Stanford Geothermal WorkshopFebruary 9-11, 2026

Geothermal wells frequently experience declining injectivity and productivity due to stress-induced alteration of flow paths, mineral scaling, and loss of connectivity within natural fracture networks. Stimulation through Hydroshearing has historically been employed to enhance permeability, where elevated pressures promote slip along pre-existing fractures. However, extensive field evidence demonstrates that the effects are largely transient. Recent field diagnostics show that sustained enhancement in geothermal systems requires maintaining mechanical aperture, achievable only through opening-mode (tensile) fractures stabilized by various proppants. This article builds a technical and economic case for proppant-based hydraulic fracturing as a sustainable stimulation strategy in hydrothermal geothermal reservoirs. Drawing on historical EGS examples, three principal paradigms where proppant placement provides distinctive value, have been proposed: (1) extending permeability away from major faults to connect low-flow zones into active reservoir corridors; (2) strategically fracturing within injector–producer patterns to improve field-scale connectivity and thermal sweep; and (3) directly propping fault and feed-zone structures to prevent stress- or thermally-induced closure. Collectively, these strategies can maintain or restore plant capacity without costly make-up wells. The article addresses overcoming the existing operational challenges, including deviated well trajectories, slotted liners, high formation temperatures, and complex fracture geometries. Modern completions and fracturing technologies including advances in stimulation chemistry portfolio are discussed. High-viscosity, non-damaging fluids, zonal isolation packers, reliable degradable diverters, and temperature-resistant ceramic proppants can enable reliable placement even in geothermal wells at 250–300°C. Laboratory tests and modeling confirm that such proppants maintain conductivity under sustained stress and thermal cycling, resisting creep and chemical degradation that limit traditional sand systems. An economic analysis contrasts the cost-benefit analysis of proppant stimulation ($1–2 million per well) with new, makeup well drilling ($6–10 million) and shows that modest injectivity improvements (5–10 %) can preserve several megawatts of capacity in a 30-50 MW power plant—translating to a significant reduction in levelized cost of electricity. Beyond economics, proppant-based fracturing offers improved predictability and design control relative to hydroshearing, supported by decades of oil-and-gas modeling tools adaptable to geothermal stress regimes. In conclusion, proppant-assisted hydraulic fracturing provides a durable, mechanically supported permeability enhancement mechanism for hydrothermal reservoirs where shear and thermal stimulation alone are inadequate. By integrating EGS learnings, high-temperature materials, and modern stimulation design, this approach can extend the productive life of hydrothermal fields, reduce the frequency of make-up drilling, and help close the gap between hydrothermal and engineered geothermal resources. The study advocates for pilot demonstrations to quantify performance gains and refine techno-economic parameters, marking a critical step toward sustainable, high-efficiency geothermal power generation.

Topic: Enhanced Geothermal Systems