Site Investigation Works

Whether it is dredging, marine engineering, reclamation, or drilling, no offshore works are executed without thorough site investigation works. Accurate estimates of soil characteristics and geotechnical properties determine the success, and profitability, of a project. Various layers of soil may be of various quality, and range from pure and fine-running sand to limestone, stiff clay, or even rock outcrops of divergent hardness.

Self-elevating fixed platforms and geotechnical drill vessels are well equipped to carry out a variety of innovative geotechnical and geophysical investigations. Current applications of techniques include large diameter vibrocoring, subsea coring, SONIC and GeoborS sampling, geophysical borehole logging, pressure meter testing, lab testing, bahymetric surveys, sub bottom profiling and side scan sonar imaging.

Offshore geotechnical soil borings in deeper waters are conducted from one of GeoSea's actively heave compensated drilling rigs which is complete with wire line system, Wison PCTP systems, HPD equipment, GeoborS samplers, piggy back coring and fully equipped offshore soil testing laboratories.

There is also a need to monitor and collect environmental parameters, such as wind velocities and waves heights, prior to the design and during the execution of offshore works. A fast, reliable, and very cost-effective alternative for a meth mast is wind mapping from an innovative, in-house developed FLidar, a floating assessment tool.


In November 2017 GeoSea acquired a majority share (72.5%) of G-tec, a Belgium-based contractor specialised in offshore geotechnical and geological site investigations, geophysical marine and environmental surveys and deep sea engineering services. The other shares are owned by the Sociéte Régionale d’Investissement de Wallonie (SRIW). G-tec was founded in 1993 and employs over 40 highly skilled staff. The company also owns the unique, offshore geotechnical investigation vessel ‘Omalius’. The company is active in offshore renewables, oil & gas, civil works and offshore mining. The highly specialised activities and know-how of G-tec represent a strategic fit, enabling DEME to further reinforce its fully integrated services in these markets. Geotechnical investigation from the GeoSea jack-up vessels is already part of the current offering. Furthermore, some years ago DEME took over G-tec’s concession for the exploration of manganese nodules in the Pacific Ocean.


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