Offshore staff
ABERDEEN, UK – Rotech Subsea has completed de-burial and post-lay trenching works on the London Array offshore wind farm in the outer Thames Estuary.
In 3Q 2021, the company’s TRS1LD controlled flow excavator completed a de-burial and post-lay trenching campaign of 1,000 m (3,280 ft) of subsea cable at the offshore wind farm. Deployed using the vessel crane of the Forth Jouster, the TRS1LD carried out the de-burial phase of the cable, which was 1-1.5 m (3.3-5 ft) below the seabed, in two passes. The cable was subsequently extracted.
The tool operated in depths of 3-10 m (10-33 ft) and soft sand soil conditions. Currents ranged from 0-2.2kts with general sea states ranging from 1 to 1.5m Hs.
In October, the subsequent post-lay trenching phase saw the TRS1LD mobilized on the Nora B with the cable buried to a minimum of 1.5 m below seabed. A first pass excavated to 1.75-2.1 m (5.74-6.9 ft) depth with a second survey pass confirming the cable had dropped to 1.5-2.6 m (5-9 ft) depth below the seabed.
In addition, the company completed the de-burial and re-burial of two export cables on the Saint-Nazaire wind farm offshore France’s Guérande peninsula.
The company used its company’s RS2 controlled flow excavator to de-bury cables C1 and C2 situated at 2 m (7 ft) below MSBL, with the cables re-buried to the same depth following jointing operations by the client.
The subsea spread of equipment was mobilized for Saint-Nazaire on the Zwerver 1 in 2Q 2021. It was deployed via crane to operate in water depths of between 8-30 m (26-98 ft) LAT, experiencing soil conditions including dense sands with a hard layer present at 2 m.
The company said the RS2 de-buried the cable to client spec with one pass at progress rates of between 2 and 3 m/min. Burial depth was achieved in one pass at a rate of 1-2 m/min with the client requesting a second flushing pass as a contingency.
12/03/2021
