Using QEMSCAN to Characterize Fracture Mineralization at the Newberry Volcano EGS Project, Oregon: A Pilot Study

Abstract

We present a pilot study that compares results obtained from QEMSCAN® analyses at the Energy and Geoscience Institute (University of Utah) with other data (petrographic thin section and XRD). Specifically, we present data from representative mineralized fractures intersected in an intermediate-depth (4410 ft) borehole (GEO-N2) at the Newberry Volcano EGS site in Oregon, which is adjacent to the proposed deep (~10 000 ft) EGS well. The Newberry Volcano EGS Demonstration project aims to develop an EGS reservoir in a high-temperature, low-permeability resource on the north-west flank of Newberry Volcano through stimulation of an existing deep well (NWG 55-29) by hydro-shearing techniques. The ability of QEMSCAN® to resolve geochemical zonation in mineralized fractures at a fine resolution (? 2 ?m scale) and generate quantitative data of the proportion of different secondary minerals in fracture zones is relevant to several aspects of geothermal science and engineering, including assessment of likely effectiveness of chemical and/or hydraulic stimulations, characterizing the relationship between fracture mineralization and rock mechanical properties, and for numerical simulations of water-rock interactions in geothermal systems.