Issue #134, 18 June 2004
Jan de Nul wins new work from offshore oil and gas market
Belgian dredging company Jan De Nul has recently been awarded for more than200 million Euro worth of contracts related to the installation of oil and gas pipelines.
On the island of Sakhalin, north of Japan, shore approach dredging andpretrenching is being executed to protect the pipelines against ice scouring.
For the landfalls, a cofferdam is being built in temperatures down to 30° C below zero in very remote areas 1000 kilometers away from the nearest supply basis.
To this effect, special adapted equipment for working in arctic conditions has been mobilised by Jan De Nul's civil department.
The shore approach dredging will be executed by Jan De Nul's large newcutter dredger JFJ De Nul. With 27,150 kW installed and accommodation for 60persons this vessel is by far the largest of its kind in the world, and particularly suited for working in remote offshore conditions without shelter possibilities.
In particular, the newly
developed spud system allows to lower and raise the spuds over a very short time, and as such limits the vulnerability of the dredger in case of upcoming bad weather.
This new dredger recently received the 2003 Dutch award for 'Ship of theYear' for its innovative design.
A further characteristic of the JFJ De Nul is that its underwater noise emission is much lower than for any other dredger. This is of particular importance forworking nearby feeding areas and not disturbing sea mammals. The lowunderwater noise emission has been achieved by compliant engine mountswhich considerably reduce structure borne vibration.
In Hong Kong, landfall dredging and approximately 1.5 million tons of rock dumping has to be executed for the gas pipeline connecting the Guangdong Liquefied Natural Gas Terminal located at Cheng Tou Jiao (Shenzhen) to the new units at Lamma Extension.
Jan De Nul will ensure the rock berm design for protecting the pipelineagainst 15.8 ton anchors by means of model
testing and computer simulations.
Installation of the rock berm will be executed by the dynamic positioned rock-dumping vessel Pompeď.
Offshore Iran, Jan De Nul's trailing suction hopper dredger Francis Beaufort has successfully completed a fast track dredging project for Statoil at the SouthPars Field.
The work consisted of soil replacement in order to improve the bearing capacityof the seabed to ensure the stability of two jackets SPD 8 and SPD 9 duringinstallation and piling.
As the works had to be executed in approximately 70m of water, Jan De Nulmobilised its new trailer Francis Beaufort on short notice.
A particular challenge was the presence of a 6m high Well Head casing within the 30 x 30m footprints to be dredged and backfilled.
This required extreme accuracy of the positioning and survey systems while dredging close to the Well Head.
Controlled sand filling of the dredged area was subsequently performed
using thesuction pipe as fall pipe.
Jan De Nul's quick response and flexibility have ensured completion of the workswithin a record time, to the full satisfaction of Statoil.
For installation of an ocean outfall in Mauritius, Jan De Nul's backhoe dredgerwill be used. As a trench has to be executed in volcanic basalt rock, the dredger is equipped with a hydraulic rock breaker.
Subsequently, a glass fiber reinforced pipeline with radial strength similar to steel will be installed and the trench filled with concrete and rock to protect the pipeline against the impact of waves.
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