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Continuum Thermal-Hydraulic-Mechanical Modeling of Long-term Heat Production for the Utah FORGE EGS Concept
Jonny RUTQVIST
[Lawrence Berkeley National Laboratory, USA]
A coupled thermal-hydraulic-mechanical (THM) model has been developed to evaluate the long-term (30-year) performance of the Utah FORGE Enhanced Geothermal System (EGS) concept. The analysis has recently been expanded to a full-scale three-dimensional continuum model around injector and producer wells using the TOUGH-FLAC simulator. Propped-open fractures connecting injection and production wells spaced between 100 and 300 meters apart is represented in the continuum model. To begin, the model was used to simulate the 2024 30-day circulation test at Utah FORGE, which involved water circulation at approximately 26 l/s. This provided a baseline comparison with field data. The simulation was then extended to cover 30 years of continuous heat extraction to assess the long-term influence of coupled THM processes. Results shows that THM effects play a much more significant role over the long term than during the short-term circulation test. Cooling of the rock surrounding the active flowing fractures leads to stress reduction and fracture opening. This suggest that the propped-open fractures may be held open over time, which could enhance heat production efficiency throughout the operational lifespan of the system.
Topic: FORGE