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    25 February 2018, Volume 5 Issue 1 Previous Issue    Next Issue
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    Upheaval Buckling of Buried High Temperature Pipelines
    XIA Qiu-ling
    2018, 5 (1):  1-5.  DOI: 10.12087/oeet.2095-7297.2018.01.01
    Abstract ( 366 )   PDF (2671KB) ( 146 )  
    For buried high temperature subsea pipelines, if the axial movements are restrained, large axial compressive forces will occur and these compressive forces will cause upward buckling (UHB), namely the upheaval buckling. After pipeline buckling occurs, there will be two possible consequences: strength failure, or other type of failure resulting from the deviation from design conditions since the buried pipeline comes out of the seabed. Recently, more and more offshore marginal fields are developed, the transporting temperature rises, and the pipeline design temperature rises accordingly, so the UHB will be probably a critical case. Aiming at this problem, three methods for UHB analysis are presented and the applicable scope is discussed.
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    On-Stream Subsidence Protection Design and Construction Performance of Large-Diameter Submarine Pipelines Across Channels
    ZHAO Dang, HE Ning, CAI Jing, YU Zhi-bing, CHEN Si, CUI Shao-min
    2018, 5 (1):  6-11.  DOI: 10.12087/oeet.2095-7297.2018.01.02
    Abstract ( 312 )   PDF (3546KB) ( 106 )  
    For a large-diameter double-insulating submarine pipeline located in Liaodong Bay, a span across channels is treated and subsidence protection is achieved during on-stream maintenance. Test results after the construction show that the subsidence depth reaches 4.5 m, which is the largest depth compared with other projects in China. In the subsequent rock dumping protection, trench soil is used to finish the first backfill layer, which can save the cost and greatly promote the construction efficiency. The design and construction methods used in this project are of value for further design of similar submarine pipeline projects.
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    Optimization Analysis for Configuration of Inert Gas System on FPSO
    SHANG Chao, WANG Chun-sheng, ZHENG Xiao-peng, ZHANG Ming, SUN Jing, WANG Hai-yan
    2018, 5 (1):  12-15.  DOI: 10.12087/oeet.2095-7297.2018.01.03
    Abstract ( 293 )   PDF (3082KB) ( 172 )  
    Floating production, storage and offloading unit (FPSO) is an important facility for offshore oilfield development. FPSO is equipped with inert gas generator to ensure the safety of crude oil transportation and production. We carry out optimization analysis for the configuration of inert gas equipment, including configuration mode optimization, type selection optimization, deck water seal and breaker sharing optimization, etc. This research could provide reference for the selection design of inert gas system on FPSO.
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    Research of Multi-Stage CFU Process for Produced Water Treatment in Offshore Heavy Oilfield
    WANG Hai-yan, WANG Chun-sheng, ZHANG Ming, SHANG Chao, SUN Hong-hui, ZHENG Xiao-peng
    2018, 5 (1):  16-19.  DOI: 10.12087/oeet.2095-7297.2018.01.04
    Abstract ( 418 )   PDF (3018KB) ( 214 )  
    Research is carried out according to the data from a multi-stage compact flotation unit (CFU) experiment on a floating produced, storage and offloading unit (FPSO) in a heavy oilfield, as well as the running data of CFU on a wellhead platform in a heavy oilfield. The oil removal rate of two-stage CFU is high, according to the experiment data from FPSO. The oil content in produced water after three-stage CFU on the wellhead platform is decreased to about 27 mg/L. So, the multi-stage CFU can achieve a good result in offshore heavy oilfield. A two-stage CFU can replace corrugated plate interceptor and gas floator. Besides, the multi-stage CFU is small and light, which is suitable to offshore oilfields.
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    H2S Variation Trends in Produced Water Treatment System of Offshore Oil Field
    CHEN Zi-jing
    2018, 5 (1):  20-23.  DOI: 10.12087/oeet.2095-7297.2018.01.05
    Abstract ( 373 )   PDF (5914KB) ( 102 )  
    H2S gas often appears in oil and gas field development. To understand its presence in the water treatment process, the H2S variation trends in produced water after treated by flotation process are discussed. The H2S content variation in vapor and water phases of compact flotation unit (CFU) is simulated by HYSYS, considering different factors such as pressure, temperature and floatation gas quantity. It leads to a certain understanding about the existence of the H2S gas in water treatment systems.
