Uneven seabeds are traditionally prepared for laying offshore pipelines by installing large volumes of rock. As an alternative to this subsea rock installation (SRI) method, Van Oord has applied the deep excavation system (DES) in Australia and Norway. On these projects, excavating several thousand cubic metres of hard and soft soil made the installation of hundreds of thousand tonnes of rock unnecessary. Combining the excavating system and SRI can be a cost-effective solution for seabed preparation.
The Deep Excavation System allows dredging to take place at depths varying from 100 - 1000 m. Van Oord’s flexible fall pipe vessels Stornes and Bravenes (operational in 2016) can be equipped with this system, which has been developed in-house. It consists of the combined application of a sophisticated grab and a fall pipe remotely operated vehicle (FPROV). The DES has a very accurate position control system and generates only very limited turbidity, which is vital in view of potential nearby sensitive marine environment like coral.
‘Nowadays, oil and gas are being extracted more and more from isolated fields in deep water and transported over long distances. Our clients face these challenges. To meet their needs, we offer tailor-made solutions by applying our marine ingenuity. The Deep Excavation System is an example of this and a valuable addition to our complete package of offshore services’, says Joep Athmer, Managing Director of Van Oord Offshore.
Adapted from press release by Hannah Priestley-Eaton