A preliminary study on seismic design criteria of offshore platforms in Bohai Sea of China

This paper analyzes the seismicity in Bohai Sea,introducing a shape factor K to characterize the seismic risk distribution in sub-regions of the sea. Based on the seismic design ground motions for 46 platforms located in the Bohai Sea,a statistical analysis was performed for different peak ground acceleration (PGA) ratios at two different probability levels. In accordance with the two-stage design method,a scheme of two seismic design levels is proposed,and two seismic design objectives are established respectively for the strength level earthquake and the ductility level earthquake. By analogy with and comparison to the Chinese seismic design code for buildings,it is proposed that the probability level for the strength level earthquake and ductility level earthquake have a return period of 200 and 1000 - 2500 years,respectively. The validity of these proposed values is discussed. Finally,the PGAs corresponding to these two probability levels are calculated for different sub-regions of the Bohai Sea.

Finite Element Method for Design of Reinforced Concrete Offshore Platforms

A design method of reinforced concrete (R. C.) offshore platforms with nonlinear finite element analysis is proposed. According to the method, a computer program is developed. In this program nonlinear constitutive relationships and strength criteria of concrete and steel bars are included, and the progressive cracking and crushing of the concrete are taken into account. Based on the stress distribution obtained by the nonlinear finite element analysis, the amount of reinforcement in the control sections can be computed and adjusted automatically by the program to satisfy the requirement of the design. The amount of reinforcement required in the control sections, which are obtained with the nonlinear finite element analysis, is agreeable to that obtained in the experiment. This shows that the design method of R. C. offshore platform with the nonlinear finite element method proposed by the authors is reliable for practical use.

Reliability-Based Full-Life Cycle Optimum Design of Offshore Jacket Platform

Based on the consideration of operation environment and structural property, an optimum design model of offshore jacket platform is developed in this paper, namely, the reliability-based full-life cycle optimum design model. In this model, the time-dependent reliability assessment method for structural members is established by combination of the decrease of sectional size and performance deterioration of material. The initial investment, maintenance cost and failure loss cost are assembled into the model. The total cost of the platform structure system in its full service period is chosen as the objective function, and the initial reliabilities of the layer elements partitioned in advance are taken as the design variables. Different models are obtained, depending on whether the system reliability constraint is considered or not. This optimum design model can result in the lowest full-life cost and the optimal initial layer reliability of an offshore jacket platform in the design of marine structures. The feasibility of this model is illustrated with an actual jacket platform in the Liaodong Gulf as an example.

Investigation of Allowable Stresses for Fatigue Design of Fixed Offshore Platforms

Fatigue design method is usually used for estimating whether a platform structure meets the requirements of fatigue resistance. It is described in API RP-2A and ZC rules for fixed offshore platforms, in which the allowable stresses for fatigue design are defined. In this paper discussed are the allowable stresses related factors, such as wave climate, structural response, fatigue behaviour of structural members.

Optimum Design for Offshore Platform Structural Reliability

In this paper, the main problems concerning reliability design of offshore platform structure are described and the general steps for the use of Safety Coefficient Method are presented.

Long-Term Effect of TMD on Vibration Control of An MDOF Offshore Fixed Platform

A three-dimensional fixed offshore platform in deep water modeled by the finite element method is studied in this paper. Analysis of the dynamic response of the MDOF structure is realized taking the non-linearity of the wave drag force and the wave-structure interaction into account. The structural response statistics, which have Gaussian distributions, are used to evaluate the vibration effect of the structure without TMD and with TMD. And an optimal method to design TMD controlling the first mode of the multi-mode structure is proposed. Moreover, the probabilities of occurrence of sea states at the platform site are considered for prediction of the long-term effect of a TMD. Simulation results demonstrate that the long-term effect of a well-designed TMD is good and the practical use is possible due to the good stability of its optimal parameters under different sea states.

基于海上平台油气处理系统标准化设计的HAZOP分析研究

海上平台油气处理系统实现了标准化设计,海上平台标准化设计虽然可以缩短开发周期,降低投资成本,但不会降低新建平台的潜在风险,甚至因为工期缩短反而会增加某些风险。文章针对海上平台油气处理的标准流程,开展HAZOP分析,识别详细偏差的原因和后果,并提出建议设计的保护措施以降低风险。分析结果具有一定的普适性,可为工艺系统危害辨识及防范提供有效参考。文章基于危害产生原因和后果影响提出建议保护措施,可以有效降低发生频率或减轻事故后果,从而达到防范风险,保障设备安全运行的目的。

