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Removal of a Downed Platform Using 3D Surveying & Modeling



The Client had a 6 pile platform that had been severely damaged by Hurricane Rita in 2005.   The decision to remove the platform was made in 2006 and by the summer of 2008, all 8 of its wells had been P&A’d and all reusable equipment, vessels and the platform’s crane had been removed.  However, just prior to the structure’s scheduled removal, Hurricane Ike passed through the area and completely toppled the platform.

Fairwinds International was asked by the Client to develop a platform salvage / removal plan for the downed structure.  Fairwinds partnered with Fugro Chance marine surveyors, who performed a specialized 3D sidescan sonar survey of the platform as it lay on the seabed.   This raw survey data was used by Fugro to produce a "point cloud” computer model of the structure .  Although this "point cloud” model gives a good picture and overview of the downed structure, it is not useful for performing the type of structural analysis that would be required to develop a removal plan.  Using the "point cloud” model as a basis, Fairwinds was able to create a detailed 3D structural model of the platform using SACS software.  This SACS structural model was then used to determine the proper sequence of dismantling the platform so as to maximize safety and efficiency.  















Results
: By using the SACS model created from the "point cloud” data, Fairwinds was able to develop a detailed, 8 stage platform removal sequence.  A 200 class liftboat with cutting equipment and a 100 ton crane will be used by divers to cut up the downed platform as it lies on the sea floor.  The removed pieces of the platform will be hauled away via barge and sold for scrap.   Having a detailed 3D computer model of the wreck area and what the platform will look like during each stage of the removal sequence will enable the divers and operators to perform this difficult task in a safe and efficient manner.



 

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