The INPEX Ichthys subsea trees (XTs) are 4.8m x 5.5m x 5.0m high and 96t each. For installation, they are lifted off the upper deck of the E5006 and deployed subsea through the Moonpool. During this mechanical handling operation, only 150mm of clearance was available between the tree and the MODU superstructure. This tight clearance coupled with the MODU motions presented an unacceptably high risk of damage to the XTs. A guidance system was therefore required to control the movement of the XT during the deployment operation.
Cube Offshore collaborated with the INPEX subsea team and Ensco to conceptualise, design, install and test an XT guidance system for deployment through the E5006 Moonpool. A laser survey was used to generate a 3D model of the Moonpool area to facilitate the design and minimise risk. The design of the guidance system was performed by Cube in Perth and required significant interfacing with Ensco. Cube supervised the construction and integration of the guidance system into the moonpool area in Singapore. To confirm the system, full scale tests run using a Cube supplied “mock-up” dummy XT was performed. The guidance system worked as required with no rework required. Video is available upon request.