Concept design of a new deep draft platform

Abstract

The authors analyzed requirements for a new deepwater platform, from conceptual design to hydrodynamic analysis. The design incorporated Deep Draft Multi-Spar (DDMS) that allowed easy fabrication, reduced costs, and provided favorable motion performance. It also provided a dry tree system and other benefits. The conceptual design process included dimension estimation, general arrangements, weight estimation, weight distribution, stability analysis, etc. A high order boundary element method based on potential theory and the modified Morison equation was used to predict the hydrodynamic and viscous effects of this new concept platform. The response amplitude operators (RAOs) were acquired and compared with those of a typical Truss Spar. The response of the platform to the JONSWAP spectra of 3 different extreme ocean conditions was analyzed to evaluate the seakeeping ability of the new concept. The results revealed favorable motion performance due to all the degrees of freedom available.

Keywords

Spar / potential theory / Morison equation / deepwater platform / mooring line / heave plate

References

[1] Agarwal A.K., Jain A.K. Dynamic behavior of offshore spar platform under regular sea waves. Ocean Engineering, 2003, 30: 487-516

[2] Almeida JCL, Jordani CG, Rossi RR, Schachter RD (2001). The development and application of a design methodology for the concept design of tension leg platform (TLPS) using non-dimensional parameters. International Conference on Offshore Mechanics and Arctic Engineering, Rio de Janeiro, Brazil, No. OFT-1242.

[3] American Bureau of Shipping (2006). Mobile offshore drilling units Part 3 hull construction and equipment, USA, 111–120.

[4] Cermelli CA, Roddier DG, Busso CC (2004). A novel concept of minimal floating platform for marginal field development. International Offshore and Polar Engineering Conference, Toulon, 538–545.

[5] Chakrabarti S. Handbook of offshore engineering, 2005, Oxford, UK: Elsevier, 419-445

[6] Chedzoy C, Lim F (2003). Design challenges of deepwater dry tree riser systems for different vessel types. International Offshore and Polar Engineering Conference, Hawaii, USA, 76–82.

[7] Chou F.S.F., Ghosh S., Huang E.W. Conceptual design process of a tension leg platform. SNAME Transactions, 1983, 91: 275-305

[8] Grove MA, Conceicao CAL, Schachter RD (2003). A concept design and hydrodynamic behavior of a spar platform. International Conference on Offshore Mechanics and Arctic Engineering, Cancun, Mexico, No. 37166.

[9] Jatar S, Dove P (2005). The planning and installation of the red hawk spar and polyester mooring system. Offshore Technology Conference. Houston, USA, No. 17234.

[10] Li B., Ou j. Heave response analysis of truss spar in frequency domain. The Ocean Engineering, 2009, 27(1): 8-16

[11] Li Y., Teng B. Wave action on maritime structures, 2002, 2nd Ed., Beijing: Ocean Press, 56-60

[12] Prslin I, Blevins RD, Halkyard JE (1998). Viscous damping and added mass of solid square plates. International Conference on Offshore Mechanics and Arctic Engineering, Lisbon, Portugal, No. 0316.

[13] Rho JB, Choi HS, Lee WS, Shin HS, Park IK (2002). Heave and pitch motions of a spar platform with damping plate. International Offshore and Polar Engineering Conference, Kitakyushu, Japan, 198–201.

[14] Schachter RD, Jordani CG, Fernandes AC (2002). A design approach for storage spar buoy platforms in the concept and preliminary design phases. International Conference on Offshore Mechanics and Arctic Engineering, Oslo, Norway, No. 28544.

[15] Srinivasan N., Chakrabarti S., Radha R. Response analysis of a Truss-pontoon Semisubmersible with heave plate. Journal of Offshore Mechanics and Arctic engineering, 2006, 128(2): 100-106

[16] Tao L., Cai S. Heave motion suppression of a spar with a heave plate. Ocean Engineering, 2004, 31(5–6): 669-692