Microseismic monitoring of Newberry Volcano EGS Demonstration

Abstract

Hydraulic stimulation of an existing deep, hot well on the west flank of Newberry Volcano was performed in the fall of 2012 as part of the Newberry EGS Demonstration. A microseismic array of 15 stations was installed in the summer to monitor the EGS growth. Eight geophones were installed in 213-246 m deep boreholes, four drilled in the summer of 2012, in order to reduce noise due to scattering in the attenuating volcanic deposits near the surface. Seven surface geophones were installed to further improve locations and allow determination of source mechanisms by enhancing focal sphere coverage. Each station is equipped with a cell phone modem which sends data in real-time to an acquisition server in Seattle After onsite assembly of moderate pressure pumps and piping, injection of cold groundwater into the EGS target well head began October 17 and continued until December 7. 174 microearthquakes with moment magnitudes between 0.0 and 2.4 were located within 1 km of the injection well, defining the EGS reservoir. Multi-zone stimulation was carried out by injecting thermally-degradable zonal isolation materials to plug stimulated fractures and shift stimulation to new fractures. The Newberry Volcano EGS Demonstration will allow geothermal industry and academic experts to develop, validate and enhance geoscience and engineering techniques, and other procedures essential to the expansion of EGS. Successful development will demonstrate to the American public that EGS can play a significant role in reducing foreign energy dependence, and provide clean, renewable, and safe baseload geothermal power generation.