Dynamic Coupling Analysis of Semisubmersible Platform Float-over Method for Docking Case

In this paper,the multi-body coupled dynamic characteristics of a semisubmersible platform and an HYSY 229 barge were investigated.First,coupled hydrodynamic analysis of the HYSY 229 barge and the semisubmersible platform was performed.Relevant hydrodynamic parameters were obtained using the retardation function method of three-dimensional frequency-domain potential flow theory.The results of the hydrodynamic analysis were highly consistent with the test findings,verifying the accuracy of the multifloating hydrodynamic coupling analysis,and key hydrodynamic parameters were solved for different water depths and the coupling effect.According to the obtained results,the hydrodynamic influence was the largest in shallow waters when the coupling effect was considered.Furthermore,the coupled motion equation combined with viscous damping,fender system,and mooring system was established,and the hydrodynamics,floating body motion,and dynamic response of the fender system were analyzed.Motion analysis revealed good agreement among the surge,sway,and yaw motions of the two floating bodies.However,when the wave period reached 10 s,the motion of the two floating bodies showed severe shock,and a relative motion was also observed.Therefore,excessive constraints should be added between the two floating bodies during construction to ensure construction safety.The numerical analysis and model test results of the semisubmersible platform and HYSY 229 barge at a water depth of 42 m and sea conditions of 0°,45°,and 90° were in good agreement,and the error was less than 5%.The maximum movement of the HYSY 229 barge reached 2.61 m in the sway direction,whereas that of the semisubmersible platform was 2.11 m.During construction,excessive constraints should be added between the two floating bodies to limit their relative movement and ensure construction safety.

Model Tests Research on A Float-Over Barge in Shallow Water Under the Undocking Conditions

In this study,the Jinzhou 9-3 CEPD float-over installation project was investigated.During the undocking condition,the water depth of the motion path of the working barge gradually changed from 10.31 m to 9.41 m.The undocking clearance of the HYSY 228 is smaller than 1 m;therefore,the barge shows highly nonlinear hydrodynamic characteristics,and it is difficult to be accurately simulated by numerical analysis.Thus,it is necessary to obtain the hydrodynamic characteristics and laws of the float-over barge at different water depths by using tank model test,to provide some reference and guidance for float-over operations in shallow water.

Numerical Simulation of Float-Over Installation for Offshore Platform

In this paper,a numerical investigation of a float-over installation for an offshore platform is presented to verify the feasibility of the actual installation.The hydrodynamic performance of a T-barge is investigated in the frequency domain,and the coupled motions are analyzed in the time domain.We then compare with those of the model test and determine that the response amplitude operator and the time series agree quite well.The barge exhibits favorable hydrodynamic behavior in the considered sea state,and the equipment loads are allowable.Themooring systemand sway fender forces are within the permissible range.Based on these results,we can verify that the actual installation of the offshore platform is feasible.We accurately simulated many important factors and effectively reduced the risk associated with the offshore installation,which is of great importance.As such,we demonstrate that the numerical simulation of the float-over installation for offshore platforms has practical engineering significance.

A new bracing system for improvement of seismic performance of steel jacket type offshore platforms with float-over-deck

In this paper, the seismic response of a newly designed steel jacket offshore platform with a float over deck （FOD） system in the Persian Gulf was investigated through incremental dynamic analysis. Comparison of incremental dynamic analysis results for both directions of the platform shows that the lateral strength of the platform in the float over direction is less than its lateral strength in other direction. Dynamic characteristics measurement of a scale model of platform was also performed using forced vibration tests. From experimental measurement of the scaled model, it was observed that dynamic characteristic of the platform is different in the float over direction compared to the other direction. Therefore, a new offshore installed bracing system for the float over direction was proposed for improvement of seismic performance of this type of platform. Finally, the structure with the modified system was assessed using the probabilistic seismic assessment method as well as experimental measurement of its dynamic characteristics. It was observed that the proposed offshore installed bracing system improves the performance of platforms subjected to strong ground motion.

我国海洋平台浮托安装技术现状及未来

随着海洋石油工业迅猛发展,海上平台正向大型化、集约化方向发展,平台上部组块的整体重量也随之增加。对海上超大型平台的安装技术及作业能力提出了更高的要求,浮托法安装技术是解决上述问题的最佳方案。我国利用浮托法完成了23个大型海洋平台的安装,本文针对我国浮托安装现状、浮托装备的研发、未来发展趋势、进行了全面综述,并对我国已经实施的浮托法安装进行了优缺点分析,对未来新型浮托法进行了分类,针对我国特定海域选取的浮托方法进行了分析,为工程及技术人员提供了参考。

海上浮托安装平台的布置设计

结合渤中BZ34-2/4海上油田的浮托安装中心平台,介绍了浮托安装平台的安装特点及过程,对海上浮托安装中心平台的总体布置设计包括的位置与方位、轴线尺寸、底层甲板高度、井口布置、甲板布置等方面分别进行了论述。其中对轴线尺寸、底层甲板高度计算方法进行了说明,对平台的位置与方位、井口布置、甲板布置中应注意的问题逐一进行分析,并对平台总体布置设计中可能影响浮托安装的因素进行了详细的解释。为海上浮托安装平台的总体布置设计提供参考。