Research On Hydrodynamic Characteristicsof The Area Of Pinghu Submarine Pipelines And Its Influence On The Submarine Pipelines

With the increasing of human demand for energy and increasingly depleted of land resources,marine oil and gas resources development may gradually be come one of the important way of energy supply.Due to the high transmission efficiency and the advantages of low cost,the submarine pipeline is one of t he important ways to transport oil and gas resourcesfrom the Sea oil and gas f ields to land terminal.Pinghu oil and gas pipelines goes from Pinghu oil and g as platformin the East China Sea to Luchaogang and Daishan island waters.Ac cording to the Marine engineering survey data,the seabed is scouring and pipeli ne exposed dangling phenomenon happens in Pinghu oil and gas pipelines Are a in recent years.According to the trend,it will further aggravate pipelines im pending and a wide range of suspended pipeline segment will happen under th e action of hydrodynamic environment in specific pipeline rupture,seriously aff ect the safety of pipeline operation.The bottom layer tidal current,the bottom water motion caused by wave and the seabed scouring may have important influence on the stability of subm arine pipelines.The length of Pinghu oil and gas pipelines is almost 400 kilo meters and the survey area needed is relatively large.The survey of the botto m layer current,waveand the orbital motion near the bottom layer caused by wave may invest a lot of manpower and material resource and have shortcomi ngs of small coverage area and synchronization.Based on FVCOM and SWAN model,the current velocity and wave para meters(wave height and the maxima of the orbital motion near the bottom lay er(Ubot))in the area of Pinghu submarine pipelines are calculated.Under extreme weather conditions such as typhoons,sediment will be erod ed very severely in theshallow shelf sea,under the coupled actions of strong n ear-bottom wave-induced orbit velocity and tidal current.A numerical experiment is established to calculate Ubot when wind velocity is 20m/s and 30m/sin NW?N?NE?E?SE and S direction.The result of current model shows thatthe zhoushan islands between chann el flowrates will increase abruptly due to the effect of cluster of the terrain.T he maximum and average of the tidal current in Daishan-Qushan Area is high er than other area.The current velocity in the area of pipeline YKP1~YKP8,s uspended submarinepipeline,is biger than others.The result of wave model shows comparing with the wave height of theo pen Sea,the wave height in the Hangzhou Bay is significantly smaller,and it is assumed that many islands and reefs outside of the Hangzhou Bay may play very good protection function.The distribution of wave significant height is z onal distribution.The result of wavenumerical experiment shows that that the wave height andUbot in the open sea near ZhoushanArchipelago is the most in the study area.TheUbotin the area of pipeline KP85~KP100,suspended submarin epipeline,is biger than others.Based on the data of the detection of the Pinghu oil and gas pipeline in r ecent years,the result shows that there is a certain correlation between seabed scouring under the hydrodynamic effect.The result suggests that scouring unde r the hydrodynamic effect have important impact on seabed scouring dynamics and the pipeline stability...