Date of Award

Fall 2016

Degree Type

Non-Thesis Project

Degree Name

Master of Science (MS)

Department

Geological Engineering

Committee Chair

Larry Smith

First Advisor

Chris Gammons

Second Advisor

Mary MacLaughlin

Third Advisor

Scott Rosenthal

Abstract

The process of sensor validation through experimentation with the Omnisens Distributed Temperature and Strain (DITEST) Brillouin Optical Time Domain Analyzer (BOTDA) proved to be a challenging project. The project encompassed sensor calibrations, system error minimization, sensor network design and deployment, and the characterization of temperatures in the Orphan Boy Mine shaft. Fiber-optic cable sensor calibrations yielded linear relationship coefficients 0.6-1.0MHZ/°F, indicating a strong positive correlation between Brillouin Frequency Shifts and temperature. Calibrated sensors demonstrated accuracies near ±0.8°F using the corrected error bounds from residual analyses as the benchmark. Fiber-optic measurement accuracy and repeatability were controlled by user-selected signal interrogator settings and design limitations within the system.

Temperatures monitored during the February-July 2016 period showed little variation except when the Geothermal Heat Exchange System was in operation. A test of the geothermal system (used to heat the Natural Resources Building on the Montana Tech campus) was documented by the fiber-optic sensor cluster deployed in this project and separately by a temperature transducer from the Montana Bureau of Mines and Geology. Temperature was an auxiliary sensing function of the DITEST; temperature profiles recorded in time and depth demonstrated the capability of the Brillouin-based signal interrogator when used primarily as a temperature sensing system.

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