Motion and responses for deepwater production systems

Transcription

1 Motion and responses for deepwater production systems PEMEX INTSOK Deepwater Technology Seminar Cuidad del Carmen, May 9 10, 2013 By Petter Andreas Berthelsen MARINTEK USA Inc Norsk Marinteknisk Forskningsinstitutt

2 Introduction Exploration of oil and gas in deeper water in areas where the weather conditions are extreme gives several challenges that need to be solved, e.g.: Wave current interaction Extreme waves; higher order and viscous drift forces Large mooring line forces Green water and wave impact VIV MARINTEK has long traditions with developing methods, carrying out analyses and verification with model tests of marine structures in deep water.

3 About MARINTEK MARINTEK is a contract research institute within marine technology. MARINTEK carries out contract R&D for marine related industries: Maritime Oil and Gas Ocean Energy Main Research areas are: Hydrodynamics and structures Energy and machinery technology Operations technology

4 MARINTEK Norwegian Marine Technology Research Institute Marine Technology Centre, Trondheim MARINTEK (USA), Inc. Bergen Trondheim Oslo Houston Main office in Trondheim, Norway Offices in Oslo and Bergen Subsidiary in Houston; MARINTEK (USA), Inc. Subsidiary in Rio de Janeiro; MARINTEK do Brasil, Ltda. MARINTEK do Brasil, Ltda. Rio de Janeiro 4

5 Ocean Basin Laboratory (80x50x10 m) MARINTEK operates national marine technology laboratories

6 Model tests in the Ocean Basin 6

7 Ocean Basin model test Typical test set up: Measurement of: 6 DoF motions by use of optical position meas. system Mooring line and riser forces Relative wave elevation close to structure Impact loads Observation (by video): Green water Motions of mooring lines and risers (by underwater video)

8 Challenge: Deepwater system design verification by model tests Hydrodynamic loads not directly influenced by mooring/riser system Ocean Basin 10m deep Model scale 1:150 Example: FPSO 3000 m water depth Can truncate mooring/risers to obtain hydrodynamic characteristics of floater

9 Truncation of mooring and riser system Truncated system should maintain the same hydrodynamic characteristics of the floater as the full depth system It is required that the responses measured with the truncated system can be reproduced by a coupled simulation model This numerical model will be used to obtain design values for the full depth system => Hybrid verification procedure

10 Hybrid verification procedure

11 Full depth and truncated mooring systems (VERIDEEP)

12 Quasi static characteristics comparison Restoring force and single line Surge vs pitch

13 Comparison of dynamic line forces (VERIDEEP) Reduced depth Full depth

14 An active hybrid decomposed mooring system (HydeMoor) for model testing of deepwater offshore platforms To be presented at OMAE2013, Nantes, France

15 From laboratories to numerical simulation tools MARINTEK analysis tools SIMO Simulation of rigid multibody system RIFLEX Global analysis of risers, mooring, umbilicals MIMOSA Mooring analysis SIMLA Simulation of Pipe laying BFLEX Local analysis of flexible risers UFLEX Local analysis of complex risers MULDIF 2 Next generation potential flow solver SIMA Graphical user interface

16 Example: Disconnected turret buoy system Coupled time domain analysis Turret buoy 6DOF rigid body Riser: FEM with pipe in pipe inside bellmouth Umbilicial: FEM

17 Example: Disconnected turret buoy system Visualization: SimVis 17

18 Example: Hybrid Risers/Disconnectable Turret/FPSO System Visualization: SimVis 18

19 Example: Hybrid Risers/Disconnectable Turret/FPSO System Visualization: SimVis 19

20 Example: Turret Disconnection Visualization: SimVis 20

21 Wave current interactions: Mooring line forces 6800 kn 4500 kn Difference is larger than the line force from the current alone 21

22 Wave current interactions: Air gap Increased wave amplification around semi columns with current present (MULDIF 1, Zhang et al., 2007)

23 MULDIF 2 Development Internal development at MARINTEK throughout 5 years Industry code implementation performed as a JIP Present participants: Statoil, Aker Solutions, NOV APL, Rolls Royce Marine, DNV, MARINTEK Overall objective to develop a hydrodynamic potential theory code that handles various problems not handled well by excisting industry codes Effect from wave current interaction Significant wave drift forces => large mooring and thrust forces Airgap (increased wave amplification) It needs to be user friendly, robust and well validated Phase 1 ( ) Focus on wave current interactions for single problems in deep and finite water depths Phase 2 ( plans) Focus on semi empirical practical nonlinear corrections for higher sea states and for viscous effects Multibody with current

24 SIMA MARINTEK Workbench Developed in a JIP between MARINTEK and Statoil ASA. The main simulation programs presently available through the SIMA interface are: SIMO RIFLEX SIMO/RIFLEX coupled analysis Future support SIMLA MULDIF2 Purpose: Make the task of setting up a simulation model of a dynamic system easier and faster. Visualize everything Workbench that presents the user with a common interface no matter which simulation software is used. 24

25 Thank you! 25

26 COUPLED ANALYSIS APPROACH Time domain finite element model (e.g. RIFLEX C: SIMO + RIFLEX) WIND WAVES CURRENT All interaction effects between mooring/risers and vessel are modelled directly