CFD Applications for Deepwater Platforms at Technip

Transcription

1 CFD Applications for Deepwater Platforms at Technip Speaker: Allan Magee, PhD R&D Manager Offshore Product Line & Technology, Technip Malaysia Technip Chaired Professor in Offshore Technology, UTP Dept of Civil Engineering CD-Adapco STAR South East Asian Conference CD Adapco STAR South East Asian Conference 5-6 Nov 2012

2 Table of Contents Technip Introduction R&D on Floating Platforms Early CFD Applications Design of Floating Platforms for Southeast Asia Riser VIV Suppression Ringing of Offshore Platform Future Work Conclusions 2

3 Technip Today With engineering, technologies and project management, on land and at sea, we safely and successfully deliver the best solutions for our clients in the energy business Worldwide presence with 32,000 people in 48 countries Industrial assets on all continents, a fleet of 34 vessels (of which 5 under construction) 2011 revenue: 6.8 billion Energy is at the core of Technip 3 Technip Slide Library

4 Three Business Segments, One Technip Subsea Offshore Onshore Tech nip Slide 4 Librar y Design, manufacture and supply of deepwater flexible and rigid pipelines, umbilicals and riser systems Subsea construction, pipeline installation services and Heavy Lift Six state-of-the-art flexible pipe and / or umbilical manufacturing plants Five spoolbases for reeled pipeline assembly as well as four logistic i bases A constantly evolving fleet strategically deployed in the world's major offshore markets Engineering and fabrication of fixed platforms for shallow waters (TPG 500, Unideck ) Engineering and fabrication of floating platforms for deep waters (Spar, semi-submersible platforms, FPSO) Leadership in floatover technology Floating Liquefied Natural Gas (FLNG) Construction yard The best solutions across the value chain Gas treatment and liquefaction (LNG), Gas-to-Liquids (GTL) Oil refining (refining, hydrogen and sulphur units) Onshore pipelines Petrochemicals (ethylene, aromatics, olefins, polymers, fertilizers) Process technologies (proprietary or through alliances) Biofuel and renewable energies (including offshore wind) Non-oil activities (principally in life sciences, metals & mining, construction) ti

5 Technip in Asia Pacific A long-standing presence in Malaysia since 1982 Nearly 4, people Kuala Lumpur Singapore Jakarta Bangkok Shanghai Tanjung Langsat Balikpapan Batam Assets in the Region Asiaflex Products: flexible pipe & umbilical manufacturing plant 1 st and only one in Asia Logistics base in Batam Future new vessel, Deep Orient (under construction): flexible & umbilical pipelaying vessel Fabrication yard: TMB Hull design: TMH Perth Regional Headquarters Operating centers Flexible pipe/umbilical plant Logistic Base Construction Yard New Plymouth Main expertise Deepwater subsea developments Offshore platform & field development Onshore facilities for oil refining, gas processing/liquefaction (LNG), petrochemicals and non-oil industries 5 Technip Slide Library

6 Table of Contents Technip Introduction R&D on Floating Platforms Early CFD Applications Design of Floating Platforms for Southeast Asia Riser VIV Suppression Ringing of Offshore Platform Future Work Conclusions 6

7 Who We Are Offshore Product Line & Technology OPL&T at Technip Malaysia Part of a broad Technip R&D effort to complement the Centers in Houston and Paris Branch in Kuala Lumpur since 2008/2009 Purpose: Bring R&D closer to the region Main Focus areas: Regional floating platform technologies Floatover Installations Model testing at local facilities Numerical wave tank with Computational Fluid Dynamics VIM of multi-column floaters (SEMI, TLP) Fluid-Structure Interaction (FSI) Links to other centers for Technology gaps Coordination Training

8 Why Computational Fluid Dynamics? Provide design assurance using the most accurate tool for first of a kind offshore structures Best available estimates of hydrodynamic loads Correlation with other models Extrapolation to fullscale Re. No. Quicker than a model test Provides more information Complements/completes test data Able to remove simplifying assumptions inherent in other theories Yet retain these results as special cases Unsteady effects included (not constant added mass/drag coefficients) Large volume structure (diffraction included - not slender members) Separated flow for bluff bodies (not potential flow) Non-linear free surface (not linear theory) Run-up/ up/ Air gap Steep and breaking waves Pressure mapping onto dynamic structural model (SACS mode shapes) Load mapping onto ANSYS modes (ongoing w/ TP Houston) Treatment t of hydrostatic, ti static ti wave and dynamic loads per API Get structures+ Hydro guys to talk the same language

9 Floating Production Platform Overview A Floating Production Platform is a complex, integrated system : Topsides Process Plant Drilling/Work over Rig Living Quarter Marine Systems Safety Equipment Hull Buoyancy yto carry Topside, Moorings and Risers Stability to avoid capsizing Motions to perform Drilling and Processing Support and Protect the Risers Moorings Station Keeping Risers Controlled transport of Hydrocarbons from Reservoir to Process Plant (import) then to Pipeline or Tanker (export) 9 Heave Plates

