fundamentals of s-lay and engineering analysis using offpipe- gep

8/17/2019 Fundamentals of S-lay and Engineering Analysis Using OFFPIPE- GEP

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Fundamentals of S-lay and Engineering Analysis using

OFFPIPEBy JBEIL Subsea Engineers Pvt. Ltd. – Oil & Gas Trainings

www.globalenergypanel.com


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• INTRODUCTION ABOUT OFFSHORE PIPELINE INSTALLATION

• OFFPIPE

• OFFSHORE PIPELINE INSTALLATION ANALYSIS

• CASE STUDY

Contents


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INTRODUCTION ABOUT OFFSHORE PIPELINE

INSTALLATION


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• Steel Pipe

• Corrosion

Coating• Concrete

Coating

•

Cutback• Field Joint

I. INTRODUCTION


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I. INTRODUCTION

J-Lay S-Lay Reel-Lay

Pipeline Tow


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I. INTRODUCTION

OFFSHORE PIPELINE INSTALLATION

Offshore pipeline installation is performed by specialized lay-vessels. There are several methods to install a

pipeline, the most common methods being S-lay, J-lay and reeling.


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I. INTRODUCTION


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I. INTRODUCTION


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I. INTRODUCTION


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I. INTRODUCTION


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I. INTRODUCTION


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PIPELAY BARGE

I. INTRODUCTION


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TENSIONER

I. INTRODUCTION


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STINGER

I. INTRODUCTION


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S-LAY CONFIGURATION

Touch Down Point

I. INTRODUCTION


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I. INTRODUCTION


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I. INTRODUCTION


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I. INTRODUCTION


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I. INTRODUCTION

STARTSTART UPUP

•Dead-man Anchor

•Elevated Hold Back

•Bow String


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I. INTRODUCTION

Dead-man Anchor Start up


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I. INTRODUCTION

Elevated Hold Back Start up


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I. INTRODUCTION

Bow string Start up


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ALLOWABLE STRESSES - Static

Overbend

Parameter On Barge On Stinger Sagbend

Allowable Stress 85% SMYS 72% SMYS 72% SMYS

Applicable code : DNV OS F101

I. INTRODUCTION


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OFFPIPE


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OFFPIPE is a finite element method based computer program. It has been developed specifically for

the modeling and structural analysis of nonlinear problems encountered in the installation and

operation of offshore pipelines.

Analysis capabilities include:

• Static and dynamic pipe laying analyses for many laybarge and stinger configurations, both

conventional and J-lay.

• Pipelay initiation, abandonment and recovery analyses;

• Calculates static pipe stresses, span lengths and deflections for irregular seabed scenarios;

• Static davit-lift analyses for conventional riser installations and subsea tie-ins

OFFPIPE

II. OFFPIPE


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The loads that are considered in the analyses are as follows:

1. Uniformly distributed pipeline self-weight including coatings.

2. Constant barge tension.

3. External hydrostatic pressure due to water column.

4. Reaction forces from the barge rollers

5. Vertical seabed reaction

OFFPIPE

II. OFFPIPE


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The pipeline and the barge are modeled as follows:

1. Lay barge is modeled from the center of the first station up to the last roller on the barge

stern then to the last roller of the stinger.

2. Lay barge is modeled through the input of the horizontal coordinates of the barge rollers and

vertical coordinates or the barge radius to form a smooth pipeline profile on the barge.

3. All roller supports are modeled in terms of simple supports that resist only the downwarddisplacement of the pipeline or cable. The pipeline or cable is free to lift off from the

support when appropriate.

4. The friction force of the barge roller is very minimal if compared to the applied tension.

Thus, for the purpose of analysis, the effect of frictional resistance between rollers and

pipeline has been ignored.

5. The properties of steel pipeline are assumed to be linear, therefore constant modulus ofelasticity has been introduced.

6. Pipeline or cable is divided into a finite number of elements.

7. The seabed is modeled as a discrete elastic foundation.

OFFPIPE

II. OFFPIPE


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COORDINATES IN OFFPIPE

X coordinate is the water surface direction

Y Coordinate is vertical direction

Z coordinate is lateral direction of the barge

Coordinate (0,0,0) is positioned at the stern ofthe barge (at seawater surface level)

II. OFFPIPE


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TRIM AND OFFSET

Trim angle is the angle between the barge

deck and seawater surface due to the barge

rotation in the Z coordinate

Offset is the distance of barge movement in

the X, Y, Z direction which is measured from

the original position of the barge.

