Results from Newberry Volcano EGS Demonstration

Abstract

The Newberry Volcano EGS Demonstration in central Oregon is a 5 year DOE-funded project begun in 2010 that was designed to test recent technological advances to reduce the cost of electrical power generated by enhanced geothermal systems (EGS) in a hot ( more than 300 C), dry well (NWG 55-29) drilled in 2008. The project started with two years of permitting, technical planning, and development of a project-specific Induced Seismicity Mitigation Plan (ISMP) to evaluate, monitor for, and mitigate felt induced seismicity. In the fall of both 2012 and 2014, the well was hydraulically stimulated using water pressure below the minimum principle stress (aka hydroshearing). Thermally-degradable zonal isolation materials (TZIMs) successfully shifted the depth of stimulation. Injectivity changes, thermal profiles and micro seismicity indicate that fracture permeability in well NWG 55-29 was enhanced during the well stimulation. This proved the viability of the three significant technological developments: 1. stimulation pumps designed to run for weeks and deliver large volumes (40,000 m3) of water at moderate well-head pressure, 2. TZIMs which temporarily seal off fractures in a geothermal well to stimulate secondary and tertiary fracture zones, and 3. the geological and geophysical tools and methods used to predict the stimulation characteristics as required by the ISMP. The ongoing 2014 stimulation has applied the lessons learned from 2012. The second stimulation has employed better monitoring equipment and techniques, a more robust stimulation infrastructure and improved operational knowledge gained during the first stimulation. To date the injectivity of the well has been improved by ~15x and 35 microseismic events have been induced at depths greater than 3 km below the ground surface.