SMART UTILITY PIGS USED TO DETERMINE AND MONITOR PIPELINE OUT-OF- STRAIGHTNESS, WITH SPECIFIC REFERENCE TO INSPECTION OF BP ALASKA'S 10' NORTHSTAR CRUDE OIL PIPELINE

摘要

Through necessity many pipelines and flowlines are required to operate under conditions where their position may be displaced over time. Such movements can occur for a wide variety of reasons, but are most commonly associated with either movement of the physical surroundings of the pipeline causing movement of the pipeline itself, and/or thermal changes in the pipeline causing expansion and contraction. Displacements as described result in the pipeline experiencing increased levels of strain at local out-of-straightness events, potentially resulting in pipeline failure. The ability to measure and monitor pipeline displacements, in particular identifying specific regions of out-of-straightness, is valuable to both the existing pipeline operator who wants to operate their assets safely, and also to the pipeline designer who is able to design future pipelines with the knowledge that such monitoring capabilities exist. Smart Utility Pig technology measures the longitudinal shape of a pipeline using an onboard accelerometer and angular velocity sensors. The data logged by these instruments allows out-of-straightness features to be identified and profiles of the vertical and horizontal shape of each to be calculated. This paper presents an overview of the requirements for such Smart Utility Pig technology, and details of out-of-straightness measurement applications. In particular, projects are identified where the technology has been deployed in such a role, including specific reference to BP Alaska's 10" Northstar crude oil pipeline.