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25 March 2014, Volume 1 Issue 1    Next Issue

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Global Structural Strength Analysis Methodology of a Typical TLP Yang LI, Zhong-min SHI, Bin XIE, Wen-hui XIE 2014, 1 (1):  3-13.  Abstract ( 285 )   HTML ( 2 )   PDF (3686KB) ( 6087 )   We focus on the global structure strength analysis of a typical tension leg platform (TLP). The objective of the TLP global structural analysis is to check the hull global structural integrity under design environmental conditions. Firstly, a global finite element model of the entire TLP is established, the hull structure is modeled in detail, whilst the deck structure is represented through a simplified deck beam model. A hydrodynamic analysis for operation and extreme conditions is conducted to get the design wave parameters for critical wave loads. After that, wave loads are mapped to the global structure finite element model, and the tendons are modeled as spring element which represents 6 degrees of freedom and rotations. Finally, the maximum stress and its distribution trends, together with the control elements, are obtained by finite element analysis according to critical wave heading, wave periods, wave heights and wave positions. Results and the TLP analysis method proposed can be used as reference for strength analysis of other offshore platforms. Figures and Tables | References | Related Articles | Metrics

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Simulation Analysis of Cementing Displacement in Offshore Extended Reach Well Hao LI, Jin-tang WANG, Bao-jiang SUN, Cheng-zhang CAO, Chun-li LI, Ke-wang XU 2014, 1 (1):  14-20.  Abstract ( 225 )   HTML ( 0 )   PDF (2591KB) ( 160 )   Displacement efficiency and interface stability are critical to the success of offshore extended reach well cementing. According to the theory of computational fluid dynamics and the basic cementing data of extended reach well in South China Sea, the cement slurry rheological property and the influence of different borehole conditions on cementing displacement are obtained by numerical simulation. The calculations demonstrate that displacement efficiency increases with the increase of cement slurry consistency index and decreases with the increase of cement slurry flow index; well-cementing displacement efficiency first increases and then decreases and finally tends to be stable as the yield stress increases; the flow index of cement slurry should not be too high when cementing, and the value of n should be controlled within 0.6; the consistency index should be greater than 1.5 Pa·sn, but not exceed 3 Pa·sn; yield stress in the range of 10~18 Pa is advantageous to replace drilling fluid with the cement slurry. It is suggested that the eccentricity should be controlled within 0.5 as eccentricity has a great influence on the stability of interface; the stability of interface is obviously improved by using casing centralizer, and the optimized best rigid centralizer swirl angle is 60°; casing buckling, causing significant reduction of displacement efficiency in the annular interface, has a great influence on the stability of interface. Figures and Tables | References | Related Articles | Metrics

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Analysis on Oil Spill Prediction, Control and Processing Technologies Used in Offshore Drilling Zheng TIAN, Jian-liang ZHOU, Shi-quan JIANG, Xi-ning HAO, Ding-zhao ZHOU 2014, 1 (1):  21-24.  Abstract ( 179 )   HTML ( 0 )   PDF (1683KB) ( 156 )   With the proceeding of offshore oil exploration and development from shallow water to deepwater, the risk of oil spill accident in oil drilling increases. High attention should be paid to the oil spill disaster, either from the viewpoint of environmental pollution or from economic losses. We introduce the research and application status of oil spill monitoring technology and effluent oil treatment. On one hand, domestic oil spill monitoring technology is studied from the principle and method of the spectral and remote sensing monitoring technologies. On the other hand, the effluent oil processing technology after the oil spill is studied. After comprehensive investigation, the methods are classified into mechanical and chemical ones and introduced separately. Figures and Tables | References | Related Articles | Metrics

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Marine Well Containment System for Subsea Blowout Scenario of Deepwater Drilling Xun-ke LI, Zhi-ming YIN, Jian LIU, Shi-quan JIANG, Jian-liang ZHOU 2014, 1 (1):  25-29.  Abstract ( 320 )   HTML ( 0 )   PDF (1865KB) ( 120 )   Deepwater drilling well blowout can cause serious damages and huge losses. In order to reduce the effects of accidents, the industry has developed several emergency response systems (marine well containment systems). We introduce the recent developments of such systems after BP Macondo subsea well blowout occurring on April 20, 2010 in Gulf of Mexico. The system functions, elements and arrangement of 14 kinds of capping stacks built by 7 companies(organizations) are reviewed. Capping stack, a hardware utilized to contain the blowout well at or near the wellhead, is the center piece of the system. Finally, we also give some recommendation for research on emergency response techniques for deepwater well blowout. Figures and Tables | References | Related Articles | Metrics

