Fervo Energy’s Deep Hot Enhanced Geothermal Well Shatters Records: 15,765 feet, 520°F, 16 days

  Fervo Energy continues to exceed expectations and drill deeper, hotter, and faster into hot dry rock. Reaching a true vertical depth (TVD) of 15,765 ft in rock at 520 degrees F in just 16 days. The drilling speed represents a 79% reduction in drilling time compared to the DOE’s baseline for such wells. The Sugarloaf appraisal well is an excellent operational achievement. According to the press release:

“These results expand the window for commercial viability of EGS into a significantly deeper and hotter regime, paving the way to deploy the technology outside of the western US.”

“DeGolyer & MacNaughton’s independent estimates of heat-in-place and reserves involved a comprehensive review of Fervo’s drilling data, geologic models, and production test results. The report highlights that Fervo’s proprietary EGS design successfully unlocks thermal recovery factors in the range of 50 to 60%, tripling the amount of useful thermal energy reserves compared to conventional geothermal technology. The report confirms that the Cape Station project area can support over 5 GW of development at depths of up to 13,000 feet. The new Sugarloaf drilling results are expected to increase Cape’s resource potential even further.”

“Back in July 2020, we performed our first EGS field trials at reservoir temperatures of around 300° F,” said Jack Norbeck, CTO and co-founder of Fervo Energy. “In just a few years, we’ve developed innovations that enable our technology to operate reliably at temperatures exceeding 500° F. These drilling results demonstrate that Fervo is operating in the optimal geothermal conditions for large-scale commercial deployment.”

     Fervo is confident in their enhanced geothermal systems (EGS) projects, which utilize key oil & gas drilling and completion technologies like PDC bits, multiwell pads, horizontal drilling, and multistage stimulation. A 2025 paper in Nature Reviews Clean Technology explains the potential of EGS. Below is a snippet from the abstract.

“Adaptation of advanced drilling techniques (including the use of polycrystalline diamond compact bits, multiwell drilling pads, horizontal drilling and multistage stimulation) is enabling an increase in scale and decrease in cost of EGS projects. As a result, in the USA, enhanced geothermal is expected to achieve plant capital costs (US$4,500 kW−1) and a levelized cost of electricity (US$80 MWh−1) that are competitive with market electricity prices by 2027. With further development of EGS to manage induced seismicity risk and increase system flexibility, EGS could provide stable baseload and potentially dispatchable electricity in clean energy systems.”

     Two important issues highlighted in the paper are the potential of EGS to get down in pricing to be competitive with other forms of energy and the dangers of induced seismicity. They also note that EGS has been proven to be effective and long-term in experimental projects in Europe, including in the Upper Rhine Graben, a part of the European Rift system. Geothermal systems as conventional convective and conductive, are distinguishable but can be developed in adjacent areas as shown below.

 

     Improvements in drilling time and effectiveness of stimulation are leading to better economic outlooks for EGS projects.

     Fervo and others are studying induced seismicity, which has been problematic in geothermal wells in Switzerland, Korea, and France, leading to the cancellation of some projects. They are working to understand the potential for induced seismicity and the best ways to manage it. We know from oil & gas issues that it can be managed. However, it may be more difficult to do so in some geothermal areas.

“Managing unwanted seismicity during hydraulic fracturing operations remains an ongoing challenge, as there is no simple formula or action that is guaranteed to avoid the occurrence of a serious event once seismicity has been initiate.”

      Technological advancements have made EGS more economically viable for the future. If these advancements continue, the costs can drop further, leading to economic deployments of EGS.

   

 

References:

 

Fervo Energy Drills 15,000-FT, 500°F Geothermal Well, Pushing the Envelope for EGS Deployment. Business Wire. June 10, 2025. Fervo Energy Drills 15,000-FT, 500°F Geothermal Well, Pushing the Envelope for EGS Deployment

Enhanced geothermal systems for clean firm energy generation. Roland Horne, Albert Genter, Mark McClure, William Ellsworth, Jack Norbeck & Eva Schill. Nature Reviews Clean Technology volume 1, pages148–160 (2025). Enhanced geothermal systems for clean firm energy generation | Nature Reviews Clean Technology