Geophysical Characterization of a Geothermal System Neal Hot Springs, Oregon, USA

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Report: Geophysical Characterization of a Geothermal System Neal Hot Springs, Oregon, USA

Abstract
Neal Hot Springs is an active geothermal area that is also the proposed location of a binary power plant, which is being developed by US Geothermal Inc. To date, two production wells have been drilled and an injection well is in the process of being completed. The primary goal of this field camp was to provide a learning experience for students studying geophysics, but a secondary goal was to characterize the Neal Hot Springs area to provide valuable information on the flow of geothermal fluids through the subsurface. This characterization was completed using a variety of geophysical surveying methods including: potential fields, deep seismic exploration, vertical seismic profiling, passive seismic monitoring, shallow seismic exploration, direct current resistivity and self potential. Each method designed survey lines that ran mostly perpendicular to the proposed fault structures to provide the best resolution in the data. In addition to these lines, a small grid was created by students to survey with a variety of methods (electrical and potential field methods). This grid location was chosen because warm fluids were found to be upwelling in the area.Each of these data sets were processed and analyzed by students to determine a unifying solution that best describes the subsurface. After careful observation of the surface geology, as well as the results of each method, it has been determined that there is a primary horst structure just east of Neal Hot Springs. This horst structure is igneous in composition and is fractured throughout. Additionally, there is one major fault (Fault A) with significant offset that was discovered by the gravity, magnetics, and Warm Spring surveys inside the greater horst body. Each of these fractures, along with the fault that binds the horst block on the west side at Neal Hot Springs, is believed to have fluid flow; however, only the Hot Springs have hot fluids. It was also determined that a minor fault structure (Fault B), on the east side of Fault A, was the path for the Warm Spring flow. While the paths of both the major flows were discovered (i.e. the Warm Spring and Neal Hot Springs), the heat source for these flows was not discovered. Further geophysical analysis would need to be completed in order determine the actual source.

Author 
Colorado School of Mines and Imperial College London





Organization 
Colorado School of Mines and Imperial College London



Published 
Colorado School of Mines and Imperial College London, 2011



Report Number 
N/A


DOI 
Not Provided
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Online 
Internet link for Geophysical Characterization of a Geothermal System Neal Hot Springs, Oregon, USA

Citation

Colorado School of Mines and Imperial College London (Colorado School of Mines and Imperial College London). 2011. Geophysical Characterization of a Geothermal System Neal Hot Springs, Oregon, USA. Golden, Colorado: Colorado School of Mines and Imperial College London. Report No.: N/A.


Related Geothermal Exploration Activities
Activities (12)


Areas (1)
  1. Neal Hot Springs Geothermal Area
Regions (0)