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25 April 2016, Volume 3 Issue 2 Previous Issue    Next Issue

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Optimization of Horizontal Injection and Production Well Pattern in Thin Oil Layer FENG Yuan-zhou, ZHAO De-xi, YANG Zhi-cheng 2016, 3 (2):  79-84.  Abstract ( 161 )   PDF (2070KB) ( 214 )   Ultra-low abundance and thin oil layers have the characteristics of low reserves abundance, thin reserves and poor permeability. Horizontal well technology can effectively solve the problem in ultra-low abundance and thin layers. Horizontal injection pattern can increase the injection rate, reduce the injection pressure, maintain the reservoir pressure and improve the production efficiency. In view of these characteristics, we establish the geological model, design the basic horizontal injection-production well pattern, and select the typical pattern to perform analysis and evaluation. The dominant pattern is obtained, which can provide the basis for enhancing reservoir production levels using horizontal well pattern in ultra-low abundance and thin layers. Related Articles | Metrics

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Selection Study of Deepwater Subsea Christmas Tree System WANG Yu, ZHANG Jun-bin, JIANG Shi-quan, LIU Yong-feng, HAO Xi-ning 2016, 3 (2):  85-92.  Abstract ( 419 )   PDF (1819KB) ( 914 )   Correct selection of subsea Christmas tree system is essential for reducing the cost of deepwater oil and gas development project. Based on extensive investigation and review, we systematically summarize the practical selection method for subsea Christmas tree system. Firstly, the characteristics of subsea Christmas tree, tubing hanger and tree cap are summarized. Secondly, the key selection issues and configuration requirements of tree wellhead connector, subsea valves and subsea monitoring and surveillance instruments are analyzed. Thirdly, the decision methods of material classes, pressure ratings, temperature classifications, product specification levels and performance requirement levels are given. Finally, the application scope of subsea production control systems and installation and workover control systems is described. Related Articles | Metrics

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Segmented Design and Calculation Method for Printed Circuit Heat Exchanger as LNG Vaporizer WU Wei-wu, WANG Dong-bao, ZHAO Li-ming, YUAN Zhen-qin 2016, 3 (2):  93-98.  Abstract ( 296 )   PDF (2229KB) ( 274 )   The development of offshore liquefied natural gas (LNG) production puts forward higher demand for heat exchanger, since it is the key component in LNG floating storage and regasification unit (FSRU). As a compact microchannel heat exchanger, printed circuit heat exchanger (PCHE) has a wide application prospect in LNG-FSRU because of its characteristics of small volume and high heat transfer efficiency. Considering the phase change phenomenon and the supercritical fluid in LNG vaporizer, a segmented thermal design method for PCHE is presented based on (LMTD) method. The temperature and the area of every segment could be calculated with boundary conditions and heat transfer correlations, and then the total heat transfer area of the vaporizer could be obtained. This method is proven to be reliable with 7.9% margin by contrasting the numerical result with the experimental one. Related Articles | Metrics

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Proving of Liquid Ultrasonic Flowmeters on FPSO ZHANG Ying, SUN Qin, SUN Jing 2016, 3 (2):  99-104.  Abstract ( 319 )   PDF (1613KB) ( 102 )   Liquid ultrasonic flowmeters have outstanding advantages in large flow rate measurement, but its proving is much more complex than other flowmeters, which limits its application. Four ultrasonic flowmeters were first used in the custody transfer system on FPSO in the South China Sea. We analyze the principle and features of ultrasonic flowmeters, and then design the proving scheme. We attempt to use pipe prover to prove ultrasonic flowmeters for the first time in China. By contrasting pipe prover and master meter proving data, we can draw a conclusion that increasing the standard volume of pipe prover and evaluating the meters with more proving runs can help to solve the proving problem of pipe prover, which is relevant for the other similar upcoming projects. Related Articles | Metrics

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In-Place Global Performance Numerical Analysis for TLP at South China Sea ZHANG Fa-fu, GAO Jing-kun, YANG Xiao-long, CAI Yuan-lang 2016, 3 (2):  105-110.  Abstract ( 246 )   PDF (2683KB) ( 321 )   The load case category and numerical calculation procedure of tension leg platform (TLP) in-place global performance analysis are systematically stated. Meanwhile, the frequency domain method and time domain method are simply introduced. According to a TLP front end engineering design project at South China Sea, modeling principles related to panel meshing, calculation methods of TLP mass properties, stiffness introduced by tendons and risers, and TLP external damping are introduced. At last, the main results of in-place global performance analysis are listed. The procedure and methods used could be a reference for other analogous projects at South China Sea. Related Articles | Metrics

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Study on the Current Force on the Columns with Different Fillet Radii of a Floating Platform XU Shan-hui, DU Qing-gui, YIN Bao-rui, ZHUANG Hong-chang, WANG Cheng-lin 2016, 3 (2):  111-115.  Abstract ( 291 )   PDF (2468KB) ( 181 )   Floating platform plays an important role in the development of deepwater oil resources. The current force acting on the floating platform is usually considered to be a critical factor for platform design. Once the design plan is finalized, the principal dimension of the column is fixed, and the current force will be mainly affected by the cross sections. The FLUENT software is used here to compute the force of the columns with cross sections of different fillet radii in a uniform viscous flow. According to the computation, the current force of the column with a fillet radius more than 2 m will be reduced by more than 50%. The research results may provide good reference to the design of a new platform. Related Articles | Metrics

