Fiji Pipeline Temperature Measurement Optical Cable System

The Fiji Pipeline uses a distributed fiber optic temperature sensing (DTS) system to provide continuous, real-time monitoring of pipeline temperatures along its entire length.Technology OverviewThe system relies on fiber optic sensor cables embedded along the pipeline, which measure temperature continuously using Raman or Brillouin scattering techniques . A laser pulse is sent through the fiber, and the backscattered light is analyzed to determine the temperature at specific points along the pipeline. This method, known as Optical Time Domain Reflectometry (OTDR), allows precise temperature profiling with spatial resolution down to one meter . The DTS system can detect temperature variations as small as ±0.1°C, enabling early identification of blockages, leaks, or integrity issues .Fiber Optic Cable DesignThe optical cables are typically armored or metal-tubing cables to withstand harsh subsea and buried environments . The fiber is embedded in a protective tube and wrapped between tensile armors during pipe manufacturing, ensuring durability against mechanical stress, rodent damage, and environmental hazards . For high-temperature or cryogenic conditions, specialized coatings such as polyimide or metal are used, while standard polyacrylate coatings suffice for normal operating temperatures . The cable terminates at the topside end fitting with an optical connector for integration with the monitoring system.Operational BenefitsThe DTS system provides real-time temperature profiles from seabed to surface, which is critical for:Flow assurance: Detecting blockages or abnormal cooling/heating along the pipeline .Integrity management: Monitoring axial movement, pipe burial, or upheaval buckling .Leak detection: Identifying hot or cold spots indicative of leaks or third-party interference .Late-life field management: Supporting intelligent operational decisions as production rates vary . The system can monitor long distances, with modern DTS setups capable of covering up to 60 km from a single instrument, extendable to 300 km using optical amplifiers . Integration with Distributed Acoustic Sensing (DAS) enhances detection of acoustic anomalies, providing a comprehensive monitoring solution .Installation ConsiderationsProper installation is essential to maintain sensitivity and durability. Cables must comply with ANSI/ICEA standards for outdoor and indoor-outdoor optical fiber cables . Armored or dual-jacket cables are recommended for direct burial to protect against mechanical damage while maintaining accurate temperature sensing. Overly protective sheaths can reduce sensitivity, while insufficient protection risks environmental damage .SummaryThe Fiji Pipeline's optical cable system leverages advanced DTS technology to provide continuous, high-resolution temperature monitoring. By combining robust fiber optic cable design with real-time data acquisition, the system ensures pipeline safety, operational efficiency, and early detection of anomalies, making it a critical component of modern subsea pipeline management .