Real-time integrity monitoring is a sensor-based monitoring system aimed at enhancing the productivity of Arctic pipelines. The intent of pipeline integrity monitoring is to assess operating conditions and performance, improve performance and pipeline throughput, extend life and inform the operator if pipeline integrity is compromised. The other purpose of the monitoring is to provide the necessary information to perform optimal Inspection and Maintenance (IM) activities. Real-time integrity monitoring provides warning when something is starting to go wrong, and provides instantaneous information when things have gone wrong. Without monitoring, the condition would continue to degrade the pipeline integrity until failure.
Due to Arctic pipeline design and operational challenges, like ice gouging, strudel scour, upheaval buckling, frost heave and permafrost thaw settlement, along with seasonal ice cover and remote location, real-time integrity monitoring is a challenge. With real-time monitoring systems that predict failures and maintenance requirements, the operator can schedule IM activities in an optimal manner. Real-time integrity monitoring balances the cost of monitoring with the benefits of early detection and subsequent warning of abnormal conditions to ensure reliability is maintained throughout the entire life of the pipeline. Arctic pipeline integrity monitoring solutions consist of different technologies, ranging from flow, pressure and temperature gauges, sand and H2S monitors, usage of in-line inspection tools and ROV, external continuous Fiber Optic Cable (FOC) temperature and strain sensors, satellite surveillance and overflight by helicopters.
The first part of this paper will focus on Distributed Temperature Sensing (DTS) and Distributed Strain Sensing (DSS) systems to detect integrity threats arising from the unique Arctic design and operational challenges. The failure to detect pipeline leaks in a timely manner could have severe safety, environmental, and economic consequences in the Arctic. Large leaks can easily be detected, but small chronic leaks may go undetected for a period of time, especially when pipelines are buried in remote locations or under seasonal ice cover. Technology evaluation based on regulatory requirements and functional criteria suggests that Fiber Optic Cable (FOC) distributed sensing systems have a high potential to be used for Arctic pipelines to detect and locate leakages. Pipeline leakage would generate a local change in temperature. These thermal anomalies can be captured by FOC DTS systems with good spatial and temporal resolution. Similarly, the acoustic signature generated by leaking fluid could be detected using FOC Distributed Acoustic Sensing (DAS) systems. The second part of this paper covers the operating principles and technology status of FOC leak monitoring system for Arctic pipelines.