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Experimental Study on Air-Oil Two-Phase Flow Patterns in a Pipeline-Riser System with an S-Shaped Riser Wen-sheng LI, Lie-jin GUO, Nai-liang LI, Bing CHENG, Hai-yuan YAO 2014, 1 (1):  30-34.  Abstract ( 155 )   HTML ( 0 )   PDF (1677KB) ( 154 )   Experiments on flow patterns during air-oil two-phase flow in a long pipeline-riser system with an S-shaped riser are carried out. The test loop with 50.8 mm internal diameter consists of a horizontal pipeline with 119 m in length, followed by a 14 m downward inclined section, and ended at an S-shaped flexible riser with 24 m in length, 15.3 m in height. The inclination angle of the downward section is -2° from the horizontal pipeline. Based on the analysis of the pressure at the riser base and liquid holdup at the riser top, the flow regimes observed are classified into three categories: severe slugging of type 2 (SS2), transition flow (TRS), stable flow (including bubble flow, slug flow and annular flow). In contrast with air-water two-phase flow, there is no sign of severe slugging of type 1 in the present study. As for SS2, the probability density function (PDF) of liquid holdup presents a bimodal distribution with two peaks at HL = 0 and HL = 1, respectively. As for TRS, the PDF curve produced by liquid holdup data presents a unimodal distribution with a single narrow peak at HL = 0. As for stable flow, the PDF of liquid holdup presents a bimodal distribution between HL = 0.3 and HL = 0.8. Figures and Tables | References | Related Articles | Metrics

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Study on Interference of the Dynamic Unbonded Flexible Riser Wei-wei ZHOU, Yong SHA, Jing CAO 2014, 1 (1):  35-41.  Abstract ( 184 )   HTML ( 1 )   PDF (3998KB) ( 132 )   The dynamic unbonded flexible riser which is the key equipment in the offshore petroleum industry owns some advantages such as easy installation, high reliability and high anti-fatigue property. The dynamic unbonded flexible riser is manufactured by twining with polymer layers and steel tape layers. The section stiffness of flexible riser is in the relative low level compared with soild steel pipe, and it is easy to move when facing to the current, so the flexible riser configuration must be specially designed to avoid the interaction between the risers and mooring lines. We use the Huse wake model and finite element method (FEM) to analyze the flexible riser and mooring line in the South China Sea environment, meanwhile perform the sensitivity analyses of riser section stiffness, pipe flow density and drag coefficient. Finally, some engneering meaningful conclusions are given. Figures and Tables | References | Related Articles | Metrics

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Adaptability Evaluation of Mixed Refrigerant Liquefaction Process for Large Scale FLNG Topside Qing WANG, Yu-xing LI, Bin XIE, Xi-chong YU 2014, 1 (1):  42-49.  Abstract ( 284 )   HTML ( 0 )   PDF (3351KB) ( 149 )   As one of the key technologies of the whole device for large scale floating liquid natural gas (FLNG) equipment, liquefaction process is mainly dominated by foreign companies at present. Mixed refrigerant liquefaction process has the advantages of simple process, less equipments, high efficiency and lower power consumption, so it has been widely applied to liquefaction plant on land. It will also be adopted in the offshore FLNG which is about to put into production firstly in the world. Mixed refrigerant liquefaction process can be divided into different types of processes, and different liquefaction processes have different characteristics and scope of application. HYSYS software is used to simulate the three mixed refrigerant cycles under various conditions of feed flow, methane component ratio and heavy components ratio. Energy consumption and device features of different processes are compared. Processes which are suited to different liquefaction capacities are analyzed. The results show that, the ratios of power consumption of propane pre-cooled mixed refrigerant (C3MR), double mixed refrigerant (DMR) and single mixed refrigerant (SMR) are 0.3309, 0.2254 and 0.2451 respectively in the condition of 65000 m3/d natural gas inflow. Mixed refrigeration process which has the largest number of key equipments is C3MR, followed by the DMR, and the minimum is SMR. C3MR requires the most refrigeration while SMR requires the least. With the change of methane content in the feed gas, the ratio of power consumption of C3MR changes the most, while those of DMR and SMR change less. Figures and Tables | References | Related Articles | Metrics

