Pathways to Superhot and Superdeep: Lesson from Deep and Hot Geothermal Projects

Abstract

Next-generation geothermal development is undergoing a fundamental transition to access deeper and hotter targets, aiming to maximize and increase energy production per well by orders of magnitude. At ‘superhot’ or ~350 C+ conditions, wells can produce up to ten times more power than conventional geothermal systems, motivating this study to identify additional firm, abundant power generation. This study utilizes reduced-order physical models grounded in analytical foundations quantifying how the interplay of fracture surface area, mass flow rate, and thermal properties dictates long-term project performance. Projects are categorized by development approach: Traditional EGS, Huff-n-Puff EGS, and closed-loop Advanced Geothermal Systems (AGS). These projects are critically assessed through their Connectivity (establishing hydraulic communication), Conductivity (maintaining open flow paths), and Conformance (ensuring uniform sweep). Analysis shows that past failures, such as rapid thermal drawdown or excessive impedance, often stem from a lack of control over one or more of these metrics. Lessons learned from deep and hot geothermal systems are then applied to superhot and superdeep geothermal resource for each next generation geothermal classification. By treating the subsurface as an engineered heat exchanger, we demonstrate that maximizing effective sweep volume is the primary lever to delay thermal breakthrough and achieve sustainable power densities. A novel "drill shallow, fracture deep" concept is introduced to recover heat from superhot formations without drilling superdeep that utilizes dense working fluids to drive fracture propagation downward into deeper, hotter formations. This approach exploits fracture mechanics to access superhot resources while bypassing the technical and economic hurdles of direct deep drilling and completion.