Oman India Pipeline: An Operational Repair Strategy Based on a Rational Assessment of Risk

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Abstract This paper describes the development of a repair strategy for the operational phase of the Oman India Pipeline based upon the probability and consequences of a pipeline failure. Risk analyses and cost benefit analyses performed provide guidance on the level of deepwater repair development effort appropriate for the Ornan India Pipeline project and identifies critical mm toward which more intense development effort should directed. The risk analysis results indicate that the likelihood of a failure of the Oman India Pipeline during its 40-year life is low, Furthermore, the probability of operational failure of the pipeline in deepwater regions is extremely low, the major proportion of operational failure risk being associated with the shallow water regions. Introduction The Oman India Pipeline (OIP) will transport natural gas approximately 1100 km from Oman to India under the Arabian Sea at water depths to 3540 meters. The majority of the Oman India Pipeline route is not diver accessible, Diverless pipeline repair systems are currently under development by the offshore industry at a modest pace, but a diverless pipeline repair has not been performed to date; although a number of pipelines are currently in operation in water depths beyond diver reach. Hydrate formation resulting from pipeline failure and subsequent water ingress is the subject of a separate program of investigation. This programmes includes physical testing and mathematical modeling to gain thorough understanding dehydrate morphology and confirm the proposed engineering solutions. Risk Analysis Overview. As part of the comprehensive risk analysis program undertaken for the Oman India Pipeline project, an operational risk assessment of the subsea pipeline was performed to determine pipeline failure probability subsequent to successful installation and start-up, during its 40-yw design life. Expected hazards which may threaten the subsea pipeline during operation and the of failure initiating events resulting from those hazards were identified. Hazards evrduated include those that stem from natural phenomena such as earthquakes, subsea landslides and ocean dynamics; third-party events such as vessel accidents and anchor dragging incidents, sabotage and military action and processes such as internal and external corrosion. The operational risk analysis was performed for discrete regions or zones along the proposed pipeline route permitting characterization of the various zones based on unique features or common susceptibility to hazards. The overall pipeline operational reliability was then obtained by integration of the reds for each zone. Zone Delineation. The subsea portion of the pipeline was segregated into sixteen zones along the planned route across the Arabian Sea and the hazard probabilities for were zones were ranked and quantified.