Page 31: of Offshore Engineer Magazine (Nov/Dec 2019)

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for Equinor off the east coast of England and the north

Combining USVs with AUVs coast of Germany. Using MBES, four pipelines totaling

However, sensors onboard USVs will only reach so deep. 120 miles in length in from 2-40 meters water depth, were If deeper water pipeline surveys are to do done with USVs, surveyed in water depths from 2-40 meters, XOCEAN has an alternative approach is needed. That’s meant deploying said. Another USV vessel operator, 4D Ocean, has per- an AUV from a USV – and that’s just what Swire Seabed formed inshore surveys for Equinor earlier this year with a has been doing for Equinor, in Norway. In October 2018, hull-mounted MBES. in the ? rst of two projects, it deployed a Kongsberg Hugin

XOCEAN has also done what it’s claimed is the ? rst AUV with a small surface vessel that enabled it to main- trailing wire cathodic protection (TWCP) pipeline sur- tain position updates and communication to a control vey from a USV, also in September 2019. This involved from in Bergen. The inspections were performed on three

TWCP surveys, with multibeam sonar, for PX Group pipelines between Kollsnes (an onshore plant) and Troll A on pipelines up to 9km from shore near Shetland and (just 65km off Bergen). In total, 180km of pipeline was off the coast of Aberdeenshire. PX Group operate and inspected over two AUV dives with bathymetric, synthetic maintains, for North Sea Midstream Partners, the St aperture sonar and HD image data acquired to verify the

Fergus Gas Terminal and associated Frigg UK and the subsea pipelines’ integrity.

Shetland Island Regional Gas Export System (SIRGE)

In July 2019, Swire then laid claim to the “? rst fully un- offshore pipelines which link the Aberdeenshire facility manned offshore pipeline inspection ‘over the horizon’”, with the North Sea.

surveying up to 100 km from the shore, again for Equinor.

Source: Shell

Visualization from Shell’s pipeline inspection campaigns.

NOVEMBER/DECEMBER 2019 OFFSHORE ENGINEER 31