Study On The Towing Technolygy Of Floating Pipes In The Extreme Shallow Water

The pipeline has been broadly used as an important part of oil transportation and storage in the ocean oil engineering. The important part in the construction process of pipeline is to transport the pipeline to the certain sea area, which is complicated and has a lot of risk. During the process of transportation, the pipeline is affected by the wind, wave and ocean current. It's very important to calculate the environment loads, analyze the strength and determine reasonable towing methods in order to insure the safty of the pipeline and reduce the transportation cost.Some home and oversea methods of pipeline laying are summarized, and suitable condition of different pipeline construction projects are compared and analyzed in this thesis. Taking the example of pipe-in-pipe which hasφ325×6mm inner pipe andφ273×8mm outer pipe, disposal of camels in the prefabrication field is detaildely analysed, and the advantage and the disadvantage of two kinks of pipeline launching projects are discussed. The pipeline is affected by the complicated environment loads during the process of transportation, which is divided into two steps to analyse. Firstly, the pipeline is supposed to be rigid body. Then the possible rotational angle caused by wind and ocean current is calculated, and the balance position is confirmed. Secondly, considering wave action the pipeline is supposed to be elastomer. Then maximal stress is calculated in FEM program,and the assistant tugboats are disposaled resonablely. When the pipeline is transported to the preconcerted position, the camels are unloaded from one end to another end so that the pipeline can be sinked slowly, and the stress is calculated in FEM program.The results and analyses show that floating pipeline method is suit for extreme shallow water area when the loads of wind, current and wave is light. It is necessary to control the bending deformation of pipeline in the process of towing, and the effective method is to add towing points. The towing project of pipe-in-pipeφ325×6mm andφ273×8mm in the extreme shallow water is designed including disposal of camels, number of tug boat and towing points with considering the loads of wind, current and wave.