• 제목/요약/키워드: Drillship

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Hydrodynamic Characteristics of Deepwater Drillship for North Sea (북해용 심해 시추 선박의 유체성능 특성 평가)

  • Kim, Mun Sung;Park, Jong Jin;Ahn, Young Kyu;Kim, Hong Su;Chun, Ho Hwan
    • Journal of Ocean Engineering and Technology
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    • v.29 no.4
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    • pp.300-308
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    • 2015
  • With the increases in oil and gas prices, and energy consumption, drillship construction has increased during the last decade. A drillship using a dynamic positioning (DP) system to maintain its position and heading angle during drilling operations. In addition, a drillship is equipped with a moonpool structure to allow its drilling systems to be operated in the midship section. A drillship for the North Sea is specially designed to endure harsh environmental loads. For safe operation in the North Sea, the drillship should have good motion response and robust hull strength. A break water should be considered on the bow and side deck to prevent the green water on deck phenomenon from incoming waves. In addition, the moonpool should be designed to reduce the speed loss and resonance motion. In this study, the hydrodynamic characteristics of a drillship for the North Sea were examined in relation to the motion, wave loads, green water, and moonpool resonance in the initial design stage.

Quay Mooring Aanlysis for a Drillship in Typhoon Conditions (드릴쉽의 태풍 시 안벽 계류 해석)

  • Park, Moon-Kyu;Cho, Jin-Woog;Chung, Jin-Hyun
    • Special Issue of the Society of Naval Architects of Korea
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    • 2011.09a
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    • pp.70-74
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    • 2011
  • This paper describes the quay mooring analysis to verify the safety of a moored drillship in typhoon conditions. Mooring system consists of mooring equipments(deck bollards, shore bitts, mooring lines, fenders) to resist the extreme environmental condition. Wind force acting on the drillship is obtained from the wind tunnel test results. The strength of quay mooring system has been checked. The static mooring analysis shows that the designed mooring system satisfies the mooring design criteria. Vertical displacements of the drillship have been calculated considering the dynamic wave motions and static heelings due to the wind force acting on the ship. With the vertical displacements and the hull draft of drillship, the required water depth for quay mooring has been derived.

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Study on Moonpool Resonance Effect on Motion of Modern Compact Drillship

  • Yang, Seung Ho;Yang, Young Jun;Lee, Sang Beom;Do, Jitae;Kwon, Sun Hong
    • Journal of Ocean Engineering and Technology
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    • v.27 no.3
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    • pp.53-60
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    • 2013
  • A drillship is a representative floating offshore installation. The boom in oil and gas field development has dramatically increased the demands for drillships. Drillships have a moonpool in the center area of the ship for the purpose of drilling. This moonpool has an effect on the seakeeping performance of a drillship in the vicinity of the resonance frequency. Because of the moonpool, drillships act in different resonance modes, called the sloshing mode and piston mode. The objective of this study was to find the moonpool effect on the motion of a drillship through the motion analysis of a currently operating modern compact drillship. The predicted resonance frequencies based on Molin's theoretical formula, Fukuda's empirical formula, and BEM-based numerical analysis are compared. The accuracy of the predictions using the theoretical and empirical formulas is compared with the numerical analysis and evaluated. In the case of the piston mode, the difference between the resonance frequency from theoretical formula and the resonance frequency from the numerical analysis is analyzed. The resonance frequency formula for more a complex moonpool geometry such as a moonpool with a cofferdam is necessarily emphasized.

A Summary on the System for Drilling Drillship (특수선 Drilling Drillship System 개요)

  • Kim, Deok-Ki
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2006.06a
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    • pp.229-230
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    • 2006
  • 해상플랫폼설치가 불가능한 심해지역이나 파도가 심한 해상에서 원유를 발굴하는 선박형태의 시추설비인데, 심해에서의 시추능력은 물론 기동성까지 겸비한 고부가치선으로서 최근 고(高)유가에 따라 발주가 늘어나고 있는 해양분야의 대표적인 성장엔진으로, 파도와 바람이 심한 해상에서도 안정적 시추가 가능한 최첨단 자동위치 제어시스템, 드릴링장비, 통합제어시스템 등, 드릴쉽이 갖추고 있는 시스템에 대해 간단히 설명한다.

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Performance of Drillship with Moonpool and Azimuth Thrusters (Moonpool과 Azimuth Thruster를 장치한 Drillship의 저항추진성능)

  • Yoo, Jae-Hoon;Choi, Soon-Ho
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.6
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    • pp.33-39
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    • 2004
  • The performance of a deep water drillship, is investigated with the view of the characteristics of the thrusters and the resistance increasement due to moonpooi. The model tests have been performed to obtain the resistance of two drillships with the moonpooi open and closed including shape changes of moonpool step. To design the DP system, thrust forces of azimuth thrusters have been measured during azimuthing at zero speed condition. Thrusters, azimuthing under the bottom of ship, have the interactions of the other thrusters due to flow changes made by other thrusters, and the existence of ship hull makes the thrust deduction higher than when the thrust operates by itself. The resistance increasement due to the moonpooi is highly dependent on the step height of the moonpool and the draft. It is found that the height of moonpool step can reduce the resistance increasement by moonpool.

Wind Load and Flow Field Change with Respect to Various Configurations of a Drillship (드릴십 형상에 따른 풍하중 및 유동장 변화)

  • Jung, Youngin;Kwon, Kijung
    • Journal of the Society of Naval Architects of Korea
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    • v.52 no.3
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    • pp.255-264
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    • 2015
  • Wind load and flow field of a drillship with respect to various super structures were experimentally investigated in KARI 1m-wide wind tunnel with an atmospheric boundary layer simulation. Six-component external balance and Particle image velocimetry technique were used to measure wind load and velocity vectors in the flow-field around the model respectively. The experimental model was an imaginary shaped drillship with an approximated model which has 1/640 scale compared with recent typical drillships. The test Reynolds number based on the overall length was about 1.5×106. It was found that dominant factors influencing on ship wind load are cabin shape and cabin height. Round cabin has smaller axial wind load and narrow boundary layer around the ship than rectangular one, but its yawing moment at certain angles becomes higher. Low cabin height also show positive effects on axial wind load too. Hull shape and forecastle shape show relatively small influences on wind loads except for slight changes around ±45° wind directions.

Reduction of Added Resistance by Internal Flow Control in the Moonpool of a Drillship (시추선 문풀의 내부 유동제어에 의한 부가저항 저감)

  • Choi, Si-Young;Lee, Young-Gill;Jeong, Kwang-Leol;Ha, Yoon-Jin
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.6
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    • pp.544-551
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    • 2011
  • The internal flows of moonpool usually causes huge added resistance on drillships, and those are very complex to analyze. Therefore, not only experimental approaches but also numerical simulations are required for better investigations when dealing with the hydrodynamic problems of moonpool. In the present research, numerical simulations are used to find out why the resistance increases by moonpool on a running drillship. That is, the three-dimensional numerical simulations and model tests are carried out to examine the characteristics of internal flow and added resistance by changing the section of the moonpool in both longitudinal and transverse directions. Finally, based on the present studies, an optimized shape of the moonpool is suggested, which effectively reduces added resistance, and that is confirmed with three-dimensional numerical simulations and model tests.