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

An ISO 9000 Company

PRESENTATION PREPARED FOR SUBSEA SOLUTIONS 06

11th May 2005

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

Steel Tube Umbilical

Integrated Production Bundle

Flexible Pipes and Steel Tube Umbilicals

Flexible Pipe

Steel Tube Umbilical

• 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 pipeline or umbilical

• Fatigue Design important for Risers

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

Regular Stress Cycle

-150

-100

-50

0

50

100

150

-0.1 -0.05 0 0.05 0.1

Pipe Dynamic-Curvature (rad/ m)

Wir

e S

tress (

MP

a)

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 EquilibriumHelically Wound Components

• 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

0,1211 tottds

d

0,2211 diffnt

0,3211 tottt

Tangential

Surface Normal

Transverse

1

2

3

Friction-Induced Stress

• MCS Structural Model for Friction – Irregular LoadingWire Stress

-80

-60

-40

-20

0

20

40

60

80

100

0 10 20 30 40 50 60

Time

Str

ess

(MP

a)

Pipe Bending Curvature

-0.025

-0.02-0.015

-0.01

-0.0050

0.005

0.01

0.0150.02

0.025

0 10 20 30 40 50 60

Time (s)

Cu

rva

ture

(ra

d/s

)

Hysteresis Loop

-80

-60

-40

-20

0

20

40

60

80

100

-0.02 -0.02 -0.01 -0.01 0.00 0.01 0.01 0.02 0.02

Pipe Curvature (rad/m)

Str

ess

(MP

a)

3D (out-of-plane) Irregular Seas

3D Pipe Bending in Irregular SeasHs = 2m, Tp = 13s, 15deg off-bow

Global Tension (left) and Curvature (right) Responses

1.40E+06

1.45E+06

1.50E+06

1.55E+06

1.60E+06

1.65E+06

1.70E+06

15 35 55 75 95 115

Time (s)

Ten

sio

n (

N)

-0.006

-0.004

-0.002

0

0.002

0.004

0.006

0.008

Cu

rva

ture

(ra

d/m

)

Tension Local-y Pipe Curvature Local-z Pipe Curvature

Tensile Armour Stress Validation

Total Stress on I nitial I ntrados Side of PipeI nner Tensile Armour

Real Life Trial Application No. 2, Regular Wave Height = 8.5m, Period = 13.0s

450

500

550

600

650

700

750

800

850

900

-0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02

Pipe Curvature (rad/ m)

Str

ess (

MP

a)

BFLEX

MCS

• 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

-50

0

50

100

150

-0.1 -0.05 0 0.05 0.1

Pipe Dynamic-Curvature (rad/ m)

Wir

e S

tress (

MP

a)

Hysteresis

Pipe Friction Moment and its ElastoPlastic Decomposition

0.0E+00

5.0E+03

1.0E+04

1.5E+04

2.0E+04

2.5E+04

3.0E+04

3.5E+04

0 0.005 0.01 0.015 0.02 0.025 0.03

Pipe Curvature (rad/ m)

Fri

cti

on

Mom

en

t (N

m)

Basis Curve Multilinear Approx. Elastoplastic-1 Elastoplastic-2

Elastoplastic-3 Elastoplastic-4 Elastic-5

Hysteresis

Hysteretic Reduction of Pipe Curvature

-0.004

-0.002

0

0.002

0.004

0.006

0.008

65 70 75 80 85 90

Time (s)

Cu

rvatu

re (

rad

/m

)

No hysteresis with Hysteresis - 50% reduction

• 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 JIPPARTICIPANT STATUSOperators1. BP (Steering Committee Chair)2. ExxonMobil3. ChevronTexaco4. Petrobras5. Kerr McGee6. Anadarko7. Dominion8. BHP BillitonTransportation Companies9. WilliamsContractors10. SBMRegulators11. Minerals Management Service12. Department of TransportationComponent Suppliers13. Oil States Industries14. RTI Energy Systems15. TechlamPipe Mill16. Tenaris

Deepwater Pipeline Installation Analysis

PipeLayTM

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

www.mcs.com

The End