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									PRESENTATION PREPARED FOR SUBSEA SOLUTIONS 06


Current Riser & Subsea Technology
Issues being addressed by MCS
Dr Patrick O’Brien, Director, MCS

11th May 2005                                   An ISO 9000 Company
Presentation Overview

• Fatigue of Flexible Pipe and Steel Tube Umbilical
  Risers
  – Progress on recent development work
  – Upcoming STU Prototype Testing

• Subsea Integrity Management
  – The SCRIM Joint Industry Project

• Deepwater Pipelay analysis


• MCS Pleased to Sponsor the Technical Seminar
  Programme for Subsea Solutions 06
  – Importance of Paris as a hub for West of Africa business by
    our recent opening of an MCS Paris office
System Architecture: Girassol Subsea
Flexible Pipes and Steel Tube Umbilicals




 Flexible Pipe                          Integrated Production
                                               Bundle

                 Steel Tube Umbilical
Flexible Pipes and Steel Tube Umbilicals

                                        • All an integral part of the
                                          SURF scope of supply

                                        • All include helically wound
                                          components

                                        • Friction between layers or
                                          helically wound
                                          components

                                        • Need to model behaviour of
                                          helically wound
                                          components on a bent
 Flexible Pipe                            pipeline or umbilical

                                        • Fatigue Design important
                                          for Risers
                 Steel Tube Umbilical
Integrated Local-Global Modelling

• Stick-Slip Bending
  – Armour / tube initially sticks on reverse bending
  – Slip is inline with and transverse to lay-direction
  – Hysteretic fatigue stress
                        150


                        100
    Wire Stress (MPa)




                         50



                                                                         Regular
                          0


                         -50
                                                                         Stress
                        -100
                                                                         Cycle
                        -150
                           -0.1    -0.05        0          0.05    0.1

                                  Pipe Dynamic-Curvature (rad/m)
Flexible Pipe and STU Fatigue Design

• MCS managed programmes
  – Real Life JIP
     • Emphasis on global analysis
     • Interface between global and local pipe loads

  – DTI – Fatigue Analysis Tool for Flexible Pipes
     • Specifically established to embody methodologies
       recommended by Real Life JIP
     • Focus on local pipe stress analysis
         – Tensile armours
         – Pressure armours

  – Fatigue Life Testing of Steel Tube Umbilicals
     • Jointly between MCS and COPPE
     • Testing of manufacturer prototypes and model calibration
Wire or Tube Equations of Equilibrium
Helically Wound Components

d 11
      t   12,tot  0      Tangential                      2
 ds
 11t n   22,diff  0    Surface Normal
                                                                       1
                                                   3
  11t t   32,tot  0   Transverse

• Method of Solution
   – Incremental curvature determines incremental non-slip axial
     stress
   – Incremental non-slip axial stress determines incremental
     tangential shear, normal interface and tranverse shear stresses
   – Check Coulomb law and gradually relax stresses while retaining
     equilibrium
   – Wire curvatures from loxidromic / geodesic equations
                    Friction-Induced Stress

          • MCS Structural Model for Friction – Irregular Loading
                                      Pipe Bending Curvature                                                                                                       Wire Stress

                     0.025                                                                                                          100
                      0.02                                                                                                           80
                     0.015                                                                                                           60
Curvature (rad/s)




                      0.01




                                                                                                                     Stress (MPa)
                                                                                                                                     40
                     0.005
                                                                                                                                     20
                         0
                                                                                                                                      0
                    -0.005
                     -0.01                                                                                                          -20
                    -0.015                                                                                                          -40
                     -0.02                                                                                                          -60
                    -0.025                                                                                                          -80
                             0   10        20       30                        40     50        60                                         0          10       20          30     40   50   60
                                                 Time (s)                                                                                                                Time
                                                                                                   Hysteresis Loop

                                                                        100
                                                                         80
                                                                         60
                                                         Stress (MPa)




