Geothermal systems occur across diverse geologic settings and the viability of a conventional development depends not only on elevated
temperatures, which are essential, but also on the distribution of permeable rocks and fractures that enable sustained fluid production.
Observations and analysis from global analogs reveal characteristic pressure and temperature behaviors that allow reservoirs to be
classified by permeability type. This classification enhances early assessments of resource potential and informs exploration and
development strategies. The characteristics of four end-member Permeability Regimes are described: Discrete, Limited Distributed,
Enhanced Distributed, and Stratigraphic. A companion study, Libbey and Murphy (2026), provides greater detail on the geology of these
regimes and resource parameters of Area and Thickness which characterize these systems as well as detailing a standardized methodology
utilizing these characteristics for estimating resource capacity.