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Nodal Deployment and Characterization of Microseismicity and Structure at Cape Modern Geothermal Field, Utah

Description: 

Microseismicity during stimulation and production related to enhanced geothermal systems (EGS) contains rich information of reservoirs including fracture locations, its orientations, fluid migration, and permeability. The Cape Modern Geothermal Field in Utah has been monitored by multiple types of seismic instrument including shallow-borehole seismometers, surface nodal arrays with and without data telemetry, and borehole distributed acoustic sensing (DAS). We apply comprehensive analyses to observed seismic data using both numerical and artificial-intelligence (AI)-aided methods for detection, location, focal mechanisms, and stress characterization to understand the evolution of seismicity and reservoir changes. Multiple fractures are revealed by the location and focal mechanisms of small events. The nodal deployment can enhance the aperture coverage for accurate estimation of focal mechanisms, although the distance from the reservoir to surface suppresses high frequency wavefields, which makes the corner frequency analysis difficult. The continuous measurements can contain rich information of ambient noise, which provides near-surface structure model to understand the geology and ground motion. Because of the frequency band of the ambient noise, the tomography is mainly sensitive to 100-500 m depth from the surface and reveals the NE-SW structures. We also compare the quality of datasets recorded by different instrument to make a recommendation of optimal network for seismic monitoring.

Session: Innovative Applications of Seismic Nodal Technology for Hazard Mitigation and Earth System Monitoring - I

Type: Oral

Date: 4/15/2025

Presentation Time: 02:15 PM (local time)

Presenting Author: Nori

Student Presenter: No

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