Very long HDD outfall into the North Sea

In January 2023, Brownline contributed to a special project: installing an optic fibre connection between the United Kingdom and Europe. This involved drilling more than 2 km / nearly 7,000 ft into the North Sea!

Commissioned by O’Connor Utilities Ltd, we surveyed this HDD using the Drillguide Gyro Steering Tool. The bore is part of a two-pronged optic fibre connection from the British east coast to the Netherlands and Belgium. After completion, Europe’s data capacity and especially the connectivity between the UK and mainland Europe will be greatly improved.

Drilling under the North Sea

This bore was part of the northern track. For the southern branch of this connection, an outfall has also been carried out using the Drillguide GST.

The first two kilometers from Dutch soil were drilled in a straight line under the dunes. About 1,600 m / 5,200 ft from the coast, the drill punched out and the bore was completed.

Using the Pressure-While-Drilling module inside the Gyro Steering Tool, the annular pressure was monitored in real time. It was important to keep an eye on these measurements in order to avoid inadvertent returns from spilling out into the North Sea.

Drill rods as cable duct

One remarkable thing about this project was that the drill rods that were used on this HDD will remain under the sea bed. The rods will serve as the product pipe for the optic fibre cable to be pulled in. The exact position of each drill rod was precisely recorded with our Gyro Steering Tool’s measurements, so there will be a clear record of where the cable is located post-completion.

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