Distributed Fiber Optic Temperature Sensing: A New Tool for Long-Term and Short-Term Temperature Monitoring in Boreholes

Abstract

The Distributed Fibre Optic Temperature Sensing Technique (DTS) represents a new physical approach for temperature measurements in geosciences This method was applied for long-term surveying temperature variations with time caused by injecting and extracting hot water in a 600 m deep well The measuring system was installed as a permanent sensor in the annulus between casing and tubings The injectiodextraction regime was monitored by repeating the measurements every few weeks Short-term variations of the temperature during injection and extraction were studied by recording the temperature profile every 1 minute over a time period of several hours Testing shows that the fibre optic temperature sensing opens new possibilities for measuring the actual temperature along the entire length of a borehole as well as for monitoring short-term and long-term temperature variations