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Study on the Oxygen Content of Airtight Water Injection System for Offshore Platform LAI Yuan, GAO Peng, ZHOU Xiao-hong, PAN Bing-xu 2016, 3 (2):  116-121.  Abstract ( 173 )   PDF (834KB) ( 126 )   According to the basic theoretical formula of two-film theory, we derive the calculation formula of oxygen content change in the offshore platform water injection system after air-water backwash. On the basis of the calculation formula, the effects of different backwash methods on the oxygen content in the process are analyzed, and the influence of the water injection process in a certain offshore oilfield on the oxygen content of the process is analyzed. Analysis results show that the air-water alternative backwash mode in offshore platform will not lead the oxygen content change to exceed the limit for injection water defined in related standards. Related Articles | Metrics

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Big Free Span Correction Scheme by Cement Grouting in LW3-1 Project WANG Peng-fei, LIN Zhen-yu 2016, 3 (2):  122-128.  Abstract ( 304 )   PDF (2744KB) ( 175 )   Free spans on subsea pipelines are spans of the pipeline unsupported by the seabed and pipelines with long free spans are subject to increased fatigue loads and reduced pipeline integrity. Free spans corrected by cement grouting have been used for many years in international engineering projects, but there are few applications in China. Sand bags are still used very commonly in domestic projects. However, most projects corrected by cement grouting are low spans, since this method is not suitable for high span correction in technology and operation. For the high and big spans, a permanent solution is needed. Based on the common grouting correction procedure, through the technology improvement and design optimization, we make it meet the requirements of large span correction. Through the practice of LW3-1 project, we introduce the method of grouting, analyze the characteristics and advantages, point out the way for its development and provide a guideline for the large span correction. Related Articles | Metrics

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Normal Laying Analysis of Flexible Line Using OrcaFlex SUN Kun, LI Xue-song, CHEN Xiao-dong, SHI Jin-kun 2016, 3 (2):  129-134.  Abstract ( 494 )   PDF (2891KB) ( 305 )   Installation of flexible lines, such as pipe, cable and umbilical, is an important part of offshore operation for exploring oil and gas, and the key issue is how to assess the installation parameters accurately and determine the weather window. A simplified model and the corresponding analysis method for normal laying of flexible line are presented based on lumped mass method with the considerations for the modeling, the input data of the analysis, the acceptance criteria of the operation and the important parameters used in the operation. Taking a cable installation project as an example, the sensitivity analysis for the layback, the analysis of the axial compression, and the determination of the maximum environmental condition for the operation are performed. The proper weather window is 2.5 m significant wave height and 30° wave direction. The results show that selecting a proper layback is good for offshore operation; it is suggested to avoid the axial compression; for laying cable in shallow water, minimum bending radius (MBR) is the main limiting criterion to decide the maximum allowable environment condition. Related Articles | Metrics

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Creep Behaviors of HDPE Applied in Composite Flexible Pipes DAI Zhi-shuang, WANG Hong-xuan, LU Cheng-lin, SONG Ping-na, CHEN Xing, YUAN Xiao-yan 2016, 3 (2):  135-139.  Abstract ( 305 )   PDF (2733KB) ( 181 )   The creep of inner liner material for subsea composite flexible pipe may result in the over-reduction of its thickness, which may consequently lead to structural failure. The radial compression stress of high-density polyethylene (HDPE) is studied by using finite element analysis (FEA) method. Under 20 MPa inner compression load, the radial compression stress is 11 MPa when the interaction of structural layers is ignored, while the radial compression stress is 19.9 MPa when the real contact status between HDPE and flat steel is considered. The compression creep properties at 11 MPa under different temperatures are measured. According to the timetemperature equivalence principle, the predicted compression creep deformation of HDPE during 30 years at 60 ℃ is 17.5%. A groove clamp with a gap span for side restrained compression creep is designed, and the side restrained compression creep properties under different temperatures are investigated. The results indicate that the reduction of thickness of HDPE during 30 years at 60 ℃ is 6.6%. The filling volume in the gap span can be calculated according to the thickness of inner liner and the size of gap span of the armour layers, which can be the guidance of construction design for the flexible pipe. Related Articles | Metrics

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Relation Between Noise Level in Living Quarter and Door Arrangement of Main Engine Room on Offshore Platform HUI Ning, GAO Peng, PANG Fu-zhen, SHEN Zhi-heng, MA Bang-yong 2016, 3 (2):  140-144.  Abstract ( 314 )   PDF (3339KB) ( 89 )   Based on the statistical energy analysis (SEA), we quantitatively study the noise level in living quarter on offshore platform influenced by closure or open of main engine room doors, and provide the detailed noise level arrangement under different cases. Furthermore, we also optimize the door arrangement and give the right usage philosophy. According to the calculation results, it is found that front door has more influence than side door. To provide a better working environment, the doors at main engine room should be arranged at the side away from the living quarter. Related Articles | Metrics