                                                                         40
                                                                         20
                                                                          0
                                                                        -20
                                                                        -40
                                                                        -60
                                                                        -80
                                                                          -0.02    -0.02   -0.01    -0.01   0.00        0.01                  0.01   0.02   0.02
                                                                                                   Pipe Curvature (rad/m)
3D (out-of-plane) Irregular Seas
                                                  3D Pipe Bending in Irregular Seas
                                                  Hs = 2m, Tp = 13s, 15deg off-bow
                                         Global Tension (left) and Curvature (right) Responses
               1.70E+06                                                                                                0.008



                                                                                                                       0.006
               1.65E+06


                                                                                                                       0.004
               1.60E+06




                                                                                                                                Curvature (rad/m)
 Tension (N)




                                                                                                                       0.002

               1.55E+06

                                                                                                                       0

               1.50E+06
                                                                                                                       -0.002


               1.45E+06
                                                                                                                       -0.004



               1.40E+06                                                                                                -0.006
                          15      35                  55                         75        95                    115
                                                                      Time (s)

                               Tension                     Local-y Pipe Curvature           Local-z Pipe Curvature
Tensile Armour Stress Validation
                                             Total Stress on Initial Intrados Side of Pipe
                                                        Inner Tensile Armour
                           Real Life Trial Application No. 2, Regular Wave Height = 8.5m, Period = 13.0s


                 900

                 850

                 800

                 750
  Stress (MPa)




                 700
                                                                                                                  BFLEX
                                                                                                                  MCS
                 650

                 600

                 550

                 500

                 450
                   -0.02    -0.015      -0.01     -0.005       0       0.005      0.01      0.015          0.02
                                                   Pipe Curvature (rad/m)



     • MCS stress computed almost instantaneously from global loads
Fatigue Analysis Highlights

• Closely integrated with global analysis
   – Takes timetraces directly from the global analysis
       • Tensions & component curvatures
       • Regular or irregular responses
   – Computes stress timetraces that are cycle (rainflow) counted

• Local analysis supports 3D bending of pipe / umbilical
   – Fully accounts for global directionality
   – Wire stress computed at several locations
   – Economically processes several loadcases

• Validated as part of the Real Life JIP

• Hysteresis effects applied to reduce conservatism
   – In either a semi-local or global analysis
Hysteresis: Global Modelling

         – Global modelling only takes the “plastic” slope
                     150


                     100
 Wire Stress (MPa)




                      50


                       0


                      -50


                     -100


                     -150
                        -0.1    -0.05        0          0.05    0.1

                               Pipe Dynamic-Curvature (rad/m)
            Hysteresis
                                         Pipe Friction Moment and its ElastoPlastic Decomposition

                           Basis Curve               Multilinear Approx.           Elastoplastic-1           Elastoplastic-2
                           Elastoplastic-3           Elastoplastic-4               Elastic-5


                       3.5E+04


                       3.0E+04
Friction Moment (Nm)




                       2.5E+04


                       2.0E+04


                       1.5E+04


                       1.0E+04


                       5.0E+03


                       0.0E+00
                                 0           0.005        0.01             0.015          0.02       0.025             0.03
                                                                 Pipe Curvature (rad/m)
Hysteresis
                                        Hysteretic Reduction of Pipe Curvature

                                   No hysteresis             with Hysteresis - 50% reduction

                     0.008


                     0.006
 Curvature (rad/m)




                     0.004


                     0.002


                         0


                     -0.002


                     -0.004
                              65   70               75              80                 85      90
                                                         Time (s)


• Improves fatigue life by factors of over 5
 Steel Tube Umbilical X-Section Analysis

• Similar Issues to Flexible Pipe Technology
  – Helically Wound Components (Tubes/Armour Wires)
  – Slip / No-Slip of Tubes
  – Hysteresis Effects
  – Complex 3D Global Motions / Loads
  – Friction Issues
  – Identical approach to global fatigue analysis
 Steel Tube Umbilicals