10 Table of Contents Technip Introduction R&D on Floating Platforms Early CFD Applications Design of Floating Platforms for Southeast Asia Riser VIV Suppression Ringing i of foffshore Platform Future Work Conclusions Seachest Deck 3 Plate Sea surface Heaveplate Centerwell sea surface Hull 10

11 CFD Application: Heave Plates with skirts Inertia coefficients i for various skirt configurations 1 Flat Plate Skirt Away Ca c/a b/a = 0.23 b/a = 0.13 no skirt Drag coefficients for various skirt configurations Cd Skirt at Edge c/a b/a = 0.23 b/a = 0.13 no skirt 11

12 Design of Floating Platforms for Southeast Asia 12 Unsteady Flow around a TLP Hull using Star CCM+

13 Background on Vortex-Induced Vibrations (VIV) Cylinder in a current develops unsteady, alternating vortex pattern in wake The alternating vortices give rise to lift forces, perpendicular to current If vortex shedding gperiod, Ts, approaches the natural vibration period, T, of lateral motion, lock-in occurs Amplitude of the motion A, is normalized by cylinder diameter D For VIV due to currents at speed U,, the most important parameter is the reduced velocity UT U r = D For large mass ratios (flagpole in the wind) the cylinder locks-out for 5<Ur>7 A/D Karman Vortex Street t behind a fixed cylinder (Wikipedia) Animation of the phenomenon. Courtesy, Cesareo de La Rosa Siqueira. Ur From Flow Induced Vibrations, R.D Blevins,1990 Model Testing of Floating Platforms at UTM 13

14 Solver Benchmarking: Model Scale Spar VIM Atluri et al, OMAE deg Heading RMS A/D Experiment Simplified (AS) Simplified Appendages (AS) Full (AS) Simplified (AN) Full (AN) Reduced Velocity (Vrn) 14

15 Objective Extend existing CFD capabilities for Spar VIM prediction to multi- column platforms such as TLP and SEMI 15

16 16 TLP Model Towed to Simulate Currents Measure Vortex-Induced Motions

17 Vortex-Induced Motions (VIM) of a TLP in Steady Current using Star CCM+

18 Calculations Using Star CCM+ Physics model: Incompressible Navier-Stokes (Air/water Volume of Fluid with free surface) Turbulence models: RANS and Spalart-Almaras / Detached Eddy Simulation (SA/DES) Eulerian, body-fixed grid 6-DOF coupled rigid body motions (DFBI) Domain size: 4m x 4m x 6m (Width x Depth x Length) Mesh: Approx. 500,000 hexahedral cells (trimmer mesh) Max cell size: 0.5m Min cell size: m Target cell size on TLP: m No. of prism boundary layers: 4 Total thickness of prism layer: 0.015m Time step: 0.01s, Implicit, 2nd order accuracy 5 sub-iterations per timestep Calculations performed at model scale (1:70)

19 Mesh Figure 10. Horizontal and vertical mesh slices showing the distribution of elements near the TLP model.

20 Calculated Sway Motions Using Star CCM+ Sway (A A/D) Time(s) Yaw (de eg) Sway (A/D D) Time (s) Yaw (deg g) Sway(A/D) Yaw(deg) Sway (A/D) Yaw (deg) Figure 11. Sway(A/D) and Yaw(deg) vs Time(sec) from CFD analysis using RANS approximation, U r (sway)~8, U r (yaw)~5, 45 heading, heavy draft case (2L/D=3) 4- Column TLP model from Ref [6]. Figure 12. Sway(A/D) and Yaw(deg) vs Time(sec) from CFD analysis using SA/DES approximation, U r (sway)~8, U r (yaw)~5, 45 heading, heavy draft case (2L/D=3) 4- Column TLP model from Ref [6].

21 TLP Heavy Draft 45 deg heading - Sway Nominal A/D vs Ur TLP Heavy Draft 45 deg heading - Yaw Nominal A vs Ur Nom minal A/D Sway Ur Model Test CFD DES Nomin nal A (deg) CFD DES Cdy 0.8 Stdev0.05 CFD DES truncate FS CFD DES Sharp Corners* CFD DES Rough3e4m CFD RANS Figure 13. Nominal sway response of CFD compared to model test results from Rf[6] Ref. [6] Yaw Ur Model Test CFD DES CFD DES Cdy Stdev CFD DES Sharp Corners CFD DES Rough 3e-4m CFD RANS Figure 14. Nominal response curves of CFD compared to model test results from Ref. [6].

