ABERDEEN, UK – Rotech Subsea has completed a program of cable de-burial, cuts and recovery at a North Sea offshore wind farm.
The company deployed its RS2-3 Hybrid CFE (controlled flow excavation) tool for de-burial of around 500 m of cable, and its RSG-C tool to complete the cable cutting at both ends followed by recovery to the ship’s deck.
The RS2-3, operating in water depths of 12-15 m, was lowered into the sea by a crane from the vessel’s stern. traveling along the 0-5-km cable to complete de-burial operations. Required excavation depth was 2m: depth was monitored in real time using a tool-mounted sonar imager, with de-burial performed in two passes.
Rotech Subsea director of subsea, Stephen Cochrane, said that due to the anticipated hard soils, the company took the precaution of having an extra RS2 excavator on standby, providing the option of using the tools in twin ‘TRS2’ configuration to provide maximum flow.
“Despite hard, sticky clay experienced, the works were carried out in just two passes, one with the RS2-3 hybrid solution, which has a maximum outlet pressure of 300 kPa and a max jet flow of 4000L/s, and one pass with the TRS2 configuration capable of 8,000 l/s of flow.”