The Newberry Super-Hot EGS Project

Abstract

Super-hot dry rock ( more than 375°C) is much more energy dense than conventional hot dry rock (less than 225°C), and the production of supercritical EGS steam would represent an energy breakthrough. A super-hot EGS well would produce 5 to 10 times more electricity than other well types, including fossil fuels. To fill the knowledge gaps and break the technological barriers associated with supercritical systems, we propose a super-hot EGS proof of concept at a location where very hot rocks are close to the surface (~5000 m) and the cost of drilling and stimulation will be relatively low. The project will be sited on Newberry Volcano, in Oregon, one of the largest geothermal heat reservoirs in the USA and a suitable, ready-to-go site with existing infrastructure including access roads, drill pads, and existing wells to ~3500 m depth. Another important goal of this project is to develop better understanding of the distribution of geothermal systems in a volcanic area. In the case of Newberry, understanding why a high thermal gradient can be sustained kilometers away from the main focus of volcanic activity (caldera and associated shallow magma chamber) will be a fundamental objective of the project. Additional important project goals include drilling into the brittle-ductile transition to test the efficiency of thermally-induced fracturing and reservoir creation; regular spot coring for detailed study of rock alteration and physical properties; and the development of drilling techniques and borehole instrumentation adapted to high temperature. Preliminary thermal and geomechanical modelling along with drilling and stimulation strategies will be presented and discussed.