Multiple offshore Arctic fields have been developed over the past three decades and the world demand for oil and gas will continue to drive hydrocarbon development in Arctic and sub-Arctic environments. Arctic pipelines are used for the safe and economic transportation of hydrocarbons. While pi pelines are designed not to leak, excessive strains due to the effect s of ice gouging, strudel scour, frost heave and p ermafrost thaw settlement along with other loading and failure mechanisms (i.e. corrosion, third party damage) could result in a leak. Failure to detect leaks in a timely manner could have severe safety, environmental, and economic impacts. 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.First, this paper reviews existing Leak Detection System (LDS) technologies for their potential use on Arctic and sub-Arctic pipelines. The technology evaluation based on regulatory requirements and functional criteria suggests that Fiber O ptic Cable (FOC) distributed sensing systems have a high pote ntial to be use d on Arcti c pipelines. Distributed sensing FOC can b e used to detect and locate leakages. Pipeline leakage would gen erate a local change in te mperature. These thermal anomalies can be captured by FOC Distributed Temperature Sensing (DTS) systems with good spatial and temporal resolution. Similarly, the acoustic signature generated by leaking fluid can be detected using FOC Distributed Acoustic Sensing (DAS) systems. Inelastic Brillouin and Raman backscattering principles are used for measuring temperature in DTS, whereas the Rayleigh backscattering principle is used for measuring acoustics in DAS. This paper presents information on a pplicable regulations, operating principles, optical budgets, system integration, sensor positioning, installation and maintenance assessment, technology status, risk an alysis using Failure Mode, Effec ts and Critic ality Analysis (FMECA) and field implementation challenges.

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In 1993, at the beginning of the Popeye Project, Shell Offshore Inc. (S01) entered into an innovative commercial agreement with Sonsub Inc. (Sonsub) to develop a technological first in the area of completion work over riser systems, Sonsub would design, manufacture and test a new concentric bore Completion Riser/Work over Control System rated for use in water depths of up to 6,000 ft. SOI would then lease the equipment on an as needed basis from Sonsub. This type of relationship proved to be an efficient approach of introducing new technology to the industry and managing the higher costs of deepwater developments. Introduction As the industry continues to extend subsea developments to deeper waters with higher pressure reservoirs, the operating limits of the required equipment (such as subsea trees, wellheads, drilling rigs, lay barges, etc.) are being constantly stretched. The commercial issues involved in funding these deepwater developments are also becoming increasingly more complex due to the high costs of the equipment and the ever important length of time to first production. One of the key equipment components necessary to complete and operate developments is the completion riser and work over control system. This paper will brieflyoutline the methodical approach taken by Sonsub and SOI throughout the initial design, manufacturing and testing. Stages and it will describe the commercial arrangement between S01 and Sonsub. It will also briefly describe the unique and universal Completion Riser Work over Control System and narrate the results of its first offshore use on the Popeye Project. A summary will follow of the ongoing additions/modifications necessary to meet the world record water depth requirements of S01's Mensa Project. Background During the early planning stages of Popeye, SOI had recognized many new technological issues that would have to be solved in order to develop Popeye and its other deepwater prospects in the Gulf of Mexico, Sonsub had also surveyed several offshore operators, including SOI, in regards to a 'Universal' deepwater completion riser and work over control system which would accommodate existing equipment from the various subsea equipment manufacturers. Various types of riser and riser coupling designs, riser spider designs, riser handling methods and various controls equipment packages were reviewed. Operations off shore were discussed in detail and, while several operators expressed a preference for a conventional dual-bore, integral non jacketed riser, most recognized that the existing designs for these types of risers were not adequate for deepwater applications, especially in water depths beyond 3,000 ft. Most operators also acknowledged the suitability of a concentric riser, if a reliable method of accessing both bores was available.