Study On The Technology Of Removing Jacket By Airbag Assisted Floating And Wet-towing

In recent years,the disposal and dismantling of jacket platform has become a research hotspot in the field of offshore engineering at home and abroad.How to improve the construction efficiency and reduce the construction cost of jacket platform demolition has become the key of jacket platform disposal technology.In this paper,the technology and process of removing jacket by air bag assisted floating method and wet towing at sea are studied.This method has the advantages of good economy,low risk,no need of large crane ship,and can be used for the removal of jacket in shallow water.Taking the decommissioned jacket platform in Bohai Sea as an example,this paper puts forward the removal technology and process of full air bag assisted floating and wet towing jacket,and analyzes the key technologies in the removal process,including cutting technology,air bag assisted floating jacket motion control technology and wet towing transportation safety,etc.The main research contents and results are as follows:(1)It summarizes the status quo and future development prospects of jacket platform demolition,and analyzes the research progress of jacket demolition technology at home and abroad,including lifting demolition method,floating demolition method and floating demolition method.(2)It comprehensively analyzes the cutting technology involved in the process of offshore platform abandonment and demolition,and puts forward a set of underwater cutting process,required equipment and construction methods combined with the target jacket structure.Based on the orthogonal decomposition method,the cutting technology is optimized and sorted,which can provide guidance for the selection of cutting technology for the same type of offshore jacket structure.(3)It puts forward the removal technology of full flexible buoy jacket in the paper,puts forward the reasonable analysis method for the key technology,and formulates the reasonable technical process.Taking the jacket platform to be demolished in Bohai Sea as an example,the configuration requirements and methods of floating buoy are proposed.(4)Based on the jacket system with buoys,the floating state and motion control method of the jacket are studied,and the multi-point mooring motion control measures are proposed.The hydrodynamic analysis model of jacket system with air bag is established,and the additional mass coefficient,radiation damping coefficient and motion response amplitude operator(RAOs)of air bag assisted floating jacket are calculated and analyzed.(5)Aiming at the multi-point mooring limit jacket system,an analysis model of floating buoy jacket and mooring system is established to calculate and analyze the motion response of the jacket under the action of wind,wave and current.Considering different marine environmental conditions,the motion response characteristics and cable tension response of the jacket system are calculated,which provides feasible motion control measures for the demolition operation of the jacket system.(6)The stability of the jacket system with air bag during towing is calculated and analyzed;Based on CFD method and resistance calculation formula,the towing resistance of jacket under different towing speeds is calculated and analyzed,and the reasonable speed of jacket during towing is determined,which provides technical support for offshore wet towing of jacket system.