0
Research Papers: Ocean Engineering

Equilibrium Position Analysis for Offloading Operations With Turret-Moored FPSO

[+] Author and Article Information
Alex S. Huang

Numerical Offshore Tank Laboratory (TPN-USP),
Universidade de São Paulo,
Av. Professor Mello Moraes, 2231,
São Paulo 05508-030, Brazil
e-mail: alex.huang@usp.br

Felipe M. Moreno

Numerical Offshore Tank Laboratory (TPN-USP),
Universidade de São Paulo,
Av. Professor Mello Moraes, 2231,
São Paulo 05508-030, Brazil
e-mail: felipe.marino.moreno@usp.br

Eduardo Aoun Tannuri

Numerical Offshore Tank Laboratory (TPN-USP),
Universidade de São Paulo,
Av. Professor Mello Moraes, 2231,
São Paulo 05508-030, Brazil
e-mail: eduat@usp.br

Joselito G. A. Câmara

PETROBRAS/Shipping New Operations
Development,
Av. Henrique Valadares, 28,
Centro,
Rio de Janeiro 20.231-030, Brazil
e-mail: joselito.camara@petrobras.com.br

1Corresponding author.

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received July 7, 2018; final manuscript received December 30, 2018; published online February 18, 2019. Assoc. Editor: Xinshu Zhang.

J. Offshore Mech. Arct. Eng 141(5), 051102 (Feb 18, 2019) (9 pages) Paper No: OMAE-18-1095; doi: 10.1115/1.4042531 History: Received July 07, 2018; Revised December 30, 2018

With the expansion of oil exploration in deep waters, assessing the risks associated with offloading operations becomes essential in preventing accidents that may cause huge environmental disasters. In this paper, the system that composed of a turret-moored floating production storage and offloading (FPSO) connected to a conventional shuttle tanker, which is assisted by a tug boat to maintain its position during an offloading operation, will be studied. Using environmental data collected over a period of 6 years, from 2004 to 2009, from the Campos Basin in Brazil, the equilibrium positions of the system were calculated, considering its constraints (operational criteria defined by Petrobras) and verifying the stability of those equilibrium points. The hydrodynamic and aerodynamic static forces were calculated using models validated in the literature. Dynamic effects and oscillations are taken into account by adding safety margins to the operational sectors. With this analysis, we calculated the FPSO heading probabilities during an offloading operation and the expected downtime of operation in Campos Basin. We concluded that the downtime of the offloading operation with a conventional shuttle tanker is close to that with a dynamic positioned (DP) shuttle tanker (10% downtime). Furthermore, the results from the stability analysis were used to generate a simplified set of rules to classify the environmental conditions into four classes of operational risk by applying an unbiased decision tree. This method obtains practical rules based on measurements of wind, wave, and current, allowing the operator to quickly evaluate the risk level before starting the operation.

FIGURES IN THIS ARTICLE
<>
Copyright © 2019 by ASME
Your Session has timed out. Please sign back in to continue.

