Table of Content

    25 June 2015, Volume 2 Issue 3 Previous Issue    Next Issue
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    Subsea Christmas Tree Tubing Hanger Installation by Simplified Landing String
    Ning ZHANG, Jia-you MAO, Jian-jun YANG
    2015, 2 (3):  145-151. 
    Abstract ( 438 )   HTML ( 349 )   PDF (6463KB) ( 394 )  

    The simplified landing string is introduced to Liuhua 4-1 Field for the installation of subsea Christmas tree (XT) tubing hanger, considering the low pressure in reservoir and absence of shallow gas. After demonstrating the feasibility of the simplified landing string system, the main equipment of this system is introduced, including the simplified landing string, umbilical system, tubing hanger running tool and tubing hanger. Then the control factors and restriction conditions are represented, followed by the detailed description of installation steps. Finally, a comparison is made between the application of conventional landing string and simplified landing string. The results can offer a reference for the exploitation of marginal subsea fields.

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    Study on the Pilot Plant’s Capacity of Floating Liquefied Natural Gas Processed by Propane Pre-Cooling and Dual-Nitrogen-Expansion Sub-Cooling
    Miao-er LIU, En-dao LI, Quan-sen YIN, Xiao-liang TAI
    2015, 2 (3):  152-156. 
    Abstract ( 248 )   HTML ( 8 )   PDF (915KB) ( 325 )  

    Based on the propane pre-cooling and dual-nitrogen-expansion sub-cooling (C3-DN2) process used for floating liquefied natural gas production, storage and offloading unit (LNG-FPSO), a pilot unit will be built to test the rationality of process configuration and key control modes, and to study the operability and flexibility of its application in offshore cases. In order to define the capacity, the pilot unit should keep the consistency of process configurations and key control modes, and the similarity of moving and flow regime with LNG-FPSO. The factors affecting the capacity of the pilot unit are further investigated, and the results show that the type of key equipment to keep the consistency of key control mode greatly impacts the capacity, and the other factors have less influence. Among the main devices, the refrigerant compressor should be considered the most carefully when defining the capacity of the pilot unit, and others such as cold box, driver, turbine expander and the heat exchanger for C3 are less important. Therefore, it is better to select the same type of refrigerant compressor in the pilot as that in the LNG-FPSO, and to design two plate-fin heat exchangers in parallel in the cold box.

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    Optimization in the Control Modes for Propane Compressor in C3/MRC Liquefaction Process
    Hong-yu PAN, Shun-li LI, Yu-xing LI, Jian-lu ZHU
    2015, 2 (3):  157-162. 
    Abstract ( 222 )   HTML ( 11 )   PDF (2376KB) ( 300 )  

    The flexibility of three reflux modes including overall reflux, gradual reflux and last stage reflux for propane compressor in C3/MRC liquefaction process is simulated respectively by dynamic simulation, on which basis high pressure control and low pressure control are added, respectively. In this way, the influence on liquefaction process and the response speed of the controller by changing the settings of controller can be analyzed. It is indicated that the high pressure control of gradual reflux can meet the demand of better stability and faster response in liquefaction process.

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    Research on Polymer Flooding Equipment Arrangement of SZ 36-1 Oilfield
    Zhi-sheng DU, Jin-jin XU, Chao MA, Fa ZHANG
    2015, 2 (3):  163-167. 
    Abstract ( 412 )   HTML ( 5 )   PDF (2235KB) ( 266 )  

    Polymer flooding has been applied to offshore platform for more than 10 years. Polymer flooding technology has been very mature by now. However, there are still some problems in polymer flooding equipment planning and compatibility for production equipment etc. According to the development of SZ 36-1 Oilfield polymer flooding project, we propose different equipment arrangement plans for varied scales of polymer flooding, including the schemes for increasing the deck area, and put forward the optimization directions of polymer flooding equipment arrangement.

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    Study on Repair Methods for Deepwater Pipeline
    Chao MA, Kun SUN, Ye-zhou HUANG, Xiao-dong CHEN, Shou-yang SUN
    2015, 2 (3):  168-174. 
    Abstract ( 151 )   HTML ( 5 )   PDF (15760KB) ( 221 )  

    The special environment conditions of oil and gas fields near Liwan 3-1 are introduced with their adverse effects on pipelines, and three damage scenarios of deepwater pipeline for repairing damaged pipeline are listed. According to the damage scenarios, methods for repairing damaged pipeline in deep water are summarized with repair procedure and equipment, and those methods are compared. Finally, the application possibility of all methods for pipeline repair in deepwater field is analyzed. It is concluded that repair with bolted clamp or connector can be main repair methods for deepwater pipelines in China.

