Transport and installation
The partners also gave careful consideration to the transport operation. According to managing director Mark Riemers of SPT Offshore, responsible for transport and installation, a MOSES model was used for calculating the transport forces. Model tests were also carried out in the towing tank at MARIN. For transport to the F3 field, considerable water depth was necessary because viewed from the top, the four 13 metre-high suction piles hung more than a metre down into the water. The operation therefore required a total draught of 14 metres and a total width of 63 metres. Including grillage and securing devices, the total transport weight was 10,150 tonnes. “To secure the legs, extendable beams weighing 2,100 tonnes were fitted to absorb the vertical forces, in combination with an 1,850 tonne fork construction to absorb the horizontal forces. On 18 August of this year, the transport barge headed out to sea. The Boa Barge 35 was towed by the Norwegian tugs BB Worker and BB Server. On the outward journey to Flushing, these tugs had already installed an anchor pattern in the F3 block, to allow the barge to be moored immediately upon arrival on site. The journey out to the F3 block took almost four days. Once on site, however, conditions proved too stormy, and the barge had to return to shore. Because of the draught, the initial plan was to use Rotterdam as safe haven. However, the authorities refused to allow the transport into the port. The storm strengthened to a force 9 gale, with waves of up to 6 metres in height.
After a 24-hour wait, we were eventually allowed to enter the port. Upon inspection, it fortunately emerged that the platform had suffered no damage whatsoever.” Once the storm had died down, a second attempt was made. Because the two Norwegian tugs were assisted in this second operation by the far more powerful Bourbon Orca, the outward journey time was shortened by ten hours, representing a reduced weather risk. On 1 September, the transport arrived in the F3 block, for the second time. “Using the strandjacks, we lowered the legs in three hours and it took just another six hours to subsequently simultaneously fix all four suction piles in position. The topsides was then released from the Boa Barge 35, and lifted up into position. When the barge was pulled away, the most precarious part of the operation in terms of weather risk was concluded. During the night of 2 to 3 September, at 1 a.m., precisely two days and four hours after arrival in the field, installation work was concluded.” Following commissioning, the drilling rig Noble Scott Marks drilled the first production well, and just after New Year, the first gas was produced from the field. The first gas delivery represents the successful conclusion for HFG, SPT Offshore and Iv-Oil & Gas of a challenging project that imposed severe demands on the partners, but at the same time generated considerable knowledge for future projects.
2011
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