References

Naciri, M. , Waals, O. , and De Wilde, J. , 2007, “ Time Domain Simulations of Side-by-Side Moored Vessels Lessons Learnt From a Benchmark Test,” ASME Paper No. OMAE2007-29756.
Wang, Q. , Sun, L. P. , and Ma, S. , 2010, “ Time-Domain Analysis of FPSO-Tanker Responses in Tandem Offloading Operation,” J. Mar. Sci. Appl., 9(2), pp. 200–207. [CrossRef]
De Wilde, J. , Serraris, J. J. , De Ridder, E. J. , Bécel, M. L. , and Fournier, J. R. , 2010, “ Model Test Investigation of LNG Tandem Offloading With Dynamic Positioned Shuttle Tankers,” ASME Paper No. OMAE2010-20684.
Zhao, W. , Yang, J. , Hu, Z. , and Xie, B. , 2013, “ Hydrodynamics of an FLNG System in Tandem Offloading Operation,” Ocean Eng., 57, pp. 150–162. [CrossRef]
Van Der Wal, R. J. , and De Boer, G. , 2004, “ Downtime Analysis Techniques for Complex Offshore and Dredging Operations,” ASME Paper No. OMAE2004-51115.
De Wilde, J. J. , Van Dijk, A. W. , Van Den Berg, J. , and Dekker, J. , 2009, “ Direct Time Domain Downtime Assessment for LNG Operations Using Computer Cluster,” 19th International Offshore and Polar Engineering Conference, Osaka, Japan, July 21–26, Paper No. ISOPE-I-09-170. https://www.onepetro.org/conference-paper/ISOPE-I-09-170
Poldervaart, L. , Oomen, H. , and Ellis, J. , 2006, “ Offshore LNG Transfer: A Worldwide Review of Offloading Availability,” Offshore Technology Conference, Houston, TX, May 1–4, Paper No. OTC18026. https://www.onepetro.org/conference-paper/OTC-18026-MS
Tannuri, E. A. , Orsolini, A. L. B. , Castelpoggi, F. S. , Yuba , Douglas, T. G. , Machado, G. B. , and Malafaia, J. L. P. , 2016, “ Defining Expanded Sectors for DP Assisted Offloading Operations in Spread Moored Platforms,” Dynamic Positioning Conference (Marine Technology Society), Houston, TX, Oct. 11–12, pp. 1–16. https://dynamic-positioning.com/proceedings/dp2016/Operations_Tannuri_pp_2016.pdf
Tannuri, E. A. , Pereira, F. R. , Fucatu, C. H. , Ferreira, M. D. A. S. , Masetti, I. Q. , and Nishimoto, K. , 2014, “ Modular Mathematical Model for a Low-Speed Maneuvering Simulator,” ASME Paper No. OMAE2014-24414.
OCIMF, 1994, Prediction of Wind and Current Loads on VLCC, 2nd ed., Oil Companies International Marine Forum, Witherby, London.
Palazzo, F. , Simos, A. N. , Tannuri, E. A. , Sparano, J. V. , and Masetti, I. Q. , 2003, “ Evaluation of the Dynamic Behavior of the P50 FPSO System Using Dynasim: Comparison With Experimental Results,” ASME Paper No. OMAE2003-37178.
Newman, J. N. , and Lee, C. H. , 2013, Wamit User Manual, Version 7.0, WAMIT, Chestnut Hill, MA.
Petrobras E&P, 2018, “ Oil Transfer Operations From FPSO, FSO and Monobuoys to Conventional Shuttle Tankers,” Petrobras, Rio de Janeiro, Brazil, Report No. E&P-PE-2 LMS-00002-F.
Hothorn, T. , and Zeileis, A. , 2015, “ Partykit: A Modular Toolkit for Recursive Partitioning in R,” J. Mach. Learn. Res., 16(1), pp. 3905–3909. http://jmlr.org/papers/v16/hothorn15a.html
Hothorn, T. , Hornik, K. , and Zeileis, A. , 2006, “ Unbiased Recursive Partitioning: A Conditional Inference Framework,” J. Comput. Graphical Stat., 15(3), pp. 651–674. [CrossRef]
Zangeneh, R. , Thiagarajan, K. P. , and Cameron, M. , 2017, “ Effect of Wind Loads and Damping on Heading Stability of FPSOs,” ASME Paper No. OMAE2017-62134.
Tannuri, E. A. , Simos, A. N. , Leite, A. J. P. , and Aranha, J. A. P. , 2001, “ Experimental Validation of a Quasi-Explicit Hydrodynamic Model: Fishtailing Instability of a Single-Point Moored Tanker in Rigid-Hawser Configuration,” J. Ship Res., 45(4), pp. 302–314. https://www.ingentaconnect.com/contentone/sname/jsr/2001/00000045/00000004/art00006;jsessionid=2kdarkddsbryt.x-ic-live-02

Figures

Grahic Jump Location
Fig. 1

Vessel horizontal dynamics

Grahic Jump Location
Fig. 2

Representation of the system

Grahic Jump Location
Fig. 3

Campos Basin—average environmental conditions

Grahic Jump Location
Fig. 4

Operational sector for offloading in turret moored platforms [13]

Grahic Jump Location
Fig. 5

Example of analysis for viability of the offloading operation

Grahic Jump Location
Fig. 6

Expected downtime for offloading operation

Grahic Jump Location
Fig. 7

FPSO heading distribution—configuration 4 (tugboat applying 20 tf)

Grahic Jump Location
Fig. 8

Decision tree for an applied tugboat force of 0 tf

Grahic Jump Location
Fig. 9

Decision tree for an applied tugboat force of 20 tf

Grahic Jump Location
Fig. 10

Decision tree for an applied tugboat force of 50 tf

Grahic Jump Location
Fig. 11

Stable, but nonacceptable situation. Forces and moment of forces (MoF) due to environmental agents are shown for each vessel—configuration 1.

Grahic Jump Location
Fig. 12

Typical stable situation, vessels align almost in the same direction—configuration 4

Tables

Errata

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In