Subsea productivity advances using 3D sonar technology

Paul Boughton
Gareth Simpson looks at the advantages of 3D sonar technology.

The Echoscope from CodaOctopus is a sonar device generating more than 16,000 beams simultaneously to produce instantaneous three-dimensional sonar images of both moving and stationary subsea objects.

Capable of up to 12 updates per second, the co-registered 3D imagery from each ping allows visualisation of the whole underwater environment in real time, enabling extremely rapid reconnaissance and inspection.

The Echoscope has been extensively used worldwide since 2005 in the oil and gas industry, harbour security applications and in dredging and port construction projects.[Page Break]

Renewable energy

Recent months have seen it deployed in a number of different ways in the rapidly expanding renewable energy sector.

In association with Nautikaris BV the Echoscope was deployed by Deep BV Hydrography and Geophysics, providing positioning and survey services for the installation of a power cable at the Thornton Bank Wind Farm off the Belgian coast.

Using Echoscope the operator was able to visualise in real time the cable's catenary and touchdown point in three dimensions as it was being laid. The sonar was also used to visualise and monitor the pull-in of the cable into the J-tube. This gave the operator an immediate 3D view of the subsea scene during the operation, resulting in rapid and confident decision making.

Furthermore, using CodaOctopus' proprietary USE software with its 'augmented reality' capabilities it was possible to overlay a computer generated image of the planned siting of the cable onto the sonar view to confirm the cable was being laid on target.

Deep BV thus used the advantages of real time 3D sonar with augmented reality to achieve significant productivity gains to the cable laying operations.[Page Break]

Adjustments online

The sonar ensured the correct siting of the cable as the operator was immediately able to make necessary adjustments on-line. The result was a continuous workflow without having to stop the lay barge and survey the laid cable to check its position in the trench. Significantly, no remedial action to the laid cable needed to be made, hence major time saving benefits were realised.

In another application at the Sherringham Shoal Offshore Windfarm, Statoil and their contractor Van Oord have been installing monopiles for 80 turbines. The installation involved the very precise placement of rocks around the side of the J-tube, where the cable enters the monopile, to form a cushion layer. This is achieved by dumping rock down a specially designed fallpipe, and it is vital that the operator is able to understand exactly where each of the elements is relative to each other.

The Echoscope was used to visualise the scene before, during and after the rockdumping, avoiding the need to slow down the operation to check progress with a conventional multibeam site survey.

Ton Hardonk, the Van Oord Surveyor on the project, said that: "The Echoscope was an enormous help during the precise rockdumping phase."

Vernon Bridges, the Statoil Vessel Representative, noted: "I have been very impressed with the Echoscope equipment, and it certainly greatly helped our contractor Van Oord place the rock more accurately than would have otherwise been possible. I am sure that this new technology will become more commonly used once people see the benefits it can bring to a project."

From those subsea projects detailed above alongside a whole host of similar underwater activities significant efficiency and productivity gains can be made by using leading edge Echoscope real time 3D sonar technology.

Enter √ at

Gareth Simpson is with CodaOctopus, Edinburgh, UK.

Recent Issues