| Title | A Proposal for Safe and Profitable Enhanced Geothermal Systems in Hot Dry Rock |
|---|---|
| Authors | Luke P. FRASH, J. William CAREY, Bulbul AHMMED, Matthew SWEENEY, Meng MENG, Wenfeng LI, Bijay K C, Uwaila IYARE |
| Year | 2023 |
| Conference | Stanford Geothermal Workshop |
| Keywords | Uncertainty Quantification, GeoDT, Net Present Value, Fracture Caging, EGS |
| Abstract | The contemporary approach to developing hot dry rock (HDR) Enhanced Geothermal Systems (EGS) is, at its core, the same today as how it was first envisioned for the 1977 Fenton Hill project. During the past four-plus decades since Fenton Hill, the geothermal community has developed increasingly sophisticated coupled process models and deployed numerous pilot projects to quantify and seek solutions to the many challenges of contemporary EGS. However, this effort appears to be leading toward the conclusion that the contemporary approach is not economic and is unlikely to become economic without the advent of technology breakthroughs. Most critically, the achievable flow rates with conventional ‘traffic-light’ protocol to prevent induced seismicity are far too low for economic power generation. Adding to the challenge, subsurface processes for cold fluid-flow through closed heterogeneous fractures tend to encourage early thermal breakthrough and reduce production capacity. In this study, we employ our Geothermal Design Tool (GeoDT) to evaluate an alternative approach to EGS development that uses only current technologies to achieve economic geothermal power production from HDR resources. This work reveals a promising multi-well approach that could use: (1) ‘limited-entry’ for injection-well zonal flow-control, (2) ‘fracture caging’ for seismicity control, (3) high-rate and high-pressure injection for ‘hydropropping’, and (4) systems engineering that accommodate decreasing production well enthalpy over time. Our numerical models based on the Utah FORGE location indicate that this new alternative approach to HDR-EGS holds promise for reliable economic geothermal power generation, but more work is needed to demonstrate its effectiveness in field applications. |