Design Code Calibration of Offshore Platform Against Typhoon/Hurricane Attacks

Hurricanes Katrina and Rita resulted in the largest number of platforms destroyed and damaged in the history of Gulf of Mexico operations. With the trend of global warming, sea level rising and the frequency and intensity of typhoon increase. How to determine a reasonable deck elevation against the largest hurricane waves has become a key issue in offshore platforms design and construction for the unification of economy and safety. In this paper, the multivariate compound extreme value distribution （MCEVD） model is used to predict the deck elevation with different combination of tide, surge height, and crest height. Compared with practice recommended by American Petroleum Institute （API）, the prediction by MCEVD has probabilistic meaning and universality.

Umbilical Cable Recovery Load Analysis

Umbilical cable is a kind of integrated subsea cable widely used in the exploration and exploitation of oil and gas field. The severe ocean environment makes great challenges to umbilical maintenance and repair work. Damaged umbilical is usually recovered for the regular operation of the offshore production system. Analysis on cables in essence is a two-point boundary problem. The tension load at the mudline must be known first, and then the recovery load and recovery angle on the vessel can be solved by use of catenary equation. The recovery analysis also involves umbilical- soil interaction and becomes more complicated. Calculation methods for recovery load of the exposed and buried umbilical are established and the relationship between the position of touch down point and the recovery load as well as the recovery angle and recovery load are analyzed. The analysis results provide a theoretical reference for offshore on-deck operation.

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.

Study on Basic Hydrologic and Meteorological Parameters in the Ice-covered Bohai Sea

Based on the sea ice investigation in Liaodong Bay and observation on Platform JZ20-2 in January, 1997, the basic hydrologic and meteorological parameters in the Bohai Sea are studied. These parameters consist of solar short wave radiation, long wave radiation, wind velocity, air humidity and some thermal properties of the sea ice. The following is obtained: (1) solar short wave radiation is an important factor affecting the energy balance in the Bohai Sea, and the simplified form of Laevastu (1960) formula can be used to calculate it in the Bohai Sea, (2) the air humidity is about 50% above the sea ice surface, and about 90% above seawater surface in winter according to the observations, (3) wind velocity and air temperature is another two important factors affecting energy balance, the stronger the wind is and the lower the temperature is, the more energy of the sea surface loses, (4) the net long wave loss of the sea surface is almost static in winter, (5) in the Bohai Sea, the thermal conductivity and latent heat of seawater condensation can be regarded as constant, but the specific heat is varying within a sizable range.

Study on H_2S stress corrosion test of welded joint for X65 pipeline steel and numerical analysis

The susceptibility of welded joint for the X65 pipeline steel to H_2S stress corrosion cracking (SCC) is investigated. SCC tests on the steel are carried out in the environment based on NACE TM-01-77 solution with saturated gaseous H_2S. The threshold stress intensity factor and crack propagation velocity are calculated according to wedge-opening loading (WOL) specimens. The three-dimensional elastic-plastic finite element analysis of WOL specimens is performed by using the FEM programming package ANSYS. Stress field and concentration of hydrogen distribution property ahead of the crack tip are obtained. This paper surveyed the microstructure of welded joint and studied on the mechanical properties of X65 pipeline steel. It provides experimental basis for studying stress corrosion. The results of numerical analysis are consistent with conclusions of stress corrosion test.

An Overview of Deepwater Pipeline Laying Technology

The technology and methods involved in pipeline laying in shallow water have evolved to the level of routine and commonplace. However, regarding the unexpected deepwater complexity, the traditional pipeline laying techniques have to confront many new challenges arisen from the increase of the water depth, diameter of the pipe and the welding difficuhy, all of which should be modified and/or innovated based on the existed mature experiences. The purpose of this investigation is to outline the existing and new engineering laying techniques and the associated facilities, which can provide some significant information to the related research. In the context, the latest deepwater pipeline laying technology and pipe laying barges of the renowned companies from Switzerland, Norway, Italy etc., are introduced and the corresponding comparison and discussion are presented as well.

海底脐带缆铺设系统动力学仿真及张力补偿研究(英文)

For studying the dynamic performance of subsea umbilical cable laying system and achieving the goal of cable tension and laying speed control,the rigid finite element method is used to discrete and transform the system into a rigid-flexible coupling multi-body system which consists of rigid elements and spring-damping elements.The mathematical model of subsea umbilical cable laying system kinematic chain is presented with the second order Lagrange equation in the joint coordinate system,and dynamic modeling and simulation is performed with ADAMS.The dynamic analysis is conducted assuming the following three statuses:ideal laying,practical laying under wave disturbance,and practical laying with tension compensation.Results show that motion disturbances of the laying budge under sea waves,especially with heaving and pitching,will cause relatively serious fluctuations in cable tension and laying speed.Tension compensation,i.e.,active back tension torque control can restrict continuous tension increasing or decreasing effectively and rapidly,thus avoiding cable breach or buckling.

