂ (CO₂-EGS) offer superior thermophysical properties and dual benefits of energy generation with carbon sequestration. However, CO₂'s inherent buoyancy creates severe thermal short-circuiting through intra-fracture channeling (gravity override) and inter-fracture channeling in the reservoir with non-uniform fracture system. These phenomena cause premature thermal breakthrough and significantly reduce energy recovery efficiency. This study introduces the concept of temperature-sensitive proppants as an autonomous solution to mitigate CO₂ flow channeling. These “smart” proppants dynamically reduce fracture conductivity in cooled zones while maintaining high conductivity in hot regions, intelligently redirecting CO₂ flow to achieve uniform thermal sweep. Through comprehensive 3D numerical simulations of a horizontal well doublet system over 30 years, we quantify substantial performance improvements. In uniform fracture networks, temperature-sensitive proppants increased cumulative heat extraction by 20 % and sustained production temperatures 22 K higher after three decades. More significantly, in non-uniform fracture systems prone to severe channeling, the technology delivered a 45 K temperature increase and 55 % improvement in heat extraction efficiency compared to conventional proppants. Results demonstrate that temperature-sensitive proppants provide transformative, self-regulating flow control that maximizes energy recovery while extending system longevity. This technology addresses the critical challenge of thermal short-circuiting in CO₂-EGS, significantly improving economic viability while advancing dual goals of clean energy generation and large-scale geological carbon sequestration.