Offset usually is used for abandon and

recovery and lifting analysis.

II. OFFPIPE


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CREATE NEW INPUT FILE

II. OFFPIPE


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Input / Output / Heading Data

For pipeline installation analysis, the field “HEAD” and “PRINT” should be defined.

II. OFFPIPE


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HEAD Screen


Problem input/output units :

“1” : English unit

“2” : SI unit

II. OFFPIPE


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PRIN Screen


II. OFFPIPE


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PRIN Screen


“1” means that the parameter shall be calculated and displayed in the OFFPIPE output,

“0” means that the parameter shall not be calculated and displayed in the OFFPIPE output (will be the same

if the field is left blank)

II. OFFPIPE


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Pipe and A&R Cable Data

“PIPE” and “COAT” field should be defined.

“CABL” is defined for the pipelay initiation and abandon and recovery analysis.

II. OFFPIPE


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PIPE – Pipe Properties

Pipeline length is defined for pipeline initiation only. Pipeline length indicates the pipeline length on the

barge which is measured from the first support position.

II. OFFPIPE


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COAT – Coating Properties

II. OFFPIPE


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COAT – Coating Properties

II. OFFPIPE


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Pipelay Vessel Data

“TENS” and “BARG” field should be defined for pipelay, abandon and recovery analysis.

For Davit lifting analysis, “DAVI’ should be defined, and the “TENS” is not defined.

II. OFFPIPE


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Pipelay Vessel Data

BARG – Barge Data and Geometry

Number of station is used to specify the number of the pipe nodes on the barge (include rollers and

tensioner). For davit lifting analysis, number of station is used to specify the number of davit lift.

The laybarge trim angle is the angle between the deck and the water surface.

II. OFFPIPE


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Pipelay Vessel Data

BARG – Barge Data and Geometry

“More -> Support Data” (Pipe Support Data and Geometry)

Note: * Davit Spacing is defined for davit lifting analysis only.

Horizontal distance of the

support (X), measured from the

stern of the barge. The X = 0 is

selected at the stern of the

barge.

Vertical distance or

height of support on

barge (Y), measured

from the deck of the

barge.

Support type:

“1” : Simple pipe support

“2” : Pipe tensioner/winch

II. OFFPIPE


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Pipelay Vessel Data

TENS – Tension

II. OFFPIPE


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Pipelay Vessel Data

TENS – Tension

II. OFFPIPE


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Stinger Data

II. OFFPIPE


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Stinger Data

STIN – Stinger Data and Geometry

II. OFFPIPE


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Stinger Data

STIN – Stinger Data and Geometry

“More -> Support Data (Support configuration on Stinger)”

Horizontal distance of the

support on stinger (X),

measured from stern of the

barge. Since the stinger

position is behind the stern,the negative value shall be

applied in this distance.

Vertical distance or height of

support on stinger (Y),

measured from surface water

elevation. Negative value

indicates the support positionis under the surface water

elevation.

II. OFFPIPE


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Sagbend and Seabed Data

“GEOM”, “SOIL”, and “CURR” should be defined for pipeline installation analysis.

II. OFFPIPE


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GEOM – Sagbend Pipe Geometry Data

Sagbend element length is defined to determined the distance between nodes at the sagbend region.

The selected water depth is the maximum water depth, considering wave, tidal, and storm surge condition.

“X Coord. Of Free End” field is only defined for davit lifting analysis

II. OFFPIPE


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SOIL – Seabed Soil Properties

II. OFFPIPE


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SOIL – Seabed Soil Properties

This field is used to define the lateral friction of the soil.

