Hydrodynamic comparison of a semi-submersible, TLP, and Spar: Numerical study in the South China Sea environment

The South China Sea contains tremendous oil and gas resources in deepwater areas. However, one of the keys for deepwater exploration, the investigation of deepwater floating platforms, is very inadequate. In this paper, the authors studied and compared the hydrodynamics and global motion behaviors of typical deepwater platforms in the South China Sea environment. The hydrodynamic models of three main types of floating platforms, e.g. the Semi-submersible, tension leg platform (TLP), and Truss Spar, which could potentially be utilized in the South China Sea, were established by using the 3-D potential theory. Additionally, some important considerations which significantly influence the hydrodynamics were given. The RAOs in frequency domains as well as global motions in time domains under time-varying wind, random waves, and current in 100-y, 10-y, and 1-y return period environment conditions were predicted, compared, and analyzed. The results indicate that the heave and especially the pitch motion of the TLP are favorable. The heave response of the Truss Spar is perfect and comparable with that of the TLP when the peak period of random waves is low. However, the pitch motion of Truss Spar is extraordinarily larger than that of Semi-submersible and TLP.     

TLP型风力机的空气动力学影响及发电预测(英文)

This research proposes a new offshore wind energy generation system that uses a tension leg platform (TLP) and describes experiments performed on a TLP type wind turbine in both waves and wind. The following conclusions can be made from the results of this research. 1) In the case of coexisting wave-wind fields, the wind effect stabilizes the pitch motion. 2) The wind effect decreases vibration of the mooring lines when waves and wind coexist. In particular, the springing (2nd or 3rd order force) also decreases in this field. 3) It can be estimated that the reduction in the rate of generation of electrical power can be up to about 6% as a result of the heel angle. In addition, the annual amount of electricity generated was estimated along with the utilization factor based on the experimental results.     

新建半潜运输船在张力腿平台运输方面的应用研究(英文)

Transportation of tension leg platform(TLP) structures for a long distance has always been associated with the use of a heavy semi-transport vessel.The requirements of this type of vessel are always special,and their availability is limited.To prepare for the future development of South China Sea deepwater projects,the China Offshore Oil Engineering Corporation has recently built a heavy lift transport vessel-Hai Yang Shi You 278.This semi-submersible vessel has a displacement capacity of 50k DWT,and a breath of 42 meters.Understanding the vessel’s applicability and preparing it for use in future deepwater projects are becoming imminent needs.This paper reviews the current critical issues associated with TLP transportation and performs detailed analysis of the designed TLP during load-out and transportation.The newly built COOEC transportation vessel HYSY 278 was applied to dry transport of the TLP structure from the COOEC fabrication yard in Qingdao to an oil field in South China Sea.The entire process included the load-out of the TLP structure from the landsite of the fabrication yard,the offloading and float-on of the platform from the vessel,the dry transport of the TLP over a long distance,and the final offloading of the platform.Both hydrodynamic and structure analysis were performed to evaluate the behavior of the transport vessel and TLP structure.Special attention was paid to critical areas associated with the use of this new vessel,along with any potential limitations.The results demonstrate that HYSY 278 can effectively be used for transporting the structure with proper arrangement and well-prepared operation.The procedure and details were presented on the basis of the study results.Special attention was also given to discussion on future use based on the results from the analysis.     

海上自升式平台动力分析方法研究(英文)

A jack-up platform,with its particular structure,showed obvious dynamic characteristics under complex environmental loads in extreme conditions.In this paper,taking a simplified 3-D finite element dynamic model in extreme storm conditions as research object,a transient dynamic analysis method was proposed,which was under both regular and irregular wave loads.The steps of dynamic analysis under extreme conditions were illustrated with an applied case,and the dynamic amplification factor(DAF) was calculated for each response parameter of base shear,overturning moment and hull sway.Finally,the structural response results of dynamic and static were compared and analyzed.The results indicated that the static strength analysis of the Jack-up Platforms was not enough under the dynamic loads including wave and current,further dynamic response analysis considering both computational efficiency and accuracy was necessary.     

