What Can Microseismicity at the First Collab EGS Site Tell Us About the Subsurface Fracture Network?

Session: Mechanisms of Induced Seismicity: Pressure Diffusion, Elastic Stressing and Aseismic Slip [Poster]
Type: Poster
Date: 4/29/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Enhanced geothermal systems (EGS) can enrich the US energy portfolio by increasing the amount of renewable baseload power available to the electrical grid. To advance EGS technological readiness, meso-scale field studies were funded by the Geothermal Technologies Office (GTO) to validate subsurface reservoir models using observed geophysical data, borehole characterization data and fluid flow information. The EGS Collab initiative is putting this collaborative multi-Laboratory and multi-university experiment into practice at the Sanford Underground Research Facility (SURF), formerly the Homestake Mine, in South Dakota. At the first site, established approximately 1.5 kilometers beneath the ground surface, 18 3-component accelerometers, four 3-component geophones and two strings of 12-sensor hydrophones were deployed in 6 observation wells and in shallow boreholes near the drift to monitor fluid movement from the injection borehole to the production borehole.

Here we present results using data from the microseismic monitoring network for microseismic events occurring before, during and after fluid injection stimulation tests between May - December 2018. We also correlate the known microseismicity with one another to characterize the similarity of seismic events within the fracture network. A comprehensive examination of the locations of these clustered events with complementary fracture information can inform us as to the character of the microearthquakes with respect to the developing and existing fracture network.

This work supported by the U.S. DOE, Office of Energy Efficiency and Renewable Energy (EERE), Office of Technology Development, GTO. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and Award Number DE-AC02-05CH11231 with LBNL. The assistance of the SURF Facility and its personnel in providing physical access and general logistical and technical support is acknowledged.

Presenting Author: Dennise Templeton

Authors