Using Sub-Bottom Imager Data to Identify Boulders in the Shallow Subsurface to Further Engineering Design

The successful planning of sub-seabed infrastructure such as pipelines and cables required the identification of sub-seabed boulders and other coarse sediments which could pose major risks to trenching and other installations works. This case study outlines how the Sub-Bottom Imager ™ (SBI) was able to mitigate that risk through the mapping of buried boulders and potentially problematic stratigraphic horizons along a proposed pipeline route in the central North Sea.

The SBI, a 3D acoustic chirp system, was able to accurately interpret the location, dimensions and burial depth of boulders along the route and found these to strongly correlate to a number of erosional unconformities in the shallow sub-surface, known to be influenced by glacial processes. With the use of supporting geotechnical and geophysical data these surfaces were able to be mapped throughout the survey route and provided valuable insight into the shallow ground conditions. Enabling a more informed engineering decision as well as demonstrating the value of the SBI in improving geohazard assessment.