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Utah FORGE 2024 Stimulations: Improvement of Surface-based Microseismic Mapping of Fracture Zones via Nodal Geophone Patches

Description: 

The Utah Frontier Observatory for Research in Geothermal Energy (FORGE), the U.S. Department of Energy's field-scale enhanced geothermal system (EGS) laboratory, offers the unique opportunity to tackle research questions regarding techniques and strategies needed to develop economically viable EGS. Monitoring microseismic activity induced by the subsurface operation is crucial for the safe application of EGS. While deep borehole instrumentations (>1000m) can deliver very low detection thresholds, the installation is expensive. During the latest stimulation experiments at Utah FORGE in April 2024, we tested a cost-efficient way of improving the microseismic monitoring from the surface by deploying geophone patches in a radius of about 2km around the Utah FORGE site. The patches comprised nine colocated nodal geophones whose records were stacked for noise suppression. The stacked waveforms have similar or superior signal-to-noise ratios compared to permanently installed sensors at the surface or in shallow boreholes (~30m). Based on the enhanced temporary data from the nodal patches and the permanent stations at the surface, we successfully mapped the development of two isolated main fracture zones during the simulations in great detail. These two zones constitute efficient pathways for fluid to circulate between the injector and the producer. Spatial offsets between sealed-off injection intervals and the mapped microseismicity in the later part of the stimulations suggest that more complex interactions within the rock and aseismic process play an important role in the reservoir dynamics.

Session: Seismology for the Energy Transition [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Kristine

Student Presenter: No

Invited Presentation: 

Poster Number: 133

Authors