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Failure Modes Analysis of Box Structure of the Containment System in FLNG Ting-ting LIU, Shi-lun RUAN, Jiang-zhou YIN, Qian-jin YUE, Bin XIE 2014, 1 (1):  50-54.  Abstract ( 174 )   HTML ( 0 )   PDF (2925KB) ( 110 )   The global and local finite element models of the mainstream containment system GTT NO96 of the floating liquid natural gas unit (FLNG) are established to evaluate the structural safety of tanks under the sloshing load. The failure modes of the models under quasi-static loading are systematically simulated by finite element method. The failure zones and extreme loads for different failure modes are obtained, which could provide a reference for the design of FLNG containment system. The results suggest that the main failure mode of the current design of FLNG container is the strength failure of the cover plate of the secondary insulation box at the intersection between the bulkheads of the primary and secondary boxes, and the extreme load is 0.38 MPa. Figures and Tables | References | Related Articles | Metrics

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Experimental Investigation of Liquid Sloshing Impact Load in a Large-Scale Prismatic Tank Zhi-jun WEI, Shi-lun RUAN, Qian-jin YUE, Bin XIE 2014, 1 (1):  55-61.  Abstract ( 184 )   HTML ( 0 )   PDF (4263KB) ( 201 )   Liquid sloshing load is one of the key issues in the design of the cargo container system of the very large-scale floating liquefied natural gas (FLNG) facility. Experimental investigation on liquid slamming in a large-scale prismatic tank under sway, surge, and roll excitations is performed, aiming at the time history of slamming pressure, the distribution of the largest impact pressure and the most serious filling rates. A series of experiments in a large-scale prismatic model is carried out. Pressure sensor array is employed to record the variation of impact pressure. The experimental results illustrate that the value between 60%~70% is the most serious filling rate. Furthermore, the position with change of curvature along the bulkhead is found to be the most serious position for tank structure. The results are useful for the research and design associated with slamming load in prismatic tank. Figures and Tables | References | Related Articles | Metrics

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Preliminary Investigation on Monitoring Methods for Deepwater Risers Bao-jun LI, Xin DENG, Xiao-hong SHEN, Ni LI, Ke HE, Zhe JIANG, Hai-yan WANG 2014, 1 (1):  62-69.  Abstract ( 213 )   HTML ( 0 )   PDF (3320KB) ( 285 )   Marine riser is the key but the most brittle assembly in deepwater oil exploration and production. The fatigue and fracture accident of deepwater risers, which are caused by factors such as vortex-induced vibration(VIV), offset of platform and so on, not only lead to huge economic loss, but also bring out marine ecological disaster and even create international political problems. The deepwater riser monitoring technology, starting from the fatigue and fracture accident the risers encountered, is the important guaranty for them to run safely during service and plays a vital role in the evaluation of structural fatigue damage and early warning of fracture accident. The advanced fatigue monitoring technologies are required urgently to meet the new journey of deepwater exploration and production industry that our country has embarked on. The why and how on fatigue monitoring of deep water riser is reviewed. The key parameters to monitor, the detecting methods and the manners of data transmission for their fatigue monitoring are introduced, and more attention is paid to the latter two. At last, the states of the art of fatigue monitoring methods in China and the test in South China Sea are discussed. Some suggestions on deepwater riser monitoring are given to support exploration and operation of deepwater oil and gas industry in a safe and environmentally responsible manner. Figures and Tables | References | Related Articles | Metrics

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New Heave Compensation System Design of Swim Car Hook and Motion Analysis Qing-you LIU, Yang TANG, Chong-jun HUANG, Wei LI 2014, 1 (1):  70-75.  Abstract ( 211 )   HTML ( 3 )   PDF (1377KB) ( 143 )   The drill string heave compensation system is an important part of offshore drilling equipment. During the operation, it can compensate heave motion of the platform, ensure a stable bottom hole pressure while drilling, keep drilling efficiency, protect the life of the drill bit and drill pipe, and improve drilling safety. At present, the drill string heave compensator device needs to be imported, and the price is very expensive, so the development of heave compensation system for offshore drilling platforms with our own intellectual property is imperative. On the basis of heave compensation device-related information and analyses on the structure, working principle and application of the existing drill string heave compensation system, considering the advantages and disadvantages of different heave compensation methods in practical operations, the new design scheme is proposed for heave compensation device. The rack-and-pinion scheme is selected for the new heave compensation device after comparison. Motion analysis on the rack-and-pinion device provides a reference for the structural design and simulation analysis of new heave compensation systems. Figures and Tables | References | Related Articles | Metrics