II. OFFPIPE


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RUN / END / Misc. Data

II. OFFPIPE


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RUN / END / Misc. Data

II. OFFPIPE


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OFFPIPE RUN AND RESULT

Run the File

II. OFFPIPE


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Offpipe Result


II. OFFPIPE


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Offpipe Result


II. OFFPIPE


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Offpipe Result


II. OFFPIPE


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Offpipe Result


II. OFFPIPE


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Offpipe Result


II. OFFPIPE


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Offpipe Result


II. OFFPIPE


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II. OFFPIPE – Dynamic Analysis

J. Ray McDermott – Jebel Ali, Dubai

Modes of Motion

Linear

• Heave

• Surge

• Sway

Rotational

• Pitch• Roll

• Yaw

Oscillatory

• Heave

• Pitch

• Roll

Non-oscillatory

• Surge• Sway

• Yaw


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Wind Loading

Wind is treated as a Time-Invariant Environment

Force, 2

2

1

w D AU C f

Density of Air

A = Structure Projected Area normal to the wind flow

Uw

= mean wind velocity, generally taken at an

elevation of 10 m from the water surface

CD is the Wind Drag Coefficient


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Current Loading

Force2

2

1 AU C f D

fluid density

A = structure projected area normal to the flow

U = uniform flow velocity

CD is the Drag Coefficient.

Equation is similar to Wind Loading


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Waves

Sea comprises a myriadof waves.

Irregular or Randomwave is changing it’sform from time to time

It is a superposition ofmany simple, regular,

harmonic wavecomponents.

I l S


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J. Ray McDermott – Jebel Ali,

Dubai

Irregular Seaway


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Dubai

Wave Spectra

Wave Energy ≈ Amplitude2

Intensity of the sea ischaracterized by it’s totalEnergy

Wave Energy Spectrum orWave Spectrum shows how thetotal energy of sea isdistributed according to the

frequencies of the various wavecomponents


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Wave Spectra


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Dubai

Spectrum Models

Pierson Moskowitz

Bretschneider

ISSC

ITTC

JONSWAP

Ochi

II OFFPIPE


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II. OFFPIPE


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III. OFFSHORE PIPELINE INSTALLATION ANALYSIS

USING OFFPIPE


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III OFFSHORE PIPELINE INSTALLATION ANALYSIS


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PIPELAY INITIATION ANALYSIS


• Pipeline initiation is performed at the start-up water depth.

• Pipeline initiation is usually performed using DMA (Dead Man Anchored) Method.

• During pipeline initiation the pullhead at the end of pipeline is connected with the cable.

• During pipeline initiation activity, the pipe joint is added on the barge and welded until the pipeline

profile touch the seabed.

• The barge tension is maintained in order to result the acceptable stresses.

Pipeline Initiation Activity is performed by considering the increasing of pipeline length due to the pipe joint

addition. The considered case for pipeline initiation are given below.

• Pullhead position after tensioner

• Pullhead position near to the barge stern

• Pullhead position at the stinger

• Pullhead position just after the stinger

• Pullhead position at the sagbend region

• Pullhead position prior to rest on seabed

• Pulhead position resting on the seabed



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PIPELAY INITIATION ANALYSIS

The offpipe calculation is performed

for several times (depend on the

number of the case), by changing the

pipeline length value.



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PIPELAY INITIATION ANALYSIS - CASES



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PIPELAY INITIATION ANALYSIS - SUMMARY



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• Normal pipelay is performed at the various water depth in order to get the applied tensions and bargeconfiguration during installation activity.

• If any variation of wall thickness and coating parameters is applied along the pipeline route, static

installation analysis should be performed based on this wall thickness and coatings variation

NORMAL PIPELAY ANALYSIS


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NORMAL PIPELAY ANALYSIS – CASE


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NORMAL PIPELAY ANALYSIS – SUMMARY



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ABANDON AND RECOVERY ANALYSIS


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ABANDON AND RECOVERY ANALYSIS – CASES



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ABANDON AND RECOVERY ANALYSIS – OFFPIPE INPUT LIST



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87INTRODUCTION OF OFFPIPE

ABANDON AND RECOVERY ANALYSIS – OFFPIPE OUTPUT LIST


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ABANDON AND RECOVERY ANALYSIS - SUMMARY



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Other Advanced Uses of OFFPIPE

• Single Point Lift

• Multi Point Davit Lift Analysis

• Midline Tie-in Analysis

• Riser analysis


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Disclaimer


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The information contained in these course/notes has been compiled from various sources and is

believed to be reliable and to represent the best current knowledge and opinion relative to the

subject.

Global Energy Panel offers no warranty, guarantee or representation as to its absolute

correctness or sufficiency.

Global Energy Panel has no responsibility in connection therewith; nor should it be assumed

that all acceptable safety and regulatory measures are contained herein, or that other or

additional information may be required under particular or exceptional circumstances.

fundamentals of s-lay and engineering analysis using offpipe- gep

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