22 Development of Novel Hull Forms: HVS Semisubmersible Advantageous for fabrication with existing regional infrastructure Potential for application as a Dry-Tree SEMI in moderate SE Asia wave environment 22

23 Hulls Screened by CFD Base Case 10 m PH Blister Case 1 Hybrid 1: Circular Strake Vertical Plate (9m) +Short Blister (9m) Base Case 12 m PH Blister Case 3 Square Strake Hybrid 3: 3 Vertical Plates (9m) +Short Blister (9m) 23 T

24 CFD vs Model Test Title of prese ntatio n in Head er Reduced Velocity ( UT / D) 24

25 Flow Visualization Title of prese ntatio n in Head er Vertical vortex core near column Small drag on pontoon Slanted vortex core away from column Higher drag on pontoon 25

26 Table of Contents Technip Introduction R&D on Floating Platforms Early CFD Applications Design of Floating Platforms for Southeast Asia Riser VIV Suppression Ringing of Offshore Platform Future Work Conclusions 26

27 VIV Suppression Devices Strakes Cd~1.8 to 2.0 Fairings Cd~0.7 Both reduce VIV Fairings can significantly reduce overall drag on the TLP Reduced payload from tendon tensions, saves $$$ But performance needs to be verified AIMS International

28 Towing Bare Riser to Simulate Currents

29 Riser with Weathervaning Fairing

30 Riser VIV Calculation Details Approx 825,000 Cells Autoselect recommended options 1 Degree of Freedom, DFBI Dt=0.01 sec, 5 sub iterations/ timestep 2 nd order time marching m m Re = s ~ 120,000 2 m 1e 06 s m s Ur = s = m 30

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32 32 Fairing Stuck at 120 degs to the flow

33 Table of Contents Technip Introduction R&D on Floating Platforms Early CFD Applications Design of Floating Platforms for Southeast Asia Riser VIV Suppression Ringing of Offshore Platform Future Work Conclusions 33

34 CFD Application: Ringing of Steel Gravity Base Structure (SGS) Remote location (NW Australia Shelf) Moderate water depth < 100m Extreme metocean criteria (100 year cyclone) Coauthors: Jang Whan Kim / Jaime Tan

35 Overview Ringing Phenomenon In designing offshore platforms located in severe wave conditions, the potential resonance response of the hull structure due to wave loads must be checked. Conventional wave load analysis based on linear wave theory does not show dynamic amplification. Steep waves are non-linear and may contain significant energy at higher harmonics of fundamental frequency. Forcing frequency of the higher-harmonic non-linear wave load ~ natural frequency of the structural vibration => ringing g occurs 35

36 Computing Resources BoxClusterDSN CPU: Intel Xeon L5520 x 2 per node, 2.26GHz Memory: 96GB (host), 48GB (client) HDD: 1TB (host), 250GB (client) OS: Red Hat Enterprise Linux 5 RAID box - QNAP TS-879U-RP Amazon Elastic Compute Cloud On-demand instances, USD2.40 per hour Cluster Compute Eight Extra Large 60.5GB memory, 88 EC2 Compute Units 2 x Intel Xeon E5-2670, 8-core Sandy Bridge architecture) OS: SUSE Linux Enterprise Server

37 37 CFD Simulation of Short-Crested Seas Implementation of Absorbing Boundary Conditions

38 Ringing Analysis Methodology 1. CFD analysis calculates dynamic pressure on structure Modal analysis Structural analysis simulates dynamic using ringing loads structural response of structure 4. Calibration of shortduration CFDmodal analysis results 3. Approximation method calculates ringing response from model test Foote r can be 38 custo mize

39 Table of Contents Technip Introduction R&D on Floating Platforms Early CFD Applications Design of Floating Platforms for Southeast Asia Riser VIV Suppression Ringing of Offshore Platform Future Work Conclusions 39

40 Tandem Riser VIV Tests Phase 3 An improved set-up for testing VIV of multiple risers. Performance of fairings in tandem Tests ongoing at UTM CFD Analysis ramping up Towing direction

41 Two-Body Interactions West Alliance TAD West Seno TLP 41

42 Experiments at NU Singapore (Jimmy Ng/ John Halkyard) Simplified Model of Kikeh Spar+TAD Column (200 scale) Study Wave/Wake Interactions Tow the (fixed) cylinders in regular waves Measure the force on the downstream cylinder section S = Strouhal Number = D = 0.18 UTs U = Current Speed = 0.05m / s T = Vortex Shedding Period = s T s D = Large Cylinder Diameter = 0.166m d = Small Cylinder diameter = 0.075m 1.5D 0.6D 5 cycles/(47s)

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45 Future Work Future applications for Gen-Y offshore engineers: Use CFD to replace aging g baby-boomer s empirical know-how. Do things the towing tank cannot do. Solve realistic oceanic flows with sheared currents with variable temperature, density and direction. Address scaling effects of model test results. Include dynamic structural response through FSI (mapping to dynamic structural model of TLP) Wind loads on offshore structures topsides Useful for initial design estimates 45

46 Conclusions CFD applications gaining from advances in software/hardware Significant advances being made solving difficult problems w/cfd Local know-how in Malaysia is improving Building CFD capability is a good use of local resources Capability to address VIM has advanced from single column (Spars) to include multi-column floating platforms Free surface applications with VOF approach allows calculation of higher-order wave loads for resonant structure behavior CFD results complement/complete model tests Now possible to perform short-crested random wave simulations More realistic and less conservative approach Benchmarking still required to assure reliable results Future work involving multiple bodies is needed to address Behavior of multiple risers/fairings Interactions of 2 floating bodies in current+waves 46

47 Thank you! Shell Sabah Petroleum and Technip for permission to show the model tests Jaime Tan for carrying out the Star CCM+ CFD Analysis Jang Whan Kim for Ringing Analysis CD-Adapco for Speaking Opportunity