Offshore CPTs, Core Logging and Sample Analysis - Marine Geological Testing in the North Sea

In the summer of last year, In Situ Site Investigation’s Marine Geotechnical Services team provided specialist geotechnical support for a major North Sea UK sector offshore wind HVDC interconnector cable route survey. Working closely with one of our regular offshore survey sector clients, the project involved marine CPT data interpretation, marine sample core logging, marine geological testing and subsequent geotechnical reporting. Over 200 offshore CPTs, 30 nearshore CPTs and 150 Vibrocore’s were completed as part of the specified marine in situ testing programme with the data being interpreted by our specialist team working to the highest accredited standard complying with ISO 22476-1.

Core logging and processing of the recovered vibrocore samples obtained during the survey was carried out at In Situ’s dedicated sample and core logging facility, based in Rotherham, South Yorkshire. The facility is equipped with two core splitters, together with core photography set-up and logging stations. Samples obtained from marine investigations are routinely processed at the specialist facility, with the recovered cores, both sediment and rock, photographed and logged by our highly experienced team of in‐house geologists to the current European standards EN ISO 14688 and 14689.

On this particular contract the processing of the samples involved the application of several marine geological testing field analysis techniques including, material shear strength analysis via hand held Torvane, Pocket Penetrometer, Hand Vane and Fall Cone testing. Material properties analysis was also undertaken via needle probe Thermal Conductivity/Resistivity testing and Wenner array Electrical Resistivity testing. These techniques are routinely required as part of any marine geological testing programme and provide vital design information on the existing seabed conditions prior to submarine HVDC cable installation. In Situ regularly provide this type of service to a wide range of clients from across the UK and European marine survey sector.