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Numerical Study on Designing Truncated Mooring Lines for FPSO Stability Analysis

FPSO 안정성 평가를 위한 절단계류선 모델링 수치 연구

Kim, Yun-Ho;Cho, Seok-Kyu;Sung, Hong-Gun;Seo, Jang-Hoon;Suh, Yong-Suk
김윤호;조석규;성홍근;서장훈;서용석

  • Received : 2014.07.01
  • Accepted : 2014.10.24
  • Published : 2014.10.31

Abstract

In this paper, a numerical analysis for an internal turret moored vessel located at a 400-m water depth is conducted. The target vessel has an internal turret that is located at the 0.2 Lpp position from the fore-side, with $3{\times}4$ complex mooring lines installed around the turret circumference. To investigate the motion response of the vessel and the structural reliability of the lines, model tests were conducted. The KRISO ocean basin has a water depth of 3.2 m, which represents 192m using a scaling of 1:60. In order to precisely represent the real-scale condition, equivalent mooring lines needed to be designed. Truncated mooring lines were designed to supplement the restriction of the flume's water depth and increase the reliability of the model testing. These truncated mooring lines were composed of two different chains in order to match the pre-tension, simultaneously restoring the curve and variation in the effective line tension. The static similarities were compared using a static pull-out test and free decaying test, and the dynamic similarities were matched via a regular wave test and combined environments test. Consequently, the designed truncated mooring system could represent the prototype mooring system relatively well in the aspects of kinematics and dynamics.

Keywords

Truncated mooring lines;Turret;Static load optimization;Dynamic response optimization;Coupled analysis

References

  1. Cho, S.K., Hong, S.Y., Hong, S., Kim, H,J., 2002, A Research on Dynamic Tension Response of Model Mooring Chain by Forced Oscillation test, Proc. of Korea Society of Ocean Engineers, JinHae Korea, 134-141.
  2. Orcina Ltd., 2011. OrcaFlex Manual ver 9.5a. Cumbria UK.
  3. Waals, O.J., van Dijk, R.R.T., 2004. Truncation Methods for Deep Water Mooring Systems for a Catenary Moored FPSO and a Semi Taut Moored Semi Submergible. Proceeding of Deep Offshore Technology Conference, 24-1, New Orleans USA.
  4. Wichers, J.E.W., 1988. A simulation model for a single point moored tanker. PhD thesis, Delft University of Technology, Netherlands.
  5. Stansberg, C.T., Karlsen, S., Ward, E.M., Wichers, J.E.W., Irani, M.B., 2004. Model Testing for Ultra Deep Water. Proceeding of Offshore Technology Conference(OTC 16587), Houston USA, 1-9.

Cited by

  1. Study on Design of Truncated Mooring Line with Static Similarity in Model Test Basins vol.31, pp.4, 2017, https://doi.org/10.26748/KSOE.2017.08.31.4.257

Acknowledgement

Grant : 설계유의파고 15m 해역의 Oil & Gas 생산을 위한 100만 배럴급 FPSO용 Turret System 설계 기술 개발, 심해공학수조 운용을 위한 연구인 프라 구축 및 심해플랜트 Pre-FEED 원천핵심기술개발

Supported by : 산업통상자원부, 해양수산부