Optimal Design of TMD Under Long-Term Nonstationary Wave Loading

Traditionally, the use of a tuned mass damper (TMD) is to improve the surviability of the primary structure under extraordinary loading environment while the design loading condition is described by either a harmonic function or a stationary random process that can be fully characterized by a power spectral density (PSD) function. Aiming at prolonging the fatigue life of an offshore platform, this study considers an optimal design of TMD for the platform under long-term nonstationary loading due to long-term random sea waves characterized by a probabilistic power spectral density (PPSD) function In principle, a PPSD could be derived based on numerous ordinary PSD functions; and each of them is treated as realization of the corresponding PPSD. This study provides a theoretical development for the optimal TMD design by minimizing the cost function to be the mean square value of the expected long term response. A numerical example is presented to illustrate the developed design procedure.

HAZOP方法在浅海导管架平台设计中的应用

概述了HAZOP分析方法的基本原理和工作流程,以某油田浅海海域导管架平台为例,介绍了HAZOP方法的实际运用情况和分析过程。结合取得的成果,探讨实施HAZOP方法所具有的优点。通过分析认为,HAZOP工作的开展将有利于减少工程设计缺陷,提高工程安全可靠性。

Overview of development, design, testing and application of compact gas-insulated DC systems up to ±550 kV

The development of high-voltage direct current gas-insulated switchgear assemblies(DC GIS)of rated voltages up to±550 kV has been completed.DC GIS provide a compact technical solution with a high functional density,optimized for projects with limited space as in offshore HVDC converter platforms,onshore HVDC converter stations and transition stations between different transmission media.Up to now,no standards for testing of gas-insulated DC systems are available,although pre-standardization work is in progress within CIGRE.Some tests can be performed as required in AC GIS standards.Special aspects of DC voltage stress,like the electric field distribution of insulators influenced by the accumulation of electrical charge carriers and the operation-related inhomogeneous temperature distribution,must be considered by additional electric and thermoelectric tests.For DC GIS,the experience of long-term performance is limited today.Although ageing is expected to be of lower importance,tests are recommended.This contribution summarizes the physical and technical background to design and develop compact DC switchgear assemblies using gas-insulated technology.It explains the developed modules of the substation and gives an overview of the performed tests.Furthermore,it provides an insight in the on-going standardization activities and describes applications in converter and transition stations,showing its space-saving characteristics.

SIL评估及HAZOP分析技术在海洋平台安全评估中的应用

针对海洋平台安全仪表系统安全可靠性要求的提高,分析海洋平台安全仪表系统SIL评估及HAZOP分析方法,对SIL评估的必要性、目的和内容、方法与流程进行论述,对SIL等级选择的HAZOP和LOPA分析方法进行介绍,对SIL评估过程中的重要数据问题进行阐述,对SIL等级验证中各参数和失效数据的选取进行说明。通过案例进一步论述SIL评估及HAZOP分析技术的要点和实施步骤,针对该案例提出了提高SIL等级的建议和措施,为海洋平台安全仪表系统的SIL评估提供重要的参考和依据。

HAZOP分析在海上生产平台的应用

对HAZOP分析方法及工作流程做了介绍,结合在海上生产平台的应用进行了分析和探讨。应用实例表明,HAZOP分析是一项提高海上生产平台设计、建造和运行安全性的行之有效的方法。

Coupled dynamic response analysis of multi-column floating offshore wind turbine with low center of gravity

To realize the application of the floating offshore wind turbine(FOWT)from deep to relatively shallow waters,a new concept of multi-column floating wind turbine platform with low center of gravity(CG)is designed and validated.The multi-column low CG platform is designed to support a 6MW wind turbine class and operated at a water depth of 50m in the South China Sea.The frequency domain software WADAM and time domain software NREL-FAST are used to simulate coupled dynamic responses of the floating wind turbine system with second-order wave loads considering.The dynamic behaviors of multi-column low CG FOWT system under normal operation and parked conditions are presented.The influence of second-order wave force on the motion responses of the multi-column platform,fore-aft force and moment of the tower base and mooring force are researched respectively.The results demonstrate that the coupled dynamic responses at rated operating condition and extreme condition meet the normal operating requirements and extreme survival requirements of FOWT system in the shallow water(50m)of South China Sea.In addition,it is found that,the wave frequency response gradually replaces the second-order low frequency response as the main influencing factor of the coupled dynamic response of the FOWT system with the increasing severity of the sea states.However,in general,the magnitude of second-order low frequency response increases with the increasing severity of the design load case.Thus,in the subsequent design of the shallow water FOWT system,the second-order effects should be paid enough attention.

