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The utilization of the pendulous motion for deploying subsea hardware in ultra-deep water

17 th FPSO Research Forum April 5 th 2006. The utilization of the pendulous motion for deploying subsea hardware in ultra-deep water. Francisco E. Roveri Petrobras R&D Rogério D. Machado Petrobras E&P Pedro F. K. Stock Petrobras E&P Maxwell B. de Cerqueira Petrobras E&P.

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The utilization of the pendulous motion for deploying subsea hardware in ultra-deep water

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  1. 17th FPSO Research Forum April 5th 2006 The utilization of the pendulous motion for deploying subsea hardware in ultra-deep water Francisco E. Roveri Petrobras R&D Rogério D. Machado Petrobras E&P Pedro F. K. Stock Petrobras E&P Maxwell B. de Cerqueira Petrobras E&P

  2. Previous installation of some subsea hardware by Petrobras • Smaller subsea hardware and shallow waters: crane barge, crane of SS, AHTS

  3. Previous installation of some subsea hardware by Petrobras • Crane barge and slings – 420 Te/620 m (1995)

  4. Previous installation of some subsea hardware by Petrobras • MODU/drilling riser – 240 Te/940 m (2001)

  5. Previous installation of some subsea hardware by Petrobras Sheave Method – 175 Te/1900 m (2002)

  6. Challenge of deployment in increasing WD(250 Te payload, 2000-3000 m WD) • Disadvantage of wire rope: self weight + axial resonance (DAF) • Alternative: special construction vessels (scarce and high daily rates)  installation costs prohibitive • Synthetic fiber rope  issues to be solved: bending and heating + axial resonance (w/o heave compensation) The Pendulous Method

  7. prescribed vertical displacement (Xo) K • K M, Ma C L = 0 ... Ltotal frequency ratio β

  8. The Pendulous Method Transportation vessel Overboarding Hangoff Pendulous Motion

  9. The Pendulous Method (cont.) • Conceived to overcome the above constraints (DAF1) • Utilization of the Pendulous Motion • Utilization of two workboats • Distance between vessels 80% of cable length • Installation cable, from subsea hardware: wire rope with DBM, polyester and chain • Due to drag the pendulous motion will be very slow

  10. DAF (displacements) Amplitude of dynamic force (KXo multiplier) damping ratio ξ = 0.20 working region frequency ratio w/wn

  11. General system configuration(side view, just after release) chain wire rope polyester wire rope and DBM polyester slings manifold

  12. System components Weight in air: 280 Te Dimensions: 16.63 x 8.50 x 5.15 m (L x B X H) CG 3.15 m above base line (CG≡CB)

  13. Physics of the problem • Equipment of complex topology • Volume of the envelope dimensions: 728 m3 • Steel volume: 35.7 m3 (< 5% total volume) • Some assumptions are needed in order to simplify the computer model • 1st aproach to concentrate drag and added mass at CG  inadequate • improvement  center of pressure and spatial distribution of drag and lift forces

  14. G≡B G≡B G≡B G≡B CN CL CN CN CN CL CL CL Physics of the problem (cont.) (1) Suspended at transportation vessel side (2) Just after release (4) Anti-clockwise rotation (3) Clockwise rotation

  15. Development of the concept • PROCAP 3000 project • Participation in JIPs: VP2002 (Odim), DISH (phases 2&3) • Conceived in 2003, based on the procedure for installation of torpedo pile • Numerical analyses with Orcaflex to demonstrate the feasibility • Model tests at LabOceano (UFRJ) in 2004 • 1:1 scale prototype test in December 2005

  16. Some results of numerical analysis • Three distinct phases: • equipment at the side of transportation vessel • pendulous motion • equipment supported by installation vessel

  17. Configuration 10 minutes after release installation vessel chain polyester wirerope and DBM manifold

  18. Cable effective tension, installation vessel side

  19. Manifold rotation (deg) 1000_sec.avi60_sec.avi

  20. Model tests • Model tests at 1:35, 1:70 and 1:130 scales for manifold #2 – excessive rotations detected in some cases

  21. 1:1 Prototype test • Decision to build and install a 1:1 prototype for qualification of the method and installation procedure

  22. Mitigation of excessive rotations • increase of sling forces at start • additional buoyancy to the distributed buoyancy modules • improvement of hydrodynamic stability • dead weight at the equipment bottom – lowers CG • a more adequate equipment geometry, e.g., vertical or near vertical (slightly slanted) panels around it

  23. Pendulous Method to install MSGLs #2 and #3 • Construction of Roncador MSGLs #2 and #3 (1850 m WD) awarded to FMC

  24. Conclusions • Utilization of conventional spread • Allow deployment of heavy equipment in ultra deep waters • Attenuation of axial force, prevents resonance • Cost effective compared to utilization of specialized installation vessels or rigs (about 30% cost reduction) • Needs improvement on control of rotations at start

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