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Extruding Research of PVDF Used in Large Diameter Flexible Pipe as Inner Pressure Sheath Wei-feng WANG, Dong-jie LIU, Zheng-she PEI, Jing CAO, Yong SHA, Li-wei LI 2014, 1 (1):  76-79.  Abstract ( 160 )   HTML ( 0 )   PDF (917KB) ( 102 )   The key points of polyvinylidene fluoride (PVDF) extruding process and the influence of manufacturing temperature are analyzed. The manufacturing process is confirmed and material properties are tested. According to the test results, PVDF can satisfy the requirements of subsea composite flexible pipes. It has good mechanical and thermal properties. PVDF also has good creep resistance and aging resistance, as well as low permeation. Figures and Tables | References | Related Articles | Metrics

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Defect Analysis and Processing in Preproduction of Composite Polyurethane-Based Insulation Coating for Pipeline Xiao-bin JIANG, Xiao-ling ZHANG, Wen-tong WU, Rui-lin KONG, Jia-dong YANG, Bao-yin DU 2014, 1 (1):  80-83.  Abstract ( 167 )   HTML ( 0 )   PDF (765KB) ( 81 )   Composite polyurethane materials, mould and pouring and coating technologies are analyzed for the defects existing in the preproduction of composite polyurethane-based insulation coating for pipeline, such as bubble, unwanted pattern, coating thickness deviation, unacceptable caking property, improper processing method of glass hollow microsphere, etc. Solutions are given to make an acceptable pipe. Moreover, a better process flow of composite polyurethane-based insulation pipe is obtained, and the process parameters are optimized. Figures and Tables | References | Related Articles | Metrics

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Power Line Communication of Subsea Production Control System: a Review Xin ZUO, Yi-ru HU, Jue WANG, Chun-li ZHU, Jia TIAN 2014, 1 (1):  84-90.  Abstract ( 223 )   HTML ( 2 )   PDF (1356KB) ( 184 )   Nowadays subsea production system has been the mainstream mode of subsea oil and gas exploitation, of which the subsea control system is the most important part. As one of the main communication methods of subsea control system, subsea power line communication has a direct influence on the safety and cost of the subsea oil and gas exploitation. Firstly, the principles of power line communication in subsea electro/hydraulic control system are introduced, and the promotions from organizations like ISO/TC 67, Intelligent Well Interface Standardization (IWIS) and Subsea Instrumentation Interface Standardization (SIIS) are summarized. Secondly, the application history of power line communication in world's subsea projects is reviewed from the aspects of transmission rate, communication distance and modulation method, etc. Lastly, considering the unique characteristics of umbilical power line, uncertain system topological configuration and electromagnetic interference from subsea boost pump, special challenges that the power line communication technology faces due to subsea environment are analyzed. Figures and Tables | References | Related Articles | Metrics

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Deepening Application of VPRM Material Coding in Offshore Oil Engineering Construction Tai-an HUANG, Zheng-rong SONG, Long YU, Xiao-gang ZHANG, Xiao-hua JIANG, Jia WANG, Geng XU, Bao-rui YIN 2014, 1 (1):  91-94.  Abstract ( 261 )   HTML ( 0 )   PDF (3901KB) ( 135 )   VANTAGE Project Resource Management (VPRM) material coding rules are designed reasonably and strictly so that "one material one code" can be ensured. The uniqueness of VPRM code can be applied to the tracking management of bulk materials commonly used in offshore oil engineering projects. At the same time, the VPRM code, which is used throughout the whole construction process including material design, procurement, warehousing, and storage, can be regarded as the main line of material management information system. Based on the research of VPRM coding, we introduce the VPRM material code examples and their application in piping material management of an offshore oil engineering project. This will provide beneficial reference for the management of other materials, and offer new ideas for the management of materials in offshore oil engineering. Figures and Tables | References | Related Articles | Metrics