Prior to any installation of subsea utilities, a detailed pre-engineering route survey is required. This will use bathymetry to chart the seafloor, geophysics to interpret the sub-seabed stratigraphy in the surface layers and assess any hazard to installation and a magnetic survey to analyse the presence of ferrous materials such as UXO.
Additionally, an ROV can be deployed to review the environmental conditions along the route. Shallow sampling such as CPT, grab sampling or vibrocoring is performed at regular intervals along the route to ground truth the geophysical survey data which allows integrated reporting of both geophysical and geotechnical data sets.
This information will be used to select the most appropriate route and plan the installation activities.
As the installation barge is laying the utility, Horizon continuously provides precise positioning and visual identification from a ROV of the subsea installation activities.
The accurate positioning of where the utility is installed is critical for future developments and nautical charting.