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How geospatial tools improve the insights gained from platform inspection and rig installation surveys

Survey data and geospatial tools

Platform inspection and rig installation surveys are required when decommissioning or redeveloping existing offshore assets. Several key datasets need to be acquired to perform such analyses, including bathymetry, seabed debris / contacts locations and still photography / video.

Additionally, point cloud data can be captured to derive 3D modelling products. These can be particularly useful for assessing existing subsea structures.

Seabed mobility

The seabed around the platform’s base can be highly mobile. To assess the degree of mobility, a comparison can be made between previously acquired bathymetry and that acquired most recently.

Different models can be used to assess the areas in which sediment has accumulated vs. scoured away.

Sandwave mobility can also be assessed by measuring from peak to peak of the old vs. current sandwave position. This can provide a rough indication of how fast the migration is and how quickly scour features may be developing.

Identifying hazards

When installing a jack-up rig at a platform location, anchors are deployed to provide stability.

To reduce the risk of an anchor landing on something it shouldn’t, an assessment can be made using acquired bathymetry and the ROV photo stills/video.

Targets identified in the bathymetry can be matched with their corresponding photos to provide better context and assessment of coverage, and whether any hazards were posed by these.

3D modelling

3D models can be derived from ROV-acquired point cloud data to better understand the existing structures' conditions. Marine growth can be digitally removed to reveal further insights, provided in-field measurements are taken to assess the thickness.

Areas of interest within the model can be cross-referenced with the images captured by the ROV to confirm the validity of the model. This helps provide assessments of the scour at each leg location.

- November 2022