Client: Fugro
Location: Australia
For this project, an ROV based Sub-Bottom Imager (SBI) was mobilised to carry out the survey. The SBI produces a 3D acoustic volume, displaying geohazards on and below the seabed down to 5 m penetration, with a 10 cm resolution. Kraken Robotics acquired 200% coverage across the entire survey area, ensuring all gaps in the magnetometer data were infilled, as well as carrying out further investigation of the pre-interpreted magnetic anomalies.
Kraken Robotics reported its observations whilst offshore, enabling the onboard Explosive Ordnance Disposal (EOD) experts to analyse the results and compare them against magnetic anomalies observed during a previous survey. Using the ROV-based Sub-Bottom Imager (SBI), Kraken delivered high-resolution 3D acoustic data that provided a detailed view of seabed and sub-seabed conditions across the survey area.
The SBI’s ability to image below the seabed supported further investigation of pre-interpreted magnetic anomalies, including areas where magnetometer data gaps required additional confidence. By acquiring 200% coverage, Kraken was able to improve data completeness and provide EOD specialists with clear, spatially referenced information to support offshore decision-making.
Unlike conventional sub-bottom profiling methods, the SBI produces a 3D acoustic volume that allows features to be assessed in context, including their depth, shape, and relationship to surrounding seabed conditions. This helped the offshore team review potential geohazards and buried targets more efficiently, reducing uncertainty during the interpretation process.
Figure 1 - Plan view image of the sub-seabed highlighting a pUXO.
Figure 2 - Profile view image highlighting the buried pUXO shown in Figure 1.
The use of the SBI meant that the EOD experts could reduce the magnetometer master target list by 87%, enabling the issue of ALARP shortly after demobilisation.
By reviewing the acoustic dimensions, shape and accurate burial depth, the EOD team were able to assess each anomaly for their likelihood to represent UXO whilst onboard the vessel.
By significantly reducing the UXO target listing, and in turn reducing the amount of vessel days on site, the project developer was able to restrict costs during target investigation by ~£165,000.
