ALE recently completed the topside load-out, float-over, offshore lifting and levelling operation of the 13,000t Lu Feng topside in the South China Sea. ALE supplied bespoke engineering, equipment and expertise to the project for COOEC.
The ALE team carried out all major aspects of the project, and the installation method, ballast system and layout had to be specially designed to handle the individual challenges.
To install the Lu Feng 7-2 platform, a bespoke installation method had to be designed around the low centre of gravity float-over to combat the constraints dictated by the width of the pre-installed jacket.
As ALE was working to strict tolerances and a tight timeframe, this operation required a high level of control and integrated monitoring to lift the 13,000t structure ten metres to its final required elevation, whilst maintaining a levelled tolerance of ten milimetres and achieving a final level tolerance of five milimetres.
To complete the onshore test lift, 24 850t-capacity strand jacks were installed to four of the eight topside legs. A custom spreading mat was designed and positioned beneath each leg to support the load of the topside during the lift. The loads within the jacks were monitored throughout by the strand jack control system to ensure that neither the ground nor structure became overstressed.
The load-out of the topside onto the transportation and float-over barge was performed at Shekou. The topside was pulled 140m from the build location to the final location on the barge using four 850t strand jacks installed in the cellar deck skid beams of the topside.
To ensure a safe operation, the load-out was monitored using ALE ballast and barge level monitoring systems, allowing the load-out superintendent to see real-time information against local tide predictions and understand the positioning of the barge in relation to the quayside, as well as providing trim and heel data of the barge.
ALE offshore services business development manager Daniel Kempin said: "The Lu Feng project brought together all of ALE’s expertise: the in-house engineering, operational optimisation and multi-skilled staff working smarter and safer to offer an innovative solution.
"Even with our reliable techniques and equipment, the main highlight for this project was the amalgamation of all of the latest developments in ALE’s monitoring systems. Each individual or combined operational phase was witnessed in real-time from a central control station, thus benefiting all stakeholders in the direct total management of the project operating with fluency to avoid any unnecessary stoppages, saving valuable time and money."
The whole operation was safely completed within three months and prior to the typhoon season.