Ship hull plate processing surface fairing with constraints based on B-spline

The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.     

Multigrid fictitious boundary method for incompressible viscous flows around moving airfoils

In this paper, an efficient multigrid fictitious boundary method (MFBM) coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NACA0012 airfoils. The calculations were carried on a fixed multigrid finite element mesh on which fluid equations were satisfied everywhere, and the airfoils were allowed to move freely through the mesh. The MFBM was employed to treat interactions between the fluid and the airfoils. The motion of the airfoils was modeled by Newton-Euler equations. Numerical results of experiments verify that this method provides an efficient way to simulate incompressible viscous flows around moving airfoils.     

Underwater hydraulic shock shovel control system

The control system determines the effectiveness of an underwater hydraulic shock shovel. This paper begins by analyzing the working principles of these shovels and explains the importance of their control systems. A new type of control system’s mathematical model was built and analyzed according to those principles. Since the initial control system’s response time could not fulfill the design requirements, a PID controller was added to the control system. System response time was still slower than required, so a neural network was added to nonlinearly regulate the proportional element, integral element and derivative element coefficients of the PID controller. After these improvements to the control system, system parameters fulfilled the design requirements. The working performance of electrically-controlled parts such as the rapidly moving high speed switch valve is largely determined by the control system. Normal control methods generally can’t satisfy a shovel’s requirements, so advanced and normal control methods were combined to improve the control system, bringing good results.     

两种直接波浪能转换系统性能的比较:阿基米德波浪摆和波能浮筒(英文)

Many wave energy conversion devices have not been well received. The main reasons are that they are too complicated and not economical. However, in the last two decades direct conversion systems have drawn the attention of researchers to their widely distributed energy source due to their simple structure and low cost. The most well-known direct conversion systems presently in use include the Archimedes Wave Swing (AWS) and Power Buoy (PB). In this paper, these two systems were simulated in the same conditions and their behaviors were studied in different wave conditions. In order to verify the simulations, results of the generator of the finite element computations were followed. An attempt was made to determine the merits and drawbacks of each method under different wave conditions by comparing the performance of the two systems. The wave conditions suitable for each system were specified.     

Measuring the effectiveness of methods for evaluating noise jammers

Reliable evaluations of a noise jammer's effectiveness are necessary to properly design, manufacture, and operate one, so it is important to have an evaluation model. Based on their characteristics and principles, relevant factors were classified in terms of their contribution to a unit's effectiveness. In this way an evaluation index system was established. In the proposed mathematical model a noise jammer is analyzed by combining the model of system effectiveness with the method of analytic hierarchical process. A simulation of underwater acoustic countermeasures was used to test the rationality and feasibility of the model. The results showed that this model is an effective way to solve the challenge of evaluating the effectiveness of non-offensive weapons under single working phase.     

自升式风电安装船桩腿强度分析和优化

近年来,随着国内海上风电行业的蓬勃发展,市场对自升式风电安装船的需求日益迫切。桩腿是影响自升式风电安装船作业安全性的关键环节,桩腿设计也是自升式风电安装船的关键技术难点之一;而海上风电场的选址逐渐向离岸更远、水深更大的方向发展,客观上也对桩腿适应更恶劣海况条件的能力提出了更高要求。本文结合近年来多型自升式风电安装船桩腿设计经验,分析研究了桩腿总强度计算和优化的过程,及其与海况环境、作业条件、可变载荷等参数之间的相关性,为自升式风电安装船的桩腿设计提供了有效方法。     

自升式钻井平台围井区结构设计

围井区结构是自升式钻井平台最重要的关键部分,在满足规范前提下进行围井区结构的优化设计。以某平台围井区结构设计为例,以提高结构强度为主要目标,同时兼顾建造的工艺及节点的优化设计,从材料选择、结构设计等方面进行论述。最终经有限元计算,分析结果表明:各工况下围井区结构强度均满足规范要求。     

