Investigating the challenges of the deep


New deepsea mining concepts were under test in MARIN’s Deep Water Offshore Basin.


Recent developments in the offshore deep- sea mining sector have resulted in new concepts for deep and ultra-deep systems to recover natural resources from the sea bottom. At water depths ranging from 300 m up to 6000 m, valuable materials can be recovered. Last February MARIN organised a demonstration model test to show the feasibility of two typical systems and to investigate their hydrodynamic challenges.


Olaf Waals o.waals@marin.nl


Natural resources can be found in the proximity of so-called “black smokers”, which are active subsea volcanic areas that produce sulphates and metallic nodules that settle down on the sea bottom. Various deepsea mining concepts are being developed to recover these resources at water depths ranging from 800 m to 3000 m and even deeper. Typical concepts involve a vertical riser system with mid-water pumps, gas lift systems or a deep water lifting arrangement to bring the material to the surface.


A demonstration test was designed to show two systems in parallel deployed from one vessel. The vertical riser system was hung off from the centre of the vessel (including two mid-water pumps, modelled as 120t mass) and the deepsea lifting arrangement was located at the stern. A stock model was used at scale 1:80 to model the deepsea mining vessel and this was tested in the deep pit of the offshore basin at a water depth of 1530 m.


From hydrodynamic research experience for the oil & gas industry in deep and ultra-deep water we know that there are challenges such as the dynamic response of floating systems in waves and current. Vortex induced vibrations and excitation of natural modes of the vertical transport system could occur. During the tests visual observations were made and accelerations in the vertical transport system were measured and these will be reported in a conference paper next year.


report 9


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24