| Title | Update on the Geology, Temperature, Fracturing, and Resource Potential at the Cape Geothermal Project Informed by Data Acquired from the Drilling of Additional Horizontal EGS Wells |
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| Authors | Steven FERCHO, Jack NORBECK, Sireesh DADI, Gabe MATSON, Jarret BORELL, Emma MCCONVILLE, Susanna WEBB, Chris BOWIE, Greg RHODES |
| Year | 2025 |
| Conference | Stanford Geothermal Workshop |
| Keywords | Horizontal Drilling, Fervo, Cape, FORGE, EGS |
| Abstract | Fervo Energy has completed the drilling of additional deep horizontal geothermal enhanced geothermal system (EGS) wells at Project Cape, following the completion of the first deep geothermal wells at the Frisco pad that was reported in 2023. The new wells were drilled north of Fervo’s Frisco Pad and west of the DOE’s FORGE project in Milford Valley on two new pads called the Gold Pad and Bearskin Pad. Fervo has more than doubled the footage drilled every year since 2021, with over 200,000 feet of new wells drilled in 2024. New datasets collected through Fervo drilling have substantially increased knowledge of the geology, temperature, state of stress, and natural fracturing in Milford Valley, updating our 3D basin models with an unprecedented amount of well data and showing remarkably consistent geology, temperatures, and stress conditions throughout the development area. Temperature and depth to the granitic basement reservoir measured in the new northern wells have validated our pre-drill basin-scale models and demonstrate a high degree of predictability within the basin. Image logs from the wellfield confirm a consistent maximum horizontal stress orientation (SHmax) of NNE-SSW, which contrasts with a dominant natural fracture orientation of NNW-SSE. Stimulation of the first series of laterals on the Frisco pad have demonstrated consistent fracture growth with precise MEQ orientations measured in well DAS fiber and surface array seismometers. The application of EGS type curve theory using completions engineering design demonstrates that energy production and thermal decline can be effectively forecasted in horizontal well EGS systems. Horizontal well EGS designs with high-intensity fracture stimulation treatments can achieve thermal recovery factors above 50% while maintaining economically viable flowing production temperatures over the life of a project. The combination of high recovery factors and multibench development strategies suggest that EGS projects can achieve gross power densities on the order of 75+ MW per square mile per bench (on a gross power basis), significantly increasing the total EGS resource potential beyond previous estimates. |