| Abstract |
Scalable superhot (>375 °C) geothermal energy demands a paradigm shift in well construction and fracture management strategies. We propose a Gravity-assisted Geothermal System (GGS) concept that could unlock ultra-deep high-enthalpy reservoirs using as few as one-well per system. Our concept centers on using low-cost densified fluids to induce high-pressures in fractures while maintaining a modest surface pressure. With a specific gravity greater than 2.2 g/cc, it becomes possible to initiate gravity fractures that grow vertically downward to access deeper rock and higher temperatures from shallower wells. This is pivotal for unlocking supercritical geothermal by averting the challenges of deep high-temperature wells. Low-cost densified fluids enable off-the-shelf drilling equipment and pressure-propped fractures to boost economics, accelerate deployment, and achieve higher system reliability. Here, we present preliminary numerical modeling and laboratory experiment results that support the feasibility of our proposed method. We analyze pressure-propped fracture morphology evolution using controlled fluid injection. Our investigation indicates that fracture caging, densified fluids, and injection volume management can facilitate fracture stabilization at depths exceeding 8 km. This same approach enables sustained superhot fluid extraction at temperatures above 350°C. Scaled up, this methodology positions superhot geothermal reservoirs as viable contenders for terawatt scale baseload power production with a levelized cost of electricity (LCOE) of $30/MWh. The synthesis of fracture control and densified fluids reduce pumping losses and enable fracture stimulation to deeper depths. This offers a robust framework to commercialize superhot geothermal energy at scale. |