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    Well Abandonment Technology and Application of Barite Plug in Bohai Well A3
    HE Peng-fei, LIU Bei-qiang, YUAN Ze-ming, XIAN Shi-dong, DONG Xiao-lin
    2018, 5 (1):  24-29.  DOI: 10.12087/oeet.2095-7297.2018.01.06
    Abstract ( 317 )   PDF (5009KB) ( 135 )  
    Cementing plugging is a common operation in oil and gas field exploration and development, usually used in side tracking, backfilling and well abandonment. The quality of cementing plugging directly affects safety and environmental protection, with the basic requirement known as “pressing stably, sealing reliably”. The well A3 is a deep well in the Bohai Oilfield. During the drill process, drilling tool sticking and dropping occurred when the drilling depth reached 5046 m. After the failure of fishing, the only choice was well abandonment and side tracking. At that time, the bottom temperature exceeded 100 ℃, and the pore pressure was 1.52 g/cm3. There is a high total gas amount at this depth, and this well belongs to the low porosity and low permeability reservoir. Considering the failure of gas blocking by cementing plugging in previous operations, the combination of cement, floating beads, latex polymer and barite plug was proposed to block the gas. With the help of pressure waiting-on-cement, gas blocking was finally achieved, which guaranteed the safety of well control and subsequent operations.
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    Recovery Technology of 339.7 mm Casing of A10 Well in the East China Sea
    YAN Wei-feng, YUAN Ze-ming, HE Peng-fei, SHI Wen-zhuan
    2018, 5 (1):  30-35.  DOI: 10.12087/oeet.2095-7297.2018.01.07
    Abstract ( 308 )   PDF (7615KB) ( 50 )  
    In the offshore oil and gas development, casing recovery technology is mainly used in sidetracking and abandoned well shaft treatment. Sidetracking technology is gradually increasingly used in the oil and gas fields of the East China Sea, mainly to improve the production and recovery, and realize the reuse of well slots. But in the casing recovery technology, new technical problems are also emerging, such as the difficulty in recovering large size casing, the uncertainties in the annulus cement quality between borehole and casing and in the annulus medium distribution, as well as the deviation of the casing from the center position. In the East China Sea, the recovery of a large size casing is successfully performed. During the recovery process of the 339.7 mm casing of A10 well, some techniques are used, including the isolation scanner (IBC) logging technology, the optimization of cutting position, and the application of fishing, casing milling, milling and other processes. The successful recovery could provide conditions for subsequent sidetrack drilling. These technologies can also be used for similar operations.
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    Treatment and Analysis of Sticking Accident of an Exploration Well in Ningbo 11-1
    WANG Xi-jie
    2018, 5 (1):  36-41.  DOI: 10.12087/oeet.2095-7297.2018.01.08
    Abstract ( 346 )   PDF (6282KB) ( 225 )  
    An exploration well of Ningbo 11-1 has been designed with a drilling depth of 4638 m. However, sticking occurs when the drilling depth of 12-1/4 inch hole reaches 4100 m and the bottom hole assembly (BHA) needs to be changed. Through the preliminary analysis of the reasons, the sticking is considered resulting from hole shrinkage or wall collapse. Various methods are adopted to solve the problem, including reverse drilling tools, large tonnage lifting and lowering, as well as pumping releasing agent, drilling fluid and sea water to match large tonnage movable drilling tools. In the absence of a loop path, new treatment measures such as annulus pressure suppression and micro fracture formation are attempted. In the end, the problem is not resolved and explosion has to be performed. Through the detailed introduction to the above technical measures and processes, countermeasures in theory and practical operation are given for such sticking accidents.
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    Development and Application of Clamping Device of the Deepwater Drilling Riser Monitoring System
    BAI Hao
    2018, 5 (1):  42-46.  DOI: 10.12087/oeet.2095-7297.2018.01.09
    Abstract ( 250 )   PDF (8899KB) ( 59 )  
    With the amount of deepwater drilling equipment steadily increasing in our country, the mating safety ensuring technology is increasingly prominent. It is of great significance to guarantee the operation safety of deepwater drilling riser, which is the link between the subsea wellhead and the drilling rig. Internationally recognized safeguard is the real time monitoring while drilling. In the 12th Five-Year Plan, a set of riser monitoring system engineering prototype has been developed. For this prototype, a bandage type clamping device for monitoring equipment installed in the riser is designed. Through the practical application in the Xingwang drilling ship, the reliability of the clamping device for monitoring equipment is verified, as well as its monitoring operation adaptability.
