Newberry Volcano, a voluminous (500 km3) basaltic/andesitic/rhyolitic shield volcano located near the intersection of the Cascade volcanic arc, the Oregon High Lava Plains and Brothers Fault Zone, and the northern Basin and Range Province, has been the site of geothermal exploration for more than 40 years. This has resulted in a unique resource: an extensive set of surficial and subsurface information appropriate to constrain the baseline structure of, and conditions within a high heat capacity magmatically hosted geothermal system. In 2012 and 2014 AltaRock Energy conducted repeated stimulation of an enhanced geothermal systems (EGS) prospect along the western flank of the Newberry Volcano. A surface based monitoring effort was conducted independent of these stimulation attempts in both 2012 and 2014 through a collaboration between NETL, Oregon State University and Zonge International. This program included utilization of 3-D and 4-D magnetotelluric, InSAR, ground-based interferometric radar, and microgravity observations within and surrounding the planned EGS stimulation zone. These observations as well as borehole and microseismic stress field and location solutions provided by AltaRock and its collaborators, in combination with well logs, petrologic and geochemical data sets, LIDAR mapping of fault traces and extrusive volcanics, surficial geologic mapping and seismic tomography, have resulted in development of a framework, subsurface geologic model for Newberry Volcano. The Newberry subsurface geologic model is a three-dimensional digital model constructed in EarthVision that enables lithology, directly and remotely measured material properties, and derived properties such as permeability, porosity and temperature, to be coregistered. This provides a powerful tool for characterizing and evaluating the sustainability of the site for EGS production and testing, particularly within the data-dense western portion of the volcano. The model has implications for understanding the previous EGS stimulations at Newberry as well as supporting future research and resource characterization opportunities. A portion of the Newberry area has been selected as a candidate site for the DOE FORGE (Frontier Observatory for Research in Geothermal Energy) Program through a collaboration between Pacific Northwest National Laboratory, Oregon State University, AltaRock Energy and additional partners. Thus, the conceptual geologic model presented here will support and benefit from future enhancements associated with that effort. --Mark-Moser et al. 2016

Newberry Volcano in Central Oregon is the site of a Department of Energy funded Enhanced Geothermal System (EGS) Demonstration Project. Stimulation and production of an EGS is a strong perturbation to the physical and chemical environment, giving rise to coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes leading to permeability changes as a result of mineral dissolution and precipitation, rock deformation, and fracture reactivation. To evaluate these processes, and to help guide EGS stimulation and reservoir development strategies, a combined native-state and reservoir model of the west flank of Newberry Volcano was created that encompasses the planned stimulation zone and a several km region of the west flank from the surface down to the supercritical region, likely close to a postulated cooling intrusive body. Temperature and pressure distributions were first modeled using TOUGHREACT with boundary conditions estimated from nearby drill holes, and compared to measurements made in the over 3 km deep NWG 55-29 drill hole. With estimates of the porosity and heat capacities for the major hydrogeologic units, thermal conductivities were calibrated by matching to the measured temperature profile. To simulate the development of the observed hydrothermal mineralogy, a reaction-transport model (THC) was developed using the pre-alteration mineralogy and shallow groundwater chemistry as the initial geochemical conditions, assuming that modeled temperature and pressure distributions were relatively constant over several thousand years. Close correspondence of modeled and observed epidote distributions support the observation that past hydrothermal activity took place under thermal gradients similar to current values, whereas calcite and sulfide abundances at depth likely require a magmatic gas component. Multicomponent geothermometry was used to estimate potential temperatures of equilibration of waters, and to evaluate the effects of kinetics on calculated mineral equilibration temperatures. The ultimate goal will be to capture both the local chemical and mechanical changes in the rock owing to stimulation as well as the potential long-term response and sustainability of the larger-scale geothermal reservoir.

Final results of a 3D finite difference thermal model of Newberry Volcano, Oregon. Model data are formatted as a text file with four data columns (X, Y, Z, T). X and Y coordinates are in UTM (NAD83 Zone 10N), Z is elevation from mean sea level (meters), T is temperature in deg C. Model is 40km X 40km X 12.5 km, grid node spacing is 100m in X, Y, and Z directions. A symmetric cylinder shaped magmatic heat source centered on the present day caldera is the modeled heat source. The center of the modeled body is a -1700 m (elevation) and is 600m thick with a radius of 8700m. This is the best fit results from 2D modeling of the west flank of the volcano. The model accounts for temperature dependent thermal properties and latent heat of crystallization. For additional details, assumptions made, data used, and a discussion of the validity of the model see Frone, 2015 (Link below).

Final results of a 3D finite difference thermal model of Newberry Volcano, Oregon. Model data are formatted as a text file with four data columns (X, Y, Z, T). X and Y coordinates are in UTM (NAD83 Zone 10N), Z is elevation from mean sea level (meters), T is temperature in deg C. Model is 40km X 40km X 12.5 km, grid node spacing is 100m in X, Y, and Z directions. A symmetric cylinder shaped magmatic heat source centered on the present day caldera is the modeled heat source. The center of the modeled body is a -1700 m (elevation) and is 600m thick with a radius of 8700m. This is the best fit results from 2D modeling of the west flank of the volcano. The model accounts for temperature dependent thermal properties and latent heat of crystallization. For additional details, assumptions made, data used, and a discussion of the validity of the model see Frone, 2015 (Link below).

