Preliminary Analysis of Continuous Seismic Monitoring at Utah FORGE: Tracking Fracture Evolution with Distributed Acoustic Sensing and Permanent Seismic Sources

Abstract

Downhole distributed acoustic sensing (DAS) and permanently installed surface orbital vibrators (SOVs) were used for monitoring subsurface changes during hydraulic stimulation at the Utah FORGE EGS research site, as part of the DOE funded FOGMORE project. SOVs generate highly repeatable compressional (P) and shear (S) waves, making them ideal for long-term subsurface imaging and monitoring. During the 2024 stimulation at Utah FORGE, we recorded continuous seismic data with DAS and recorded a series of interstage vertical seismic profile (VSP) gathers using autonomous permanent sources, SOVs. By monitoring the stimulation using VSP data acquired with SOV/DAS, we can detect scattering events from fractures, giving insights into fracture dynamics. In this study, we present preliminary results of the VSP data acquired in monitoring well 16B(78)-32. We installed SOVs at four locations and evaluated the quality of the acquired SOV/DAS VSP data. All SOV locations present a rich wavefield recorded on the VSP gathers, with SOV2 and SOV3 showing the highest signal-to-noise ratio. SOV2 location reveals existing structure within the granite body. Further analysis is needed to detect potential changes associated with hydraulic fracturing.