Fracture Stimulation as Seen Through Picoseismicity, Borehole Displacement Probes and Distributed Fiber-Optic Sensing: The EGS Collab Experiment

Session: Mechanisms of Induced Seismicity: Pressure Diffusion, Elastic Stressing and Aseismic Slip
Type: Oral
Date: 4/29/2020
Time: 11:30 AM
Room: 215 + 220
Description: 

The future efficacy of enhanced geothermal systems (EGS) requires techniques and tools capable of successfully characterizing and predicting the behavior of crystalline rock masses during fluid injection operations. The US Department of Energy’s EGS Collab project at the Sanford Underground Research Facility in Lead, SD aims to test and develop these capabilities for deployment at future EGS testbeds and projects. Towards this goal, the Collab site has been densely instrumented with a number of monitoring systems across eight boreholes (one production, one injection and six for dedicated monitoring systems). These systems include active/passive seismic acquisition, electrical resistivity, flow/pressure monitors and distributed fiber-optic sensing (DSS/DTS/DAS). Several fracture stimulation tests have been performed to date at a depth of 4850 m with planning underway for a second testbed at 4100 m depth.

Here we present passively-recorded seismic data, distributed fiber-optic strain sensing and μm-sensitive 3-dimensional displacement (SIMFIP) in relation to a series of hydrofracturing tests between 22 and 25 May, 2018. During this time, we detected and located more than 700 picoseismic events, which allowed for near-real-time tracking of the development of the stimulated fractures. Where the fractures intersect the monitoring boreholes, we show distributed fiber-optic sensing techniques (e.g. DSS and DAS) to be highly sensitive to the breakthrough and corroborate the locations of the fractures inferred from seismicity.

Presenting Author: Chet Hopp

Authors