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    25 December 2016, Volume 3 Issue 6 Previous Issue    Next Issue
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     Research and Application of the Heading Determination Method for Semi-Submersible Drilling Platform in Internal Wave Current
    JIANG Wei
    2016, 3 (6):  331-337. 
    Abstract ( 282 )   PDF (5202KB) ( 67 )  
     The environmental force acting on the South China Sea semi-submersible platform is analyzed and studied through the example of a semi-submersible drilling platform with anchor location. For the heading determination of a platform operating in the internal wave flow waters, it is very important to consider the influence of wave function on the platform positioning. Through calculation and analysis, it is definitely concluded that the principle for determining platform heading is to minimize the environmental force acting on the platform. The heading of the platform should be set to the direction of incoming waves, so as to reduce the current force on the platform, and to ensure stable and safe operation of positioning. For operations in the South China Sea where internal waves are frequently found, we need reasonable standards and guidelines to avoid the drift and damage of the platform caused by the internal waves and to ensure the safety of deepwater operation.
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     Spectrum Fatigue Analysis Method with Application to the Structural Analysis of Spar Platforms
    LI Hua-xiang
    2016, 3 (6):  338-345. 
    Abstract ( 328 )   PDF (5719KB) ( 158 )  
     Based on the offshore spectrum fatigue theory, this paper is to calculate the fatigue strength and life predication of truss spar platforms. By means of the classical wave spectrum theory and the engineering fatigue theory, a software tool is developed for the spectrum fatigue analysis of structures. Meanwhile, based on the Goodman theory, the effect of mean stresses on fatigue limit is evaluated. The developed software is linked with a finite element analysis tool for offshore structures. Then, the chain work of finite element modeling, hydrodynamic load calculation and mapping to structural models, finite element strength analysis, and fatigue computation is automatically implemented. Numerical examples indicate that for a truss spar platform, the fatigue failure occurs at the stressed places and the intersection of hard tank and truss, which provides an important reference for local structural reinforcement and optimization.
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     General Layout of Topside of Semi-Submersible Platform with Three Columns
    HAO Meng-jiang, WANG Jin, HE Yan-fei, DU Guo-qiang, YANG Guang
    2016, 3 (6):  346-349. 
    Abstract ( 241 )   PDF (3433KB) ( 66 )  
     The production platform with three columns is a new type of platform. It has good economical efficiency, safety and reliability, and can perform production and drilling in deep water. Compared with the traditional semi-submersible platform with four columns, the new type platform holds the advantages of high utilization and low total cost. According to the characteristics of the semi-submersible platform, we study the general layout of topside of the three-column platform, which can reserve technology for the future development of the deepwater marginal oilfield in the South China Sea, and provide reference for the design of similar platforms.
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     Research on the Interruptions among Subsea Hydraulic Actuators in the Opening Process
    WANG Xin, ZUO Xin, YANG Qing-qing, MA Tian-ran, YE Tian-yuan, WANG Ting
    2016, 3 (6):  350-355. 
    Abstract ( 152 )   PDF (5681KB) ( 51 )  
     There are many hydraulic actuators on one subsea Christmas tree. When the hydraulic actuators are turned on in sequence, mutual influence among the hydraulic actuators will happen and sometimes even lead to the generation of malfunction. In this paper, the software AMESim is adopted, the model of many hydraulic actuators on one subsea Christmas tree interfering with each other in the process of action is established and the simulation analysis is made on the interaction among them which leads to interference of normal operating conditions so as to improve the situation properly. The results show that increasing the size of the accumulator and increasing the oil supply pipe diameter of umbilical cable can improve or even eliminate the malfunction caused by the interaction among the hydraulic actuators. And then how to combine these two methods to save the economic costs and avoid the malfunction of hydraulic actuators is analyzed theoretically.
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     Seismic Analysis for M-Type Rigid Jumper
    WANG Lin, LI Xu, YANG Hu
    2016, 3 (6):  356-360. 
    Abstract ( 116 )   PDF (3600KB) ( 63 )  
     Seismic analysis is carried out for the M-type rigid jumper. We summarize the analysis cases, load type and check method of the M-type rigid jumper. By using the finite element method (FEM), we give the method for fault, ground crack and seismic wave vibration analysis of rigid jumper. This research can offer a reference for M-type rigid jumper design in seismic active zone.
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     Application and Development of Extended Reach Well Techniques in Oilfields in Bohai
    HE Peng-fei
    2016, 3 (6):  361-366. 
    Abstract ( 349 )   PDF (6528KB) ( 64 )  
     Extended reach well is been drilled in many oilfields in Bohai. According to technical difficulties and stratigraphic characteristics of Bohai, a series of techniques such as well design, well trajectory control, drag and torque monitoring, drilling string optimization, drilling fluid technology, borehole cleaning, borehole wall stabilization, casing tripping in and so on, are researched and applied. Using these techniques combined with real-time decision system, a well horizontal displacement to vertical depth ratio of about 2.62 is realized.