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    Taut Mooring System Design and Analysis of Octagon FDPSO
    Qiang SUN, Qing-hui DONG, Gui-sheng PENG, Tian TIAN, Bin XIE, Shi-sheng WANG, Xi-chong YU, Jing-rui ZHAO
    2015, 2 (3):  175-183. 
    Abstract ( 260 )   HTML ( 4 )   PDF (2706KB) ( 395 )  

    The existing mooring systems are compared and analyzed with the consideration of vessel shape, environmental condition and design cases. Average-distributed taut mooring system is finally selected for the octagon floating drilling, production, storage and off loading system (FDPSO) in the South China Sea. According to the requirements of station keeping and line forces, an averaged-distributed taut mooring system is designed based on the environmental condition at the depth of 2 000 m in the South China Sea. Compared with the traditional catenary mooring system designed for the same FDPSO, the averaged-distributed taut mooring system reduces the mooring system self-weight and the mooring radius on seabed. In addition, the offset of FDPSO with one mooring line damaged can be efficiently managed under 100-year environmental condition. The proposed mooring system can meet the requirements of octagon FDPSO. Furthermore, the research results will offer references for the mooring design of similar floating structures.

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    Parameter Research on the Contact Load of the Over-Bend of Flexible Pipe During Laying
    Hai-bin YE, Jian-feng YUE, Yong-biao YE, Qian-jin YUE, Jin-long CHEN
    2015, 2 (3):  184-188. 
    Abstract ( 160 )   HTML ( 2 )   PDF (4785KB) ( 281 )  

    The over-bend of the flexible pipe will be subjected to obvious contact load during horizontal laying and failure may occur because of crushing. This usually restricts the application of horizontal laying in deep water. Therefore, it is significant to accurately estimate the contact load on the over-bend of the flexible pipe during laying. We carry out theoretical research on the over-bend contact load, deduce a simplified calculation formula, and investigate the key parameters which affect the contact load in the laying cases by numerical simulation. The results can offer a specific guidance for the over-bend contact load analysis in flexible pipe laying, and provide a reference for the laying design as well.

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    Manufacturing Technique Analysis of 20 Inch Double-Carcass Reeling Offloading Hose
    Xue-yong SHAN, Yi ZHOU
    2015, 2 (3):  189-195. 
    Abstract ( 131 )   HTML ( 4 )   PDF (30612KB) ( 108 )  

    Marine offloading hose is an important equipment which has been installed between oil production and storage unit and shuttle tanker. Marine offloading hose has a complex structure and plays a key role in oil transportation, which makes it require high technology. For a long time, a few companies from developed countries have a monopoly on this industry. We introduce the long course of marine offloading hose localization and analyze the production technology of 20 inch double-carcass reeling floating main hose through the characterization of its structure and material with the international standard GMPHOM 2009 for marine offloading hose as a reference.

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    Subsea Pipeline Span Analysis Based on Fatigue Life
    Xiu-feng LI, Xian-hong FENG
    2015, 2 (3):  196-200. 
    Abstract ( 643 )   HTML ( 2 )   PDF (2536KB) ( 538 )  

    Traditionally, span analysis determines the maximum allowable free span length based on the condition that no vortex induced vibration (VIV) will happen and the assumption of strength ultimate limit state (ULS). The cost of span mitigation rises rapidly with the increase of water depth. Free span analysis based on fatigue life could remarkably increase the maximum allowable span length and cut the engineering cost. We present the free span analysis method and criteria for subsea pipeline. Based on the engineering project which is the first time to use fatigue limit for pipeline design, the free span analysis is conducted by fatigue limit state (FLS) and finite element method, and the results minimize the number of span mitigation.

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    UPS Sizing Calculation for Offshore Platform
    Zhi-gui GUO, Xiao-hua YAO
    2015, 2 (3):  201-204. 
    Abstract ( 320 )   HTML ( 1 )   PDF (964KB) ( 263 )  

    Uninterruptible power supply (UPS) is a key device in the electrical system on the offshore oil platform. It supplies the key loads such as the communication equipment, instrument control, electric protection, and control panels or workstation for the key machines when the normal and the emergency power supplies both fail. We deal with the calculating method for sizing of UPS and perform engineering calculation on the UPS sizing of a certain offshore platform. It is proved that the calculating method is simple and convenient, and can be used for the electrical design of other offshore oil platforms.

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    Classification and Application of Offshore Pipeline Trenching Technology and Equipment
    Song GAO
    2015, 2 (3):  205-208. 
    Abstract ( 189 )   HTML ( 4 )   PDF (20960KB) ( 205 )  

    To assure the stability of offshore pipeline and avoid hazard from the external environment, normally the pipelines are protected by trenching in the shallow sea. The pipeline trenching methods and installation tools are presented, and their function and characteristics are described. Furthermore, the selection of trenching methods and tools are studied. This research can provide the solution to trenching method of offshore burial pipeline in the earlier stage of engineering design.

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    Design and Application of SDH Fiber Optic Network for Offshore Oil and Gas Field
    Jin-hong XIE, Xiao-peng LI, Jian-mei GAO
    2015, 2 (3):  209-214. 
    Abstract ( 133 )   HTML ( 1 )   PDF (1404KB) ( 240 )  

    As the growing needs of data transmission rate and reliability in oil field production, synchronous digital hierarchy (SDH) fiber optic network is applied to offshore oil fields. We introduce such a new fiber optic network technology from two aspects, i.e., network structure and self-healing ring network, and frame structure and transmission rate. The design method, optical fiber design and design of optical terminal equipment are analyzed using the CFD11 project as an example. Through the successful application in the project, we draw a conclusion that the SDH technology is completely applicable to offshore oil and gas fields.

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