• Some Key Differences to Flexible Pipe
  Technology
  – Much Smaller Lay Angles (2º to 10º)
  – More Complex and varied Cross-Sections
  – Complex Contact Pressure Scenarios
  – More Prone to Disorientation
MCS STU Technology Development

 • Research Project – Fatigue Life Testing of Steel
   Tube Umbilicals

 • Joint Project between MCS and COPPE
    – COPPE - Graduate School and Research Institute from
      the Federal University of Rio de Janeiro

 • Funding by Petrobras and Brazilian
   Government

 • STU Samples from Marine Production Systems
   (Oceaneering Multiflex) and Prysmian (Pirelli)
 COPPE Test Rig

•Bosch-Rexroth Hydraulic System
•Tension Capacity of 225 ton
•Max Bending Moment of 200 ton.m
•Angle Range from -15° to +30°
•Sample maximum length of 12m
•Variable Tension Loads
•In or Out of Phase Load Combinations
•Full Instrumentation

•Continuous Monitoring
Summary of STU Research Project

 • Full Scale Dynamic Test of Two Samples
    – Using COPPE‟s test rig in Rio

 • Global and Local Numerical Modelling of STUs

 • Calibrate MCS Cross-Section Models against
   Test Results

 • Preliminary Guidelines for Fatigue Analysis of
   STUs
Summary of STU Research Project (cont.)

 • Project Schedule
   – 12 month schedule

   – May ‟06 to April „07

 • Deliverables
   – Qualify Two STU Designs

   – Gather Full Scale Test Data

   – Calibrate Models

   – Preliminary Guidelines
Subsea Integrity Management

• Integrity management for subsea
  components evermore important
  – Deep water, remote locations: cost of
    intervention
  – High profile failure incidents around the world
    (Brazil, GOM)
  – Gulf of Mexico
     • Hurricane conditions in excess of 1000 year event
     • Accelerated growth in use of Steel Catenary Risers
       (SCRs) combined with uncertainty in design of SCRs
     • Regulator framework for riser CVA from the MMS
     • All leading to an increased focus on safety and integrity
    SCR Integrity Management (SCRIM) JIP


•    Primary objectives of the SCRIM
     JIP have been:
     –   to develop a systematic
         methodology for the risk-based
         integrity management of SCR
         field systems.
     –   to investigate best technology
         in terms of inspection and
         monitoring methods for SCRs,
         and identify emerging
         technologies for SCR inspection
         and monitoring.
SCRIM JIP
PARTICIPANT STATUS
Operators
1. BP (Steering Committee Chair)
2. ExxonMobil
3. ChevronTexaco
4. Petrobras
5. Kerr McGee
6. Anadarko
7. Dominion
8. BHP Billiton
Transportation Companies
9. Williams
Contractors
10. SBM
Regulators
11. Minerals Management Service
12. Department of Transportation
Component Suppliers
13. Oil States Industries
14. RTI Energy Systems
15. Techlam
Pipe Mill
16. Tenaris
Deepwater
Pipeline
Installation
Analysis
Developed with the Industry
State of the Art User Interface
Rollerbox Modelling Options


• Range of options
  provided

• Simplest can be used
  in preliminary studies
   – extremely fast

• Most complex
  combines realistic
  model with fast
  solutions times
Applications

• Deep and shallow water pipeline
  installation analysis

• Start-up procedures:
   – Sheave
   – Stab and hinge over
   – Dead man anchor

• Abandonment & Recovery

• In-line structure
• SCR transfer
• And more …
Conclusions

• Leading Edge Fatigue Methodology for Flexible Pipe
  and Steel Stube Umilical Risers
  –   Globally integrated stress methodology
  –   Much improved interface between global and local analyses
  –   Numerically efficient
  –   Generic equations to solve helically wound elements
  –   Ongoing full scale tests to validate and calibrate
      methodologies

• Subsea Integrity Mangement
  – Industry iniative to develop methods for SCR integrity
    management

• Pipelay analysis
  – A new generation tool for dynamic pipelay analysis
 The End



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