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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 H 2 S 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.

In the design of ultra-deepwater steel pipelines, it is important to be able to determine the pipe behaviour while subjected to external pressure and bending. In many cases, the ultra-deepwater lay process, where these high loads exist, governs the structural design of the pipeline. Much work has been performed in this area, and it is generally recognized that there is a lack of test data on full-scale samples of line pipe from which analyses can be accurately benchmarked. This paper presents the results of a nil-scale test program and finite element analyses performed on seamless steel line pipe samples intended for ultra-deepwater applications. The work involved obtaining full-scale test data and further enhancing existing finite element analysis models to accurately predict the collapse and post-collapse response of ultra-deepwater pipelines. The work and results represent a continuing effort aimed at understanding the behaviour of pipes subjected to external pressure and bending, accounting for the numerous variables influencing pipeline collapse, and predicting collapse and post-collapse behaviour with increasing confidence. The test program was performed at C-FER Technologies (C-FER), Canada, with the analyses undertaken by the Center for Industrial Research (CINI), Argentina. The results of this work have demonstrated very good agreement between the finite element predictions and the laboratory observations. This allows increased confidence in using the finite element models to predict collapse and post-collapse behaviour of pipelines subject to external pressure and bending.

Much research has been performed over the past twenty-five years to refine our basic understanding of tubular stability, which includes bifurcation, imperfect systems, factors influencing tubular stability and post-buckling behaviour. Tubular instability resulting from load combinations is not a trivial topic, particularly when inelastic material behaviour occurs. Many influencing factors must be considered when attempting to understand (and predict) the onset of instability. Many existing collapse predictive methods are either simplistic or involve advanced plasticity or finite element methods. Simplistic methods are typically semi-empirical, and contain a degree of uncertainty resulting in conservative collapse predictions. Nonetheless, they are generally considered satisfactory for design purposes. Advanced methods normally involve high-end calculations using specialized software programs that might not be available for general use. Therefore, a relatively easy-to-use method that accurately predicts the actual collapse resistance is, in many cases, the most desirable option. This paper presents a collapse predictive methodology, developed from a variety of research projects performed over the last fifteen years. The prediction method, which can easily be entered into a spreadsheet program, is applicable to most forms of tubular members, including pipelines. Applicable load combinations include external pressure, axial tension and bending. An overview of the parameters influencing collapse resistance is also provided, including manufacturing history, material modelling, and tubular geometry and imperfections. Also presented is a summary of accuracy of the method to predict some test results. The test database largely contains results of collapse tests on tubular members subject to only external pressure, and axial tension with external pressure. The adaptation of the method to include external pressure with bending is summarized, and the accuracy of the prediction method is demonstrated by predicting the results of the Oman-India and Blue Stream pipeline collapse test programs, and comparing these predictions with those of other well known methodologies.