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Ultrasonic and Electromagnetic Sensors for Downhole Reservoir Characterization

The current work covers the evaluation of ultrasonic and electromagnetic (EM) techniques applied to temperature measurement and flow characterization for Enhanced Geothermal System (EGS). We have evaluated both ultrasonic techniques and microwave radiometry for temperature gradient and profile measurements. A waveguide-based ultrasonic probe was developed to measure the temperature gradient. A statistic approach on estimating the average grain size via spectral analysis of the scattered ultrasonic signals is introduced. For directional temperature measurement, different microwave antenna designs are compared numerically and an array loop antenna design is selected for further development. Finally techniques to characterize the porosity and permeability of a hot dry rock resource are presented.