基于随机森林的导管架海洋平台结构模型修正方法

提出一种基于随机森林的有限元模型修正方法,能够快速、准确地给出导管架海洋平台结构模型的修正参数。选定平台不同的设计参数,对设计参数和基频进行Pearson相关性分析,得到与基频相关系数较大的参数,并重新设计试验参数获得基频。通过随机森林网络增加两者之间的非线性差异,验证网络精度及其泛化能力。结合实测数据,对比分析有限元模型的修正的效果。结果表明:模型的回归分数可达0.998,修正后的有限元模型可更准确地反映真实平台的动力特性。

海上采油平台改造项目的常用安全分析方法

海上采油平台改造项目在现代工程建设中起着重要作用。然而,由于复杂的海洋环境和高风险因素,海上采油平台改造项目的安全性成为关注的焦点。文章研究海上采油平台改造项目中常用的安全分析方法,帮助工程师和项目管理者更好地评估和控制潜在的安全风险。

无人海上平台登临栈桥结构强度校核

针对目前无人海上平台登临系统安全能力不足、适应调整能力较差以及克服海况能力偏弱等问题,设计了一种可依据平台结构特点进行改造的新型无人平台登临栈桥。新型登临栈桥可进行伸缩、俯仰、水平旋转等3个自由度的运动,满足海上多种工况下的登临需求。对栈桥自身结构及安装栈桥的导管架平台的局部结构进行作业工况与极端工况下的数值模拟,借助建模及有限元软件分析不同工况下的位移和等效应力,对结构进行局部强度校核,验证该无人平台登临栈桥设计的可行性。结果表明:该登临栈桥设计可保障无人平台日常工作的安全和稳定,整体设计具有较高的安全冗余度,为今后的海上平台改造奠定了基础。

中国海洋平台结构抗冰设计关键问题及研究建议

渤海海域是中国重要的油气产区,但该海域冬季会出现结冰区,因此该区域海洋平台结构的抗冰设计对保障油气增储上产十分重要。渤海海域平台抗冰设计经历了起步、探索、对外合作和独立自主4个发展阶段。本文系统总结了中国渤海地区海洋平台结构抗冰设计面临的关键问题,并给出了相关研究建议。在海冰设计条件方面,受全球气候变化影响,中国海冰冰情整体变弱,现有的海冰区域划分不够精细,部分冰区参数与实际冰情差异较大,且重叠冰设计参数忽视了不同冰区的差异问题,建议基于最新的卫星遥感、业务化预报和实测数据,开展高精细化程度的海冰区域划分研究,并探究工程设计中重叠冰厚度以及强度的合理取值;在结构静态冰载荷计算方法方面,现有计算方法不能适用大径厚比条件,建议基于现场冰力实测和冰水池模型试验,构建新的冰力计算公式,并深入探究多腿结构的遮蔽系数与非同时破坏系数;在动态抗冰设计方法方面,目前尚缺乏明确的可执行规定,尚未建立统一的动冰力模型和疲劳分析算法,建议构建合理的海冰参数概率分布模型,制定平台冰激振动及疲劳设计的设计和评价方法。相关研究成果为中国渤海地区平台结构抗冰设计的优化及下一步研究提供了参考。

标准化设计在渤海油气设施定型中的研究与应用

基于渤海海域开发特点,以渤海典型在役平台为样本,结合工程设计、开发生产需求,以标准化设计为主要方法,开展海上油气设施定型研究。文章总结出一套适用于渤海油田的组块系列定型方案和导管架系列定型方案,并在“十四五”期间渤海油田平台设计与建造中推广应用,实现了加快勘探开发一体化、提高采办与建造安装效率、提升油气田全生命周期经济效益的显著效果。

平台延寿设计与油田开发方式的平衡优化研究

到达设计寿命的海上采油平台需要根据最佳的油藏开发方式延寿改造实现长期继续服役。从经济效益角度设计了平台延寿与油田开发方式相结合下的方案评价方法、原则及评价指标。根据设计的经济评价方法和指标对海上开发区块的油藏开发方式及平台延寿方案优选流程进行了详述。

BIM技术在海工脚手架设计中的应用前景与策略探讨

海洋平台上部组块建造过程中的脚手架搭设较为复杂,需综合考虑结构、电气、管线、机械等各专业的需求。为此,文章在海工脚手架设计中引入BIM技术,分析其与海工脚手架的适配性,并明确核心环节为基于项目三维模型实现脚手架可视化设计,对其应用的关键技术手段二次开发技术作了简要介绍。同时展望了基于BIM的脚手架工程概算系统,认为BIM应用于海工脚手架后,能在一定程度上细化脚手架方案,改善工作流程,优化施工组织,从而达成节省成本的目的。