深水钻井平台定位系统评估(英文)

This paper addresses the need for systematic evaluation of the station keeping systems of deepwater drilling semi-submersibles.Based on the selected drilling semi-submersible configuration, the mooring systems were analyzed and designed for a range of water depths using different mooring line materials.These were steel wire rope, polyester rope and HMPE (high modulus poly ethylene).The mooring analysis was carried out using the advanced fully coupled time domain analysis method in the computer software package HARP.Diffraction analysis was first applied to solve the hydrodynamic properties of the vessel and then the motion equations of the complete dynamic system including the drilling rig, the mooring lines and risers were developed and solved in the time domain.Applying the advanced analysis method, a matrix of mooring systems was developed for operating in water depths of 1000 m, 1500 m, and 2 000 m using various mooring materials.The development of mooring systems was conducted in accordance with the commonly adopted mooring design code, API RP 2SK and API RP 2SM.Fresh attempts were then made to comparatively evaluate the mooring system's characteristics and global performance.Useful results have been obtained in terms of mooring materials, water depths, and key parameters of mooring configurations.The results provide in-depth insight for the design and operation of deepwater mooring systems in the South China Sea environment.

Application of a Newly Built Semi-submersible Vessel for Transportation of a Tension Leg Platform

紧张腿站台(TLP ) 的交通组织因为长距离总是与一个重半运输容器的使用被联系了。这类容器的要求总是是特殊的，并且他们的可获得性是有限的。为华南海深海的工程的未来发展准备，中国近海油工程公司最近造了重电梯运输 vessel-Hai 杨实你 278。这个半能沉入水中的容器有 42 米的 50k DWT，和呼吸的一个排水量能力。理解容器适用性并且在未来为使用准备它深海的工程正在成为逼近的需要。这份报纸考察与 TLP 交通联系的当前的关键问题并且在装载外面和交通期间执行设计 TLP 的详细分析。新建 COOEC 交通容器 HYSY 278 被使用在华南在 Qingdao 从 COOEC 制造院子弄干 TLP 结构的运输到一块油地海。全部进程从制造院子，从容器，在长距离上的 TLP 的干燥运输，并且平台的最后的卸载卸载和平台的漂浮上的 landsite 包括了 TLP 结构的装载外面。水动力学和结构分析被执行评估运输容器和 TLP 结构的行为。特殊注意对与这个新容器的使用联系的批评区域被给予，与任何潜在的限制一起。结果证明 HYSY 278 能有效地被用于与合适的安排和准备得好的操作搬运结构。过程和细节根据学习结果被介绍。特殊注意也从分析基于结果被给未来使用的讨论。

Optimized Design for the Plow of a Submarine Plowing Trencher

耕作 trencher 的潜水艇的犁是主要功能的机制之一，并且它的优化是很重要的。设计参数在决定一个容器的拖引的力量的要求起一个很重要的作用。一个多客观的基因算法在获得犁的最佳的设计的努力基于犁表面的分析模型被检验了并且适用。为一个特定的土壤条件，草稿力量和是在犁的工作过程的关键参数的犁板表面区域被发现犁片穿入角度的相应最佳的价值和犁的主要的切片的二个表面角度优化。象偏差，犁板电梯角度，正切线的尖变化，和跨越的长度的犁板方面角度那样的参数也沿着土壤流动方向关于犁板表面的力量被分析。结果证明优化的犁有改进的犁表演。分别地，主要的切片和犁板的草稿力量是 10.6% 和 7% 不到原来的设计。犁板的 Gaussian 弯曲的标准差被 64.5% 降低，它暗示优化犁板表面的光滑比原版大得多。

Optimizing Winding Angles of Reinforced Thermoplastic Pipes Based on Progressive Failure Criterion

This paper examines a scheme to optimize the multiple winding angles of reinforced thermoplastic pipes(RTPs)under internal and external pressures.To consider the nonlinear mechanical behavior of the material under changes of winding angle due to deformation,we use three-dimensional(3D)thick-walled cylinder theory with the 3D Hashin failure criterion and theory of the evolution of damage to composite materials,to formulate a model that analyzes the progressive failure of RTPs.The accuracy of the model was verified by experiments.A model to optimize the multiple winding angles of the RTPs was then established using the model for progressive failure analysis and a multi-island genetic algorithm.The optimal scheme for winding angles of RTPs capable of withstanding the maximum internal/external pressure was obtained.The simulation results showed that the ply number of the reinforced layer has a prominent nonlinear effect on the internal and external pressure capacity of the RTPs.Compared with RTPs with a single angle of±55°,the multiple winding angle overlay scheme based on the multi-angle optimization model improved the internal and external pressure capacity of the RTPs,and the improvement in the external pressure capacity was significantly better than the internal pressure carrying capacity.

Difficulties and measures of driving super long piles in Bohai Gulf

Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element （FE） analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed orocedure to exolain the nile refusal phenomenon.

Development of Strip Flatness and Crown Control Model for Hot Strip Mills

The strip flatness and crown control model is the foundation of automatic strip shape control. Considering the metal transverse flows and the inter stand second deformation, the trip flatness and crown control model has been developed, which can be applied to CVC mills and PC mills as well as normal four-high mills. The strip flatness and crown control model has high precision, and has been successfully applied to the automatic strip shape control system reconstruction of Tangshan Ganglu 1 250 mm hot strip plant.

Ribbon bridge in waves based on hydroelasticity theory

For the design and operation of a floating bridge,the understanding of its hydroelastic behavior in waves is of great importance.This paper investigated the hydroelastic performances of a ribbon bridge under wave action.A brief introduction on the estimation of dynamic responses of the floating bridge and the comparisons between the experiments and estimation were presented.Based on the 3D hydroelasticity theory,the hydroelastic behavior of the ribbon bridge modeled by finite element method(FEM)was analyzed by employing the mode superposition method.And the relevant comparisons between the numerical results and experimental data obtained from one tenth scale elastic model test in the ocean basin were made.It is found that the present method is applicable and adaptable for predicting the hydroelastic response of the floating bridge in waves.