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Applying Waveform Correlation Analysis to Microseismicity at the Forge Sites to Detect and Characterize Fractures

Description: 

The Frontier Observatory for Research in Geothermal Energy (FORGE) is a geothermal project located at Milford, UTAH, providing pioneer research in Enhanced Geothermal Systems (EGS). Microseismic monitoring is essential during stimulation that aims at creating a permeable fracture network. During hydraulic fracturing, different fractures are activated, some of which have low seismogenic potential while others can host large seismic events. Waveform cross-correlation is a powerful tool to identify events originating from the same faults and long-term monitoring with matched filter detection can identify the early onset of fault activation, which is an essential step for developing a proactive traffic light system. Waveform cross-correlation can also identify isolated asperities that generate events with nearly identical waveforms. Application to the 2019 stimulation found several similar event clusters that correspond to different stimulation stages and repeated activation of asperities. The 2022 stimulation features over 2000 microseismic events over three stages. Applying a machine-learning- based clustering algorithm to the microseismic event catalog found several fracture planes. However, different algorithms identify different sets of fractures, likely due to uncertainties in event location. Here, we apply waveform correlation analysis to microseismic events during stage 3 of 2022 stimulation to further detect fractures via similar event clusters, and asperities with nearly identical waveforms. We will measure precise relative magnitude based on principle component analysis of aligned waveforms, which will be used for magnitude calibration. The improved magnitude will be used to characterize the seismogenic potentials of different fractures, and their relationship with injection history. Analysis of the waveforms will provide the basis for the end goal of developing a proactive traffic light system to detect the early onset of fault activation.

Session: De-risking Deep Geothermal Projects: Geophysical Monitoring and Forecast Modeling Advances [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Richard Asirifi

Student Presenter: Yes

Invited Presentation: 

Authors