As part of DEEPEN (DE-risking Exploration of geothermal Plays in magmatic ENvironments), a 3D play fairway analysis (PFA) was conducted at Newberry Volcano in Central Oregon for multiple play types (conventional hydrothermal, superhot EGS, and supercritical). For use in this PFA, combined full tensor broadband magnetotelluric (MT) and gravity data were acquired, processed, and inverted by Enthalpion Energy LLC (Enthalpion) with support from NREL staff. The data collection efforts took place from June 19th to July 24. Data were collected with the goal of gaining an improved understanding of the South Flank and the extent of the magma chamber. This GDR submission includes the raw data, single inversions, joint inversions, resolution matrices, and a report on these processes. More detailed information about the folder structure of the datasets included in this submission may be found on pages 94-97 of Magnetotelluric and Gravity Survey Report.pdf below.

As part of DEEPEN (DE-risking Exploration of geothermal Plays in magmatic ENvironments), a 3D play fairway analysis (PFA) was conducted at Newberry Volcano in Central Oregon for multiple play types (conventional hydrothermal, superhot EGS, and supercritical). For use in this PFA, combined full tensor broadband magnetotelluric (MT) and gravity data were acquired, processed, and inverted by Enthalpion Energy LLC (Enthalpion) with support from NREL staff. The data collection efforts took place from June 19th to July 24. Data were collected with the goal of gaining an improved understanding of the South Flank and the extent of the magma chamber. This GDR submission includes the raw data, single inversions, joint inversions, resolution matrices, and a report on these processes. More detailed information about the folder structure of the datasets included in this submission may be found on pages 94-97 of Magnetotelluric and Gravity Survey Report.pdf below.

These data are Pacific Northwest National Lab inversions of an amalgamation of two surface gravity datasets: Davenport-Newberry gravity collected prior to 2012 stimulations and Zonge International gravity collected for the project "Novel use of 4D Monitoring Techniques to Improve Reservoir Longevity and Productivity in Enhanced Geothermal Systems" in 2012. Inversions of surface gravity recover a 3D distribution of density contrast from which intrusive igneous bodies are identified. The data indicate a body name, body type, point type, UTM X and Y coordinates, Z data is specified as meters below sea level (negative values then indicate elevations above sea level), thickness of the body in meters, suscept, density anomaly in g/cc, background density in g/cc, and density in g/cc. The model was created using a commercial gravity inversion software called ModelVision 12.0 (http://www.tensor-research.com.au/Geophysical-Products/ModelVision). The initial model is based on the seismic tomography interpretation (Beachly et al., 2012). All the gravity data used to constrain this model are on the GDR: https://gdr.openei.org/submissions/760.

These data are Pacific Northwest National Lab inversions of an amalgamation of two surface gravity datasets: Davenport-Newberry gravity collected prior to 2012 stimulations and Zonge International gravity collected for the project "Novel use of 4D Monitoring Techniques to Improve Reservoir Longevity and Productivity in Enhanced Geothermal Systems" in 2012. Inversions of surface gravity recover a 3D distribution of density contrast from which intrusive igneous bodies are identified. The data indicate a body name, body type, point type, UTM X and Y coordinates, Z data is specified as meters below sea level (negative values then indicate elevations above sea level), thickness of the body in meters, suscept, density anomaly in g/cc, background density in g/cc, and density in g/cc. The model was created using a commercial gravity inversion software called ModelVision 12.0 (http://www.tensor-research.com.au/Geophysical-Products/ModelVision). The initial model is based on the seismic tomography interpretation (Beachly et al., 2012). All the gravity data used to constrain this model are on the GDR: https://gdr.openei.org/submissions/760.

The proposed Newberry Volcano FORGE site is in central Oregon on the northwest flank of the largest volcano in the Cascades volcanic arc. Beneath Newberry Volcano is one of the largest geothermal heat reservoirs in the western United States, extensively studied for the last 40 years. The large, shallow (200 deg C at less than 2 km depth), conductive thermal anomaly has already been well characterized by extensive drilling and geophysical surveys. Four deep (greater than 3,000 m) boreholes completed on the leasehold currently managed by AltaRock have conductive thermal gradients with bottom hole temperatures above 320 deg C. Three large geothermal pads and two deep geothermal wells exist on the leasehold as well as eight, 200-290 m deep monitoring boreholes that have been used for seismic monitoring and sampling of shallow groundwater. All these investments have built the scientific foundation that establishes the site as high EGS potential, demonstrates a record of addressing potential risks (induced seismicity, wildlife, groundwater, etc.), and has developed true support and engagement with the local and regional communities. The high temperatures at relatively shallow depths at the site will allow a greater variety of drilling methods to be tested and a greater share of funds to be reserved for non-drilling activities.

The proposed Newberry Volcano FORGE site is in central Oregon on the northwest flank of the largest volcano in the Cascades volcanic arc. Beneath Newberry Volcano is one of the largest geothermal heat reservoirs in the western United States, extensively studied for the last 40 years. The large, shallow (200 deg C at less than 2 km depth), conductive thermal anomaly has already been well characterized by extensive drilling and geophysical surveys. Four deep (greater than 3,000 m) boreholes completed on the leasehold currently managed by AltaRock have conductive thermal gradients with bottom hole temperatures above 320 deg C. Three large geothermal pads and two deep geothermal wells exist on the leasehold as well as eight, 200-290 m deep monitoring boreholes that have been used for seismic monitoring and sampling of shallow groundwater. All these investments have built the scientific foundation that establishes the site as high EGS potential, demonstrates a record of addressing potential risks (induced seismicity, wildlife, groundwater, etc.), and has developed true support and engagement with the local and regional communities. The high temperatures at relatively shallow depths at the site will allow a greater variety of drilling methods to be tested and a greater share of funds to be reserved for non-drilling activities.