Protecting HSE: Monitoring Pipe Bending Stress Using Temperature Compensated Distributed Fiber-Optic Strain Sensor for Enhancing Pipeline Integrity Situational Awareness

Abstract A distributed fiber-optic strain and temperature sensor (DSTS) with less than 1mW (Laser Class 1M) of pump power has been developed by controlling depletion of pump beam resulting from coherent interaction of probe and depleted pump (CIPDP). DSTS with CIPDP technique ensures flat-noise-floor over entire fiber length, which offers same resolution and accuracy over entire fiber length and makes simultaneous measurement of strain and temperature possible. Bending stress monitoring of an 11km pipeline located in northern Alberta, Canada using temperature compensated distributed fiber-optic strain sensor with CIPDP technique is presented. The results showed that some parts of the pipeline experienced 3,063µε during winter from November 2022 when the pipeline was installed to April 2023 when the soil was still frozen. The pipeline leaks due to the ambient temperature change are presented also. The leak volume of 2.187gal with the injection pressure of 105psi and the temperature difference of 39°F (21.6°C) between the line temperature and the soil temperature has been detected in one minute after a leak occurred through 1/8" orifice. All leaks with different volumes controlled by injection pressure, orifice, line temperature, and duration have been detected successfully.