Case studies for intelligent pigging of 'unpiggable' offshore pipelines
Proceedings Publication Date
Edwin Rosier
Edwin Rosier
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Offshore pipelines are often very challenging pipeline for pigging and inspection. Riser pipes are vulnerable and critical for the asset owners, especially in the splash zone. Some pipeline end up to a manifold (PLEM) or a Bouy for loading ships. Sometimes Wye-pieces are constructed in the line or different diameters occur. Near the platform itself some difficult (unbarred) Tee-pieces, back-to-back bends or factory 1,5D bends create challenging configuration that give ILI vendors a headache.

As a 30 years experienced inspection company Intero Integrity gained a lot of experience using their creative solutions to tackle these ‘unpiggable’ pipelines. Some anonymous case studies can show the solutions possible to inspect (and clean or gauge) the pipeline for the offshore oil companies around the globe. We also consider jetty- and loading lines as well as subsea pipelines to this topic.

Most projects start with mobilizing offshore certified equipment to the platforms. This may include temporary pig traps, pumps in various types, electrical winches and some pipe spools to create a piggable and pumpable system.

  • Dual diameter pipelines can be handled using a Wilson pig as pulling body.
  • Thethered tools need to used when pumping is not possible.
  • Bi-directional tools can sometimes be the only solution for jetty-lines or export lines to manifolds.
  • Pre-loaded pig launchers can be a solution to pass Wye-pieces when pigging in one direction is only possible.
  • Magnetic markers and divers are sometimes a necessity to secure a save inspection operation.
  • Creatives solutions to save water usage and handling can be found by using piggy-bag lines.
  • For some dry gas pipelines where flexible UT inspection tools are the only solution for save pigging the pipeline needs to be dried with nitrogen to enable operations afterwards.

A lot of solutions are proven concept with respect to cost efficiency.

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