Pipeline Inspection

Ultra-High resolution pipeline inspection

fugro-pipe

The article is originally featured in Fugro Group Magazine Cross Sections.

In the Azerbaijan sector of the Caspian Sea sixty per cent of BP’s 1,232 kilometres of offshore pipeline assets lie in water depths between 12 and 25 metres.

In these waters, particularly in shallow parts, poor water clarity makes General Visual Inspection (GVI) of pipelines via ROV problematic. Delays due to poor visibility on the continental shelf of the Absheron Peninsula are compounded by restricted vessel availability, leading to increased costs.Working with BP, Fugro has developed, designed and deployed an acoustic method of pipeline inspection (PINS) that dramatically reduces the time taken to carry out pipeline

inspection and produces improved information and novel deliverables to assist pipeline engineers in pipeline integrity assurance.

TRADITIONAL INSPECTION METHODS

External pipeline inspection can be carried out visually (GVI) by cameras mounted on an ROV, electrically by current sensors mounted on an ROV and acoustically. Acoustic PINS traditionally involves either sidescan sonar or multibeam echo sounder (MBES) – or both. The sidescan sonar is towed behind a survey vessel so that the pipeline remains within the detection envelope of the transducer. With the MBES technique the transducer is rigidly mounted and the survey vessel maintains a position that keeps the pipeline within the detection envelope of the transducer.

TECHNOLOGY DEVELOPMENT

The poor water clarity of this area, together with restricted vessel availability made it difficult to meet BP’s annual targets for GVI PINS. Investigation into alternative methods highlighted the “FlexMode” option in RESON’s 7125 MBES, which was specifically designed for pipeline inspection operations. This functionality allows part of its fan of acoustic beams to be operated in “equi-angle” mode, creating a narrow, steerable sector of densely spaced beams to deliver a very highly resolute and dense data set of the area of the seabed upon which it (the steerable sector) impinges. The vessel is piloted to keep the dense steerable sector of beams impinging on the pipeline and the seabed on either side of it. Small lateral offsets are compensated for by steering this sector electronically to keep the pipeline in view.

Sumber : http://www.teledyne-reson.com/news/ultra-high-resolution-pipeline-inspection/