The Wagenborg Foxdrill team recently completed a very special offshore lifting project: the dismantling of a complete derrick on an offshore platform about 50 kilometers off the coast of Congo.
A class of its own
Dutch-based Dixstone Shipyard Holland BV awarded the complex derrick-removal scope to Foxdrill because of the specific skills and experience on derrick removal operations of the Foxdrill team. Dixstone is operating as a turnkey contractor for the platform conversion scope.
In other words: a top-class derrick dismantling project, both in terms of the engineering and work preparation, as well as the techniques and rope access activities used. Bart Oude Ophuis, Operations Manager, and Sander Hilbrink, Project Manager, give an insight.
100 meters high
‘This offshore platform is being converted into an unmanned production platform,’ Bart begins. That means, among other things, dismantling the derrick. And that’s no easy task, as the top of the derrick is more than 100 meters above sea level!’
‘In addition, the cranes on the platform do not have sufficient lifting height to remove the upper part of the derrick,’ adds Sander. ‘One option is to use an offshore crane barge. But then it is important to have a fixed timeframe for the work, which was not possible on this project. Moreover, the use of an offshore crane barge is a very costly affair.’
Floating Ginpole
‘We therefore proposed to our client a completely different approach to dismantling the derrick,’ says Bart. ‘A method where the derrick is not removed in one piece, but rather in smaller pieces. The use of our Floating Ginpole proved that it was possible to dismantle the top of the derrick in sections. The Floating Ginpole is a modular and flexible lifting solution developed in-house by Wagenborg Foxdrill. It is a tailor-made lifting tool for lifting work on high structures. The solution with our Floating Ginpole offered the client the required flexibility in planning as well as considerable cost savings. The decision was therefore made quickly.’
The challenge
‘And so began a challenging project for us,’ continues Sander. ‘With challenges in terms of techniques to be used, engineering, work preparation, logistics, human resources and planning. We therefore set up a Foxdrill multi-disciplinary expert team for this special assignment. Our starting point for the project was to properly map the complete derrick, including the equipment. With the help of the original design drawings, all kinds of other documentation and an extensive survey by our rope access experts on the platform itself, we got a complete picture of the derrick, all the accessories and the dismantling options.’
Drawing board
‘Our engineering and work preparation team then worked out the whole project step by step,’ explains Bart. ‘We determined the correct lifting method for each structural component. We looked at how and where the lifting equipment needed to be installed, how the structural parts had to be separated, the intended lifting path to the platform deck below and how exactly the Floating Ginpole needed to be positioned for working on the top of the derrick. Finding out and documenting all this in detail was a huge task. But at Foxdrill we stand for ‘first time right’: on an offshore platform where we work at height, there can be no surprises or ambiguities. Everything has to be right so that the right equipment is on site and we can do the job properly and safely. To prepare for the deployment of the Floating Ginpole, our planning team even organised a training course in our own training facility.’
Clockwork
Sander: ‘How nice it is when all the pieces of the puzzle fit together on site! First we used winches to remove all the equipment from the derrick. Then began the daring feat of lifting at height: dismantling the upper structural parts of the derrick using the Floating Ginpole. A team of seven specialists worked on this for about three weeks: four rope access specialists carried out the work at height and three lifting specialists operated and monitored the Floating Ginpole from the deck. The work went like clockwork, right on schedule. Despite the tropical working conditions on the platform.’
Teamwork
Bart and Sander agree that this project is not only a technical masterpiece, but also a testament to excellent teamwork. ‘The collaboration with our client Dixstone has been very fruitful. And we can unequivocally say that this project is exceptional. The entire Foxdrill team have used their knowledge, skills and experience to not only ensure success, but to create something unlike anything else. Together we have achieved a feat that is a testament to our capabilities and one of which we are immensely proud!’