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Seismic Velocities and Induced Seismicity at the Utah Forge: How Creating Fractures Helps Us Understand the Spatial and Temporal Evolution of an EGS Reservoir

Description: 

The Utah FORGE (Frontier Observatory for Research in Geothermal Energy) is a field-scale laboratory with the goal to enhance our knowledge on how to utilize hot, dry rock for geothermal energy production, which may act as one of the base-load capable components contributing towards the clean energy transition. To transport heat from the underground to the surface, fluids circulate though the reservoir. Considering the low permeability of granite at the targeted depth of ~3km, it is necessary to create fluid pathways through hydraulic stimulation. This process may involve the opening of new fracture or re-activation of existing ones, potentially inducing seismicity.
To better understand where and when stimulation induces seismicity, it is essential to have a comprehensive overview of the seismic activity and potential structures in the larger area. Utah FORGE provides an extensive seismic dataset that includes recordings from a permanent network first emplaced in 2016 and continuously expanded since and multiple temporary nodal arrays and downhole geophone chains. Using this extensive dataset, we: i) utilize machine learning models to create a continuous enhanced event catalogue for the Milford valley, ii) improve the event localization by jointly inverting for the velocity model and earthquake location and iii) utilize ambient noise to investigate relative seismic velocity changes (dv/v) over time.
The three key outcomes - earthquake localization, velocity model, and temporal changes in dv/v – are inherently interdependent. Apart from the location, orientation and evolution of the created fractures or reactivated faults that are highlighted by the seismicity, a combined interpretation of seismic velocities and event occurrence may provide improved insight in the spatial distribution of the physical properties within the reservoir rock and how the fluid injection with the subsequent fracturing might alter those properties. Such knowledge of the underground, together with hydrological and mechanical input, is essential to improve mitigation strategies for induced seismicity in geothermal energy production.

Session: From Drilling to Ground Shaking: Mechanisms, Monitoring and Mitigation of Induced Earthquakes [Poster]

Type: Poster

Date: 4/17/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Elisabeth Glück

Student Presenter: No

Invited Presentation: 

Poster Number: 95

Authors