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     Application of New Technology Qualification in Offshore Oil and Gas Exploration Field
    WANG Ling-han, HU Peng, CHE Qiang, JIAN Zhi-yong
    2016, 3 (6):  367-370. 
    Abstract ( 179 )   PDF (3580KB) ( 77 )  
     Offshore oil and gas development is of high risk, especially the subsea and downhole system. The reliability and risk management of technology for subsea and downhole system have been highly valued by the industry. Technology qualification (TQ), as a system of technical evaluation standards, can be used for the risk assessment and process control system of offshore oil and gas development of new technology/new equipment (especially in subsea field). Through describing and analyzing the present application scope and situation of technology qualification in foreign offshore oil and gas technology development field, and comparing those with the current status of research and development of subsea equipment in China, we summarize the application method of technology qualification in the development process, and put forward the advice that research institute in China should apply technology qualification in the development of new technology/new equipment in offshore oil and gas development.
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     Study on Motion Characteristics for Semi-Submersible Platform of Offshore Wind Turbine
    RUAN Sheng-fu, FAN Bing, WANG Tao, TIAN Wei-xing
    2016, 3 (6):  371-375. 
    Abstract ( 242 )   PDF (5098KB) ( 63 )  
     With the water depth of offshore wind farm and the power of wind turbine increasing gradually, the traditional fixed foundations are not applicable. The floating foundations with excellent characteristics have become a research focus. The semi-submersible foundation and mooring system are designed for a 600 kW wind turbine with a horizontal shaft, and the water depth is 60 m. SESAM software is used to establish the finite element model of this semi-submersible platform. The motion responses are calculated in both frequency domain and time domain. Motion performance and mooring line tension are also investigated. This research has some guiding values for the development of offshore wind farm with floating foundation.
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     Study on Crushing Test of Submarine Single-Layer Insulation Pipeline Weight Coating
    LIU Xin-shuai, LI Yang, XU Liang, XIANG Zheng-le
    2016, 3 (6):  376-380. 
    Abstract ( 208 )   PDF (5356KB) ( 79 )  
     The weight coating of submarine pipeline is commonly sprayed with high density concrete material. The compressive strength of the weight coating plays a very important role to ensure the pipeline to be safely laid. Taking a submarine single-layer insulation pipe-lay project in Bohai area as an example, we check the compressive properties of pipe materials by using crushing test method, inspect the function of each layer structure in the crushing test process, and evaluate the capacity of weight coating resisting the tensioner clamping force, so as to provide instruction for the offshore installation.
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     Feasibility Analysis of Medium Voltage Power Supply for Electrically Driven Fire Pump on Offshore Oil Platform
    LAI Yuan, LI Yan-hua, DOU Pei-ju
    2016, 3 (6):  381-384. 
    Abstract ( 190 )   PDF (3408KB) ( 62 )  
     During starting stage, electrically driven fire pump produces 4-7 times electric current than the rated electric current, which will result in surge impact on the electric grid. Usually two small power pumps are used to replace one big power pump to solve the electric current surge problem, but this will increase the acceleration time of the fire pump and postpone the response of the fire water system. If the electrically driven fire pumps are supplied by medium voltage power source, the starting electric current will be reduced and the surge impact will be eliminated. An equivalent method is raised to replace the medium voltage fire resistance cable under the situation that there is no qualified product at the market. The proposed scheme can meet the related standards and design rules, and provide a solution to the medium voltage driven fire pump on offshore oil platform.
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     Safety Considerations in Layout Design of Four-Leg Wellhead Platform with Two Wellhead Areas
    WANG Hong-hong, WANG Kui-tao
    2016, 3 (6):  385-388. 
    Abstract ( 212 )   PDF (3496KB) ( 47 )  
     At present, CNOOC's conventional independent four-leg wellhead platform cannot simultaneously meet the requirements of arranging 32 well slots, living quarter, and workover rig module, and using general drilling ship to carry out drilling and completion operations. To achieve all of the above functions, a new type four-leg wellhead platform with two wellhead areas is designed in Bohai oilfield development project. Considering that the space on the four-leg platform is limited, when the drilling ship is on site, there is potential risk of collision between the ship and the workover rig. Through risk identification for the layout plan of the wellhead platform, the layout design result successfully solves the problem, and allows reasonable rest for the platform crane. This platform has produced its first oil.
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     Software Development of Pre-Nesting for Composite Beam-Steel Based on API Standards
    WEI Xu-ming, ZHANG Qiang, ZHANG Chuan-rong, CHEN Cheng, DU Yang-yang, CHEN Huai-qi
    2016, 3 (6):  389-392. 
    Abstract ( 197 )   PDF (3340KB) ( 46 )  
     Based on the requirements from American Petroleum Institute (API) standards and a theory of pre-nesting for section steel, a calculation model of pre-nesting for composite beam-steel is given by the Visual Basic (VB) computer language. The software of purchase and pre-nesting is then developed, which is named BYMAX 1.0. The main functions can be summarized as below. The first part is to calculate the size and number of steel plates with a smart and high-speed process. And the second part is to check the results and to show the nesting pictures by calling AutoCAD. This part can guarantee the accuracy of the previously obtained results.
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