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    Offshore Drilling-Workover Rig Global Structure Strength Analysis Based on Structure Inspection
    CHANG Shuang-li
    2018, 5 (1):  47-52.  DOI: 10.12087/oeet.2095-7297.2018.01.10
    Abstract ( 272 )   PDF (6896KB) ( 63 )  
    The drilling-workover rig module, which is installed on offshore production platform and mainly provides drilling and workover operations, needs regular testing and maintenance. For a drilling-workover rig module, global structure inspection and stress analysis should be performed after 4-year service, together with the analysis on the test data. Finite element model is established and used to calculate the structural strength and stability, based on which one can evaluate fatigue life, effectively prevent risks, and ensure the safety of the offshore rig.
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    Analysis on Protection of DC Zone Distribution System of Offshore Platform Drilling Device
    MA Yun-xu-zi, GAO Di-ju, WANG Xiao-yu
    2018, 5 (1):  53-57.  DOI: 10.12087/oeet.2095-7297.2018.01.11
    Abstract ( 339 )   PDF (3467KB) ( 139 )  
    With the promotion of power electronics, direct current (DC) zone distribution system is to be applied in drilling device of offshore platform, and relay protection is one of the key technologies for the distribution system. The structure features and protection difficulties of the DC zone distribution system is analyzed. With the application of power electronic building block (PEBB) technology, a DC zone distribution system and its relay protection system are set up by replacing the traditional converter and circuit breaker with turnoff converter and capacitor DC circuit breaker. On this basis, fault detection and location, fault current interrupt and fault device isolation are discussed and analyzed. Finally, the method of setting the threshold for protection and the collaborative protection for different protection areas are investigated.
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    Research on Power System for Large Capacity Electrically Driven Compressors on Offshore Platform
    LIU Guo-feng, WAN Guang-fen, GAO Xuan
    2018, 5 (1):  58-62.  DOI: 10.12087/oeet.2095-7297.2018.01.12
    Abstract ( 474 )   PDF (2606KB) ( 72 )  
    The application of large capacity electrically driven compressor will cause significant changes in the power system of offshore platform. Based on a specific offshore project, we introduce the overall electrical system plan for the platform with electrically driven compressors, and point out the key technical problems that should be focused on to optimize the power system. In particular, simulation calculations are required to ensure the stability of power system. Results from the study will have some guidance and reference for similar projects in the future.
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    Research on Deepwater Pipeline Coating Removal Equipment for 2000 m Water Depth
    LI Long-xiang, YE Yong-biao, FU Fang-chao, XU Meng-meng, CAO Chen-lei
    2018, 5 (1):  63-66.  DOI: 10.12087/oeet.2095-7297.2018.01.13
    Abstract ( 423 )   PDF (4168KB) ( 219 )  
    The current status of pipeline coating removal equipment suitable for in-situ pipeline repair in shallow water in China is discussed, and a survey is presented on state-of-the-art equipment for deepwater operations from oversea suppliers. Selection of equipment configurations for operations in 2000 m water depth is conducted with considerations in practicality and safety perspectives. Based on the actual requirements from China's offshore oil and gas pipeline inspection, maintenance and repair(IMR) operations, a thorough comparison between deck-mounted and subsea high pressure water pumps work model is carried out to identify the ideal equipment configuration for pipeline coating removal in 2000 m water depth. We also highlight the significance of acquisition of such equipment and technology.
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    Study on Air Purge Scheme of LNG Pipeline
    XIE Yong-chun, ZHANG Hong-bin, CHENG Zhao-xin
    2018, 5 (1):  67-73.  DOI: 10.12087/oeet.2095-7297.2018.01.14
    Abstract ( 431 )   PDF (6754KB) ( 126 )  
    Welding slags, iron dusts and other foreign matter appear during liquefied natural gas (LNG) pipeline construction. Such materials need to be removed by cleaning or purging so as to meet the cleaning requirements. Through the use of air purge scheme during pipeline construction, we summarize the air source selection schemes. According to different air sources, different methods can be adopted to complete the cleaning of the main pipeline and branches. According to the theory of drag force, evaluation of air blowing effectiveness is demonstrated. Based on cleaning criteria, one can determine whether or not the pipeline achieves acceptance requirements. This research will provide reference for the pipeline construction using air purge scheme.
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    Application of PDMS Development in Offshore Oil Platform
    WANG Jing, LI Zhen, GUAN Di
    2018, 5 (1):  74-76.  DOI: 10.12087/oeet.2095-7297.2018.01.15
    Abstract ( 395 )   PDF (2285KB) ( 105 )  
    Plant Design Management System (PDMS), published by AVEVA company, is a threedimensional (3D) modeling software based on multiprofessional collaboration. PDMS can directly generate labelled professional diagrams. We use programmable macro language (PML) to secondarily develop PDMS software. It provides a number of extended functions for offshore platform of cable laying and arrangement. It improves the integrality of offshore oil platform model design.
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