Sensitive Analysis of Different Types of Deep Water Risers to Conventional Mooring Systems


1 B.Sc., Faculty of Marine Engineering, Petroleum University of Technology

2 Assistant Professor, Faculty of Marine Engineering, Petroleum University of Technology


Structural response of different types of conventional deep water riser affected by mooring systems in harsh environment is focused in this study. With increasing water depth, the mooring system design of a floating-type production platform becomes more important and complicated from cost as well as safe operation point of view. With the development of offshore oil and gas exploitation, FPSO with many advantages can better adapt to the complicated environment of deep sea. According to the current mooring system development, this study compares the effect of spread mooring system and turret mooring system on riser structural response. Both systems consists of 12 mooring lines and each line is made from two components. Three types of more conventionally used deep water risers have been selected and applied with the mooring systems, resulting in 6 different case studies. The case studies have been modeled in OrcaFlex software with same extreme environmental conditions. Comparing bending moment in the risers, as one of the main design parameter, shows the effect of proper selection of the riser and mooring system.


[1] Bowline, C. and Duggal, A., "Understanding Fatigue for Deepwater Mooring," in Deep Offshore Technology, New Orleans, USA, November 2004.
[2] Qiao, D; Jinping, O; Wu F, "Design Selection Analysis for Mooring Positioning System of Deepwater Semisubmersible Platform," in International Offshore and Polar Engineering Conference, Rhodes, Greece, 2012.
[3] S. Wu, "the motions and internal forces of a moored semisubmersible in," Ocean Engineering, vol. 24 (7), pp. 593-603, 1997.
[4] X. H. Chen, "Motion and mooring line loads of a moored semi-submersible in waves," in International Conference on Offshore Mechanics and Arctic Engineering, OMAE.
[5] Maffra S., Pacheo C. & Menezez M., "Genetic Algorithm Optimization for Mooring System," Rio de Janeiro, Brazil, 2003.
[6] W. O.J., "The Effect of Wave Directionality on Low Frequency Motions and Mooring Forces," in 28th International Conference on Offshore Mechanics and Arctic Engineering, Honolulu, Hawaii, USA, 2009.
 [8] "The Comparison and Analysis between Catenary Mooring System and Taut Mooring System of FPSO," 2013.
[9] Y. Tang, "Development of Study on the Dynamic Characteristics of Deep Water Mooring System," Journal of Marine Science and Application, vol. 6.4, pp. 17-23, 2007.
[10] B. Tong, J. Yang, X. Li, "Comparison and Analysis of Dynamic Effect for Mooring System of Semi-submerged Platform in Deep Water," The Ocean Engineering, vol. 27.1, 2009.
[11] "Spread Moored or Turret Moored FPSO’s for Deepwater Field Developments," in Offshore West Africa, 2006.
[12] Shahab Shahriari, Saeed Imani Bidgoli, Pedram Edalat, "Riser Characteristic Assessment for Deep Water: TDP and Bending Moment," in 6th International Offshore Industries Conference, Tehran, Sharif University of Technology, 4 and 5 May 2015.
[13] "DNV-OS-F201, Dynamic Risers, 2001&2010, Det Norske Veritas, Norway".
[14] "Halil Dikdogmus, RISER CONCEPTS FOR DEEP WATERS June 2012, Master Thesis, Department of Marine Technology Norwegian University of Science and Technology.".
[15] Bai, Y., & Bai, Q., Subsea Engineering Handbook, Gulf Professional Publishing, 2010.
[16] "DNV-RP-F201, Design of Titanium Risers(2001), Det Norske Veritas, Norway".
[17] "ISO 19901 PART7 Stationkeeping systems for floating offshore structures and mobile offshore units".
[18] "OrcaFlex Manual version 9.8a 2014, section 1, 5.5.1, 5.6, 5.12, 6.1.". [19] "Spread Moored or Turret Moored FPSO’s for Deepwater Field Developments," Offshore West Africa , 2006.