400英尺自升式钻井平台目标海域和目标用户研究

自升式钻井平台属于海上移动式平台,是浅海大陆架海域油气资源勘探开发事业的主力装备。结合400英尺自升式钻井平台的性能特点,通过分析钻井平台市场的现状与趋势,论述全球蕴涵油气资源海域的地质特性及勘探远景,归纳国内外钻井平台用户特征及市场需求,总结出最适合该型平台工作的目标海域,明确该型平台最适合的目标用户,使400英尺自升式钻井平台的研发更具市场针对性。     

“中油海62”修井作业平台升降系统设计

“中油海62”平台是一艘自升式修井作业平台，最大作业水深达到40m。自升式平台要做到“站得住、升得起、拔得出”，升降系统是关键。吸取国内外同类型平台的优点，该平台采用圆柱形桩腿带桩靴配以电动齿轮齿条升桩机构，可以连续升降、操作方便、安全可靠，经济实用。通过阐述升降系统的组成，载荷分析和强度计算，对升降系统设计作较详细的介绍以供参考。     

海洋平台风载荷的数值分析

风载荷是海洋平台主要的设计载荷,常规的规范算法在结果上偏于保守。本文基于N-S方程(Navier-Stokes)方程对某自升式钻井平台进行了风载荷的数值分析,控制方程—RANS(Reyolds Averaged Navier-Stokes)和连续性方程使用有限体积法离散。在此基础上,对数值分析中湍流模型选择及网格划分方法进行了讨论,分别采用CFX及FLUNET软件对海洋平台整体及单个构件的风载荷和形状系数进行了研究。     

基于有限元分析的自升式平台桁架腿选型优化设计

桁架腿作为自升式平台最为常见的桩腿结构型式,其拓扑型式、结构形状和构件尺寸设计对平台结构响应有重要影响。针对这一问题．笔者将有限元分析和数值优化方法有机结合,建立了复杂环境下桁架腿结构的多约束条件的优化模型,应用ANSYS优化模块进行求解。优化过程中,针对两层设计变量耦合困难的问题,分层优化方法。为验证优化模型和方法的可靠性,对某自升式平台桁架腿进行了选型优化设计。优化结果表明,本文采用的优化模型和方法简单实用,优化效果显著,为自升式平台桁架腿的概念设计提供了一种有效工具。     

A study of jack-up leg drag coefficients

The accurate prediction of drag coefficients for truss-type jack-up legs is an important part of a unit's design. Over the past 14 years, a series of windtunnel tests have been conducted on both square and triangular cross-section leg configurations. A calculation method which closely fits the model test data has also been adopted. A previous paper described the early testing and the MMEC calculation method for square legs. Since then, testing and research have continued on both square and triangular leg designs. This paper describes the more recent testing performed on square legs, and it details the testing and the MMEC method for triangular legs. In addition, the effects of cornerpost design and surface roughness are discussed. Several example calculations are provided in Appendices.     

自动化轨道吊门腿形式对轨道运行公差的适应性

针对自动化轨道吊"双刚腿"和"一刚一柔"两种门腿形式,根据技术参数和计算工况,分析在不同轨道运行公差情况下的适应性,并结合2种门腿形式轨道吊的运行案例,提出对堆场基础沉降导致轨道变形的敏感性,为码头建设单位轨道吊选型提供参考。     

自升式平台板壳式桩腿设计

桩腿是自升式平台的关键部件,其设计强度不仅决定着平台的作业能力和相应环境条件的选取,而且是平台升降系统选型及其主要性能参数确定的重要依据。结合近年来海上风能开发的热点,以目前市场上主流的自升式风电安装平台为研究对象,结合其作业和功能特点,综合平台载荷工况的特征和强度要求,对桩腿截面型式的选取、内部环筋加强结构和桩腿桩靴连接区域结构的设计及插销孔的强度分析等关键技术进行深入研究。得到适用于柱型桩腿设计和强度分析的工程化方法,为此类结构设计提供参考。     

Preloading of independent leg units at locations with difficult seabed conditions

This paper, based on analyses of case histories, reviews soil conditions causing sudden uncontrolled leg penetrations, together with site data needed to plan safe installations of jack-up drilling units. Punch-through-like failure in uniform clay profile is analysed. Preloading procedures aimed at minimizing potential damage to the unit are suggested and discussed.