Coupling Dynamic Response Of Floatover Installation Process Based On Fast Load Transfer Technology

The offshore platforms play a significant role in the development of ocean oil gas resources.In recently years,the size of the offshore platform topsides are designed larger.And the weight of topside is heaver with the increases of size.The floatover method can meet the need of large topside installation.In this method,the topside is supported and transported to the installation site by a barge,and then transferred from the transportation barge onto the supporting structure through tide level changing or barge ballasting.The traditional floatover process usually depends on tide level and barge ballast systems to adjust the draft of barge.With the change of draft,the load of the topside is transferred to the platform foundation.The installation may take several hours or days to complete.The rapid load transfer technology can make the floatover installation more efficiency.The tension jack or hydraulic support device are used to adjust the height of the topside,and then transfers the topside to the jacket rapidly within a few minutes after the completion of the docking.The work time can spend less and the installation will be more efficiency.The studies of floatover based on rapid load transfer technology are less.The coupled motion of the barge and topside and the force response of LMU and DSU during installation are still uncertain.In this thesis,a barge “HYSY228” with rapid load transfer technology is studied by numerical simulations and model test.The model tests are carried out by using the lifting screw system and the distributed ballast tank to complete the continuous transfer process of the topside.The numerical simulation is carried out by SESAM code "HYSY 228".The coupled motion response of the barge and the topside and the force characteristics of LMU and DSU at different stages of load transfer are simulated.Based on the above research content,the whole process of floatover installation based on rapid load transfer technology is simulated.And the numerical simulation and model test results are fitted.The motion of the barge and the topside,and the force characteristics of the LMU and DSU under different working conditions are analyzed.the riskiest stage and the most dangerous part of installation system are conclude.When the insert tips of topside contact the LMU for the first time in transfer process,the motion amplitude of the barge and the topside are large and have a certain degree of synchronization,and the vertical force fluctuation of LMU and DSU are also large.During the load transfer stage,the movement amplitude of the barge and the topside is relatively small.After the load transfer is completed,the barge is no longer affected by the topside and the movement amplitude increases.The above research content can provide experimental and theoretical basis for the application of rapid load transfer technology in floating installation,and provide reference for actual engineering design.