Sampler For Soft Clay Layers

A.P. van den Berg of Heerenveen (the Netherlands) and research institute NGI of Oslo (Norway), have jointly developed a new sampler for obtaining accurate and reliable soil data from soft clay layers of the seabed, especially in deep water. Particularly those layers are easily disturbed and hard to be brought to the surface. With their long-time experience in offshore soil investigation and equipment A.P. van den Berg and NGI developed a sampler that is able to take high-quality samples at great water depths. The sampler characterises itself through:

• a new type of cutting shoe


• the core retainer


• a piston that seals off the upper side of the sampler from the surrounding pressure so that the force exerted on the sample is limited to a minimum


• positioning system that keeps the piston positioned within a couple of millimeters


• a sample tube connection system with which the sample is cut on the spot without disturbing it

After a development phase of 3 years the sampler was tested on the North Sea end of 2005 in co-operation with offshore UK-based operators Gardline and Lankelma. The testing procedure included taking a sample of 12.5 metre length from 300 metres depth. Laboratory tests by NGI showed that the quality of the sample could be qualified as very good to excellent, and that especially the quality of the sample from the soft upper layer was considerably improved with respect to that of existing samplers. A.P. van den Berg and NGI expect that the sampler will become available on the market for samples with a length of 12.5 metre in the second half of 2006.